ftab284Competition and correspondence in syntactic change:
null arguments in Latin and Romance

nigel vincent

Department of Linguistics, University of Manchester, M13 9PL, UK
nigel.vincent@man.ac.uk
 
3.1 Introduction
The vast preponderance of work to date on syntactic changefrom the perspective of formal linguistics has been couched within thePrinciples & Parameters (P&P) framework — see Battye & Roberts (1995) and van Kemenade & Vincent (1997) forrepresentative collections of papers. Inevitably, too, giventhe time at which the research reported in these volumes was conducted,both principles and parameters were construed in absolute terms. Aparameter was either on or off, and once set could not be overridden;principles had to be obeyed absolutely. Put inother terms, the constraints on such a system were of the ‘hard’ variety. In the present paper we suggest instead that a number of classicissues in the study of grammar change come into sharper focus once we (a)adopt the assumptions of a different analytical framework, namely Lexical-Functional Grammar (LFG), and (b) interpretthe system of grammatical constraints as ‘soft’ or violablealong the lines of Optimality Theory (OT). Two fundamental concepts —competition (drawn from OT) and correspondence (drawn from LFG)— will receive particular attention in what follows.  Conversely, we willargue that the evidence of change provides further support for such anLFG/OT conception of linguistic systems. The specific case study aroundwhich the argument is built concernssome of the changes that take place in the licensing of null and overtarguments as Latin develops into the Romance languages.
	The structure of the paper is as follows. In §3.2and §3.3 we review some basic concepts of OT and LFG respectively andsituate the notions of competition and correspondence in a widertheoretical context. §3.4 reviews the theory of pronominals presented in Bresnan (1998b) andgives a first sketch of the role it can play in accounting for syntacticchange. §3.5 refines this model while §3.6 sets out the patterns of change in the pronominal system between Latinand Romance that are the principal empirical focus of this study. In§3.7 we elaborate a formal account of these changes drawing on the ideasintroduced in §§3.2,3.3 and 3.4. Finally, in §3.8 we reflect on the general lessons for thetheoretical modelling of syntactic change that can be learnt from thematerial presented here. §3.9 sums up our conclusions.

3.2 Optimality Theory and syntax: the notion of competition
We begin then by briefly rehearsing the general featuresof the OT approach to characterizing linguistic systems. As is by now well known, the keyconstructs are constraints and the ranking of constraints. The universal set of constraints,under a ranking which is language particular, apply to a set of candidate forms generated (by a function gen) for a given input. The eval(uation) function defined by the constraint ranking then determines thesuccessful output, which is thereby identified as the grammatical expression of that content(or input) in the language in question. A grammar of a language on thisview is then a ranking of constraints consistent with the attestedoutputs.
	OT may not have had everything its own way in syntax as seems to havehappened in phonology (Archangeli 1997: 25-6), but an impressive body ofwork nonetheless by now exists. In an already classic paper, Grimshaw (1997) demonstrates how a minimal predicate-argument structureinput such as {see (John, who)} is paired with the output Who did John see? via the interaction of constraints which require, amongst other things,that an operator be in a specifier position, that the operator c‑commandthe clause over which it has scope, that X-bar heads be filled, and so on.Here is notthe place to repeat all the details of Grimshaw’s intricate andelegant analysis. I will focus instead on just one constraint to illustratethe flavour of the argumentation. Grimshaw postulates a constraint stay which privileges non-movement of syntactic categories. In the example justgiven, stay is in conflict with the requirement that an operatorbe in a suitably c-commanding specifier position (the constraint op-spec). If who remains in object position, op-spec will be violated; if not thenstay suffers the violation. The form of English interrogativesshows us that in this conflict it is op-spec which wins out and hence that this constraint must be ranked higher thanstay in the grammar of English. Consider now the different inputin which the functions of the arguments are reversed: {see (who,John)}. Now John fills the object position and who already fills Spec VP, so whocan satisfy the requirements of op-spec without movement, thus atthe same time satisfying stay. One striking and attractive consequence of this approach is that only as much structure as is necessary isprojected: Who did John see? is a CP but Who saw John? is a VP,and by parity of argumentation Who will John see? is an IP. Note toothat of these structures, only Who saw John? is free of any constraint violations, yet all are perfectly grammatical.In other words, the interaction of constraints works according to aprinciple of optimality to determine the best candidate in thecircumstances, but once chosen, the best candidate, however many constraint violations it has incurred, is absolutelygrammatical. Different constraint rankings generate different languages, so thatre-ranking of constraints provides a mechanism for encoding bothtypological variation (Ackema & Neeleman 1998) and diachronic change, as wewill see in what follows.
	Despite the unconventional nature of some ofGrimshaw’s conclusions, the underlying logic of her analysis is notin fact far removed from Minimalist ideals. The spirit of Economy is wellmet by banningmovement except where necessary and even then only over the shortestdistance (since each step in a movement chain such as V-to-I-to-C incurs aseparate violation penalty), and by projecting no more structure than isstrictly needed to satisfy independentrequirements. This point is made in extenso by Speas (1997: 180-185),who notes:
“PPT/MP [i.e. Principles & ParametersTheory/Minimalist Program] claims that the principles of UG are inviolable,but …
• all of these principles contain hedges which restrict the domainin which the principle is inviolable.
• the Minimalist Program makes violability explicit in its economyprinciples.” (Speas 1997: 185)
	Some aspects, then, of the OT philosophy ofgrammatical analysis and description chime with current views withingenerative syntax. At the same time, it is important to appreciate that OT is not itself atheory of syntax (or indeed of phonology). It is a theory of howcombinatorial cognitive systems such as natural languages may becharacterized. This fundamental point is perhaps less obvious, and less crucial, in phonology whereconstraints refer for the most part to aspects of structure that aredirectly translatable into more or less theory-neutral concepts such asVoice, Onset, Left/Right, etc. In syntax, the matter is more complex since we do not have an independently observableuniversal domain parallel to phonetic substance to fall back on. Thetraditional assumption that semantics can fill such a role for syntax,while not without its attractions or itsmodern advocates (cf Langacker 1987, Anderson 1997 to name but two works inthis vein), is much more fraught with difficulty.  OT syntax, therefore,will inevitably vary according to the theory in which the analysis isconducted. For instance, Grimshaw’s already mentioned constraint stay presupposes an accountin which movement is an option within the grammatical metalanguage; a modelwhich has no analogue of Case Theory will not require her case constraint; and so on. Different researchers therefore may well agree on the desirability of adopting an OT approach to syntax, whilediverging radically from each other on the framework in which the accountis cast and therefore on the constraints proposed. It is instructive inthis respect to compare Grimshaw’s (1997) account of the English wh-construction withBresnan’s (1997) re-analysis. Alternatively, scholars may largely share theoreticalframeworks but differ on the role, if any, which OT may play in theiranalyses: compare, from the perspective of the Minimalist Program,Speas’ (1997) wholehearted embracing of OT with Pesetsky’s (1997) morecautious distinction between areas where the OT remit may run and areaswhere it may not. Many others no doubt remain unreservedly sceptical of thewhole enterprise.

3.3 Lexical-Functional Grammar and the concept ofcorrespondence
If we wish to explore the consequences of OT in thediachronic domain, therefore, we must first choose a particular frameworkwithin which to construct the analysis and thus define the constraints. I will adopt L(exico)-F(unctional) G(rammar): for details see thepapers collected in Dalrymple et al (1995), notably Kaplan & Bresnan (1982), and for recent OT-inspireddevelopments within the framework see Bresnan (1997, 1998a,b) andreferences therein. This choice is not arbitrary, but is based on afundamental asymmetry between function-based systemssuch as LFG and a position-based system such as Principles & Parameters(P&P), namely thatall positions have a function but not all functions have a(phonetically expressed) position. For a system like P&P this means thatempty categories/positions have to be postulated to bear the overtlyunrealized functions and a separate sub-theory, Case Theory, has to berecruited to constrain the links between positions and functions. Consider for example the problem PRO poses for CaseTheory under the Visibility interpretation (Chomsky 1986: 93-5) and theartifice that is then required of assigning null Case to the empty categoryin order to ensure that it is kept in grammatical play (see Chomsky & Lasnik 1993 (=Chomsky 1995: 119) andthe excellent critique in Hornstein 1999). None of this is necessary if PROis seen simply as the unexpressed subject function of an infinitivalpredicate (Bresnan 1982, Culicover &Wilkins 1986).
	A further objection to a configuration-based metalanguage, ofparticular relevance in what follows, is that it privileges those languagesthat realize function through position over those that adopt some form ofmorphological encoding. We will assume instead that abstract grammatical relations — subject andobject will be all that will concern us here — can be expressed inone of three possible (and sometimes overlapping) ways, viz:
a)		configuration/position: e.g. English,Italian, Turkish;
b)	dependent marking (cases and adpositions):e.g. Latin, Chechen 						(Nichols 1986);
c)		 head marking (agreement and incorporation): e.g. Mohawk (Baker					1995), Abkhaz (Nichols 1986).
Moreover, the particular options employed from within thisbroad typological range may vary with the passage of time (Kiparsky 1997),as we shall see quite clearly in the present study.
	LFG then distinguishes f(unctional)-structures expressed in terms ofattribute-value matrices (features) and c(onstituent)-structure expressedin terms of X-bar. Since c-structure serves only to define surface form, itmay be freely substituted by morphology or by no marking at all depending on the language. Grammaticalrelations of the kind which require c-command, wh-movement, Case-checking, etc in a P&P type of architecture are expressed in the f-structurewithout recourse to configuration. The relation which holds between anf-structure and the c‑structure and/or morphology which expresses it is one of correspondence orrealization. 
	Adopting a system like LFG where there are no emptypositions and no movement will obviously have drastic effects on thestandard P&P typology of null elements. In anybody’s system, thephenomenology of wh- -constructions constitutes a class apart and we will not be concerned withthem here. Intra-clausal NP-traces (passives and middles) are treatedlexically and will only impinge marginally on the present analysis;inter-clausal NP-traces (aka ‘raising’) are relevant to our account and following the proposals ofBresnan (1982) will be assimilated to the analysis of controlconstructions. In sum, therefore, we will be focussing on the changes inthe distribution of pro and PRO, the [+ pronominal] elements of the standard Chomskyan typology, and integrating these into a broader account of the changes in the distribution of variouskinds of overt pronominal. The unified nature of the resulting diachronicanalysis can in turn be seen as a further argument in support of the waythe grammatical phenomena are divided up under the assumptions of LFG rather than those of P&P.

3.4 A theory of pronominals
It is important to be clear about the relation ofnon-overt pronominal elements (i.e. those referred to above as PRO/pro) to various kinds of phonetically realizedpronouns. To this end, we will adopt the correspondence theory ofpronominals proposed in Bresnan (1998b), which contains the followingcomponents:
	i) A universal scale of pronominal form: elementswhich have pronominal function can be ranged along a scale according to thedegree of (prosodic and/or morphological) independence they exhibit,viz:

(1)	zero	<	bound	<	clitic	<	weak	<	pronoun

In this conception of things, ‘zero’ meanshaving no overt realization at all, whether morphological or syntactic. Examples include the marking of subject and object in Chinese and Japanese,and of object in Latin. By contrast, the encoding of subject in Latin via asystem of person inflection here falls under the heading ‘bound’. ‘Clitic’ is to be understood in the sense of Zwicky’s (1977) ‘specialclitics’, that is to say elements whose syntactic positioning is determined byrules other than those which dictate the position of full nominals. Thewell-known clitics of the Romance languages are a clear case in point.‘Weak’ pronominals are syntactically free in the sense that their distributionfor the most part parallels that of full NPs but they are prosodicallysubordinate to another word (in this respect they behave very like ‘light’ verbs, articles and some prepositions). A pronoun in the sense intendedhere is by contrast both distributionally and prosodicallyindistinguishable from a full NP/DP.
	ii) A universal set of features for pronominalcontent: in similar vein the possible dimensions of pronominal content maybe broken down into three: 
	a) semantic: pronouns have meaning in virtue ofreference internally within a text or externally to entities in the realworld. This aspect of their function is treated in terms ofvalues of afeature PRO.
	b) information-structural: the status of all(pro)nominals varies from discourse context to discourse context. This iscaptured as values for a feature TOP.
	c) morphosyntactic:  pronominal phi-features, which express theirgrammatical content, are treated as values for the class of features heresubsumed under the label AGR (i.e. person, number, etc).
All such features are privative and a feature may be absent from therepresentation of the content of a given item: for example, there is no AGRin Japanese verb forms. Thus, the feature constellation [PRO, TOP] definesthe class of items that have variable referentiality (PRO) and topic anaphoricity (TOP). It subsumes [PRO, TOP,AGR], the class of items which also have grammatical properties like personand number, and is subsumed by [PRO], the class of items which simply have variable reference.Constellations of these features will provide the input for evaluation by alanguage’s constraint hierarchy, and thus be linked to members of the class ofpossible pronominal forms identified in (i) above. To this end we furtherneed:
	iii) A universal set of constraints onform-content correspondences: these constraints express recurrent patternsof correlation between the content of an argument type and its expressionacross languages. There are two important dimensions here. The first limits which elementson the scale in (1) can be encoded overtly and the second those which canbe encoded by elements which are in some sense segmentally or prosodicallyreduced. Thus we have two contrasts as follows:

(2)	a)		Overt (all except zero) vs non-overt (zero)
		b)	Reduced (all except pronoun) vs non-reduced (pronoun)

Table 1 shows the relations between the constraints in (2)and the items in (1):

non-overt	overt				
zero	bound	clitic	weak	full	
reduced				unreduced	
TABLE 1					

We are now in a position to formulate thefollowing (families of) constraints:

(3)	harmony constraints:
(a)	Reduced € TOP:	pronominals are reduced iff they are specialized for topicanaphoricity.
(b)	Overt € AGR:		pronominals are inherently specified for person/number/ genderiff they are overt.

(4)	structural markednessconstraints:
	(a)	Cross-linguistically the unmarkedpronominal is a full pronoun.
	(b)	Zero or a bound element associated withPRO violates iconicity (since separate pronominal content is notmatched by separate form).
	(c)	A clitic or weak elementassociated with PRO violates allotaxy (since there is more thanone way of expressing pronominal content).

(5)	faithfulnessconstraints:	require that all and only the content of the input beexpressed in the output. 

The initial state of the language learner is assumed to beone in which the following dominance relations hold between these (familiesof) constraints:

(6)	harmony	»		struct	»		faith

To determine the correct output for a given language, westart with a featural characterization of the input — e.g. [PRO,TOP] — and evaluate possible form-content pairings under the constraint rankingthat is postulated to hold for the language in question. Thus, assume that we are dealing with a language in which the learner has notacquired evidence to alter the default rankings in (6) which characterisehis/her initial state. This situation is represented in TableauI.

Input	[PRO, TOP]		harmony	struct	faith	
		Zero:		[PRO,TOP]			*!		
		Bound:		[PRO, TOP]		*!	*		
		Pronoun:	[PRO, TOP]		*!			
+	Pronoun:	[PRO, AGR]					*	
Tableau I					

In other words, in such a language, of which English is an example, if wewant to express a pronominal topic, the constraints predict that the freepronoun is required even though this in fact does not express only topics.A zero pronominal with this function would violate the iconicity member (4b) of the structural markednessconstraint family, whereas overt pronominals without phi-features violate the harmony constraint (3a). The remainingcandidate is one which does not exclusively express the desired content. Itnevertheless ends up the optimal form since the violation thus incurred isof the lower ranked faithfulness constraints, and according to the postulated dominance hierarchy in (6) it ismore important to respect structural markedness and harmony than to exactlymatch input and output.
	iv) Language particular constraint rankings:		Languages may deviate from the above universally unmarked constraintranking if the constraint rankings are changed. Thus a pro-drop languagelike Italian is generated if one of the struct constraints, namely that which bans the association of anaffix with PRO(nominal) value, is ranked lower than faith, as isshown in Tableau II. (For the Chinese type of pro-drop, by contrast, in which there is no overtagreement morpheme to do pronominal duty, switch the columns headed *Ø[PRO] and *af [PRO] in Tableau II.) In other words, it is more important to be faithful to the input than to avoid violating the particularmember of the structural markedness family of constraints which penalisesthe morphologically bound expression of pronominal content. 

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]	
		Zero:		[PRO, TOP]				*!			
+	Bound:[PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II							

On this ranking, appropriate for Italian or Latin subjects,the affix emerges as the best candidate for expressing topic anaphoricpronominal reference. However, for non-topic pronominal meaning we still require afull pronoun as the next tableau shows:

Input	[PRO]			harm	*Ø [PRO]	faith	*af [PRO]	
		Zero:		[PRO, TOP]				*!			
		Bound: [PRO, TOP, AGR]						*!	
+	Pronoun:	[PRO, AGR]								
Tableau III							

Expansion of the pronominal inventory can thus be modelledby constraint re-ranking. When the purpose of the exercise is to comparethe different pronominal systems of languages as geographically andgenetically separate as Chinese and Chichewa, the effect of constraint re-ranking is to permit us to capturetypological generalizations. When, on the other hand, the languages beingcompared form a historical progression, as in the case of Latin andRomance, then the outcome is the first steptowards a constraint-based model of syntactic change. We will seek todevelop this insight further in what follows, but first we consider arevision in one aspect of Bresnan’s system.

3.5 the pronominal model refined
Bresnan’s model needs to be refined to deal with the double role of Latin and Italian verbal inflection as boththe expression of pronominal content when there is no overt subject and asmarkers of agreement when an overt subject is present. As Cecilia Goria(p.c.) has pointed out to me, the account offered in §3.4 seems to fail in one important respect, namely that the use of an overtpronoun in a non-topical context does not suppress the corresponding affixbut simply pre-empts its pronominal function. The affix remains but itsfunction shifts from encoding a pronominal argument to expressing agreement with anindependent argument whether pronominal or nominal. To see the implicationsof this point, consider the following Italian example, an instance ofso-called clitic left dislocation (Cinque 1990):

(7)	Io 		Valerio	non	lo 				voglio 				sposare
		I.nom	V			not	objcl.3sgm	want.pres.1sg	marry.inf
		‘I don’t want to marry Valerio’

The precise informational status of such an example, whichhas two fronted arguments io ‘I’ and Valerio, is acomplex matter and need not concern us here. Rather, we should note thediscrepancy between the status of the clitic lo which picks up thefronted object Valerio and the inflection -o which encodes thefronted subject io. Omission of the clitic is possible in other contexts; indeed it isobligatory if the object is overt and in the canonical post-verbalposition. Thus:

(8)	a)		Voglio sposare Valerio
				‘I want to marry Valerio’
		b)	Lo voglio sposare
				‘I want to marry him’
		c)		*Lo voglio sposare Valerio

Whatever the context, on the other hand, the person/numberinflection -o is never omissible. The constraint at work here might be thought to be amorphological one which determines the wellformedness of Italian inflected verb forms independent of the circumstances of their use. While such a solutionwould in fact work for modern Italian verb inflection, it would not generalise to the data from theinflected infinitive construction we consider in §3.6.2 where thepresence of the inflection is in certain contexts optional. At the same time there are languages in which the verbalmorphology, albeit ‘rich’, does not serve to license nullarguments or, in our terms, does not have pronominal value. Sigur∂sson (1993) shows convincingly that Icelandic is a case in point. And ofcourse many languages with no overt agreement do not allow pro-drop, as forinstance Danish and Swedish. In fact all logical possibilities exist, asthe following table demonstrates:

	overt agreement	zeroagreement	
null argument	Italian	Chinese	
*null argument	Icelandic	Danish	
Table II			

Something similar is observable in some clitic systems, namely thosecharacterized by so-called clitic doubling, where a clitic and an overtargument co-occur. Naturally, since zero clitics by definition do notoccur, we only find two rather than four possibilities if agreement is of the clitic rather than the morphologicaltype.
	Bresnan (1998b: 22, note 16) proposes that theagreement property noted here can be handled by letting the PRO value beoptionally parsed. In this way, morphological endings and clitics withpronominal content count as arguments and those without do not (cf Börjars & Chapman 1998). In the Italian type of system exemplified in (8)clitics do not allow for optional parsing of their pronominal content, and thus they always assume argument status when theyoccur. In a clitic doubling system, by contrast, the option exists and theclitics are to that extent more grammaticalized and partake already of theproperties of an agreement system. The optional parsing solution, however, would not easily generalise tocover optionality of morphological endings.
	 An alternative account involves postulating anAgreement Hierarchy as in (9) which can be linked to the pronominalhierarchy by the Alignment Constraint in (10):

(9)	Agreement Hierarchy:	zero	<	affix	<	clitic

(10)	Align pro-agr (zero/affix/cl)	

The three terms on the Agreement Hierarchy match the lowerend of the pronominality scale, but as we have seen the agreement andpronominality do not have to be aligned. If there is no alignment, agreement has nopronominal effect (the case of Icelandic). When Align Pro-agr is sufficiently highly ranked, by contrast, it will determine for thelanguage in question at what point, if any, agreement and pronominalitycoalesce. Thus (10) subsumes the constraint hierarchy in (10'):

(10')	Align Pro-Agr (zero) » Align Pro-Agr (bound) » AlignPro-Agr (cl)

Interaction with faithfulness determines which parts of thehierarchy are expressed in overt linguistic form. In the same way, we can envisage that the presence of agreementis expressed by a constraint, which for the sake of argument we will dub'Realize Agr'. Languages may vary in the way they interleave this with thefiniteness hierarchy discussed in §3.7.3. A high rank for such a constraint would ensure that all verbsforms, finite and non-finite, bear agreement markers — an examplewould be Old Neapolitan — while a low rank would mean no overtagreement of any kind, as in Danish.
	The advantage ofthis kind of approach is that it captures the implicational structuring ofthe typological space that contains the possible systems. If a languagealigns the agreement hierarchy and the pronominal hierarchy at the cliticpoint then the two hierarchies will also be in alignment at all lower points. Thus, a clitic doubling systemsuch as River Plate Spanish will have pronominal Agr as well, whereasStandard Italian, which also has pronominal Agr does not have cliticagreement. The prediction therefore is that a language will not have clitic agreement combined with non-pronominalAgr; in other words clitic doubling would not be an option for a languagelike Icelandic even if it were to develop a clitic system. In the same way,the interleaving of the expression of agreement within the finiteness hierarchy would allow us to capture thetypological implication stated in Vincent (1998: 147) to the effect if alanguage has subject-verb agreement for non-finite forms, then it also hasit with finite forms, but not necessarily vice versa.
	The concept of alignment of hierarchies is further explored in Aissen(1998) and Artstein (1998), and forms the basis for the foregoingdiscussion. The key idea that emerges from their work is that whiledifferent hierarchies may align or interleave at different points in different languages, thus leading to typologicalvariation, the terms in the hierarchies may not shift their positionsrelative to each other. This is important since the fixedness of therelative values of the hierarchically organized items reflects a language external ontologicalpatterning which limits the nature of possible constraints and constraintinteractions. In this way we are enabled at one and the same time torespond to a frequent criticism of OT, namely‘What are the constraints on the constraints?’, and to embarkon the enterprise of grounding a formal model of grammar in conceptualcategories (see also below §3.7.2). 

3.6. Pronominals in Latin and Romance
Bresnan (1995, 1998) develops accounts of competition between different pronominal elements within the synchronicgrammars of different types of languages and in the genesis of pidgins andcreoles. A third obvious arena in which to test this model is provided bydiachronic changes in the form and function of pronominals. Here too it is natural to hypothesise that patterns ofgrammatical attrition and renewal should work themselves out as shifts inthe priority of individual candidates for morphosyntactic expression. Thehistorical developments which took place in the transition from Latin to modern Romance are a clear case inpoint. We shall look at two case histories. The first concerns thedifferential status of null arguments of finite verbs — ‘small pro’ — in Latin and Romance. The second involves the relation between thenon-overt subject of inflected and non-inflected infinitivals. In thissection we offer a pre-theoretical sketch of the data before developing aformal analysis in §3.7. 

3.6.1 Subject and object pro
As is well known, Latin is a classic (and classical!) null subject language, and the well described nullsubject properties of Italian, Spanish etc are, from a diachronicperspective, simply the continuation of this earlier state of affairs(which can in turn be reconstructed right back to Proto-Indo-European). French and the Northern Italian dialects, bycontrast, have in their different ways (M. Adams 1987, Vance 1997, Roberts1993a, Benincà 1994) innovated new systems of pronominal subject marking, which are insome sense a compensation for, but at the same time crucially not a direct replacement of, theloss of the Latin agreement morphology. We will seek to show how anOT-inspired approach can model both the continuity and discontinuityevident in such a diachronic profile.
	Less often called attention to than the null subject property of Latinsyntax is the fact that it also exhibits null objects (but cf van der Wurff1993, Luraghi 1997, Pieroni 1999). There is a striking difference from thenull subject cluster of effects in that Latin does not exhibit any system of verbal inflection which mightbe said to license null objects. By contrast, the Romance languages, all ofwhich exhibit systems of clitic pronouns unknown to Latin, systematicallyexclude null objects. Thus consider thefollowing ( (13) = (2), (14) = (20) in Luraghi (1997); (15) = (18) inPieroni (1999)):

(13)	senatus 			haeci					 intellegit, 
		senate.nomsg	this.neut.accpl	understand.3psg.pres
		consul 			Øi	videt										(Cic. Cat. 1.2)
		consul.nomsg		see.3psg.pres
		‘the Senate understands these things, the consul seesthem’

(14)	militesi				imperat; 				Øi	mittunt	(Caes BC 1.15)
		soldier.accpl	call-for.3psg.pres			send.3ppl.pres	
		‘he calls for soldiers; they send them/some’

(15)	“vinum”		inquit				“si	non	placet			
		wine.nomsg	say.3psg.pres	if		not	please.3sgpres
		Øi	mutabo”															(Petr 48.1)
				change.1sg.fut
		‘He said: “if the wine does not please (you) Iwill change it”’

The translation of (13) - (15) into any Romance languagewould require an explicit object in the second clause just as in theEnglish rendering given here. We will suggest that emergence of clitics andthe loss of object pro are related effects to be explained through a change in constraintpriority. In particular once a clitic system develops, object pro isautomatically lost.
	In the light of Cole’s (1987) typology of null objects, it isimportant to establish whether Latin null objects are genuine pronominalsor variables. Van der Wurff (1990) argues that they must be analysed as variables or as null resumptive pronouns, observing that the classictest for genuine object pro, namely null object in a strong cross-over context, does not go through.Looked at from another perspective, we can say that Latin has null objectsin contexts of high topic continuity (Pieroni 1999). This is the context inwhich Italian, for example, allows null subjects (Samek-Lodovici 1996) but crucially does not allow nullobjects. We thus get the following change (the categories refer to Bresnan’spronominal scale and ‘Romance’ stands for the early stages ofall Romance languages):

	(16)	latin	romance	
subject topics	bound					>	bound	
object topics	zero						>	clitic	

This is the first change that we will seek to model.		

3.6.2 Null subjects of non-finite forms
A standard result in modern syntactic theory is thatsubjects of infinitives are necessarily covert — ‘bigPRO’ — unless special factors intervene to license an overt subject. It is hardlysurprising therefore that both Latin and the Romancelanguages have control constructions. There are nonetheless a number ofsignificant differences in the syntax of infinitivals that need to beaccounted for. First, Latin allowed an infinitive to take an overt subjectin the accusative case. This AcI construction, which cannot be treated as a kind of Exceptional Case Marking sinceit occurs as the complement of adjectival and nominal predicates,disappears in the Romance languages except in learned syntax (Skytte 1978,Pountain 1998). Second control infinitives in Romance are introduced by a new class of overt infinitivalcomplementizers. Third, a number of Romance languages exhibit overtnominative subjects in so-called personal or inflected infinitiveconstructions, that is to say in contexts in which the infinitive may/must bear an overt person/number inflection. It is this third aspect which will be our principal concernhere.
	We display in (17) the paradigms of a number of theseinflected infinitives in different Romance languages:

(17)			Old Neapolitan						Portuguese
		SING			PLUR				SING			PLUR
	1	perdere			perderemo			comprar		comprarmos
	2	perdere			perderevo			comprares		comprardes
	3	perdere			perdereno			comprar		comprarem
				Sardinian								Galician
		SING			PLUR				SING			PLUR
	1	cantarepo		cantaremus		andar			andarmos
	2	cantares		cantaredzis		andares			andardes
	3	cantaret		cantaren			andar			andaren

The fact that Old Neapolitan (to which we can assimilatesporadic attestations in other Southern Italian dialects), Sardinian andPortuguese/Galician involve different patterns of morphological marking, both asregards distribution and form of the suffixes, suggests that these areindependent innovations. At the same time, distributional similaritiesacross the languages argue for a commonoriginal syntactic template. In particular, in all languages the inflectedinfinitive is not possible with complements of modals, causatives,perception verbs and subject-to-subjectraising verbs. 
	To see the contexts in which the inflected infinitivedoes occur consider the Sardinian examples (from Jones 1993) set out in(18):

(18)	a)		Juanne	nos	at						natu
				John		us	have.3sg.pres	tell.pstpr
				a			colàremus
				comp	call.inf.1pl
				‘John told us to call by’
		b)	Keljo				cantare		una	canthone
				want.1sg.pres	sing.inf	a		song	
				prima	de		sink’andaren
				before	comp	go away.inf.3pl
				‘I want to sing a song before they goaway’
		c)		Non	keljo				a			bi		vénneres			
				not	want.1sg.pres	comp	here	come.inf.2sg
				tue/*te
				you.nom/*acc
				‘I don’t want you to come’

Note that the construction is always a CP, as shown by theintroductory infinitival complementizers a and de; that the subject of the infinitival clause may differ from that of themain clause, and that an overt subject does not have to be present but thatif it is, then it must be nominative and not accusative.
	The examples in (19) from Portuguese (Raposo 1987)exhibit the same patterns:

(19)	a)		Eles			aprovarem			a		proposta	será
				they.nom	approve.inf.3pl	the	proposal	be.3sg.fut
				difícil
				hard
				‘It will be hard for them to approve theproposal

		b)	 Eles		estão			ansiosos
				they.nom	be.3pl.pres	anxious.pl
				de/por	votarem		a		proposta
				comp	vote.inf.3pl	the	proposal
				‘They are anxious to vote on the proposal’
		c) 	A		Mara	entrou 				em	casa 
				the	Mary	enter.3sg.pst	in		house
				sem			os meninos/eles				ouvirem
				without		the children/they.nom		hear.inf.3pl	
				‘Maria entered the house without the childrenhearing'

These constructions have nodirect precursor in Latin but are a Romance innovation. The question whichhas divided scholars is: which emergess first, the inflection or the overtnominative subject? The traditional answer is that the inflection camefirst since these forms derive from a finite series, namely the Latin imperfect subjunctive. This would also seem to be the answer most consistent with a licensingview of the function of agreement; you need the licenser before you canhave the licensee. The objections to this view are however that it does not explain the contexts in which the inflectedinfinitive occurs in the modern languages, that there is some historicalevidence for the overt subject being attested before the inflectedinfinitival forms (Maurer 1968), that a number ofareas have overt subjects with infinitives that do not have inflections(Cresti 1994, Lipski 1991, Jones 1993: 282 on the Sardinian dialect ofCampidanese), and that there are also attested inflected gerunds and participles, whichcannot possibly derive from Latin subjunctives. As examples of this latter category, consider (20).The (a) example is from Old Neapolitan (Vincent 1998) and the (b) examplefrom Algarve Portuguese (Coelho da Mota 1997: 342):

(20)	a)		vedendeno	li	Grieci 	tanta	copia 		de	cavalieri					see.ger.3pl	the	Greeks	such	quantity	of	knights		
				armati	…	fortemente	se maraviglyaro	de	la
				armed			greatly			wonder.pst.3pl	of	the							multetudene	loro
				multitude		them	
				‘When the Greeks saw somany armed knights, they (=the 						Greeks) weretruly amazed at the multitude thereof’
		
			b)	tu				querendos,		podemos		namorar
					you.nom 	want.ger.2psg	can.3pl.pst 	court.inf
					‘if you want, we can go outtogether’

Given the fact that the geographical distribution of the inflected gerundas exemplified in (20) is more restricted than that of the inflectedinfinitive, and is only attested in dialects which also have the latter, weshall conclude that the spread of the person endings to the gerund is later than to the infinitive (cf already Loporcaro 1986 for this same view). There thus appears to be an analogical generalization of the person inflections first from the finite forms to the infinitive and thence to the gerund.

3.7 Modelling the changes
3.7.1. The diachrony of object pronominals from Latin to Romance
Recall that null objects in Latin are topical (Pieroni1999). Thus to describe the Latin situation we need to provide a constraintranking such that the input [PRO, TOP] is expressed by zero (since there isno object agreement morphology of any kind). The required ranking is set out in TableauIV. 

Input	[PRO,TOP, OBJ]			harm	*af [PRO]	faith	*Ø [PRO]	
+	Zero:		[PRO, TOP]						*	
		Bound:[PRO, TOP, AGR]				*!			
		Pronoun:	[PRO, AGR]						*!		
Tableau IV							

Latin null objects are like Italian (and Latin) nullsubjects except that the structural markedness constraint that falls belowfaith is the one which forbids zero being associated with pronominal content. Inother words, Latin is prepared to envisage a violation of the iconicity constraint (4b). The situation in Italian and otherRomance languages requires instead the constraint ranking established inTableau V. 

Input	[PRO,TOP, OBJ]			harm	*Ø ~ af [PRO]
iconicity	faith	*cl [PRO]

allotaxy	
		Zero:		[PRO, TOP]				*!			
+	Bound:[PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau V							

Italian objects are like Italian subjects; they have to beencoded and this is done by a clitic pronoun. Assuming clitics aredifferent from affixes, this means the downgrading of a different member ofthe set of struct constraints to a position below faith. In this instance,the iconicity constraints are respected but the allotaxy ones areviolated.
	The foregoing analysis works within the systemproposed in Bresnan (1998). However a comparison of Tableau IV with TableauII reveals that the constraints *∆[PRO] and *af [PRO] have been reversed in their priority. It is exactly this kind ofreversal which is outlawed in the hierarchical approach to constraintranking developed by Aissen (1998) and Artstein (1998), and discussedbriefly in §3.5 (cf also footnote 18). We must leave it for the moment as an openquestion whether these data are a counterexample to such an approach or, asseems more probable, further research will find a way of reconciling thetwo. Under either approach,change is modelled as a shifting in constraint rankings, and morespecifically in those drawn from the set defined in (4) above as structuralmarkedness constraints. This is all well and goodbut still leaves open the question as to why such a re-ranking shouldoccur. What drives this change? Our answer is the independent developmentof a clitic pronoun system in Romance (Vincent 1997). This means that whenit comes to encoding a particular content — in the present instance that of pronominal object topic— there is a better, more iconic in the sense of (4) above,candidate available in the Romance languages than there was in Latin. 

3.7.2 A role for grammaticalization
If we assume with Bresnan a universal initial state withthe ranking Harmony » Structure	»	Faithfulness, then alternative rankings must be driven by exposure to data. How couldthis arise? Note that the hierarchy of markedness above reflects theuniversal patterns attested in studies of grammaticalization (Hopper &Traugott 1993: Ch 6). Let us assume that these patterns of grammaticalization reflect universal semantic potentialsdefinable in terms of a cognitive space which encompasses grammaticizabledomains like tense, number, pronominality, definiteness, etc. There is an analogy here with the waysound changes reflect universal phonetic potentials definable over theparameters that govern the working of the vocal tract. We can thenpostulate a potential for semantic drift external to the grammatical system leading to a grammatical change just asphonetic drift leads to phonological change (Ohala 1993). Hence just as theoperation of a sound change may obscure a previously motivated phonologicalalternation — the creation of new phonemes out of the originally allophonic products ofGerman umlaut is the textbook example — so the effect of a morphophonemic change, namely the emergence of clitics,may inadvertently as it were remove the availability of a previouslyavailable structure: a kind of diachronic emergence of the unmarked. The mechanisms ofgrammar, that is to say the constraint rankings, then encode the outcome ofthese changes for the next generation.
	If a scenario of this kind is on the right lines, itprovides an interesting alternative to a commonly held view of change ingenerative grammar. Consider the following remark by Longobardi (1996: 2):“… outside phonological change, linguistic systems are in principlediachronically inert, unless some specifically motivated conditionsapply.” There is a remarkable similarity between this view andthe Neogrammarian insistence on the ‘blindness’ of sound change, which has long been known tooversimplify, indeed falsify, the relation between phonological andgrammatical change (see Harris 1978 for an effective diagnosis of the problem). The model ofchange as constraint re-ranking that we have adumbrated here offers analternative approach. I would rather adapt Longobardi’s remark bysaying “outside phonetic and semantic change”, subsuming grammaticalization under the latter but not treating it as asubstitute for a formal syntactic theory, here modelled as a set ofOT-style constraints. Research in grammaticalization would then be acontribution to mapping out the space within which grammars of particular languages can be stated, but it would not obviatethe need for such grammars (pace Bybee et al 1994: 1). This wouldalso be consistent with the view expressed by Aissen (1998: 11):
“The ranking of constraints in a subhierarchy is universally fixed, andexpresses the universal markedness relations in this domain.Language-particular variation can be described through the interpolation ofother constraints among those in a subhierarchy, but not through differences in ranking within the subhierarchyitself.” 

We turn now to our second change which will show a rolewithin OT for that other classic weapon from the nineteenth-centuryarmoury, namely analogy.

3.7.3 The diachrony of the personal infinitive/gerund
Following the discussion in §3.6.2, we will assume that the right historical chronology is that firstovert subjects are possible in infinitival and gerundival constructions andsecond that the inflectional morphology extends its domain to encode thatfact. We can achieve this end by refining our account of the StructuralMarkedness Constraint labelled in §3.4 *af [PRO], whose effect was to ban structures in which pronominality wasencoded via affixes as a violation of iconicity. Instead of taking this asa single constraint we will treat it as a family of constraints applying tothe whole range of possible verb forms. If the direction of spread is as in (21) then we will need theconstraint hierachy in (22):

(21)			 finite forms		>		 infinitive			>		gerund

(22)			*af [PRO]ger		»		*af[PRO]inf		»		*af [PRO]fin

Thus, (22) says that a violation of the ban on affixes attached to gerundsis worse than violating the ban on infinitival inflection which in turn isworse than violating the ban on finite inflection. Tableau II above, whichpermitted bound inflection to express pronominality — the classic pro-drop effect — inLatin,  should in this more refined system be replaced by Tableau II’:

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]fin	
		Zero:		[PRO, TOP]				*!			
+	Bound: [PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II’							

The grammar of an innovating language such as Portuguese orSardinian can then be represented as in Tableau II’’, whereboth the infinitival and finite members of the family have fallen below thefaith.

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]f/i	
		Zero:		[PRO, TOP]				*!			
+	Bound: [PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II’’							

 In the extreme case, where all the members of the*af [PRO] constraint family have fallen below faith, the grammar will then license the full portfolio of inflected forms andtheir pronominal arguments found in Old Neapolitan and some Algarvedialects of modern Portuguese. Thus:

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]f/i/g	
		Zero:		[PRO, TOP]				*!			
+	Bound: [PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II’’’							

Notice once again that this account makes a quite clearprediction, namely that one will not find languages with an inflected gerund and inflected finite forms but no inflected infinitives. There arethus constraints on the constraints (Grimshaw 1998), namely that they mustnot violate the universally definable and hierachically organized space ofpossible grammars. It is not a consequence of OT that anything in the world can count as a constraint,despite persistent malicious and ill-informed gossip to the contrary!

3.7.4 A role for analogy
Just as in accounting for the replacement of null objectsby clitics we found a role for the traditional concept of grammaticalization, so the use of an orderedprogression through the members of a family of constraints may be thoughtof as the OT analogue of the traditional concept of ‘analogicalextension’. Thus, once again the constraint hierarchy models the structure of the domain, in the present instance the clinefrom finite to infinitive, and the re-ranking of the constraints reflectsthe direction of the analogical shifts. In this sense, the model proposedhere follows the logic of Kury∏owicz’s (1949) classic intervention, suggesting that the directionality ofanalogical change is (at least in part) predictable from considerations ofmarkedness. Like him, we do not propose a predictive account of whenanalogy may take place, but only of the direction in which will move if it occurs. We may also recall Meillet’s (1912: 131) observation that analogy and grammaticalization exhaust thepossible types of morphosyntactic change. What the present account seeks todo is to use OT as a way of conceptualizing the relation between analogy, grammaticalization and the internalmechanisms of grammar.

3.8 Lessons for a theory of syntactic change
In this section we reflect on the theoretical lessons that can be learnedfrom the account of the Latin-Romance data presented above. There we haveemphasised two general concepts: competition and correspondence. Let usconsider the diachronic implications of each in turn. 

3.8.1 Why a competition-based account is superior to an absolutistone
The intuition behind a competition-based model of a synchronic system is that thegrammaticality of a given structure is precarious: it is always potentiallythreatened by the other universally available competitors, which are onlykept at bay by the language particular constraint ranking operative at that point in time and space. Any change in thatranking would force a different solution to the ever-present problem thatlanguages (and language users) face: how to match form and content toexpress the intended meaning withinthe resources available. Historical linguists, of course, have alwaysemphasised the notion of competition between forms as the basis of change.For instance, Hopper & Traugott (1993: 123) write: ‘Rather than replace a lost or almost lost distinction, newly innovatedforms compete with older ones … this competition allows, even encouragesthe recession or loss of older forms’. The same point is also madeby Kroch (1992: 113): ‘Languages at any synchronic moment of their existence may be seen assystems of competing forms’, who goes on to note that ‘quiteabstract linguistic subsystems, not just isolated forms, may be theelements in competition.’ Standard derivational frameworks model this sort of scenario rather badly;they frequently provide neat and elegant accounts of given synchronic states expressed as the interaction ofuniversal principles and the individual values of particular parameters(Lightfoot 1991; Roberts 1993a). They do not however readily extend toinclude in the picture the notion of alternative solutions waiting, so to speak, in the grammatical wings.Kroch’s original answer to this was to envisage the speaker’s competence as containing internally competing grammars (Kroch 1989). Theproblem with this approach is that every time a new setof competing forms are identified within a language, a new set of parallelgrammars will have to be postulated. Such proliferation of grammarsinvolves taking a very powerful hammer to crack the variationist nut.  Morerecently, Kroch (1995) has suggestedthat the competition is between alternative functional heads. Following upthis line of argument, Pintzuk (1998: 123) observes: ‘If we characterize the difference between OV and VO languages in terms offeatures of grammatical formatives, the source of the variation is not the order within the VP but rather the directionalityfeature of some functional head. Contra our original assumptions, thisentails that all non-finite verbs move out of the VP to the head of ahigher functional projection, one that is distinct from I or its components, and that the directionality feature ofthis functional head is undergoing change’. Proliferation of grammars is replaced by proliferation of functionalheads. However, whereas many functional heads have both overt form and morphosyntactic content, and are indeed the result of processes ofgrammatialization (Vincent 1993), the heads being postulated here are emptyand distinct from the items with grammatical content (‘I and itscomponents’); they are simply a way of encoding word order variation into a syntactic configuration. Word order and wordorder changes are not reduced to independently available functional headsas proposed for example in Roberts (1997), but are restated in terms ofspecially invented and otherwise unmotivated new heads. These heads are the Last Resort solution, as envisagedunder the Minimalist Program (Chomsky 1995, Lasnik 1999: Ch 6), to thederivation of the required structure, while still respecting the universalrequirement of Economy (Chomsky 1995: Ch 2).  With no restriction on the number and type of functional heads,however, this approach runs a clear risk of unfalsifiability (Börjars,Payne & Chisarik 1999).
	The insight that functional heads are the end product of processes ofgrammaticalization (Vincent 1993) certainly seems worth preserving. At thesame time it is necessary to counter the standard objection togrammaticalization theory from those within the formalist tradition — and it appears to me a very substantial and forceful objection — namely, that it is conducted in an intuitionistic way with too strong afaith in a direct correlation between linguistic form and meaning andfunction (Croft 1995, Newmeyer 1998). It does not allow enough space forfunctionally arbitrary synchronic structure, for the presence of language universals not driven by functionalneeds, and crucially it does not provide any means of modelling linguisticstructure in a way that allows the consequences of particular shifts to becomputed across the rest of the system. In that sense it seems wilfully to discard the achievements of morethan half a century of formal linguistics, both structuralist andgenerativist (cf Bybee et al 1994; 1). This metaphysical stance has made it all too easy for generativetheorists of language change such as Lightfoot (1991, 1999) to ignorerather than confront the evidence of grammaticalization (though see Roberts1993b for an honourable exception). Yet the evidence needs to be confronted. Grammaticalization chains orpaths seem to bereal and recurrent phenomena in the histories of natural languages, and assuch constitute a genuine empirical challenge to the stepwise, abductiveand potentially reversible view of change that typifies work in thegenerative tradition. They are the diachronic counterpart of the morphosyntactic hierarchies discussed above.
	In the present paper I have sought to argue that anOT-inspired interpretation of grammatical change provides the means toachieve a much needed reconciliation of the two approaches: we can model, as precisely and computably as necessary, both the structuralproperties of individual systems and their interaction with universallyavailable and hierarchically organized (hence potentially directional)dimensions of change. In particular, by requiring that constraints be grounded in finite systems of independentlydefinable grammatical primitives, we can avoid the charge that OT simplyreplaces an infinite set of functional heads with an infinite set ofconstraints. The difference is that, as I have tried to show here, a finite constraint domain plus the notion ofre-ranking can capture the required effects, whereas a derivationalmovement-based model seems doomed to spawn potentially limitless numbers offunctional heads to achieve the same ends.

3.8.2 Why a correspondence model is preferable to a derivational one
The last section sketches an argument for the correctnessof the competition-based account of change that the OT vision imposes. Atthe same time, in the data we have discussed andthe model we have adopted, another concept has been fundamental, namelythat the relation between linguistic form and content should be based oncorrespondence and not on derivation. What is the justification for thisassumption? As we have noted, correspondence depends on the idea that the structure of sub-domains of thelinguistic system reflects the natural categories and primitives of thedomain in question; there is no a priori reason to believe that the form of representation most appropriate tophonology, for example, will generalize to syntax, or that what is naturalin semantics is equally natural in morphology. In particular, morphologicalstructure does not have to be‘syntacticized’ and represented as an X-bar tree, and emptycategories or zeros(whether morphological or syntactic) do not have to be postulated simply inorder to ensure that form corresponds to content. Historically this meansthat the input can be the same — in the material discussed hereconstellations of [PRO, TOP, AGR]— even when its realization can vary over time from morphological tosyntactic and back again. 

3.9 Conclusion
In this paper I hope to have shown three things. First, and most directly,I have demonstrated that the OT-inspired account of pronominals and theircross-linguistic markedness relations offered in Bresnan (1998b) can beapplied in a simple and elegant way to the diachronic data presented by some of the changes in the patterns ofargument marking between Latin and Romance. Second, I have argued that suchan account provides answers to puzzles that had previously eluded solution,and to that extent offers a genuine conceptual advance over — andnot just a simple reformulation of — earlier treatments, both those which were philological and those whichwere theoretical linguistic in inspiration. Third, I have sought to showthat the best account of the data in question crucially involves both the notions of competition and correspondence. In addition, via theparallel correspondence type of architecture linked to competition, we havea way to incorporate the insights of grammaticalization, which — pace Lightfoot (1999) and Newmeyer (1998) — are real and important, without forsaking formalizability or incurring thepenalty of teleology. To the extent that all these notions only converge inan LFG type of architecture under an OT interpretation as developed by Bresnan (1997, 1998a,b), I believe I have in turn provided a furtherand original line of argumentation in favour of this approach to linguisticinquiry in general, whether synchronic or diachronic. 

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- --============_-1266959668==_============Content-Type: text/plain; charset="us-ascii"Nigel Vincent	               Tel: +44-(0)161-275 3194Department of Linguistics      Fax: +44-(0)161-275 3187University of Manchester       e-mail: nigel.vincent@man.ac.ukManchester M13 9PL		http://lings.ln.man.ac.uk/Html/NBV/UK		    	         Visit our web-page:				http://lings.ln.man.ac.uk/- --============_-1266959668==_============--------- End of Forwarded MessageFrom bresnan@csli.Stanford.EDU Wed Dec 15 13:07 EST 1999Received: from leonard.anu.edu.au (leonard.anu.edu.au [150.203.2.15])	by pretty.anu.edu.au (8.8.8/8.8.8) with ESMTP id NAA29379	for <andaling@pretty.anu.edu.au>; Wed, 15 Dec 1999 13:07:03 +1100 (EST)Received: from anugpo.anu.edu.au (anugpo.anu.edu.au [150.203.2.6])	by leonard.anu.edu.au (8.9.3/8.9.3) with ESMTP id NAA13412	for <e760020@leonard.anu.edu.au>; Wed, 15 Dec 1999 13:07:02 +1100 (EST)Received: from hypatia.Stanford.EDU (hypatia.Stanford.EDU [171.64.22.122])	by anugpo.anu.edu.au (8.9.3/8.9.3) with ESMTP id NAA09088	for <Avery.Andrews@anu.edu.au>; Wed, 15 Dec 1999 13:06:52 +1100 (EST)Received: from csli (IDENT:bresnan@sunet-s5as01-1-dynamic-56.Stanford.EDU [171.66.164.56])	by hypatia.Stanford.EDU (8.9.3/8.9.3) with ESMTP id SAA02098	for <Avery.Andrews@anu.edu.au>; Tue, 14 Dec 1999 18:06:16 -0800 (PST)Message-Id: <199912150206.SAA02098@hypatia.Stanford.EDU>To: Avery.Andrews@anu.edu.au (Avery Andrews)Subject: nigel vincent: attachmentDate: Tue, 14 Dec 1999 18:07:48 -0800From: Joan Bresnan <bresnan@csli.Stanford.EDU>Content-Type: textContent-Length: 138072X-Lines: 2368Status: ROReturn-Path: POPmailReceived: from borate.Stanford.EDU (borate.Stanford.EDU [171.64.7.37])	by hypatia.Stanford.EDU (8.9.3/8.9.3) with ESMTP id BAA10544	for <bresnan@csli.stanford.edu>; Tue, 14 Dec 1999 01:12:36 -0800 (PST)Received: from probity.mcc.ac.uk (probity.mcc.ac.uk [130.88.200.94]) by borate.Stanford.EDU (8.8.8/8.7.3) with ESMTP id BAA05797 for <bresnan@stanford.edu>; Tue, 14 Dec 1999 01:12:31 -0800 (PST)Received: from w12101.art.man.ac.uk ([130.88.58.79])	by probity.mcc.ac.uk with esmtp (Exim 1.92 #3)	id 11xo0U-00008Q-00; Tue, 14 Dec 1999 09:12:30 +0000Message-Id: <l03102803b47bba725d5f@[130.88.58.79]>Mime-Version: 1.0Date: Tue, 14 Dec 1999 09:13:48 +0000To: andaling@pretty.anu.edu.au, Joan Bresnan <bresnan@stanford.edu>From: nigel vincent <nbvint@nessie.mcc.ac.uk>Subject: attachmentContent-Type: multipart/mixed; boundary="============_-1266959668==_============"X-UIDL: a605a68bed266c22a3b5aa7c7006c957- --============_-1266959668==_============Content-Type: text/plain; charset="us-ascii"Joan & Avery,I forgot the attachment!Nigel- --============_-1266959668==_============Content-Type: text/plain; name="vincent.rtf"; charset="us-ascii"Content-Disposition: attachment; filename="vincent.rtf"ftab284Competition and correspondence in syntactic change:
null arguments in Latin and Romance

nigel vincent

Department of Linguistics, University of Manchester, M13 9PL, UK
nigel.vincent@man.ac.uk
 
3.1 Introduction
The vast preponderance of work to date on syntactic changefrom the perspective of formal linguistics has been couched within thePrinciples & Parameters (P&P) framework — see Battye & Roberts (1995) and van Kemenade & Vincent (1997) forrepresentative collections of papers. Inevitably, too, giventhe time at which the research reported in these volumes was conducted,both principles and parameters were construed in absolute terms. Aparameter was either on or off, and once set could not be overridden;principles had to be obeyed absolutely. Put inother terms, the constraints on such a system were of the ‘hard’ variety. In the present paper we suggest instead that a number of classicissues in the study of grammar change come into sharper focus once we (a)adopt the assumptions of a different analytical framework, namely Lexical-Functional Grammar (LFG), and (b) interpretthe system of grammatical constraints as ‘soft’ or violablealong the lines of Optimality Theory (OT). Two fundamental concepts —competition (drawn from OT) and correspondence (drawn from LFG)— will receive particular attention in what follows.  Conversely, we willargue that the evidence of change provides further support for such anLFG/OT conception of linguistic systems. The specific case study aroundwhich the argument is built concernssome of the changes that take place in the licensing of null and overtarguments as Latin develops into the Romance languages.
	The structure of the paper is as follows. In §3.2and §3.3 we review some basic concepts of OT and LFG respectively andsituate the notions of competition and correspondence in a widertheoretical context. §3.4 reviews the theory of pronominals presented in Bresnan (1998b) andgives a first sketch of the role it can play in accounting for syntacticchange. §3.5 refines this model while §3.6 sets out the patterns of change in the pronominal system between Latinand Romance that are the principal empirical focus of this study. In§3.7 we elaborate a formal account of these changes drawing on the ideasintroduced in §§3.2,3.3 and 3.4. Finally, in §3.8 we reflect on the general lessons for thetheoretical modelling of syntactic change that can be learnt from thematerial presented here. §3.9 sums up our conclusions.

3.2 Optimality Theory and syntax: the notion of competition
We begin then by briefly rehearsing the general featuresof the OT approach to characterizing linguistic systems. As is by now well known, the keyconstructs are constraints and the ranking of constraints. The universal set of constraints,under a ranking which is language particular, apply to a set of candidate forms generated (by a function gen) for a given input. The eval(uation) function defined by the constraint ranking then determines thesuccessful output, which is thereby identified as the grammatical expression of that content(or input) in the language in question. A grammar of a language on thisview is then a ranking of constraints consistent with the attestedoutputs.
	OT may not have had everything its own way in syntax as seems to havehappened in phonology (Archangeli 1997: 25-6), but an impressive body ofwork nonetheless by now exists. In an already classic paper, Grimshaw (1997) demonstrates how a minimal predicate-argument structureinput such as {see (John, who)} is paired with the output Who did John see? via the interaction of constraints which require, amongst other things,that an operator be in a specifier position, that the operator c‑commandthe clause over which it has scope, that X-bar heads be filled, and so on.Here is notthe place to repeat all the details of Grimshaw’s intricate andelegant analysis. I will focus instead on just one constraint to illustratethe flavour of the argumentation. Grimshaw postulates a constraint stay which privileges non-movement of syntactic categories. In the example justgiven, stay is in conflict with the requirement that an operatorbe in a suitably c-commanding specifier position (the constraint op-spec). If who remains in object position, op-spec will be violated; if not thenstay suffers the violation. The form of English interrogativesshows us that in this conflict it is op-spec which wins out and hence that this constraint must be ranked higher thanstay in the grammar of English. Consider now the different inputin which the functions of the arguments are reversed: {see (who,John)}. Now John fills the object position and who already fills Spec VP, so whocan satisfy the requirements of op-spec without movement, thus atthe same time satisfying stay. One striking and attractive consequence of this approach is that only as much structure as is necessary isprojected: Who did John see? is a CP but Who saw John? is a VP,and by parity of argumentation Who will John see? is an IP. Note toothat of these structures, only Who saw John? is free of any constraint violations, yet all are perfectly grammatical.In other words, the interaction of constraints works according to aprinciple of optimality to determine the best candidate in thecircumstances, but once chosen, the best candidate, however many constraint violations it has incurred, is absolutelygrammatical. Different constraint rankings generate different languages, so thatre-ranking of constraints provides a mechanism for encoding bothtypological variation (Ackema & Neeleman 1998) and diachronic change, as wewill see in what follows.
	Despite the unconventional nature of some ofGrimshaw’s conclusions, the underlying logic of her analysis is notin fact far removed from Minimalist ideals. The spirit of Economy is wellmet by banningmovement except where necessary and even then only over the shortestdistance (since each step in a movement chain such as V-to-I-to-C incurs aseparate violation penalty), and by projecting no more structure than isstrictly needed to satisfy independentrequirements. This point is made in extenso by Speas (1997: 180-185),who notes:
“PPT/MP [i.e. Principles & ParametersTheory/Minimalist Program] claims that the principles of UG are inviolable,but …
• all of these principles contain hedges which restrict the domainin which the principle is inviolable.
• the Minimalist Program makes violability explicit in its economyprinciples.” (Speas 1997: 185)
	Some aspects, then, of the OT philosophy ofgrammatical analysis and description chime with current views withingenerative syntax. At the same time, it is important to appreciate that OT is not itself atheory of syntax (or indeed of phonology). It is a theory of howcombinatorial cognitive systems such as natural languages may becharacterized. This fundamental point is perhaps less obvious, and less crucial, in phonology whereconstraints refer for the most part to aspects of structure that aredirectly translatable into more or less theory-neutral concepts such asVoice, Onset, Left/Right, etc. In syntax, the matter is more complex since we do not have an independently observableuniversal domain parallel to phonetic substance to fall back on. Thetraditional assumption that semantics can fill such a role for syntax,while not without its attractions or itsmodern advocates (cf Langacker 1987, Anderson 1997 to name but two works inthis vein), is much more fraught with difficulty.  OT syntax, therefore,will inevitably vary according to the theory in which the analysis isconducted. For instance, Grimshaw’s already mentioned constraint stay presupposes an accountin which movement is an option within the grammatical metalanguage; a modelwhich has no analogue of Case Theory will not require her case constraint; and so on. Different researchers therefore may well agree on the desirability of adopting an OT approach to syntax, whilediverging radically from each other on the framework in which the accountis cast and therefore on the constraints proposed. It is instructive inthis respect to compare Grimshaw’s (1997) account of the English wh-construction withBresnan’s (1997) re-analysis. Alternatively, scholars may largely share theoreticalframeworks but differ on the role, if any, which OT may play in theiranalyses: compare, from the perspective of the Minimalist Program,Speas’ (1997) wholehearted embracing of OT with Pesetsky’s (1997) morecautious distinction between areas where the OT remit may run and areaswhere it may not. Many others no doubt remain unreservedly sceptical of thewhole enterprise.

3.3 Lexical-Functional Grammar and the concept ofcorrespondence
If we wish to explore the consequences of OT in thediachronic domain, therefore, we must first choose a particular frameworkwithin which to construct the analysis and thus define the constraints. I will adopt L(exico)-F(unctional) G(rammar): for details see thepapers collected in Dalrymple et al (1995), notably Kaplan & Bresnan (1982), and for recent OT-inspireddevelopments within the framework see Bresnan (1997, 1998a,b) andreferences therein. This choice is not arbitrary, but is based on afundamental asymmetry between function-based systemssuch as LFG and a position-based system such as Principles & Parameters(P&P), namely thatall positions have a function but not all functions have a(phonetically expressed) position. For a system like P&P this means thatempty categories/positions have to be postulated to bear the overtlyunrealized functions and a separate sub-theory, Case Theory, has to berecruited to constrain the links between positions and functions. Consider for example the problem PRO poses for CaseTheory under the Visibility interpretation (Chomsky 1986: 93-5) and theartifice that is then required of assigning null Case to the empty categoryin order to ensure that it is kept in grammatical play (see Chomsky & Lasnik 1993 (=Chomsky 1995: 119) andthe excellent critique in Hornstein 1999). None of this is necessary if PROis seen simply as the unexpressed subject function of an infinitivalpredicate (Bresnan 1982, Culicover &Wilkins 1986).
	A further objection to a configuration-based metalanguage, ofparticular relevance in what follows, is that it privileges those languagesthat realize function through position over those that adopt some form ofmorphological encoding. We will assume instead that abstract grammatical relations — subject andobject will be all that will concern us here — can be expressed inone of three possible (and sometimes overlapping) ways, viz:
a)		configuration/position: e.g. English,Italian, Turkish;
b)	dependent marking (cases and adpositions):e.g. Latin, Chechen 						(Nichols 1986);
c)		 head marking (agreement and incorporation): e.g. Mohawk (Baker					1995), Abkhaz (Nichols 1986).
Moreover, the particular options employed from within thisbroad typological range may vary with the passage of time (Kiparsky 1997),as we shall see quite clearly in the present study.
	LFG then distinguishes f(unctional)-structures expressed in terms ofattribute-value matrices (features) and c(onstituent)-structure expressedin terms of X-bar. Since c-structure serves only to define surface form, itmay be freely substituted by morphology or by no marking at all depending on the language. Grammaticalrelations of the kind which require c-command, wh-movement, Case-checking, etc in a P&P type of architecture are expressed in the f-structurewithout recourse to configuration. The relation which holds between anf-structure and the c‑structure and/or morphology which expresses it is one of correspondence orrealization. 
	Adopting a system like LFG where there are no emptypositions and no movement will obviously have drastic effects on thestandard P&P typology of null elements. In anybody’s system, thephenomenology of wh- -constructions constitutes a class apart and we will not be concerned withthem here. Intra-clausal NP-traces (passives and middles) are treatedlexically and will only impinge marginally on the present analysis;inter-clausal NP-traces (aka ‘raising’) are relevant to our account and following the proposals ofBresnan (1982) will be assimilated to the analysis of controlconstructions. In sum, therefore, we will be focussing on the changes inthe distribution of pro and PRO, the [+ pronominal] elements of the standard Chomskyan typology, and integrating these into a broader account of the changes in the distribution of variouskinds of overt pronominal. The unified nature of the resulting diachronicanalysis can in turn be seen as a further argument in support of the waythe grammatical phenomena are divided up under the assumptions of LFG rather than those of P&P.

3.4 A theory of pronominals
It is important to be clear about the relation ofnon-overt pronominal elements (i.e. those referred to above as PRO/pro) to various kinds of phonetically realizedpronouns. To this end, we will adopt the correspondence theory ofpronominals proposed in Bresnan (1998b), which contains the followingcomponents:
	i) A universal scale of pronominal form: elementswhich have pronominal function can be ranged along a scale according to thedegree of (prosodic and/or morphological) independence they exhibit,viz:

(1)	zero	<	bound	<	clitic	<	weak	<	pronoun

In this conception of things, ‘zero’ meanshaving no overt realization at all, whether morphological or syntactic. Examples include the marking of subject and object in Chinese and Japanese,and of object in Latin. By contrast, the encoding of subject in Latin via asystem of person inflection here falls under the heading ‘bound’. ‘Clitic’ is to be understood in the sense of Zwicky’s (1977) ‘specialclitics’, that is to say elements whose syntactic positioning is determined byrules other than those which dictate the position of full nominals. Thewell-known clitics of the Romance languages are a clear case in point.‘Weak’ pronominals are syntactically free in the sense that their distributionfor the most part parallels that of full NPs but they are prosodicallysubordinate to another word (in this respect they behave very like ‘light’ verbs, articles and some prepositions). A pronoun in the sense intendedhere is by contrast both distributionally and prosodicallyindistinguishable from a full NP/DP.
	ii) A universal set of features for pronominalcontent: in similar vein the possible dimensions of pronominal content maybe broken down into three: 
	a) semantic: pronouns have meaning in virtue ofreference internally within a text or externally to entities in the realworld. This aspect of their function is treated in terms ofvalues of afeature PRO.
	b) information-structural: the status of all(pro)nominals varies from discourse context to discourse context. This iscaptured as values for a feature TOP.
	c) morphosyntactic:  pronominal phi-features, which express theirgrammatical content, are treated as values for the class of features heresubsumed under the label AGR (i.e. person, number, etc).
All such features are privative and a feature may be absent from therepresentation of the content of a given item: for example, there is no AGRin Japanese verb forms. Thus, the feature constellation [PRO, TOP] definesthe class of items that have variable referentiality (PRO) and topic anaphoricity (TOP). It subsumes [PRO, TOP,AGR], the class of items which also have grammatical properties like personand number, and is subsumed by [PRO], the class of items which simply have variable reference.Constellations of these features will provide the input for evaluation by alanguage’s constraint hierarchy, and thus be linked to members of the class ofpossible pronominal forms identified in (i) above. To this end we furtherneed:
	iii) A universal set of constraints onform-content correspondences: these constraints express recurrent patternsof correlation between the content of an argument type and its expressionacross languages. There are two important dimensions here. The first limits which elementson the scale in (1) can be encoded overtly and the second those which canbe encoded by elements which are in some sense segmentally or prosodicallyreduced. Thus we have two contrasts as follows:

(2)	a)		Overt (all except zero) vs non-overt (zero)
		b)	Reduced (all except pronoun) vs non-reduced (pronoun)

Table 1 shows the relations between the constraints in (2)and the items in (1):

non-overt	overt				
zero	bound	clitic	weak	full	
reduced				unreduced	
TABLE 1					

We are now in a position to formulate thefollowing (families of) constraints:

(3)	harmony constraints:
(a)	Reduced € TOP:	pronominals are reduced iff they are specialized for topicanaphoricity.
(b)	Overt € AGR:		pronominals are inherently specified for person/number/ genderiff they are overt.

(4)	structural markednessconstraints:
	(a)	Cross-linguistically the unmarkedpronominal is a full pronoun.
	(b)	Zero or a bound element associated withPRO violates iconicity (since separate pronominal content is notmatched by separate form).
	(c)	A clitic or weak elementassociated with PRO violates allotaxy (since there is more thanone way of expressing pronominal content).

(5)	faithfulnessconstraints:	require that all and only the content of the input beexpressed in the output. 

The initial state of the language learner is assumed to beone in which the following dominance relations hold between these (familiesof) constraints:

(6)	harmony	»		struct	»		faith

To determine the correct output for a given language, westart with a featural characterization of the input — e.g. [PRO,TOP] — and evaluate possible form-content pairings under the constraint rankingthat is postulated to hold for the language in question. Thus, assume that we are dealing with a language in which the learner has notacquired evidence to alter the default rankings in (6) which characterisehis/her initial state. This situation is represented in TableauI.

Input	[PRO, TOP]		harmony	struct	faith	
		Zero:		[PRO,TOP]			*!		
		Bound:		[PRO, TOP]		*!	*		
		Pronoun:	[PRO, TOP]		*!			
+	Pronoun:	[PRO, AGR]					*	
Tableau I					

In other words, in such a language, of which English is an example, if wewant to express a pronominal topic, the constraints predict that the freepronoun is required even though this in fact does not express only topics.A zero pronominal with this function would violate the iconicity member (4b) of the structural markednessconstraint family, whereas overt pronominals without phi-features violate the harmony constraint (3a). The remainingcandidate is one which does not exclusively express the desired content. Itnevertheless ends up the optimal form since the violation thus incurred isof the lower ranked faithfulness constraints, and according to the postulated dominance hierarchy in (6) it ismore important to respect structural markedness and harmony than to exactlymatch input and output.
	iv) Language particular constraint rankings:		Languages may deviate from the above universally unmarked constraintranking if the constraint rankings are changed. Thus a pro-drop languagelike Italian is generated if one of the struct constraints, namely that which bans the association of anaffix with PRO(nominal) value, is ranked lower than faith, as isshown in Tableau II. (For the Chinese type of pro-drop, by contrast, in which there is no overtagreement morpheme to do pronominal duty, switch the columns headed *Ø[PRO] and *af [PRO] in Tableau II.) In other words, it is more important to be faithful to the input than to avoid violating the particularmember of the structural markedness family of constraints which penalisesthe morphologically bound expression of pronominal content. 

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]	
		Zero:		[PRO, TOP]				*!			
+	Bound:[PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II							

On this ranking, appropriate for Italian or Latin subjects,the affix emerges as the best candidate for expressing topic anaphoricpronominal reference. However, for non-topic pronominal meaning we still require afull pronoun as the next tableau shows:

Input	[PRO]			harm	*Ø [PRO]	faith	*af [PRO]	
		Zero:		[PRO, TOP]				*!			
		Bound: [PRO, TOP, AGR]						*!	
+	Pronoun:	[PRO, AGR]								
Tableau III							

Expansion of the pronominal inventory can thus be modelledby constraint re-ranking. When the purpose of the exercise is to comparethe different pronominal systems of languages as geographically andgenetically separate as Chinese and Chichewa, the effect of constraint re-ranking is to permit us to capturetypological generalizations. When, on the other hand, the languages beingcompared form a historical progression, as in the case of Latin andRomance, then the outcome is the first steptowards a constraint-based model of syntactic change. We will seek todevelop this insight further in what follows, but first we consider arevision in one aspect of Bresnan’s system.

3.5 the pronominal model refined
Bresnan’s model needs to be refined to deal with the double role of Latin and Italian verbal inflection as boththe expression of pronominal content when there is no overt subject and asmarkers of agreement when an overt subject is present. As Cecilia Goria(p.c.) has pointed out to me, the account offered in §3.4 seems to fail in one important respect, namely that the use of an overtpronoun in a non-topical context does not suppress the corresponding affixbut simply pre-empts its pronominal function. The affix remains but itsfunction shifts from encoding a pronominal argument to expressing agreement with anindependent argument whether pronominal or nominal. To see the implicationsof this point, consider the following Italian example, an instance ofso-called clitic left dislocation (Cinque 1990):

(7)	Io 		Valerio	non	lo 				voglio 				sposare
		I.nom	V			not	objcl.3sgm	want.pres.1sg	marry.inf
		‘I don’t want to marry Valerio’

The precise informational status of such an example, whichhas two fronted arguments io ‘I’ and Valerio, is acomplex matter and need not concern us here. Rather, we should note thediscrepancy between the status of the clitic lo which picks up thefronted object Valerio and the inflection -o which encodes thefronted subject io. Omission of the clitic is possible in other contexts; indeed it isobligatory if the object is overt and in the canonical post-verbalposition. Thus:

(8)	a)		Voglio sposare Valerio
				‘I want to marry Valerio’
		b)	Lo voglio sposare
				‘I want to marry him’
		c)		*Lo voglio sposare Valerio

Whatever the context, on the other hand, the person/numberinflection -o is never omissible. The constraint at work here might be thought to be amorphological one which determines the wellformedness of Italian inflected verb forms independent of the circumstances of their use. While such a solutionwould in fact work for modern Italian verb inflection, it would not generalise to the data from theinflected infinitive construction we consider in §3.6.2 where thepresence of the inflection is in certain contexts optional. At the same time there are languages in which the verbalmorphology, albeit ‘rich’, does not serve to license nullarguments or, in our terms, does not have pronominal value. Sigur∂sson (1993) shows convincingly that Icelandic is a case in point. And ofcourse many languages with no overt agreement do not allow pro-drop, as forinstance Danish and Swedish. In fact all logical possibilities exist, asthe following table demonstrates:

	overt agreement	zeroagreement	
null argument	Italian	Chinese	
*null argument	Icelandic	Danish	
Table II			

Something similar is observable in some clitic systems, namely thosecharacterized by so-called clitic doubling, where a clitic and an overtargument co-occur. Naturally, since zero clitics by definition do notoccur, we only find two rather than four possibilities if agreement is of the clitic rather than the morphologicaltype.
	Bresnan (1998b: 22, note 16) proposes that theagreement property noted here can be handled by letting the PRO value beoptionally parsed. In this way, morphological endings and clitics withpronominal content count as arguments and those without do not (cf Börjars & Chapman 1998). In the Italian type of system exemplified in (8)clitics do not allow for optional parsing of their pronominal content, and thus they always assume argument status when theyoccur. In a clitic doubling system, by contrast, the option exists and theclitics are to that extent more grammaticalized and partake already of theproperties of an agreement system. The optional parsing solution, however, would not easily generalise tocover optionality of morphological endings.
	 An alternative account involves postulating anAgreement Hierarchy as in (9) which can be linked to the pronominalhierarchy by the Alignment Constraint in (10):

(9)	Agreement Hierarchy:	zero	<	affix	<	clitic

(10)	Align pro-agr (zero/affix/cl)	

The three terms on the Agreement Hierarchy match the lowerend of the pronominality scale, but as we have seen the agreement andpronominality do not have to be aligned. If there is no alignment, agreement has nopronominal effect (the case of Icelandic). When Align Pro-agr is sufficiently highly ranked, by contrast, it will determine for thelanguage in question at what point, if any, agreement and pronominalitycoalesce. Thus (10) subsumes the constraint hierarchy in (10'):

(10')	Align Pro-Agr (zero) » Align Pro-Agr (bound) » AlignPro-Agr (cl)

Interaction with faithfulness determines which parts of thehierarchy are expressed in overt linguistic form. In the same way, we can envisage that the presence of agreementis expressed by a constraint, which for the sake of argument we will dub'Realize Agr'. Languages may vary in the way they interleave this with thefiniteness hierarchy discussed in §3.7.3. A high rank for such a constraint would ensure that all verbsforms, finite and non-finite, bear agreement markers — an examplewould be Old Neapolitan — while a low rank would mean no overtagreement of any kind, as in Danish.
	The advantage ofthis kind of approach is that it captures the implicational structuring ofthe typological space that contains the possible systems. If a languagealigns the agreement hierarchy and the pronominal hierarchy at the cliticpoint then the two hierarchies will also be in alignment at all lower points. Thus, a clitic doubling systemsuch as River Plate Spanish will have pronominal Agr as well, whereasStandard Italian, which also has pronominal Agr does not have cliticagreement. The prediction therefore is that a language will not have clitic agreement combined with non-pronominalAgr; in other words clitic doubling would not be an option for a languagelike Icelandic even if it were to develop a clitic system. In the same way,the interleaving of the expression of agreement within the finiteness hierarchy would allow us to capture thetypological implication stated in Vincent (1998: 147) to the effect if alanguage has subject-verb agreement for non-finite forms, then it also hasit with finite forms, but not necessarily vice versa.
	The concept of alignment of hierarchies is further explored in Aissen(1998) and Artstein (1998), and forms the basis for the foregoingdiscussion. The key idea that emerges from their work is that whiledifferent hierarchies may align or interleave at different points in different languages, thus leading to typologicalvariation, the terms in the hierarchies may not shift their positionsrelative to each other. This is important since the fixedness of therelative values of the hierarchically organized items reflects a language external ontologicalpatterning which limits the nature of possible constraints and constraintinteractions. In this way we are enabled at one and the same time torespond to a frequent criticism of OT, namely‘What are the constraints on the constraints?’, and to embarkon the enterprise of grounding a formal model of grammar in conceptualcategories (see also below §3.7.2). 

3.6. Pronominals in Latin and Romance
Bresnan (1995, 1998) develops accounts of competition between different pronominal elements within the synchronicgrammars of different types of languages and in the genesis of pidgins andcreoles. A third obvious arena in which to test this model is provided bydiachronic changes in the form and function of pronominals. Here too it is natural to hypothesise that patterns ofgrammatical attrition and renewal should work themselves out as shifts inthe priority of individual candidates for morphosyntactic expression. Thehistorical developments which took place in the transition from Latin to modern Romance are a clear case inpoint. We shall look at two case histories. The first concerns thedifferential status of null arguments of finite verbs — ‘small pro’ — in Latin and Romance. The second involves the relation between thenon-overt subject of inflected and non-inflected infinitivals. In thissection we offer a pre-theoretical sketch of the data before developing aformal analysis in §3.7. 

3.6.1 Subject and object pro
As is well known, Latin is a classic (and classical!) null subject language, and the well described nullsubject properties of Italian, Spanish etc are, from a diachronicperspective, simply the continuation of this earlier state of affairs(which can in turn be reconstructed right back to Proto-Indo-European). French and the Northern Italian dialects, bycontrast, have in their different ways (M. Adams 1987, Vance 1997, Roberts1993a, Benincà 1994) innovated new systems of pronominal subject marking, which are insome sense a compensation for, but at the same time crucially not a direct replacement of, theloss of the Latin agreement morphology. We will seek to show how anOT-inspired approach can model both the continuity and discontinuityevident in such a diachronic profile.
	Less often called attention to than the null subject property of Latinsyntax is the fact that it also exhibits null objects (but cf van der Wurff1993, Luraghi 1997, Pieroni 1999). There is a striking difference from thenull subject cluster of effects in that Latin does not exhibit any system of verbal inflection which mightbe said to license null objects. By contrast, the Romance languages, all ofwhich exhibit systems of clitic pronouns unknown to Latin, systematicallyexclude null objects. Thus consider thefollowing ( (13) = (2), (14) = (20) in Luraghi (1997); (15) = (18) inPieroni (1999)):

(13)	senatus 			haeci					 intellegit, 
		senate.nomsg	this.neut.accpl	understand.3psg.pres
		consul 			Øi	videt										(Cic. Cat. 1.2)
		consul.nomsg		see.3psg.pres
		‘the Senate understands these things, the consul seesthem’

(14)	militesi				imperat; 				Øi	mittunt	(Caes BC 1.15)
		soldier.accpl	call-for.3psg.pres			send.3ppl.pres	
		‘he calls for soldiers; they send them/some’

(15)	“vinum”		inquit				“si	non	placet			
		wine.nomsg	say.3psg.pres	if		not	please.3sgpres
		Øi	mutabo”															(Petr 48.1)
				change.1sg.fut
		‘He said: “if the wine does not please (you) Iwill change it”’

The translation of (13) - (15) into any Romance languagewould require an explicit object in the second clause just as in theEnglish rendering given here. We will suggest that emergence of clitics andthe loss of object pro are related effects to be explained through a change in constraintpriority. In particular once a clitic system develops, object pro isautomatically lost.
	In the light of Cole’s (1987) typology of null objects, it isimportant to establish whether Latin null objects are genuine pronominalsor variables. Van der Wurff (1990) argues that they must be analysed as variables or as null resumptive pronouns, observing that the classictest for genuine object pro, namely null object in a strong cross-over context, does not go through.Looked at from another perspective, we can say that Latin has null objectsin contexts of high topic continuity (Pieroni 1999). This is the context inwhich Italian, for example, allows null subjects (Samek-Lodovici 1996) but crucially does not allow nullobjects. We thus get the following change (the categories refer to Bresnan’spronominal scale and ‘Romance’ stands for the early stages ofall Romance languages):

	(16)	latin	romance	
subject topics	bound					>	bound	
object topics	zero						>	clitic	

This is the first change that we will seek to model.		

3.6.2 Null subjects of non-finite forms
A standard result in modern syntactic theory is thatsubjects of infinitives are necessarily covert — ‘bigPRO’ — unless special factors intervene to license an overt subject. It is hardlysurprising therefore that both Latin and the Romancelanguages have control constructions. There are nonetheless a number ofsignificant differences in the syntax of infinitivals that need to beaccounted for. First, Latin allowed an infinitive to take an overt subjectin the accusative case. This AcI construction, which cannot be treated as a kind of Exceptional Case Marking sinceit occurs as the complement of adjectival and nominal predicates,disappears in the Romance languages except in learned syntax (Skytte 1978,Pountain 1998). Second control infinitives in Romance are introduced by a new class of overt infinitivalcomplementizers. Third, a number of Romance languages exhibit overtnominative subjects in so-called personal or inflected infinitiveconstructions, that is to say in contexts in which the infinitive may/must bear an overt person/number inflection. It is this third aspect which will be our principal concernhere.
	We display in (17) the paradigms of a number of theseinflected infinitives in different Romance languages:

(17)			Old Neapolitan						Portuguese
		SING			PLUR				SING			PLUR
	1	perdere			perderemo			comprar		comprarmos
	2	perdere			perderevo			comprares		comprardes
	3	perdere			perdereno			comprar		comprarem
				Sardinian								Galician
		SING			PLUR				SING			PLUR
	1	cantarepo		cantaremus		andar			andarmos
	2	cantares		cantaredzis		andares			andardes
	3	cantaret		cantaren			andar			andaren

The fact that Old Neapolitan (to which we can assimilatesporadic attestations in other Southern Italian dialects), Sardinian andPortuguese/Galician involve different patterns of morphological marking, both asregards distribution and form of the suffixes, suggests that these areindependent innovations. At the same time, distributional similaritiesacross the languages argue for a commonoriginal syntactic template. In particular, in all languages the inflectedinfinitive is not possible with complements of modals, causatives,perception verbs and subject-to-subjectraising verbs. 
	To see the contexts in which the inflected infinitivedoes occur consider the Sardinian examples (from Jones 1993) set out in(18):

(18)	a)		Juanne	nos	at						natu
				John		us	have.3sg.pres	tell.pstpr
				a			colàremus
				comp	call.inf.1pl
				‘John told us to call by’
		b)	Keljo				cantare		una	canthone
				want.1sg.pres	sing.inf	a		song	
				prima	de		sink’andaren
				before	comp	go away.inf.3pl
				‘I want to sing a song before they goaway’
		c)		Non	keljo				a			bi		vénneres			
				not	want.1sg.pres	comp	here	come.inf.2sg
				tue/*te
				you.nom/*acc
				‘I don’t want you to come’

Note that the construction is always a CP, as shown by theintroductory infinitival complementizers a and de; that the subject of the infinitival clause may differ from that of themain clause, and that an overt subject does not have to be present but thatif it is, then it must be nominative and not accusative.
	The examples in (19) from Portuguese (Raposo 1987)exhibit the same patterns:

(19)	a)		Eles			aprovarem			a		proposta	será
				they.nom	approve.inf.3pl	the	proposal	be.3sg.fut
				difícil
				hard
				‘It will be hard for them to approve theproposal

		b)	 Eles		estão			ansiosos
				they.nom	be.3pl.pres	anxious.pl
				de/por	votarem		a		proposta
				comp	vote.inf.3pl	the	proposal
				‘They are anxious to vote on the proposal’
		c) 	A		Mara	entrou 				em	casa 
				the	Mary	enter.3sg.pst	in		house
				sem			os meninos/eles				ouvirem
				without		the children/they.nom		hear.inf.3pl	
				‘Maria entered the house without the childrenhearing'

These constructions have nodirect precursor in Latin but are a Romance innovation. The question whichhas divided scholars is: which emergess first, the inflection or the overtnominative subject? The traditional answer is that the inflection camefirst since these forms derive from a finite series, namely the Latin imperfect subjunctive. This would also seem to be the answer most consistent with a licensingview of the function of agreement; you need the licenser before you canhave the licensee. The objections to this view are however that it does not explain the contexts in which the inflectedinfinitive occurs in the modern languages, that there is some historicalevidence for the overt subject being attested before the inflectedinfinitival forms (Maurer 1968), that a number ofareas have overt subjects with infinitives that do not have inflections(Cresti 1994, Lipski 1991, Jones 1993: 282 on the Sardinian dialect ofCampidanese), and that there are also attested inflected gerunds and participles, whichcannot possibly derive from Latin subjunctives. As examples of this latter category, consider (20).The (a) example is from Old Neapolitan (Vincent 1998) and the (b) examplefrom Algarve Portuguese (Coelho da Mota 1997: 342):

(20)	a)		vedendeno	li	Grieci 	tanta	copia 		de	cavalieri					see.ger.3pl	the	Greeks	such	quantity	of	knights		
				armati	…	fortemente	se maraviglyaro	de	la
				armed			greatly			wonder.pst.3pl	of	the							multetudene	loro
				multitude		them	
				‘When the Greeks saw somany armed knights, they (=the 						Greeks) weretruly amazed at the multitude thereof’
		
			b)	tu				querendos,		podemos		namorar
					you.nom 	want.ger.2psg	can.3pl.pst 	court.inf
					‘if you want, we can go outtogether’

Given the fact that the geographical distribution of the inflected gerundas exemplified in (20) is more restricted than that of the inflectedinfinitive, and is only attested in dialects which also have the latter, weshall conclude that the spread of the person endings to the gerund is later than to the infinitive (cf already Loporcaro 1986 for this same view). There thus appears to be an analogical generalization of the person inflections first from the finite forms to the infinitive and thence to the gerund.

3.7 Modelling the changes
3.7.1. The diachrony of object pronominals from Latin to Romance
Recall that null objects in Latin are topical (Pieroni1999). Thus to describe the Latin situation we need to provide a constraintranking such that the input [PRO, TOP] is expressed by zero (since there isno object agreement morphology of any kind). The required ranking is set out in TableauIV. 

Input	[PRO,TOP, OBJ]			harm	*af [PRO]	faith	*Ø [PRO]	
+	Zero:		[PRO, TOP]						*	
		Bound:[PRO, TOP, AGR]				*!			
		Pronoun:	[PRO, AGR]						*!		
Tableau IV							

Latin null objects are like Italian (and Latin) nullsubjects except that the structural markedness constraint that falls belowfaith is the one which forbids zero being associated with pronominal content. Inother words, Latin is prepared to envisage a violation of the iconicity constraint (4b). The situation in Italian and otherRomance languages requires instead the constraint ranking established inTableau V. 

Input	[PRO,TOP, OBJ]			harm	*Ø ~ af [PRO]
iconicity	faith	*cl [PRO]

allotaxy	
		Zero:		[PRO, TOP]				*!			
+	Bound:[PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau V							

Italian objects are like Italian subjects; they have to beencoded and this is done by a clitic pronoun. Assuming clitics aredifferent from affixes, this means the downgrading of a different member ofthe set of struct constraints to a position below faith. In this instance,the iconicity constraints are respected but the allotaxy ones areviolated.
	The foregoing analysis works within the systemproposed in Bresnan (1998). However a comparison of Tableau IV with TableauII reveals that the constraints *∆[PRO] and *af [PRO] have been reversed in their priority. It is exactly this kind ofreversal which is outlawed in the hierarchical approach to constraintranking developed by Aissen (1998) and Artstein (1998), and discussedbriefly in §3.5 (cf also footnote 18). We must leave it for the moment as an openquestion whether these data are a counterexample to such an approach or, asseems more probable, further research will find a way of reconciling thetwo. Under either approach,change is modelled as a shifting in constraint rankings, and morespecifically in those drawn from the set defined in (4) above as structuralmarkedness constraints. This is all well and goodbut still leaves open the question as to why such a re-ranking shouldoccur. What drives this change? Our answer is the independent developmentof a clitic pronoun system in Romance (Vincent 1997). This means that whenit comes to encoding a particular content — in the present instance that of pronominal object topic— there is a better, more iconic in the sense of (4) above,candidate available in the Romance languages than there was in Latin. 

3.7.2 A role for grammaticalization
If we assume with Bresnan a universal initial state withthe ranking Harmony » Structure	»	Faithfulness, then alternative rankings must be driven by exposure to data. How couldthis arise? Note that the hierarchy of markedness above reflects theuniversal patterns attested in studies of grammaticalization (Hopper &Traugott 1993: Ch 6). Let us assume that these patterns of grammaticalization reflect universal semantic potentialsdefinable in terms of a cognitive space which encompasses grammaticizabledomains like tense, number, pronominality, definiteness, etc. There is an analogy here with the waysound changes reflect universal phonetic potentials definable over theparameters that govern the working of the vocal tract. We can thenpostulate a potential for semantic drift external to the grammatical system leading to a grammatical change just asphonetic drift leads to phonological change (Ohala 1993). Hence just as theoperation of a sound change may obscure a previously motivated phonologicalalternation — the creation of new phonemes out of the originally allophonic products ofGerman umlaut is the textbook example — so the effect of a morphophonemic change, namely the emergence of clitics,may inadvertently as it were remove the availability of a previouslyavailable structure: a kind of diachronic emergence of the unmarked. The mechanisms ofgrammar, that is to say the constraint rankings, then encode the outcome ofthese changes for the next generation.
	If a scenario of this kind is on the right lines, itprovides an interesting alternative to a commonly held view of change ingenerative grammar. Consider the following remark by Longobardi (1996: 2):“… outside phonological change, linguistic systems are in principlediachronically inert, unless some specifically motivated conditionsapply.” There is a remarkable similarity between this view andthe Neogrammarian insistence on the ‘blindness’ of sound change, which has long been known tooversimplify, indeed falsify, the relation between phonological andgrammatical change (see Harris 1978 for an effective diagnosis of the problem). The model ofchange as constraint re-ranking that we have adumbrated here offers analternative approach. I would rather adapt Longobardi’s remark bysaying “outside phonetic and semantic change”, subsuming grammaticalization under the latter but not treating it as asubstitute for a formal syntactic theory, here modelled as a set ofOT-style constraints. Research in grammaticalization would then be acontribution to mapping out the space within which grammars of particular languages can be stated, but it would not obviatethe need for such grammars (pace Bybee et al 1994: 1). This wouldalso be consistent with the view expressed by Aissen (1998: 11):
“The ranking of constraints in a subhierarchy is universally fixed, andexpresses the universal markedness relations in this domain.Language-particular variation can be described through the interpolation ofother constraints among those in a subhierarchy, but not through differences in ranking within the subhierarchyitself.” 

We turn now to our second change which will show a rolewithin OT for that other classic weapon from the nineteenth-centuryarmoury, namely analogy.

3.7.3 The diachrony of the personal infinitive/gerund
Following the discussion in §3.6.2, we will assume that the right historical chronology is that firstovert subjects are possible in infinitival and gerundival constructions andsecond that the inflectional morphology extends its domain to encode thatfact. We can achieve this end by refining our account of the StructuralMarkedness Constraint labelled in §3.4 *af [PRO], whose effect was to ban structures in which pronominality wasencoded via affixes as a violation of iconicity. Instead of taking this asa single constraint we will treat it as a family of constraints applying tothe whole range of possible verb forms. If the direction of spread is as in (21) then we will need theconstraint hierachy in (22):

(21)			 finite forms		>		 infinitive			>		gerund

(22)			*af [PRO]ger		»		*af[PRO]inf		»		*af [PRO]fin

Thus, (22) says that a violation of the ban on affixes attached to gerundsis worse than violating the ban on infinitival inflection which in turn isworse than violating the ban on finite inflection. Tableau II above, whichpermitted bound inflection to express pronominality — the classic pro-drop effect — inLatin,  should in this more refined system be replaced by Tableau II’:

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]fin	
		Zero:		[PRO, TOP]				*!			
+	Bound: [PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II’							

The grammar of an innovating language such as Portuguese orSardinian can then be represented as in Tableau II’’, whereboth the infinitival and finite members of the family have fallen below thefaith.

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]f/i	
		Zero:		[PRO, TOP]				*!			
+	Bound: [PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II’’							

 In the extreme case, where all the members of the*af [PRO] constraint family have fallen below faith, the grammar will then license the full portfolio of inflected forms andtheir pronominal arguments found in Old Neapolitan and some Algarvedialects of modern Portuguese. Thus:

Input	[PRO,TOP]			harm	*Ø [PRO]	faith	*af [PRO]f/i/g	
		Zero:		[PRO, TOP]				*!			
+	Bound: [PRO, TOP, AGR]						*	
		Pronoun:	[PRO, AGR]						*!		
Tableau II’’’							

Notice once again that this account makes a quite clearprediction, namely that one will not find languages with an inflected gerund and inflected finite forms but no inflected infinitives. There arethus constraints on the constraints (Grimshaw 1998), namely that they mustnot violate the universally definable and hierachically organized space ofpossible grammars. It is not a consequence of OT that anything in the world can count as a constraint,despite persistent malicious and ill-informed gossip to the contrary!

3.7.4 A role for analogy
Just as in accounting for the replacement of null objectsby clitics we found a role for the traditional concept of grammaticalization, so the use of an orderedprogression through the members of a family of constraints may be thoughtof as the OT analogue of the traditional concept of ‘analogicalextension’. Thus, once again the constraint hierarchy models the structure of the domain, in the present instance the clinefrom finite to infinitive, and the re-ranking of the constraints reflectsthe direction of the analogical shifts. In this sense, the model proposedhere follows the logic of Kury∏owicz’s (1949) classic intervention, suggesting that the directionality ofanalogical change is (at least in part) predictable from considerations ofmarkedness. Like him, we do not propose a predictive account of whenanalogy may take place, but only of the direction in which will move if it occurs. We may also recall Meillet’s (1912: 131) observation that analogy and grammaticalization exhaust thepossible types of morphosyntactic change. What the present account seeks todo is to use OT as a way of conceptualizing the relation between analogy, grammaticalization and the internalmechanisms of grammar.

3.8 Lessons for a theory of syntactic change
In this section we reflect on the theoretical lessons that can be learnedfrom the account of the Latin-Romance data presented above. There we haveemphasised two general concepts: competition and correspondence. Let usconsider the diachronic implications of each in turn. 

3.8.1 Why a competition-based account is superior to an absolutistone
The intuition behind a competition-based model of a synchronic system is that thegrammaticality of a given structure is precarious: it is always potentiallythreatened by the other universally available competitors, which are onlykept at bay by the language particular constraint ranking operative at that point in time and space. Any change in thatranking would force a different solution to the ever-present problem thatlanguages (and language users) face: how to match form and content toexpress the intended meaning withinthe resources available. Historical linguists, of course, have alwaysemphasised the notion of competition between forms as the basis of change.For instance, Hopper & Traugott (1993: 123) write: ‘Rather than replace a lost or almost lost distinction, newly innovatedforms compete with older ones … this competition allows, even encouragesthe recession or loss of older forms’. The same point is also madeby Kroch (1992: 113): ‘Languages at any synchronic moment of their existence may be seen assystems of competing forms’, who goes on to note that ‘quiteabstract linguistic subsystems, not just isolated forms, may be theelements in competition.’ Standard derivational frameworks model this sort of scenario rather badly;they frequently provide neat and elegant accounts of given synchronic states expressed as the interaction ofuniversal principles and the individual values of particular parameters(Lightfoot 1991; Roberts 1993a). They do not however readily extend toinclude in the picture the notion of alternative solutions waiting, so to speak, in the grammatical wings.Kroch’s original answer to this was to envisage the speaker’s competence as containing internally competing grammars (Kroch 1989). Theproblem with this approach is that every time a new setof competing forms are identified within a language, a new set of parallelgrammars will have to be postulated. Such proliferation of grammarsinvolves taking a very powerful hammer to crack the variationist nut.  Morerecently, Kroch (1995) has suggestedthat the competition is between alternative functional heads. Following upthis line of argument, Pintzuk (1998: 123) observes: ‘If we characterize the difference between OV and VO languages in terms offeatures of grammatical formatives, the source of the variation is not the order within the VP but rather the directionalityfeature of some functional head. Contra our original assumptions, thisentails that all non-finite verbs move out of the VP to the head of ahigher functional projection, one that is distinct from I or its components, and that the directionality feature ofthis functional head is undergoing change’. Proliferation of grammars is replaced by proliferation of functionalheads. However, whereas many functional heads have both overt form and morphosyntactic content, and are indeed the result of processes ofgrammatialization (Vincent 1993), the heads being postulated here are emptyand distinct from the items with grammatical content (‘I and itscomponents’); they are simply a way of encoding word order variation into a syntactic configuration. Word order and wordorder changes are not reduced to independently available functional headsas proposed for example in Roberts (1997), but are restated in terms ofspecially invented and otherwise unmotivated new heads. These heads are the Last Resort solution, as envisagedunder the Minimalist Program (Chomsky 1995, Lasnik 1999: Ch 6), to thederivation of the required structure, while still respecting the universalrequirement of Economy (Chomsky 1995: Ch 2).  With no restriction on the number and type of functional heads,however, this approach runs a clear risk of unfalsifiability (Börjars,Payne & Chisarik 1999).
	The insight that functional heads are the end product of processes ofgrammaticalization (Vincent 1993) certainly seems worth preserving. At thesame time it is necessary to counter the standard objection togrammaticalization theory from those within the formalist tradition — and it appears to me a very substantial and forceful objection — namely, that it is conducted in an intuitionistic way with too strong afaith in a direct correlation between linguistic form and meaning andfunction (Croft 1995, Newmeyer 1998). It does not allow enough space forfunctionally arbitrary synchronic structure, for the presence of language universals not driven by functionalneeds, and crucially it does not provide any means of modelling linguisticstructure in a way that allows the consequences of particular shifts to becomputed across the rest of the system. In that sense it seems wilfully to discard the achievements of morethan half a century of formal linguistics, both structuralist andgenerativist (cf Bybee et al 1994; 1). This metaphysical stance has made it all too easy for generativetheorists of language change such as Lightfoot (1991, 1999) to ignorerather than confront the evidence of grammaticalization (though see Roberts1993b for an honourable exception). Yet the evidence needs to be confronted. Grammaticalization chains orpaths seem to bereal and recurrent phenomena in the histories of natural languages, and assuch constitute a genuine empirical challenge to the stepwise, abductiveand potentially reversible view of change that typifies work in thegenerative tradition. They are the diachronic counterpart of the morphosyntactic hierarchies discussed above.
	In the present paper I have sought to argue that anOT-inspired interpretation of grammatical change provides the means toachieve a much needed reconciliation of the two approaches: we can model, as precisely and computably as necessary, both the structuralproperties of individual systems and their interaction with universallyavailable and hierarchically organized (hence potentially directional)dimensions of change. In particular, by requiring that constraints be grounded in finite systems of independentlydefinable grammatical primitives, we can avoid the charge that OT simplyreplaces an infinite set of functional heads with an infinite set ofconstraints. The difference is that, as I have tried to show here, a finite constraint domain plus the notion ofre-ranking can capture the required effects, whereas a derivationalmovement-based model seems doomed to spawn potentially limitless numbers offunctional heads to achieve the same ends.

3.8.2 Why a correspondence model is preferable to a derivational one
The last section sketches an argument for the correctnessof the competition-based account of change that the OT vision imposes. Atthe same time, in the data we have discussed andthe model we have adopted, another concept has been fundamental, namelythat the relation between linguistic form and content should be based oncorrespondence and not on derivation. What is the justification for thisassumption? As we have noted, correspondence depends on the idea that the structure of sub-domains of thelinguistic system reflects the natural categories and primitives of thedomain in question; there is no a priori reason to believe that the form of representation most appropriate tophonology, for example, will generalize to syntax, or that what is naturalin semantics is equally natural in morphology. In particular, morphologicalstructure does not have to be‘syntacticized’ and represented as an X-bar tree, and emptycategories or zeros(whether morphological or syntactic) do not have to be postulated simply inorder to ensure that form corresponds to content. Historically this meansthat the input can be the same — in the material discussed hereconstellations of [PRO, TOP, AGR]— even when its realization can vary over time from morphological tosyntactic and back again. 

3.9 Conclusion
In this paper I hope to have shown three things. First, and most directly,I have demonstrated that the OT-inspired account of pronominals and theircross-linguistic markedness relations offered in Bresnan (1998b) can beapplied in a simple and elegant way to the diachronic data presented by some of the changes in the patterns ofargument marking between Latin and Romance. Second, I have argued that suchan account provides answers to puzzles that had previously eluded solution,and to that extent offers a genuine conceptual advance over — andnot just a simple reformulation of — earlier treatments, both those which were philological and those whichwere theoretical linguistic in inspiration. Third, I have sought to showthat the best account of the data in question crucially involves both the notions of competition and correspondence. In addition, via theparallel correspondence type of architecture linked to competition, we havea way to incorporate the insights of grammaticalization, which — pace Lightfoot (1999) and Newmeyer (1998) — are real and important, without forsaking formalizability or incurring thepenalty of teleology. To the extent that all these notions only converge inan LFG type of architecture under an OT interpretation as developed by Bresnan (1997, 1998a,b), I believe I have in turn provided a furtherand original line of argumentation in favour of this approach to linguisticinquiry in general, whether synchronic or diachronic. 

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