1 Introduction

It has become exceedingly common in contemporary linguistic theorizing to come across claims of the following sort: “It may appear that verbs in language L do not agree with their arguments, but that is just an arbitrary fact about the morpho-phonology of L. In other words, the relevant exponents in L just happen to lack segmental content. Syntactically, agreement is operative in L just as it would be in a morphologically richer language.” I will refer to this type of analysis as abstract agreement, by analogy with abstract case (Vergnaud 1977; Chomsky 1981). For a representative example of an analysis that resorts to abstract agreement, see Chomsky (2000: 123ff.) on supposed agreement between v and the direct object in English.

The primary goal of this paper is to show that when it comes to agreement in φ-features (PERSON, NUMBER, GENDER/NOUN-CLASS), this type of reasoning is almost always mistaken. I will show that, generally speaking, there is no such thing as abstract agreement; φ-feature agreement is only there when you can see it.

Until quite recently, the existence of abstract agreement would have seemed inevitable, as a consequence of the following widely held premises:

Taken together, these premises entailed that any noun phrase that could not plausibly be analyzed as a bearer of inherent case had to be the target of an agreement relation; and insofar as there was no morpho-phonological evidence of such a relation (as is the case with, e.g., direct objects in English), abstract agreement had to be at play.

By now, however, it has become quite clear that neither (1a) nor (1b) is correct.¹ The case-theoretic underpinnings of abstract agreement have therefore faded away, rendering its existence ripe for re-evaluation.

In the course of this investigation, we will encounter one notable exception to the generalization that there is no abstract agreement. This exception involves the agreement relation that prefigures clitic doubling. Following Rezac (2008a); Roberts (2010), a.o., I take clitic doubling to be an instance of syntactic movement. We will see that syntactic movement is not generally dependent on a prior agreement relation (contra Chomsky 2000, et seq.; see section 6.2). To explain why clitic doubling in particular does require a prior agreement relation, I will offer a novel perspective on the interaction of locality, head movement, phrasal movement, and the Principle of Minimal Compliance (Richards 1998; 2001).

The aforementioned clitic-doubling exception also means that the ban on abstract agreement is unlikely to have the status of a steadfast principle of grammar. I will suggest, instead, that these facts may arise by way of a conservative acquisition strategy with respect to the placement of unvalued φ-features on functional heads.

2 A note on terminology

In the context of this paper, the term agreement refers to transmission of φ-feature values (PERSON, NUMBER, GENDER/NOUN-CLASS) from a noun phrase to a functional head.

Recent years have seen a flurry of putative reductions-to-agreement: attempts to reduce various other linguistic phenomena to the same formal operation hypothesized to underpin agreement. Examples include: Binding Theory and fake indexicals (Kratzer 2009; Reuland 2011; Rooryck & Vanden Wyngaerd 2011), negative concord (Zeijlstra 2004; 2008b), modal concord (Zeijlstra 2008a), noun-modifier concord (Mallen 1997; Carstens 2000; Baker 2008), and the formation of in-situ questions (Bobaljik & Wurmbrand 2014). These reductions are not the primary focus of this paper; though if the paper’s conclusions are correct, they cast considerable doubt on the veracity of some of these reductions—in particular, those that avail themselves of abstract agreement in φ-features (see also section 8).

3 A short primer on the Person Case Constraint (PCC)

The argument I will present in sections 4–5 against abstract agreement is based on the distribution of Person Case Constraint (PCC) effects. Therefore, I will begin with a primer on the PCC itself.

The PCC (also known as the “*me-lui Constraint”) is a restriction governing the PERSON features of different arguments in relation to one another, usually affecting combinations of multiple internal arguments of a single predicate. It is therefore most commonly found with ditransitive verbs. It is demonstrated here using data from Basque.

As a first approximation, the PCC in Basque can be characterized as in (2):

The consequences of (2) are illustrated in (3a–b):

The examples in (3a–b) involve the same verb, with the same argument structure, but with a different combination of arguments in each case. In (3a), the direct object (liburu-a ‘book-ART.SG.(ABS)’) is 3rd person, and the indirect object (niri ‘me.DAT’) is 1st person. In (3b), on the other hand, it is the direct object (ni ‘me(ABS)’) that is 1st person. Thus, (3b) stands in violation of (2), rendering the sentence ungrammatical; but (3a) does not, and is well-formed.

As (3a–b) already illustrate, the PCC is fundamentally asymmetric: it restricts the PERSON features of the direct object in the presence of an indirect object, but there is no corresponding restriction limiting the PERSON features of the indirect object in the presence of a direct object. The PCC is asymmetric in another way: it restricts only the PERSON features of the relevant argument—and not, for example, its NUMBER features. As Nevins (2011: 944) puts it, there is no Number Case Constraint.

Another noteworthy property of the PCC is that it seems to only arise when there is overt morphology reflecting φ-agreement with the relevant arguments. This has led some to view the PCC as a morphological filter (see, e.g., Bonet 1991; 1994). I return to this point in section 5.

This pattern, demonstrated in Basque, is one of a family of effects documented in the literature that have been referred to as “PCC effects.” Scholars distinguish (2), which has been referred to as the Strong variant of the effect, from the Weak, Me-First, Total, Super-Strong, and Ultra-Strong varieties. (The latter is also known as Strictly-Descending, and is a conjunction of the Weak and Me-First varieties.) See Haspelmath (2004); Anagnostopoulou (2005); Nevins (2007); Graf (2012); Sturgeon et al. (2012); Doliana (2014), for discussion. Of course, referring to all of these as PCC effects is a terminological choice; the extent to which they represent a unitary phenomenon is a matter of analysis. For example, the so-called “Total PCC” is just a prohibition on any combination of two weak pronominal objects, and as such may just be a matter of prosody. For the remainder of this paper, I will assume that at least those variants that are sensitive to PERSON features (i.e., all but the Total variant) can be treated as a unitary phenomenon at a sufficient level of abstraction (see also section 4).

4 The PCC is syntactic

As noted above, the PCC is sometimes thought of as a morphological effect. However, Albizu (1997) and Rezac (2008b) show that it is in fact syntactic in nature. They do so by examining two-place unaccusatives in Basque: verbs that take an absolutive argument and a dative argument, but no ergative argument (what Rezac refers to as applicative unaccusatives). It turns out that there are two classes of these verbs in Basque: those where the dative argument c-commands its absolutive co-argument (DAT≫ABS), and those where the structural relations are reversed (ABS≫DAT). This is demonstrated below using reflexive binding:

Note that the order of the absolutive and dative arguments of two-place unaccusatives in Basque is relatively free. Thus, as (6) shows, there is nothing intrinsically wrong with the absolutive-before-dative order of arguments in (4b). The arguments in examples like (4b, 5a) simply occur in the order that would give the example its best chance at acceptability, given the general dispreference for cataphora.

The state of affairs in (4–5) is crucially different from what one finds with true, three-place ditransitives in Basque, which always adhere to an ERG≫DAT≫ABS structure (Elordieta 2001; Rezac 2008a). Importantly, among two-place unaccusatives, only those that exhibit DAT≫ABS behavior show PCC effects. Compare (7), on the one hand, with (8b), on the other. (While (5a) and (7) involve different verbs, they both belong to the class of two-place unaccusatives of motion, all of which are ABS≫DAT verbs; see Rezac 2008b: 72.)

The putative target form of the finite auxiliary in the ungrammatical (8b) is identical to the one in the grammatical (7). This is not merely phonological identity, but morphological identity: the two express the same set of associations between φ-features and case, {ABS:1SG, DAT:3SG}.

These facts have several consequences. First, they show that at least in Basque, the effect in (2) (the PCC in ditransitives) is actually a subcase of a slightly broader pattern:

Because ditransitives in Basque always adhere to a ERG≫DAT≫ABS structural hierarchy, the effect described in (2) is derivable as a special case of (9).

Second, these data show that the effect in question cannot be a morphological filter: the putative auxiliary form in (8b) is morphologically identical to the one in (7). Either the form in question is morphologically licit (in which case the wrong prediction is made for (8b)), or it is not (in which case the wrong prediction is made for (7)). Insofar as there is a meaningful distinction between syntax and morphology, the finer hierarchical organization of arguments relative to one another—which is what distinguishes these two cases—is the purview of syntax, not morphology.

We could, of course, endow one of the datives in (7–8) with a diacritic that is missing on the other, and grant morphology access to this diacritic in evaluating PCC violations. But since there are no actual differences in the morphology between the two types of datives (neither in dependent-marking nor in head-marking), this would amount to a restatement of the problem faced by morphological analyses of the PCC, not a solution to it. And it would make the correlation with structural asymmetries (4–5) accidental (cf. the syntactic analysis, surveyed below).

An alternative would be to grant morphology access to finer structural distinctions of the sort shown in (4–5). It seems to me, however, that this would stand in rather blatant violation of the point of modularizing the grammar in the first place. We could therefore rephrase the point being made here as follows: either the PCC is syntactic in nature, or else there is no meaningful distinction between syntax and morphology qua grammatical modules—in which case we could still say that the PCC is syntactic, without any loss of generality.

The same results rule out accounts of the PCC in terms of usage-based grammaticalization (cf. Haspelmath 2004). These rely on the idea that configurations involving 1st/2nd person animate direct objects together with indirect objects are exceedingly rare in naturally-occurring data; and thus, the relevant morphological combinations fail to undergo grammaticalization. As (7) demonstrates, the target form in (8b) is in no way missing from the grammatical vocabulary of the language, therefore this cannot be the source of ill-formedness in (8b).

How, then, does the PCC arise in syntax? And why is it sensitive to the structural hierarchy of internal arguments, in the manner shown above (i.e., DAT≫ABS versus ABS≫DAT)? A body of work by Anagnostopoulou (2003; 2005), Béjar & Rezac (2003), Nevins (2007), and others, has already provided the answer to these questions. The remainder of this section is devoted to summarizing, by way of example, Béjar & Rezac’s (2003) proposal—and showing how it derives the PCC in a way that is sensitive to structural hierarchy.

Before proceeding, it is worth pointing out that the Béjar & Rezac account is specifically tailored to derive the Strong PCC, and it is not immediately clear to what extent it can be modified to account for other variants of the PCC (see section 3). However, as will become clear shortly, the only part of the account that is crucial to what follows is that the PCC arises as the result of how minimality applies to syntactic agreement (cf. Nevins 2007 for an alternative account, which extends to other PCC variants, but still depends crucially on how syntactic agreement interacts with minimality). Béjar & Rezac’s account is therefore intended, in the present context, as a representative example of the broader family of minimality-based approaches to the PCC.

Let us first consider monotransitives and unaccusative intransitives—configurations where there is only one non-oblique internal argument.² In this scenario, a probe seeking valued φ-features will reach the internal argument without impediment:

This will give rise to what one would typically call “object agreement morphology.”

Adding a dative co-argument to (10) located lower than the other DP will not affect φ-probing, since minimality dictates that the closer of the two will be targeted:

However, adding a dative co-argument to (10) that is located higher than the other DP will result in intervention, and the disruption of φ-probing:

(On dative intervention, as well as the more general inability of dative nominals to satisfy probing for φ-feature values, see Preminger 2014: 129–175 and references therein.)

We now add one final ingredient, the Person Licensing Condition (Preminger 2011b: 930–934; cf. Nichols 2001; Béjar & Rezac 2003; Bruening 2005; Baker 2008, a.o.):

The term canonical agreement target in (13) is defined as follows:

Together, (13) and (14) predict that a 1st/2nd person non-oblique internal argument in a DAT≫ABS structure like (12) will be illicit, because its [participant] feature will fail to participate in a valuation relation with the φ-probe. In contrast, a non-oblique internal argument will be licit regardless of its person features in the other two structures (10–11)—because in those cases, the φ-probe can access this argument.⁴

The result is precisely the effect exemplified using the two types of two-place unaccusatives in (4–5, 7–8), and summarized in (9).

There is a tantalizingly simpler version of the PLC, which has been put forth in the literature (see, e.g., Baker 2008: 126–150, Béjar & Rezac 2003: 53, a.o.; cf. Nichols 2001: 525–526), which can be stated as follows: a [participant] feature on a DP must participate in a valuation relation. This simpler formulation has proven inadequate, however. As Preminger 2011b has shown, [participant]-bearing nominals are able to occur in positions that could not have been targeted for agreement. In Basque, for example, the absolutive argument of a ditransitive can be 1st/2nd person, provided that the clause is not one in which agreement is observed:

This is so despite the fact that dative arguments are higher than their absolutive co-arguments in ditransitives like saldu (‘sell’) (Elordieta 2001), and that non-clitic-doubled datives are interveners for agreement in Basque (Preminger 2009). In other words, the [participant] feature on the absolutive argument in the embedded clause in (15) could not have possibly participated in a valuation relation; and yet no PLC violation arises. The same can likely be said for 1st/2nd person nominative arguments in certain embedded infinitives in Icelandic (Preminger 2011b: 932).

This means that the PLC cannot be reduced to properties of the φ-probe or the goal DP unto themselves; instead, it must be viewed as a relational or processual requirement. There was at one point a prominent hypothesis, embodied in Chomsky’s (2000; 2001) uninterpretable features system, which stated that constraints like the PLC should always be reducible to a representational property of one (or both) of the elements under consideration. As Preminger (2014) has shown, however, this hypothesis is false: even the obligatoriness of regular φ-agreement cannot, in the general case, be reduced to properties of the probe and/or the goal alone, and must instead be thought of as a relational or processual requirement (Preminger 2014: 85–100). The PLC, as formulated in (13–14), is just one more such case.

Before concluding, let me address a putative alternative view of these results. Suppose that we were to concede everything stated in this section so far, but insist that the Person Licensing Condition was itself a morphological filter: the requirement would not be that [participant] on a DP participate in a (syntactic) valuation relation—but rather that, if the verb is capable of reflecting agreement morphology, 1st/2nd person morphology on a DP must be reflected on the verb. The factors determining whether agreement with the non-oblique DP did or did not occur would still be syntactic, but the constraint responsible for the PCC would operate in the morphological component.

The problem with such a view is, again, that it flies in the face of what the separation of syntax from morphology is supposed to accomplish, in the first place. Note that the PLC can be satisfied at arbitrary linear and structural distance, as far as the representation handed off from syntax to morphology is concerned; that’s because the nominal targeted by the φ-probe can subsequently undergo movement to an arbitrarily distant position:

Importantly, this is not just an artifact of the PLC as a theoretical construct. Basque, for example, allows scrambling of DP arguments, and thus, the DPs involved in PCC effects in Basque can be arbitrarily far away from the finite verb or auxiliary which hosts the relevant morphology.

While there have been recent proposals that allow morphology to traffic in objects like chains, copies, traces, etc. (cf. Marantz 1991; Bobaljik 2008), modular separation should entail some difference in the sets of primitives available to each module. That is not to say that the two sets should be disjoint: there must be some overlap in the primitives of syntax and morphology, otherwise the output of one would be wholly illegible to the other. Heads and their features seem like good candidates to fill this role of “shared vocabulary” between syntax and morphology. But if there was ever a candidate for a primitive that is syntactic but not morphological, it would be the chains/copies/etc. formed by syntactic movement. Consequently, insofar as there is any meaningful distinction between syntax and morphology, relations like those in (16)—those that can cross arbitrary linear and structural distances—should be the purview of syntax and not of morphology.

There is no adequate morphological implementation of the PLC, then, in any meaningful sense of the term. And because the PLC is necessary to derive the kind of hierarchy-sensitive PCC effects surveyed here, there is no viable account of the PCC that is truly morphological, either.

5 The sensitivity of the PCC to the overtness of agreement morphology, and the consequences of this sensitivity

As briefly noted in section 3, the PCC is known to be restricted to those environments where overt φ-feature agreement with internal arguments is found. (The term overt φ-feature agreement is meant descriptively, and collapses φ-agreement together with clitic doubling. This distinction, and its consequences, are the topic of section 6.)

As an example, consider Hebrew ditransitives. In Hebrew, when the dative argument precedes the accusative(=non-oblique) one, the dative is the hierarchically higher of the two arguments (Landau 1994; Preminger 2006). This is demonstrated in (17), where gender is used to disambiguate the antecedent of the bound reflexive:

Thus, dative-first ditransitives in Hebrew show the same hierarchical order of internal arguments as their Basque counterparts in (3). However, Hebrew lacks overt agreement with internal arguments; accordingly, no PCC effects arise, as shown in (18). (There is, of course, overt φ-agreement with the subject in (18); but that is irrelevant to the distribution of PCC effects among multiple internal arguments of, e.g., a ditransitive verb.)

This is an example of how the PCC covaries with the presence of overt agreement morphology cross-linguistically. But the same is true intra-linguistically, as well. Consider the PCC-violating Basque sentence in (19), repeated from (3b):

This example, demonstrating the PCC, involves a finite clause—an environment which, in Basque, is associated with overt φ-agreement morphology. In contrast, non-finite environments in Basque, including nominalizations, exhibit no φ-agreement morphology—and in particular, no overt agreement with the internal arguments. Crucially, if we take the same verb with the very same combination of arguments, and place it in such an environment, PCC effects disappear. This can be seen in (20), repeated from (15):⁵

Note that this is a fact about overt agreement morphology, not a fact about finiteness. We can see this by comparing Basque to Spanish, for example. Spanish also exhibits overt agreement morphology reflecting the φ-features of internal arguments (or more precisely, it has internal argument clitics; see section 6 for further discussion). But unlike Basque, Spanish infinitives retain this agreement morphology. Accordingly, in Spanish, the PCC persists even in infinitives:

It has been claimed that some languages that lack overt agreement with internal arguments—notably, English and Swiss German—nevertheless show PCC effects when only weak pronouns are involved (Bonet 1991; Haspelmath 2004; see also Anagnostopoulou 2008). It is worth noting, however, that the judgments in these languages that purport to differentiate sentences with 1st/2nd person weak-pronoun Themes from their 3rd person counterparts are quite subtle (as is sometimes acknowledged in the literature on this topic). This seems quite distinct from the PCC effects in (19, 21a–b), for example, which give rise to very clear judgments.⁶ Moreover, a sensitivity to the strong vs. weak pronoun distinction would be somewhat unexpected were the English and Swiss German facts of a piece with the other PCC facts discussed here. The reason is as follows: while it is true that in some languages, the use of strong pronouns ameliorates PCC effects that would have arisen with their weak-pronoun counterparts, this amelioration seems to be associated with the addition of a PP, or similar oblique structure, around the pronouns in question. This is overtly discernible in French and Spanish, for example. In languages where there is no such structure around strong pronouns, as in Basque (and Icelandic; see fn. 5), the strong vs. weak distinction does not seem to affect the PCC.⁷ Now, crucially, both English and Swiss German are like Basque in lacking any discernible oblique structure around strong pronouns. The fact that the relevant effect in English and Swiss German is nevertheless sensitive to the strong vs. weak pronoun distinction suggests that it is of a different sort—namely, something about the licensing conditions on weak pronouns in these languages. I therefore conclude that it is a reasonable move to tentatively exclude these cases from the empirical domain that falls under the heading of “PCC effects” (at least as it is applied to cases like (3b, 21a–b)).

In sum, real PCC effects seem to come and go along with overt φ-agreement with internal arguments, both cross- and intra-linguistically. Let us now juxtapose these facts with the results in section 4. As noted earlier, this sensitivity of the PCC to overtness was a central motivation for the view of the PCC as a morphological filter; but the results of section 4 render such an approach untenable. What we have in the PCC, then, is a syntactic effect par excellence, which nevertheless only arises in the presence of overt agreement morphology. This immediately raises the following question: How can something in narrow syntax be sensitive to the overtness of agreement morphology?

As best I can tell, the only possible answer that maintains the modularity of syntax vs. morpho-phonology is that the mechanisms of agreement and dative intervention, which are implicated in the PCC, are only in place when we can see them. To put this another way, there is no such thing as “null agreement.” Importantly, this refers to agreement that is null across the entire paradigm; there is of course no prohibition against particular cells being null in what is otherwise an overt paradigm, as the PCC still arises when agreement with internal arguments has some null cells but is otherwise overt.

Thus, the PCC goes away in the absence of overt agreement morphology—e.g., in Hebrew, and in non-finite clauses in Basque—not because it is a morphological filter. (We already saw in section 4 that it cannot be a morphological filter.) It goes away because in the absence of overt agreement morphology, there is simply no agreement there in the syntax. Not even “abstract” agreement.

I will refer to this as the no-null-agreement generalization:⁸

I label this a generalization rather than a principle, for reasons that will become apparent in section 7.

6 The clitic-doubling caveat

In describing the distribution of PCC effects in section 5, I abstracted away from an important detail: the distinction between φ-agreement in the narrow sense, and clitic doubling. To accurately capture the intra- and cross-linguistic distribution of PCC effects, we need clitic doubling (and/or syntactic cliticization) of internal arguments to also count as “overt agreement morphology.” To see why this is an issue at all, let us first review the central properties of the two kinds of relations.

7 Towards an account of the clitic-doubling caveat

In this section, I propose an explanation for what I have called the clitic-doubling caveat (section 6): the fact that clitic doubling must “count” as syntactic φ-agreement, if we are to correctly capture the distribution of the PCC. This, even though clitic doubling is not syntactic φ-agreement, nor can it be maintained that it is prefigured by syntactic φ-agreement simply by dint of being a movement operation. The explanation is based on an account of clitic doubling as long head movement of D⁰ out of the doubled DP. I therefore begin, in sections 7.1–7.2, by sketching this account.

7.4 The complementary locality conditions on head movement and phrasal movement

Taken at face value, the A-over-A-like condition identified in section 7.3 seems to rule out head movement altogether (except in the trivial case that the head is also the phrase). For Hornstein (2009), this suggests that head movement might be better modeled as a PF phenomenon, completely outside the purview of syntax. This is a fairly common position concerning head movement (Chomsky 1995; Brody 2000; Abels 2003, among many others), but it is often contested on the grounds that some instances of head movement appear to have interpretive effects (Lechner 2006; Hartman 2011, a.o.). Since it is trivially true that head movement affects pronunciation, if it turns out that it also affects semantic interpretation then it must occur in the part of the derivation that feeds both form and interpretation, i.e., syntax. In what follows, however, I suggest a different reason why we should be skeptical of attempts to remove head movement from the syntactic component.

As noted in section 7.1, Travis’ (1984) Head Movement Constraint (HMC) is counter-exemplified by several kinds of head movement. Nevertheless, it is beyond question that the HMC often holds; Emonds (1970; 1976), Travis (1984), and others would not have been able to make the observations they made if this were not the case. Let us contrast this with the state of affairs when it comes to phrasal movement. Here, the literature recognizes a condition known as anti-locality (Bošković 1994; Murasugi & Saito 1995; Bošković 1997; Ishii 1997; 1999; Saito & Murasugi 1999; Abels 2003; Grohmann 2003; Kayne 2005; Abels 2012). Specifically, there appears to be a ban on phrasal movement that is too local; there is a minimal amount of structural distance that phrasal movement must traverse. For the purposes of the current discussion, I will assume Abels’ (2003) version of the constraint, which simply bans movement from the complement position of a given head to the specifier of the same projection (though see section 7.5 for a refinement of this proposal):

(46)

a.

b.

What is less often noted, however, is that these two locality conditions—on head movement and on phrasal movement—stand in a complementary relation to one another (or near-complementary, once exceptions to the HMC are considered). The picture that emerges is that phrasal movement cannot be maximally local, while head movement (in most cases) must be maximally local. One case where this complementarity is explicitly noted is in the work of Pesetsky & Torrego (2001), who assume that it holds without exception, and build it into their Head Movement Generalization:

(47)	HEAD MOVEMENT GENERALIZATION (Pesetsky & Torrego 2001: 363)
	Suppose a head H attracts a feature of XP as part of a movement operation.
	a.	If XP is the compl. of H, copy the head of XP into the local domain of H.
	b.	Otherwise, copy XP into the local domain of H.

In other words, (47) states that if H⁰ attracts a feature on XP, then XP will move to [Spec,HP]—unless XP is the sister of H⁰, in which case X⁰ will head-move to H⁰. This is an idealization, in that (47) entails the strict and invariant HMC, which, we have already seen, is not quite right. And even abstracting away from this issue, (47) does not derive the complementarity in question, it merely asserts it. In the remainder of this paper, I will propose a theory of the locality of head movement and its relation to phrasal movement that derives their (near-)complementarity.

What I wish to emphasize here, however, is that if this complementarity of locality conditions is real, it constitutes an argument in and of itself that head movement should remain part of syntax. Modularizing the grammar is vacuous unless different modules make use of different primitives, and access different kinds of information. Phrasal movement clearly resides within syntax proper, since it often has semantic effects as well as phonological ones. It would be quite an odd coincidence, then, if a different operation, situated in a different module (e.g., PF), ended up satisfying complementary conditions to those that phrasal movement satisfies.

Of course, the strength of this argument hinges on the precise nature of this complementarity. If the complementarity is only approximate—as the aforementioned deviations from the HMC might suggest—then the coincidence would be less pronounced, and it would perhaps be less dubious to situate the two types of movement in different modules. I will argue, however, that we can do better. In the next subsection, I will present a theory for the locality of head movement and its interaction with phrasal movement, which, while allowing certain deviations from the HMC, has Abels-style anti-locality as its consequence. Crucially, the theory in question requires a computation that makes reference to both types of movement, and therefore requires them both to reside in the same computational module.

7.5 Head movement meets the Principle of Minimal Compliance (PMC)

7.5.1 The PMC

Richards (1998; 2001) argues for a principle that regulates the way the grammar enforces syntactic locality constraints in general. Consider, first, the following pair:

(48)	a.	*[Which book]k did the journalist spread the rumor that the senator wanted to ban tk?
	b.	?[Which journalist]i ti spread the rumor that the senator wanted to ban [which book]k?

One might be tempted to explain the contrast between (48a) and (48b) in terms of whether or not the lower wh-phrase, which book, undergoes movement. The idea would be that (48b) is well-formed because in this example, the wh-phrase in question has not undergone movement out of the Complex NP island. What Richards shows is that such an explanation is, at best, insufficient:

1. (49)

1. Bulgarian (Richards 1998: 607)

1.  
1. a.

1. *[Koja
2.     which
1. kniga]_k
2. book
1. razprostranjavaše
2. spread
1. žurnalistaȃt
2. journalist
1. [malvata
2. rumor
1. če
2. that
1. senatoraȃt
2. senator
1. iska
2. wanted
1. da
2. to
1. zabrani t_k ]?
2. ban
1.    ‘[Which book]_k did the journalist spread the rumor that the senator wanted to ban t_k?’

1.  
1. b.

1. ?[Koj
2.     which
1. žurnalist]_i
2. journalist
1. [koja
2.   which
1. kniga]_k
2. book
1. t_i
2.  
1. razprostranjavaše
2. spread
1. [maȃlvata
2. rumor
1. če
2. that
1. senatoraȃt
2. senator
1. iska
2. wanted
1. da
2. to
1. zabrani t_k ]?
2. ban
1.    ‘[Which journalist]_i t_i spread the rumor that the senator wanted to ban [which book]_k?’

In contrast to its English counterpart, the pair-list question in (49b) involves overt movement of both wh-phrases, including the one that originates within the Complex NP island, and yet it is well-formed. It is also not the case that Bulgarian simply lacks the Complex NP Constraint. As (49a) illustrates, such movement is illicit in Bulgarian, too, when not accompanied by movement of a second wh-phrase (cf. the English (48a)).

Richards shows that locality conditions such as Subjacency (or whatever subsumes Subjacency as an explanation of the Complex NP Constraint) need only be satisfied once with respect to a given landing site. Once a single Subjacency-compliant wh-chain has terminated in a given CP periphery, subsequent wh-chains landing in the same position are exempt from similar locality conditions. Note that this explanation generalizes to the English data in (48a–b), as well, on the assumption that apparent in situ wh-phrases in English pair-list questions do move, albeit covertly (see also Nissenbaum 2000: 197–201). The converse crucially does not hold: the putative explanation of (48b) based on lack of movement of the second wh-phrase could not possibly generalize to (49b).

Importantly, such interactions are only possible among multiple wh-phrases landing at the same clausal periphery. Violations of island constraints are not ameliorated if they target a CP periphery that is not itself targeted by a separate, island-respecting movement chain. Compare (49b) with (50):

1. (50)

1.     Richards (1997: 256)
1. *Kakvo_k
2.   what
1. kazva
2. tells
1. tozi
2. this
1. služitel
2. official
1. na
2. to
1. [žurnalistite,
2.  
1. kojto_i
2. journalists
1. [t_i
2. who
1. razsledvat
2. investigate
1. t_k]],
2.  
1. če
2. that
1. komunistite
2. communists
1. sa
2. AUX
1. zabludili
2. deceived
1. redaktorite
2. editors
1. im?
2. their
1.    Intended: ‘What_k does this official tell journalists who_i [t_i are investigating t_k] that the communists have deceived their editors?

Richards proposes the following principle to capture these effects:

(51)	PRINCIPLE OF MINIMAL COMPLIANCE (orig. version; Richards 1998: 601)
	For any dependency D that obeys constraint C, any elements that are relevant for determining whether D obeys C can be ignored for the rest of the derivation for purposes of determining whether any other dependency D′ obeys C.

The same principle also explains why, in pair-list questions in Bulgarian, the two wh-phrases exhibit standard superiority effects, but in tuple-list questions involving more than two elements, there are no superiority effects among the (n–1) non-highest wh-phrases (see Richards 2001: 282).

I will adopt a slight variation on (51) which, as far as I can tell, performs equally well with respect to the Bulgarian data discussed here, but which generalizes more readily to the head-movement scenario that is our current focus (cf. also Richards 2001: 199):

(52)	PRINCIPLE OF MINIMAL COMPLIANCE (revised version)
	Once a probe P has successfully targeted a goal G, any other goal G′ that meets the same featural search criterion, and is dominated or c-commanded by G (= dominated by the mother of G), is accessible to subsequent probing by P irrespective of locality conditions.

7.5.2 The A-over-A-like condition meets the PMC

Let us now reconsider head movement in light of the Principle of Minimal Compliance (PMC). Section 7.3 ended with the observation that Bare Phrase Structure (BPS), combined with Iterative Downward Search (IDS)—specifically, (43a) and (43b)—appears to ban head movement altogether. No featural search criterion could possibly be satisfied by a head without also being satisfied by the maximal projection of that same head, and the latter will be encountered by the probe first. That is, if α⁰ and αP are distinct, it is αP that must be targeted. This was referred to as the A-over-A-like locality condition on probe-goal relations.

If this is a locality condition, then we predict that it would be subject to the PMC. Consequently, it is only the first relation targeting α that should be subject to this A-over-A-like condition. After the condition has been satisfied once, subsequent relations between the same probe and (some projection of) α are, by hypothesis, exempt from it. Therefore, we predict that it should be possible for a probe H⁰ to target the head of αP to the exclusion of other material in αP, as long as this is not the first relation initiated by H⁰ that targets (some projection of) α.

All of this is not enough to make head movement possible, however. Recall: (i) probes must search for their goals using a featural search criterion (45); (ii) the phrasal node (“XP”) is, by hypothesis, featurally identical to the head (“X⁰”); and (iii) the phrasal node is unambiguously closer to the probe than the head is, in terms of the explicit iterative downward search algorithm (IDS) given in (44). So if movement of heads to the exclusion of the rest of their phrases is indeed attested, the impetus for moving the head alone cannot come from the search criterion. It must have a different source.

There is a persistent intuition in the syntactic literature that there is something fundamentally superfluous about phrasal movement. After all, the featural properties of the moving constituent are determined by its head; and so, if movement is a response to the featural needs of some higher attractor, phrasal material outside of the attracted head is not implicated in the mechanism that drives movement in the first place.¹⁸ In line with this intuition, I propose the following condition:

(53)	MINIMAL REMERGE: If X0/Xmin is movable, move only X0/Xmin.

Importantly, the antecedent of the conditional in (53) is often false. Without a previous relation in place between the probe and XP, a relation which would adhere to the A-over-A-like condition and satisfy the PMC (52), there would be no way for X⁰/X_min to move on its own. The condition in (53) can only wield its influence when a previous relation of this sort is already in place.¹⁹

In sections 7.5.3–7.5.4, I will discuss in detail how (53) interacts with the A-over-A-like locality condition and the PMC, both in local configurations (where the relevant probe is the immediate sister of XP) and in non-local ones (where the probe is more structurally distant). In the meantime, let us note the following: once a probe H has employed a featural search criterion f to target XP, subsequent relations involving f between H and X will necessarily target the head X⁰ alone, because of (53).

7.5.3 Locality, c-selection, and anti-locality

The relation that most often plays the role of satisfying the PMC, and thus rendering X⁰ movable, is c-selection. In configurations where a head H attracts a feature borne by its complement, the complement XP already stands in a c-selection relation with H (indicated in (54) with a wavy line):

1. (54)

1. 

Being a relation between H and XP, c-selection satisfies the A-over-A-like locality condition. The PMC then dictates that subsequent relations between H and anything dominated or c-commanded by XP are licit. This means that X⁰ is now movable, and MINIMAL REMERGE (53) can now wield its influence. And its influence will be to rule out phrasal movement of XP, and to only permit head movement of X⁰:

(55)

a.

b.

The reader will notice that (55a–b) is an anti-locality effect. In particular, it recapitulates Abels’ (2003) version of the constraint, but with one important difference. Abels’ version bans movement of an element from [Compl,H] to [Spec,HP], full stop. The system just presented predicts there would be one specific instance in which such movement would be licit, namely, when—unlike in (55)—the constituent in [Compl,H] is non-branching:

1. (56)

1. 

This is because, on the current view, the effect in (55) arises through the interplay of c-selection, the PMC, and MINIMAL REMERGE. What MINIMAL REMERGE (53) mandates is that the minimal movable projection of an X be the constituent that undergoes movement. In a scenario like (56), where the moving X only has one level of projection in the first place, the effects of MINIMAL REMERGE are vacuous. To put it another way, there is no penalty on moving the entire constituent in [Compl,H] in (56) because there is no smaller projection of X that could have moved.

The question, of course, is whether this deviation from Abels’ version of anti-locality is in fact warranted. One consideration that bears on this question involves Matushansky’s (2006) theory of head movement. On Matushansky’s approach, head movement involves a non-branching constituent undergoing regular syntactic movement into a specifier position, followed by m-merger between this specifier and the adjacent head. In light of this, consider movement of an intransitive V⁰ (or root) to v⁰. In this case, the step prior to m-merger is movement of the lower head to [Spec,vP]:

1. (57)

1. 

Because the complement of v⁰ in (57) is non-branching, this movement would be in violation of Abels’ version of the anti-locality constraint: it is movement of the entire [Compl,v] constituent into [Spec,vP].²⁰ Thus, if we want to maintain Matushansky’s approach to head movement, we cannot maintain Abels’ version of the constraint. Importantly, however, the version of anti-locality derived here is compatible with such movement (cf. (56), above).

7.5.4 The clitic-doubling caveat: long head movement revisited

Recall that clitic doubling is, by hypothesis, long head movement of D (section 7.1). Given the system laid out in sections 7.5.1–7.5.2, any instance in which a probe H triggers movement of a head X must be prefigured by another syntactic relation between H and XP (the maximal projection of X) involving the same featural search criterion. This is necessary in order to satisfy the PMC with respect to the relevant A-over-A-like locality condition (section 7.3). In cases of maximally local head movement, it was c-selection between H and XP that filled this role. But in cases of long head movement, H and XP do not stand in a sisterhood relation, making c-selection between the two impossible (cf. Chomsky 1994; 1995).

I propose that in cases of clitic doubling, the cliticization host H first enters into agreement with the full DP. It is this agreement relation that satisfies the PMC, enabling subsequent movement of the D head, on its own, to H:

(58)

[H = the cliticization host (T / v / etc.)]

This explains why it does not matter, for the purposes of PCC distribution, whether a given instance of agreement morphology is an instance of agreement proper (i.e., feature valuation on a functional head), or the result of clitic doubling. That is because clitic doubling still depends on establishing a prior agreement relation of the former kind. Syntactic agreement is therefore implicated in both types of agreement morphology, and as already shown in section 4, it is also the key to understanding PCC effects—especially in light of their sensitivity to finer syntactic hierarchy.²¹

An immediate question raised by this view of clitic doubling is its status with respect to the no-null-agreement generalization discussed in section 5, and repeated from (22):

(59)	THE NO-NULL-AGREEMENT GENERALIZATION
	There is no such thing as morpho-phonologically undetectable ϕ-feature agreement.

In many (perhaps, most) cases of clitic doubling, there is no overt morpho-phonological expression of a prior agreement relation. In (60), for example, there is no overt exponence of an agreement relation between the cliticization host (v⁰) and the object. (The verb displays agreement with the subject, but there is no agreement with the object independent of the clitic.) And this is paradigm-wide, i.e., it is not a matter of the particular φ-features of profesor (‘professor’).

1. (60)

1.   Leísta Spanish (Bleam 1999: 45)
1. Le
2. CL
1. vi
2. I.saw
1. al
2. A-the
1. profesor
2. professor
1. ayer.
2. yesterday
1. ‘I saw the professor yesterday.’

Instances of clitic doubling do exist where, alongside the clitic itself, one finds overt agreement with the doubled argument—for example, clitic doubling of subjects in certain Northern Italian dialects (Poletto 2000). While this may provide circumstantial support for the idea that clitic doubling is prefigured by syntactic agreement as in (58), it does not change the facts of (60) and many cases like it.

There is no way around the fact that if, as argued above, agreement with the object is implicated in cases like (60), then it is an agreement relation that stands in violation of the no-null-agreement generalization. And this, in turn, means that this generalization cannot be a steadfast, combinatorial principle of grammar. But we cannot abandon (59), either; recall that it was a necessary component of any adequate account of the distribution of PCC effects, given the evidence that the PCC was a fundamentally syntactic effect (sections 4–5).

Are we at an impasse, then? In the next section, I suggest that the answer is no—and that this apparent tension can be resolved by viewing (59) not as a grammatical principle unto itself, but as the outcome of a particular kind of acquisition strategy affecting the placement of unvalued φ-features on functional heads.

8 The nature of the no-null-agreement generalization: A conservative acquisition strategy for unvalued φ-features

In earlier sections, we saw evidence in favor of the no-null-agreement generalization, which states that there is generally no such thing as agreement that is morpho-phonologically null across the entire paradigm. Without this generalization, there would be no way to account for the distribution of the PCC, given that the latter is a syntactic effect par excellence (section 4), and yet it comes and goes with the presence of overt agreement morphology (section 5). In section 7, we saw an argument that clitic doubling involves a prior agreement relation between the cliticization host and the full DP of which the clitic is a subpart. Crucially, this agreement relation often goes unexponed, in apparent violation of the aforementioned generalization.

The solution I put forth is to view the aforementioned generalization not as a steadfast principle of grammar, but as the result of a particular kind of acquisition strategy. Before spelling out the strategy in detail, it is worth pointing out that were this generalization a principle of grammar per se, it would raise the same kind of modularity issue discussed in relation to the PCC in section 5. Consider: if agreement is a syntactic operation, then it occupies a part of the grammar where reference to the morpho-phonological content of terminals is impossible. The problem would be even more severe, in fact, because the principle would have to be trans-derivational: it is not the morpho-phonological content of a particular terminal in a particular derivation that is at issue, but rather the fact that some cells in a paradigm must be overt.

Instead, what I propose is that the no-null-agreement generalization, and its exceptions, arise because of how language acquisition proceeds. Specifically, the learner begins with the assumption that there are no unvalued φ-features on any functional heads (this includes T⁰ and v⁰). Recall that this does not pose any case-related problems—not even for languages with rich and easily evident case morphology—given the evidence that has accumulated in recent years against structural case being assigned by agreement (Preminger 2014, a.o.; see also section 1). There is then a specific and, crucially, limited set of triggers that would cause the learner to revise this hypothesis, and posit unvalued φ-features on a given functional head:²²

Crucially, the list in (61) is anything but open-ended. It absolutely cannot include, for example, the existence of a binding or fake-indexical relation involving H⁰ (cf. Kratzer 2009). If such phenomena were also triggers for positing unvalued φ-features on H⁰, a proper account for the distribution of PCC effects would be rendered impossible. Recall that the PCC arises wherever there is overt agreement or clitic doubling (section 5); the presence of binding and/or fake-indexicals in a given construction does not suffice to give rise to PCC effects. The conclusion, already argued elsewhere on independent grounds (Preminger 2013; Preminger & Polinsky 2015), is that phenomena of the latter sort do not involve syntactic agreement in φ-features.

This proposal provides us with a “roadmap” for how a language with PCC effects is acquired. (Or, to be more precise, how a construction with a particular inventory of functional projections that ends up generating PCC effects is acquired.) The learner starts with the assumption that there are no unvalued φ-features on the relevant functional projection—say, v⁰. Very quickly, however, she will be driven to revise these assumptions, either because v⁰ shows morpho-phonologically overt covariance in φ-features with the direct object (as is the case in Basque, for example; Arregi & Nevins 2008; Preminger 2009; Arregi & Nevins 2012), or because there is a D associated with the direct object that cliticizes to (i.e., undergoes long head movement to) v⁰, as in Spanish. In the latter case, the learner can deduce with certainty that there must be a prior agreement relation between v⁰ and the direct object, for the reasons discussed in section 7.5.

Importantly, misidentifying clitic doubling as “pure” agreement, or vice versa, will be fairly innocuous at this stage, since in either case the learner will end up positing unvalued φ-features on the relevant functional head. This is a desirable property: while agreement and clitic doubling are clearly different phenomena, the kind of data that distinguish the two are fairly subtle (see section 6.1 and references therein). It is not unreasonable to assume that, in the course of language acquisition, one may initially be identified as the other; and, in fact, this may be the etiology of one type of language change, wherein pronominal clitics are reanalyzed as markers of agreement (i.e., valuation of formal features on a probe; see, for example, Gelderen 2011).

Either way, once the learner has posited unvalued features on v⁰, the PCC then arises as a direct consequence of agreement and intervention, as discussed in section 4.

On the other hand, the learner acquiring a language that lacks agreement morphology with internal arguments will never be driven to posit unvalued φ-features on v⁰. Consequently, as discussed in section 5, the PCC will not arise in such a language.

Finally, let us consider once more the status of pro arguments. Essentially the same acquisition profile obtains here: if the learner encounters agreement morphology on some head H⁰ in the verbal projection, but there is no overt argument corresponding to that morphology, she may conclude that this morphology is (i) “pure” agreement (i.e., valued φ-features on H⁰); or (ii) a D head adjoined to H⁰ In both cases, the learner will then be driven to posit unvalued φ-features on H⁰. This is trivially true in the former scenario; in the latter case, given that D is not part of the extended verbal projection, and that the only mechanism for syntactic cliticization is the one identified here, encountering a D head adjoined to a verbal projection would constitute unambiguous evidence for unvalued φ-features on H⁰ (in accordance with (61b)). Again, the overall result (regardless of the distinction between “pure” agreement and cliticization/clitic doubling) is the positing of unvalued φ-features on H⁰ and, consequently, the emergence of PCC effects.

9 Conclusion

This paper began by surveying some of the evidence that the Person Case Constraint (PCC) is sensitive to the kind of fine-grained hierarchical distinctions that characterize syntax proper. This means that in any system where there is a meaningful modular distinction between morphology and syntax, the PCC is part of the latter module. I then surveyed, in broad strokes, what a syntactic account of the PCC that is capable of deriving this sensitivity would look like (building on Anagnostopoulou 2003; Béjar & Rezac 2003; Anagnostopoulou 2005, a.o.), based on mechanisms of syntactic agreement and intervention.

Next, I turned to the fairly well known fact that the PCC seems coupled to the existence of overt agreement morphology with the arguments involved: as this morphology comes and goes, so does the PCC effect itself. This was shown to hold even intra-linguistically, as demonstrated by the distinction between finite and non-finite environments in Basque. I then juxtaposed this with the earlier results concerning the fundamentally syntactic nature of PCC effects, and its account in terms of agreement and intervention. Assuming that syntax does not make direct reference to the morpho-phonological content of terminals, this led to the conclusion that contexts that do not exhibit the PCC simply lack agreement with internal arguments altogether. I labeled this the no-null-agreement generalization.

An important caveat to this characterization involves clitic doubling: even though clitic doubling is a species of movement (as evinced by its ability to repair Weak Crossover violations), it behaves, for the purposes of the PCC, as though it were agreement. I then showed that we cannot maintain that all movement (or even just all DP movement or A-movement) is prefigured by φ-agreement. This therefore cannot be what underpins the clitic-doubling caveat.

I argued that a more promising alternative can be found by investigating the interplay of Bare Phrase Structure (Chomsky 1994), Iterative Downward Search (Kitahara 1994; Takano 1994; Koizumi 1995; Müller 1996; Kitahara 1997; Müller 1998), and the Principle of Minimal Compliance (Richards 1998; 2001). In particular, the idea is that movement always “strives” to move only the head, but this is seldom possible because Bare Phrase Structure and Iterative Downward Search together yield an A-over-A-like locality condition that demands that the entire phrase be the target of the syntactic relation. Crucially, however, when the attractor already stands in some prior relation with this phrasal node (e.g., c-selection, agreement), this satisfies the relevant locality condition. It follows, given the Principle of Minimal Compliance, that subsequent syntactic operations involving the same relata need not adhere to the same locality condition again, which is what enables movement of the head alone.

Clitic doubling, qua long head movement, cannot be prefigured by c-selection because it does not involve a sufficiently local configuration (namely, sisterhood). Some other syntactic relation must therefore be what satisfies the A-over-A-like locality condition in this case. I proposed that syntactic agreement is the relation that plays this role. Clitic doubling thus “counts” as syntactic agreement for the purposes of the distribution of PCC effects because it invariably involves an initial agreement step. The agreement involved in clitic doubling, however, seemed to pose a challenge for the no-null-agreement generalization, since in many clitic-doubling languages, there is no morphology indicating valuation appearing alongside the clitic itself.

I then showed how this picture could arise as the result of a conservative acquisition strategy, where the learner does not posit unvalued φ-features on functional heads unless and until faced with a particular kind of positive evidence. This type of strategy could give rise to the no-null-agreement generalization, as well as its clitic-doubling caveat.

Abbreviations

1 = first person, 2 = second person, 3 = third person, ABS = absolutive, ACC = accusative, ART = article, AUX = auxiliary, BEN = benefactive, CL = clitic, COMP = complementizer, COP = copula, DAT = dative, DET = determiner, ERG = ergative F = feminine, FUT = future, HAB = habitual, IMPF = imperfective, INF = infinitive, LOC = locative M = masculine, NEG = negation, NMZ = nominalization, NOM = nominative, PL = plural, PPRT = past-participle, PROG = progressive, PRT = participle, REFL = reflexive, SBJNCT = subjunctive, SG = singular, ϕ = a morphological slot which is phonologically empty, √ = lexical root.

Competing Interests

The author has no competing interests to declare.