1 Why- and how-questions regarding successive cyclic A’-movement

Why there is “movement” in natural languages and how it is to be implemented have been central questions throughout the generative enterprise. The consensus that has emerged in the past decades is that movement creates a configuration that allows the establishment of a required relation between two syntactic objects (partially addressing the why-question) by linking two syntactic positions (partially addressing the how-question). The movement of what in (1), for instance, is analyzed as being triggered by a required relation between the embedded interrogative complementizer and the wh-constituent and this involves establishing a connection between the embedded [Spec,CP] and the embedded object position.

This general picture still requires further elaboration in view of the body of evidence stemming from Chomsky (1973; 1986) that shows that (A’-)movement generally does not proceed in one fell swoop, but rather in smaller steps. However, the need for such intermediate steps does not seem to follow from either of the partial answers sketched above.

Within the phase-based model, Chomsky (2000; 2001) has provided an interesting rationale for this step-by-step, Barriers-style computation with respect to A’-movement, by exploring the tension between the potentially unbounded nature of A’-relations and computational efficiency. On the one hand, we have the empirical fact that syntactic interactions of the A’-type may involve elements that are generated in unbounded distance from one another, as is the case of standard wh-movement. On the other hand, computation efficiency leads us to expect that instead of inspecting the whole syntactic object for convergence, the computational system should ship smaller chunks of the structure under construction to the interfaces so that crashing can be locally detected. Assuming that these computational guidelines can be formulated in terms of the Phase Impenetrability Condition (PIC) in (2) below, long distance A’-relations can be established in consonance with the PIC if elements that may participate in an A’-relation with elements located in a different phase are repeatedly pushed to the next phase up so that the expected relationship can eventually be established within a configurational span limited by phase heads.¹

From this perspective, the derivation of (1), for instance, cannot involve a direct relation between the embedded interrogative complementizer Q (a phase head) and the wh-phrase in its base position, due to the intervention of v (another phase head), as illustrated in (3a) below. However, this minimality effect can be voided if the wh-phrase moves past v to the lower phase edge, as illustrated in (3b), where it can interact with Q in consonance with the PIC.

(3)	a.
	b.

As Bošković (2007: Section 5.1) notes, the PIC provides a rationale for intermediate steps of A’-movement, but not for the final step (the initial why-question above). Given that a local agreeing relation can be established between Q and what in (3b), for instance, one would expect (4) below to be grammatical, contrary to fact. Assigning an obligatory EPP-type of feature to Q to trigger movement of what in (3b), yielding (1), is actually a way of encoding the problem, rather than providing a solution. To put it in general terms, the ungrammaticality of (4) under the derivation sketched in (3b) is related to the general issue of why local movement is necessary in a system where syntactic relations can be established via Agree.

This paper focuses on a related how-question: Assuming that syntactic movement is featurally driven (see, e.g., Chomsky 1995), how exactly is successive cyclic A’-movement triggered and licensed? More specifically, I will be concerned with the overarching consequences of the answers to the two intertwined questions in (5).

I argue that much of the crosslinguistic variation involving wh-movement may follow from answers to (5a) and (5b). If the specific answers to be provided in the following sections are on the right track, they pave the way for a unified analysis for why partial wh-movement is generally disallowed; why parasitic gaps generally cannot be licensed by in situ wh-phrases; why adjunct control may be affected by A’-movement in some languages; why some languages impose restrictions on local subject extraction, whereas others impose restrictions on local object extraction; why one may usually find allomorphy affecting phase heads tied to A’-movement; why this allomorphy may be exclusively related to local A’-extraction in some languages but not in others; why some phase heads in some languages do not allow extraction from their domains, while others require that their domain contain an extraction site; and why A’-movement is subject to anti-locality. Although space limitations prevent me from providing here a detailed case study and a proper comparison with other approaches regarding each of these empirical phenomena (something that is taken up in work in progress with a fuller presentation of this proposal), I hope to show that the fact that the proposal advocated here may connect these apparently unrelated domains under a uniform analysis makes it worth considering.

The paper is organized as follows. In section 2 I examine problems and advantages of placing the feature that triggers successive cyclic movement on phase heads (Chomsky 2000) or moving elements (Bošković 2007). Based on Nunes (2014; 2016a), I propose that these are not mutually excluding possibilities, but actually describe different grammatical options. In section 3 I contrast English and Brazilian Portuguese and show that their differences regarding adjunct control and extraction of subjects and objects follow from their differences with respect to the lexical hosts of edge features (phase heads in English and wh-elements in Brazilian Portuguese). In section 4 I discuss cases of allomorphy involving phase heads and propose that they are linked to possibility of phase heads hosting (valued or unvalued) edge features. In section 5 I show how the value of EF on a given functional head may induce anti-locality restrictions on A’-movement. Finally, section 6 concludes the paper.

2 Edge features on either phase heads or moving elements

To account for long distance A’-movement in consonance with the PIC, Chomsky (2000: 108) proposes that after a phase is completed, its head may optionally be assigned an EPP-type of feature, which then attracts a local wh-element. Under this proposal, the derivations of the sentences in (6a) and (7a) below, for instance, proceed along the lines respectively sketched in (6b) and (7b) (irrelevant details omitted). In (6b), the embedded C and v are not assigned EPP and accordingly, the embedded object remains in situ. By contrast, in (7b) all phase heads are assigned EPP, thus triggering successive cyclic movement of the embedded object.

Despite being able to encode successive cyclicity, this approach faces some problems of internal cohesion and restrictiveness. Assignment of EPP features in the course of the derivation violates the Inclusiveness Condition (see Chomsky 1995), as these features are not present in the relevant numerations. Furthermore, the optionality of EPP-assignment leads to overgeneration, as particularly emphasized by Bošković (2007). Crucially, assignment of the EPP-like feature to a given phase head is independent from other potential assignments. Thus, a sentence such as (8a) below, for instance, is incorrectly ruled in as a multiple interrogative sentence if an EPP feature is assigned to the lowest phase head, as sketched in (8b). Crucially, the matrix interrogative complementizer is licensed by who, as in (6a), and the movement of what is licensed by Last Resort, as it checks the EPP of the embedded v. In other words, movement of what in (8b) is as legitimate as the first movement of what in (7b).

To circumvent problems similar to this one, Chomsky (2001: 34) suggests that a phase head is assigned an EPP feature only if this assignment has an effect on the outcome. Although this suggestion correctly prevents EPP-assignment to the lowest phase head in (8b), it must invoke lookahead and global computations (see Bošković 2007: Section 6.1). To see this, let us consider the derivation of the sentences in (9) below. The question is whether EPP-assignment at the step sketched in (10) contributes to convergence. It does in the case of (9a), but not in the case of (9c); hence, movement should be enforced in (9a) but not in (9c) (cf. (9b)). However, this can only be determined much later in the derivation (several phases up), after the structure sketched in (11) has been assembled. EPP-assignment in (10) contributes to convergence if K in (11) merges with an element such as John (see (9a)), but not if K merges with an element such as who (see (9b) vs. (9c)). In other words, computations such as these are completely at odds with the spirit of the phase model, which strives to keep computational decisions within the derivational span defined by the PIC.

For Bošković (2007), the fundamental problem in Chomsky’s (2000; 2001) system is that the EPP feature is hosted by the potential target of movement. He proposes an alternative based on the following assumptions: (i) every uninterpretable feature must function as a probe in order to be licensed; (ii) the PIC holds for Move but not for Agree; and (iii) the uninterpretable feature that triggers successive cyclic movement (uF) is hosted by the moving element. The assumption in (iii) is actually a corollary of assumptions (i) and (ii). In a configuration such as (12) below, for instance, each uF feature must be licensed by probing its domain (assumption (i)). The head H can license its uF feature simply by directly agreeing with wh, if Agree is not subject to the PIC (assumption (ii)). By contrast, the uF feature on the wh can only be licensed if it moves to [Spec,H], arguably the closest position from where wh can probe its domain and find a suitable licenser (per assumption (i)). However, if Move, as opposed to Agree, is subject to the PIC (assumption (ii)), wh is forced to stop at the edge of each intervening phase on its way to [Spec,H]. Therefore, successive cyclic movement is tied to properties of the moving element rather than the target (assumption (iii)).

As far as crosslinguistic variation goes, Bošković proposes that in multiple wh-fronting languages such as Bulgarian, wh-phrases always bear uF; in wh-in-situ languages such as Korean, wh-phrases bear iF (that is, F is interpretable); and in languages like English, which has in situ wh-phrases in multiple interrogatives (see (6a) and (9c)), the wh-phrases are optionally specified for uF and the interrogative complementizer is obligatorily specified for uF. Under this approach, what must bear uF in (7a) and (8a), but not in (6a); hence, what stays put in (6a). As for the contrast between (7a) and (8a), what must move all the way to the Spec of an interrogative C so that uF can function as a probe and be appropriately licensed. This is the case of what in (7a), as sketched in (13a) below, but not in (8a), as sketched in (13b). Similar considerations apply to the derivation of the sentences in (9).

This alternative overcomes the three problems pointed out above regarding Chomsky’s (2000) proposal. First, uF in (13a), for example, enters the derivation as part of the feature matrix of what; hence, its presence in the structure is fully compatible with Inclusiveness. Second, unwanted cases of partial wh-movement such as (13b), for instance, are ruled out with no need to appeal to global lookahead. The presence of an unchecked instance of uF on what in (13b) when it undergoes Transfer causes the derivation to crash, regardless of further computations down the road. Finally, the sentence in (4), repeated below in (14) is correctly ruled out without postulating an EPP-feature on the embedded interrogative complementizer: if what bears uF, it must move to the embedded [Spec,CP] to have uF licensed; if it doesn’t, it shouldn’t have moved to the edge of the embedded vP to begin with. Furthermore, if what does not have uF and remains in situ, as in (15), the embedded interrogative complementizer cannot license its uF feature via agreement with another instance of uF and the derivation crashes, as well.

Despite its merits, Bošković’s (2007) approach raises some issues. The first one is related to his proposal that every uninterpretable feature must function as a probe in order to be licensed (assumption (i) above). Under this approach, a sentence like (16) below, for instance, which has an ECM preposition, should involve agreement between the preposition for (arguably the relevant Case licenser) and him to license the Case of for; then movement of him past for so that him can have its own Case licensed; and finally, movement of for to a position above him (as indicated by the linear order). As pointed out by a reviewer, an analysis along these lines has indeed been explored by Watanabe (1993), who proposes that the complex for to is generated under I and for later moves to C (see also Bošković 1997), and may find support in constructions such as (17) in Belfast English (see Henry 1995). Whether such movements and positions can be generalized to constructions analogous to (16) in every language is not obvious, though. Brazilian Portuguese, for instance, allows ECM constructions with the preposition pra ‘for’ (see, e.g., Perini 1974; Lightfoot 1991; and Salles 1997), as illustrated in (18), but there appears to be no independent motivation for postulating that at some point in the derivation of (18), pra is generated inside the infinitival or the embedded subject moves past the preposition. To put it broadly, the price to pay for an obligatory overt movement analysis of structural Case in every language is the call for justification for a number of nonobvious movements and positions.

However, it is worth pointing out that it is possible to maintain the gist of Bošković’s proposal without necessarily assuming an obligatory overt movement approach to structural Case. If Case valuation on a DP is just a reflex of φ-agreement, as proposed by Chomsky (2001), this may disqualify Case as a probe in Bošković’s sense as its specification is dependent on an independent probe-goal relation involving φ-features. Under this view, structural Case licensing can always occur in absence of movement, for the φ-features on the probe are uninterpretable and the φ-features of the goal DP interpretable. This is the position I will take below, for reasons that will become clear.

Let us now consider Bošković’s proposal that Agree, as opposed to Move, is not subject to the PIC (assumption (ii) above). Given the computational motivations for assuming the PIC (see section 1), it would be desirable that a crashing result could be detected when Transfer applies, regardless of whether it followed from movement or agreement failure. Thus, from a conceptual point of view, one would expect Move and Agree to be both subject to the PIC (even more so if Move encompasses Agree, as suggested by Chomsky (2000; 2001)). On the empirical side, it is not clear that this assumption is indeed required in the realm of wh-movement. In Bošković’s system, it is employed in the account of wh-in situ languages such as Korean, as sketched in (19), where the interrogative complementizer can license its uF feature by agreeing with the interpretable [iF] feature of the wh-element, across an unlimited number of phases.

However, in the absence of a proper description of what F really is and what it means to say that it may be interpretable or uninterpretable on a wh-element, one may instead simply assume that in languages like Korean, the interrogative complementizer lacks uF and this in turn entails that we may also eliminate the postulation of an additional [iF] feature on wh-phrases, as illustrated in (20). Once no uF is involved, no agreement or movement takes place in languages of this type, as desired.

Notice that a configuration like (19) may actually be what underlies the ungrammaticality of (15) if the PIC applies to Agree, as well. Suppose, for instance, that the uF on the interrogative complementizer in (15) is an uninterpretable wh-feature that may be licensed via agreement with a wh-element. If Agree is subject to the PIC, the interrogative complementizer in (15) cannot agree with what in object position, which causes the derivation to crash. In short, it is not obvious that the crosslinguistic variation regarding wh-movement forces us to abandon the null hypothesis that Move and Agree should be both restricted by the PIC. In the proposal to be advanced below, I will stick to the null hypothesis.³

The last point I would like to raise with respect to Bošković’s (2007) proposal regards the potential blocking effect that some phase heads impose on A’-movement, as illustrated by the familiar that-trace effect in (21) below (see, e.g., Perlmutter 1971). If who in (21) were endowed with uF, as represented in (22a), it should move as far as the matrix [Spec,CP] to check uF, as shown in (22b), and the presence or absence of that in the embedded clause should be completely irrelevant. In other words, Bošković’s (2007) system should be supplemented with an independent account of that-trace effects,⁴ for the presence of an uF feature on a wh-element (triggering its movement) makes it oblivious to the specific heads it crosses.

Upon reexamination, Chomsky’s (2000) approach looks more prone to incorporating that-trace effects and similar ECP effects as it crucially takes A’-movement to be dependent on features of phase heads. This in turn suggests that it may be worth considering an approach combining the positive aspects of both proposals. This is the goal I now turn to.

Building on Nunes (2014; 2016a), this paper advances an approach that combines the core aspects of Chomsky’s (2000) and Bošković’s (2007) proposals, while circumventing the problems seen above. Let us start with the familiar fact that human languages may require that some (A’-)relations be established between elements located in different phasal domains. Take the simple abstract configuration in (23) below, for instance, where the phase head Ph₂ needs to establish an agreement relation with α. For concreteness, let us say that Ph₂ has an uninterpretable feature [α]. Assuming with Chomsky (2000) that Agree is subject to the PIC, the required agreement relation is blocked in (23) due to the intervention of the phase head Ph₁, but it may eventually take place if α moves past Ph₁ to a position c-commanded by Ph_2. It follows from this reasoning that if the agreement relation between Ph₂ and α is to succeed, there must be an independent uninterpretable feature that triggers movement of α and places it within the reach of Ph₂. Let us refer to this feature as an edge feature (EF).

The question now is to determine which elements may bear EF. I would like to propose that Chomsky’s and Bošković’s proposals in this regard actually reflect two different grammatical options explored by natural languages, which may interact along the lines of (24).⁵

Metaphorically speaking, Chomsky’s view is that a strong phase head functions as a border control agent, whose optional EPP-feature may or may not open the gate for a passing wh-traveler, whereas Bošković’s view is that the wh-traveler may or may not have a quick pass (the uF feature) and in case it does, it does not need permission from the control agent to cross the border. Continuing with the border control agent metaphor, (24) says that strong phase heads may or may not stamp the wh-traveler’s passport (i.e. assign it an edge feature) giving it permission to cross the border. The guiding intuition is that EFs allow communication between two elements located in different phases (Ph₂ and α in (23), for example), but the intervening phase heads do not themselves participate in the relevant relation (like Ph₁ in (23)). In fact, the PIC allows the head of a phase to be accessible to computations in the higher phase, without the help of an edge feature. Thus, if a phase head is lexically endowed with an instance of EF, it will not move itself, but may assign this feature to an appropriate element in its probe domain (section 4.2 below for another possibility), ultimately triggering its movement. One may think of EF assignment as analogous to Case assignment under government within GB. That is, EF may enter the computation as part of the feature matrix of a phase head and is then transferred to a wh-element in the probe domain of the phase head, as sketched in (25).⁶

Notice that (24) circumvents the problems raised to Chomsky’s (2000, 2001) proposal. According to Chomsky’s (1995: 228) Inclusiveness Condition, “any structure formed by the computation (in particular, π and λ) is constituted of elements already present in the lexical items selected for N; no new objects are added in the course of the computation, apart from rearrangements of lexical properties”. The introduction of EFs in the derivation in a system adopting (24) does not violate Inclusiveness as they are part of the lexical items that feed the computation (phase heads or wh-elements); in turn, EF assignment (or EF inheritance; see footnote 6) amounts to a rearrangement of lexical properties, also in consonance with Inclusiveness. Furthermore, if we assume with Bošković (2007) that every uninterpretable feature must function as a probe in order to be licensed, a wh-element that is assigned EF by a phase head must also keep moving until it reaches a position where it can license EF via probing. In other words, the PIC entails that an element bearing an unchecked instance of EF in the domain of a phase head H must move to the edge of H; otherwise, the derivation crashes when the domain of H undergoes Transfer. (This basically follows Bošković 2007 in recasting Chomsky’s 2000; 2001) reasoning in terms of features of moving elements). Moreover, Last Resort requires that the system employ the minimal number of movement operations; hence, if a single movement to the edge of H suffices to allow EF licensing or avoid a local crash, a single movement will be employed. In the absence of independent motivations for additional movements, Last Resort in tandem with the PIC then ensures that successive cyclic A’-movement proceeds from phase edge to phase edge, as proposed by Chomsky (2000; 2001) (see footnote 1). Finally, no problems of look-ahead or overgeneration arise when EFs are lexically hosted by phase heads, because they ultimately end up associated with wh-elements. Thus, if a wh-element is assigned EF by a phase head but remains in situ, the derivation crashes when the domain containing the wh-element undergoes Transfer and this is locally detected at the phase level (exactly as in Bošković’s 2007 system).

This conflation of Chomsky’s and Bošković’s proposals has far-reaching consequences. To illustrate, consider the abstract configurations in (26), with a wh-element in object position in (26a) and in the external argument position in (26b).

If we are examining (26) in a language where EFs are located on wh-elements (option (24i)), subjects and objects will behave alike with respect to wh-extraction, depending on whether the relevant wh-element has EF. By contrast, in a language where EFs are lexically encoded on phase heads (option (24ii)), the wh-object in (26a) may undergo wh-extraction at this derivational step if it has been assigned EF by v. As for (26b), even if v were lexically specified for EF, the wh-element could not have received it, for it is not in the probe domain of v (see (24)). Therefore, in such a language the wh-subject of a configuration like (26b) can only undergo wh-movement if it is assigned EF by a higher phase head. This in turn creates a potential subject-object asymmetry if one of the relevant phase heads is lexically specified for EF but not the other, paving the way for a straightforward account of that-trace effects across languages.

We discuss these possibilities in detail in the next sections.

3 Optionality of EF on phase heads vs. optionality of EF on moving elements

Let us consider the effects of the options in (24i) and (24ii) by examining two languages that optionally allow wh-in situ such as Brazilian Portuguese (henceforth BP) and English. As shown in (27) below, wh-in situ is a generally available option in BP (see, e.g., Kato & Mioto 2005). In English, on the other hand, wh-in situ is much more constrained, being generally restricted to echo and multiple wh-questions (see (6a) and (9c)).⁷ I take these differences to be related to the possibilities in (24). More precisely, I take BP and English to be specified as in (28).

The differences between BP and English stated in (28) make the prediction that they should behave alike with respect to objects but not necessarily so with respect to subjects. In the case of objects, the trigger for wh-movement is found phase internally in both languages; that is, given the vP phase in (26a), the object will undergo wh-movement if it is specified for EF in BP or if it is assigned EF by v in English. In the case of subjects, on the other hand, the trigger for wh-movement is to be found within the vP phase in BP as a matter of lexical specification on the subject itself, but outside the vP phase in English, for the external argument is not in the probe domain of v (see (26b)). Let us examine these predictions in more detail, by considering some examples of “upward” and “sideward” movement of wh-elements in these two languages.

3.1 Upward movement of objects and subjects

(29) and (30) below show that English and BP allow for a wh-object to remain in situ (see footnote 7) or overtly move, but if movement takes place, it cannot be partial and must reach the checking position.⁸

From the perspective explored here, the derivations of (29a) and (30a) start with the phase represented in (26a), with no EF; hence no wh-movement. By contrast, the derivations of (29b-c) in English and (30b-c) in BP start with the structures in (31) and (32), respectively.

In the case of English, v in (31) assigns EF to the wh-object in its probing domain (see (24ii)/(25)), yielding (32). From then on, English and BP behave alike in that the wh-phrase must move overtly in order for its EF to probe a head that can license it. This is what happens in (29c) and (30c), where EF can probe and be licensed by an interrogative complementizer, but not in (29b) or (30b). Notice that this discussion basically recasts Bošković’s (2007) analysis in terms of the proposal outlined above and hence, the ungrammaticality of (29b) and (30b) can also be accounted for in a local fashion. After the derivation reaches the embedded CP phase, the wh-element at the edge of the embedded vP must move to the edge of CP. If it doesn’t, Transfer applies and the presence of an unlicensed EF in the embedded vP of (29b) and (30b) suffices to cause the derivation to crash at the next phase, with no need of lookahead.

Let us now examine wh-movement of subjects, starting with BP. If EF is lexically optional on wh-elements in BP (see (28a)), we should expect its subjects and objects to behave alike regarding wh-movement. The wh-word quem ‘who’ in (33) below, for instance, may optionally bear EF. If it does, movement of quem to the Spec of the interrogative complementizer is required to license EF (see (33c)) and partial wh-movement, as in (33b), for instance, causes the derivation to crash due to the unchecked EF in the matrix [Spec,vP]. On the other hand, if quem does not have EF, it stays put in the embedded subject position (see (33a)).

In English, on the other hand, EF is lexically optional on strong phase heads (see (28b)). In the case of external arguments, the subject is not generated in the probe domain of a transitive v (see (26b)) and therefore cannot receive EF from it (see (24)). In the case of internal arguments of unaccusative and passive verbs, the subject is generated in the probe domain of v, but it does not count as a strong phase head for being φ-incomplete (see Chomsky 2001). This means that a (non-ECM) subject in English should receive EF from the local C.⁹ The fact that English has an overt and a null version of declarative C raises the possibility that each version has a different specification regarding EF. Exploring this possibility, I would like to propose that declarative that in English is not specified for EF, but the null declarative C may be so, as stated in (34) below. Crucially, English declarative C_Ø, like v, cannot be obligatorily associated with EF, for it may also be employed in declarative sentences with no wh-movement involved, as sketched in (35).

Bearing the specifications in (34) in mind, let us consider standard that-trace effects such as the one illustrated in (36), which shows that only the local that creates problems for wh-movement of subjects.

If the lowest vP of (36) were as represented in (37), we would have a nonstarter: a phase head can only assign EF to an appropriate element in its probe domain (see (24)) and who is not in the probe domain of v. An unchecked EF should then cause the derivation to crash regardless of future computations.

Thus, a convergent derivation of (36) must start with v with no EF, as sketched in (38):

Now comes the crucial part. Suppose that the next step following (38) involves the merger of that, as illustrated in (39a) below. Since that does not have an EF to assign to who (see (34a)), who cannot undergo further movement. If it does not move, the uninterpretable wh-feature of the interrogative complementizer that is introduced later in the derivation (see Bošković 2007) remains unchecked, as shown in (39b), and the derivation crashes. (Recall that I am assuming with Chomsky 2000; 2001 and contra Bošković 2007 that Agree is also subject to the PIC). Note that even if the intermediate v or the intermediate C_Ø in (39b) had EF, the PIC would prevent them from assigning it to who.

The convergent continuation of (38) must therefore merge a null complementizer, which according to the specification in (34b) may bear EF. If it does indeed, we obtain the configuration in (40a) below. C can then assign EF to who in its probe domain (see (40b)) and from then on, who can (and must) move as far as the matrix [Spec,CP] to have its acquired EF checked (see (40c)). Notice that once who is endowed with EF, the type of C it crosses becomes irrelevant, for it has already acquired the “stamp” on its passport (see section 2). Hence, the intermediate clause in (36) may involve that or an EF-less C_Ø.

As is well known, subject relative clauses in English differ from the case of subject extraction in (36) in that they display a local anti-that-trace effect, requiring the presence of that, as illustrated in (41a) below. This indicates that declarative and relative complementizers in English differ with respect to their specification for EF.

Rizzi (1990) has proposed an ECP analysis of constructions such as (41a), according to which the relative complementizer that has an Agr-feature that makes it able to properly govern the trace of the local subject. Adapting Rizzi’s proposal to the current framework, relative Cs in English should have the opposite specifications of their declarative counterparts, as shown in (42) below. This amounts to saying that only the relativization of a local subject requires the overt version of the relative C. In (41b), for instance, v assigns its EF to the object, which can then raise regardless of whether or not the relative complementizer is overt. In turn, relativization of the subject in (41a) is only licensed if the relative complementizer assigns EF to the subject; hence, the overt version of the relative complementizer specified for EF must be employed in (41a) (see (42a)). Finally, the most embedded subject in (41c) can only move if it receives EF from the local declarative complementizer, which must then be null (see (34b)). Once it has received EF, the subject then moves and is completely oblivious as to whether the relative complementizer is overt or null.¹⁰

Two apparently unrelated correlations connected to that-trace effects may find a common source under the approach proposed here. The first one involves lack of that-trace effects in pro-drop languages with “strong” agreement (see, e.g., Rizzi 1982). Assuming that declarative complementizers in Romance null subject languages are like declarative that in English in not being specified for EF, the relevant Infl head that is associated with “strong” agreement and is able to license null subjects in Romance may be taken to bear EF and assign it to a wh-subject within vP, rendering it independent from the local complementizer. The second correlation is associated with the fact that that-trace effects in English may be circumvented if certain adverbials intervene between the embedded complementizer and the trace of the subject, as illustrated in (43) below (see, e.g., Culicover 1993, Browning 1996, Bošković 2016, Erlewine 2016, and Douglas 2017, for relevant discussion). From the present perspective, the functional head intervening between C and T that hosts these adverbials may be specified for EF and assign it to the wh-element in Spec of TP, allowing wh-movement to be launched regardless of the inertness of declarative that.¹¹ To put it in general terms, it is no accident that these two correlations make (tacit) reference to a functional head intervening between C and the subject (see section 5 below for further discussion). If C does not bear EF, a wh-subject not lexically specified for EF can only undergo A’-movement if it receives EF from a functional head lower than C. These phenomena indicate that some relaxation regarding the type of elements that may bear EF (see (24ii)) is needed. Given the role played by phase heads in blocking or licensing movement, I tentatively suggest that EFs may also be lexically associated with functional heads of the extended projections of phase heads.

To summarize, upward wh-movement of subjects is less restricted in BP than in English because in BP the motivation for movement can be found on the wh-subject itself, whereas in English it is dependent on the properties of local complementizers (more specifically, their lexical specification for EF).¹² A related difference between English and BP wh-subjects is also observed with respect to “sideward” movement, as we will now see with the derivation of adjunct control and parasitic gap constructions.

3.2 Sideward movement of subjects and objects

In this section I assume Hornstein’s (2001) analysis of adjunct control and Nunes’s (2001; 2004) analysis of parasitic gaps, which are both based on the notion of sideward movement. Space limitations prevent me from comparing these analyses with other alternatives. What is relevant to our purposes is that the locus of EFs affects sideward movement in the same way it affects upward movement.¹³

4 Edge features and morphological realization

5 Edge features and anti-locality

Assuming that English interrogative complementizer has an uninterpretable wh-feature (see, e.g., Bošković 2007), let us compare the derivation of the sentences in (97) with the derivation of (98).

From the perspective of the proposal made in section 2, the PIC prevents the embedded interrogative complementizer from agreeing with what in (97a). If the embedded v bears EF, it may assign it to what, allowing what to move to its edge, yielding (97b). The interrogative complementizer can agree and be licensed with what in (97b), but what still needs to license the EF it received from v. Thus, the derivation should crash unless what moves to the embedded [Spec,CP], yielding (97c). The derivation of (98), on the other hand, need not resort to movement. As illustrated in (99), the interrogative complementizer can license its wh-feature by probing and agreeing with who, in compliance with the PIC; who then remains in its position, as it does not have any other features to be licensed.

Recall however that I have proposed that EFs may be optionally associated with phase heads in English. So, in principle, a derivation of (98) along the lines of (100) below should also be permitted. In (100), Q exercises the option of bearing EF as it enters the derivation and assigns it to who after licensing its wh-feature (see (100b–c)); who must then move to the specifier of Q (see (100d)), much like what we saw with respect to what in (97b–c).

Arguably, we cannot resort to economy considerations to rule out the more complex derivation in (100) in view of the simpler possibility in (99), for they are based on different numerations, with distinct lexical entries for the interrogative complementizer (see Chomsky 1995). However, the derivation in (100) may be independently excluded if the movement of who in (100d) counts as too local, violating some anti-locality restriction on movement (see, e.g., Abels 2003; Grohmann 2003; Bošković 2016; Erlewine 2016; and Douglas 2017 for relevant discussion). Take Erlewine’s (2016) formulation of anti-locality in (101) below, for instance. According to (101), movement of who in (100d) is to be excluded, for it crosses no maximal projection other than TP.

In this section I would like to briefly discuss the relevance of the locus of EFs for anti-locality, showing that the effects of (101) can in fact be deduced. Recall that the role of EFs is to allow communication between two syntactic objects in different phase domains (see section 2). As uninterpretable features, EFs must function as probes in order to be licensed (see Bošković 2007), which entails that an element bearing EF may have to move in order to license its EF via probing. Recall also that the value of EF ultimately specifies how far the element bearing EF should move (see section 4.1). Notice, however, that if two syntactic objects are within a phasal span conforming to the PIC, they need no extra help from edge features to interact with each other. The absence of EFs on phase heads in this scenario can be taken to follow from a general economy condition barring superfluous features (features whose role is to require the establishment of a relation that is independently established). Suppose this condition is formulated along the lines of (102).

What (102) amounts to saying is that specifications like Q_[EF:Q], Top_[EF:Top], etc. are redundant in a system that adopts Agree and takes it to be subject to the PIC. Q and Top, for instance, can find a proper goal in their probe domains defined by the PIC, without forcing the goal to be dislocated to a position within their projection. Once Q_[EF:Q] is lexically excluded by the Anti-locality Restriction on Feature Bundling in (102), the issue of EF assignment in a derivation like (100) does not arise, capturing the effects of (101).²⁹

From this perspective, the fact that English allows local object topicalization, but not local subject topicalization (see Lasnik & Saito 1992) may also be taken to follow from (102). A sentence such as (103a) below, for instance, can be derived along the lines of (104), where v assigns the object an EF valued as Top, which triggers movement of Mary to [Spec,TopP] to license EF.

As for the ungrammatical subject topicalization sentence in (103b), John is generated outside the probe domain of v (see (105a) below) and therefore could not be assigned [EF:Top] by v even if it were so specified (see (24)). The subject then moves to [Spec,TP] and the Top head is merged. The Anti-locality Restriction on Feature Bundling prevents Top from lexically bearing an EF valued as Top. Thus, John does not have any motivation to move to [Spec,TopP] and therefore cannot be interpreted as a topic or be assigned the prosodic contour presumably induced by the Top head (see (103b)).

To put things in a broader perspective, whenever a given element Y with an uninterpretable edge feature valued as X (Y_[EF:X]) moves overtly to check [EF:X] against the head X, either (i) Y is intrinsically specified for [EF:X] (e.g. wh-phrases in BP; see section 3) or (ii) there is a head Z intervening between X and Y that assigns [EF:X] to Y, triggering Y’s movement (e.g. v in (104); also see the discussion around (43)). As we should by now expect, the presence of EF on the intervening Z may have morphological reflexes. In this regard, let us reexamine focus in Defaka. As discussed in section 4.4, focalization of a local subject involves the particle ko (see (106a)), whereas any other type of focalization involves the particle ndo (see (106b,c)), including focalization of nonlocal subjects (see (106c)):

Bennett, Akinlabi & Connell (2012) propose that ko stands for a syncretic form conflating a focus head (Foc) and a head responsible for subject licensing (Subj), allowing the subject to move to its Spec and satisfy both its focus and Case requirements. When an element other than the local subject is focused, each head hosts a different element in its specifier and the focus head is spelled out as ndo. Reinterpreting Bennett, Akinlabi & Connell’s (2012) proposal in terms of the current system, a moved focused element must have been assigned an EF valued as Foc ([EF:Foc]). Crucially, it cannot have received from the Focus head itself. In the case of objects and nonlocal subjects, such assignment would violate the PIC; whereas in the case of local subjects, it would comply with the PIC, but the putative specification of the Foc head in this situation (Foc_[EF:Foc]) would violate the Anti-locality Restriction on Feature Bundling in (102). Thus, given that focalization of a local subject is possible in Defaka, there must be a head bearing [EF:Foc] intervening between the focus head and the local subject. For concreteness, let us follow Bennett, Akinlabi & Connell (2012) and assume that such head is Subj, as sketched in (106).

In (106), Subj assigns [EF:Foc] to SU, which must then move to [Spec,FocP] to license the edge feature. We may take ko to be the allomorph of Subj when it is lexically specified as bearing [EF:Foc] and the Focus head ndo to be deleted in the morphological component when adjacent to Subj (even if the focused subject moves to [Spec,SubjP], it must still move to [Spec,FocP], which leaves Foc adjacent to Subj after the copy of the subject in [Spec,SubjP] is deleted). In short, we have here another case of allomorphy conditioned by the presence of EF lexically associated with a given head.

6 Concluding remarks

Two related questions have been at the center of the generative enterprise in one way or another: (i) why does successive cyclic movement exist? and (ii) what kind of features must be postulated to ensure that successive cyclicity obtains? Chomsky’s (2000; 2001) phase model has proposed a very interesting answer to (i), by exploring the tension between unbounded A’-relations and computational efficiency (see section 1). Assuming that the reasoning behind phase-based computations brackets the question in (i), the question in (ii) comes to the fore. Chomsky (2000; 2001) has proposed that the relevant trigger for successive cyclicity resides on phase heads, whereas Bošković (2007) argues instead that it should be located on the moving elements. Exploring the positive aspects of both approaches, I have modified and expanded on a proposal by Nunes (2014; 2016a), arguing that UG allows for such “edge features” to be lexically hosted by either phase heads or moving elements and that the choice for one or the other option has interesting empirical consequences (that-trace effects and additional interpretations for adjunct control, for example). Under the assumption that edge features are uninterpretable, I have also examined the two logical possibilities for their characterization in the lexicon (as intrinsically valued or intrinsically unvalued). The conclusion was again that UG allows for both types of specification, with each specification associated with different empirical consequences (the ability to license an A’-specifier as an escape hatch, for instance).

If the general approach sketched above is on the right track, we may have a unified analysis for why partial wh-movement is generally disallowed and why parasitic gaps generally cannot be licensed by in situ wh-phrases (EF must function as a probe); why adjunct control may be affected by A’-movement in some languages (an EF lexically hosted by a wh-element may preempt Merge-over-Move and trigger sideward movement, giving rise to object control into adjuncts); why some languages impose restrictions on local subject extraction, whereas others impose restrictions on local object extraction (subjects and objects may be assigned EF by the local phase heads); why one may usually find allomorphy affecting phase heads tied to A’-movement (EFs may be lexically hosted by phase heads); why this allomorphy may be exclusively related to local A’-extraction in some languages but not in others (EFs may be intrinsically valued or unvalued); why some phase heads in some languages do not allow extraction from their domains, while others require that their domain contain an extraction site (an instance of [EF:u] signals that only heads bearing EF can license an escape hatch for A’-movement); and why A’-movement is subject to anti-locality (edge features are not required for relations defined within a derivational span conforming to the PIC).

The proposal outlined above is admittedly programmatic and has skirted many important issues. However, to the extent that it has for the most part stuck to the logical possibilities made available by the theory (whether edge features are hosted by phase heads or moving elements and whether they can be intrinsically valued or intrinsically unvalued), its rich empirical coverage over apparently unrelated domains makes it look worth exploring.

Abbreviations

ø = phonetically null, 3PL = third person plural, COND = conditional, EF = edge feature, F = feature, FOC = focus particle, FUT = future, GEN = genitive, i = interpretable, NEG = negation, NFUT = nonfuture tense, OB = object, PAST = past tense, Q = interrogative, S2 = singular second person, REL = relative, SU = subject, SUBJ = head of SUBJP, Top = topic, TRANS = transitivity marker, U = unvalued, VAL = valued.

Funding information

I would like to thank FAPESP (grant 2017/22560-9) for its support to this research.

Competing interests

The author has no competing interests to declare.