In this paper, we investigate the effects of coordination on the status of multiple sluicing constructions in English. We build on the observation that coordination sometimes improves the status of constructions that are ungrammatical without coordination. This is, for example, what happens in multiple wh-questions: the ungrammatical sequence of two fronted wh-phrases in (1a) becomes grammatical when the two wh-phrases are coordinated, as shown in (1b) (Browne 1972; Kazenin 2002; Whitman 2002; 2004; Gračanin-Yuksek 2007; Gribanova 2009; Scott 2012; Citko and Gračanin-Yuksek 2013; 2016, among many others):

Similarly, the ungrammatical sequence of a complementizer followed by a wh-phrase in (2a) becomes grammatical when a conjunction separates them, as shown in (2b) (Giannakidou and Merchant 1998; Citko and Gračanin-Yuksek 2017).

We focus on a similar contrast, involving multiple sluicing constructions. In English, multiple sluicing is quite restricted: the ungrammatical multiple sluicing example in (3a) improves when the two wh-phrases are coordinated, as shown in (3b) (Bolinger 1978; Hoyt and Teodorescu 2012).12

We examine possible sources for coordinated sluices, and show that coordinated sluices like (3b) above cannot be derived from multiple sluices in (3a). We also show that they cannot be derived from coordinated wh-questions or coordinated clefts, illustrated in (4a–b), respectively.

We propose instead that coordinated sluices involve coordination of two CPs, with a single wh-phrase sluiced in each, as shown in (5).

We proceed as follows. In Section 2, we investigate coordinated wh-questions as a possible source for coordinated sluices and show that deriving coordinated sluices from coordinated wh-questions makes an incorrect prediction for English that the two should be subject to the same restrictions. In Sections 3 and 4, we argue against deriving coordinated sluicing from multiple sluicing and coordinated clefts, respectively. In Section 5, we present our proposal, and in Section 6, we address the question of why coordinated wh-questions and coordinated sluices cannot share the same underlying structure. Section 7 is the conclusion.

On some accounts, sluicing can be derived from non-isomorphic pre-sluice sources (i.e., short sources, predicative sources, cleft sources) (Erteschik-Shir 1973; Merchant 2001; Marušič and Žaucer 2013; Barros, Elliott and Thoms 2014; 2015; Vicente 2018, among others). In more concrete terms, this means that the source of the sluice in (33) is the “short” string in (33b) or the cleft string in (33c), rather than the isomorphic string in (33a) containing an island. Since neither (33b) nor (33c) involves an island, the availability of such short sources is one way to derive the lack of island effects in sluicing.11

Abels and Dayal (2017a: 25) suggest that coordinated sluices, like the one in (34a), “are derived from a different pre-sluice”, indicated by their cleft source and/or predicative source paraphrases in (34b).

In this section, we focus on cleft sources and the question of whether coordinated sluices in general can be derived from coordinated clefts along the lines schematized in (35).

The same considerations that rule out a cleft source for singular sluices rule out a cleft source for coordinated sluices. We show this by applying to coordinated sluices a subset of the ten diagnostics that Merchant (2001) used to argue against deriving singular sluices from clefts. Van Craenenbroeck (2010) showed some of Merchant’s original diagnostics to be inconclusive due to the fact that they do not distinguish between the cleft source and the non-elliptical wh-question source for the sluice.12 Thus, we focus primarily on the diagnostics that do make this distinction.

The first diagnostic involves compatibility with adjuncts. Merchant shows that adjuncts can appear in sluices but not in clefts, as shown in (36a). The fact that adjuncts are possible in coordinated sluicing, as shown in (36b), shows that the coordinated sluice in (36b) cannot be derived from the coordinated clefts in (36c).

The second diagnostic concerns implicit arguments. Example (37a) shows that implicit arguments are possible as correlates of wh-phrases in sluicing constructions, but not as pivots of clefts. Implicit arguments are also possible as correlates of wh-phrases in coordinated sluices, as shown in (37b), which shows that coordinated sluices cannot be derived from coordinated clefts in (37c).13

The next diagnostic involves what Merchant refers to as ‘mention-some’ modification.14 He shows that wh-pivots in pseudoclefts are impossible with modifiers like ‘for example’. However, such modifiers can modify sluiced wh-phrases. This is shown in (38).

Coordinated sluices also allow ‘mention-some’ modification, as shown in (39):

The last diagnostic we consider involves case.15 Cleft pivots tend to have designated cases. For example, in languages in which wh-pivots in clefts are nominative, we expect to find wh-remnants in coordinated sluicing to be nominative as well if coordinated sluices are derived from coordinated clefts. We show with data from Polish that this is not what we find (see Sag and Nykiel 2011 for a discussion of case in Polish non-coordinated sluices).

Given the differences between coordinated sluicing and coordinated clefts discussed in this section, it is reasonable to conclude that the two constructions are not derivationally related.

In the next section, we present an analysis that derives the properties of coordinated sluicing and explains why these properties differ from the properties of constructions that we have entertained as possible sources of coordinated sluicing: coordinated wh-questions, multiple sluicing and coordinated clefts.

The analysis of coordinated sluicing must account for the fact that coordinated sluicing is not subject to the clause-mate condition (unlike multiple sluicing), that there are no restrictions on the category of wh-phrases in coordinated sluicing (unlike in multiple sluicing), that coordination of arguments is possible in coordinated sluicing (unlike in CWHs), and that coordinated sluicing does not have the at-all reading (unlike CWHs).

Our starting point is the observation that in examples involving coordinated sluicing, such as the one in (41a), modeled after Merchant’s (1999: 484) examples, the interpretation of the second sluice is (41b), and not (41c): The speaker is not wondering whether Abby called some suspect, the speaker is wondering whether Abby called the suspect mentioned in the first conjunct (whoever he/she might be).

This interpretation is reminiscent of the interpretation, given in (42b), of single sluicing examples like (42a) below, discussed first by Merchant (1999).

Merchant proposes that in examples like (42a), the elided TP contains a pronominal correlate of the wh-trace in the antecedent clause, the ^Pe in (43). This pronominal correlate, according to Merchant, is interpreted as an E-type pronoun.

Building on this semantic similarity between examples of coordinated sluicing like the one in (41a) and examples involving coordinated questions with a single sluice, like the one in (42a), we propose that the two have the same underlying structure; i.e., that coordinated sluicing is derived from coordination of singular wh-questions, with an E-type pronoun in the second conjunct, co-indexed with the trace of the wh-phrase in the first conjunct (see also Scott 2012 and Barros and Kotek 2019), as shown in (44a–b).16

The bi-clausal structure we propose for coordinated sluices explains why coordinated sluicing does not have the properties found in multiple sluicing, coordinated wh-questions, or coordinated clefts. While coordinated sluices involve coordination of single wh-questions with ellipsis in each conjunct, multiple (non-coordinated) sluices, coordinated wh-questions, and coordinated clefts have different underlying structures, given (in a somewhat simplified manner) in (45a–c), respectively.

The structure we propose straightforwardly derives two properties of coordinated sluicing: the absence of the clause-mate condition and the absence of the restriction on the category of wh-phrases that can be coordinated.

The clause-mate condition – the requirement that multiple moving wh-phrases originate in the same clause – arises only when the multiple instances of wh-movement interact so that their paths either nest or cross. Abels and Dayal (2017a; b), for example, account for the clause-mate condition in multiple sluicing by assuming that covert wh-movement is clause-bound and subject to superiority (for these authors the second wh-phrase in a multiple sluicing configuration undergoes covert wh-movement). The fact that the restrictions that derive the clause-mate condition in multiple sluicing hold of covert movement implies that there is another, overt instance of wh-movement and the fact that one instance of wh-movement is overt and the other one is covert indicates that the two are, in some relevant sense, evaluated in the same domain, i.e., that they interact. On our analysis of coordinated sluicing, schematized in (46b), the two instances of wh-movement happen in separate clauses, unlike in multiple sluicing, schematized in (46a).

Since in (46b) there is no interaction between the two instances of wh-movement (neither is non-first in a single domain), it is expected that the clause-mate condition does not constrain coordinated sluicing, as shown by the grammaticality of the (b) examples and the contrast between the (a) and (b) examples in (47) and (48).

Our analysis also derives the fact that there are no restrictions on the category of wh-phrases that can be coordinated in multiple sluicing. Recall that English multiple sluicing is degraded if both wh-remnants are simplex wh-DPs and improves if the second wh-phrase is a PP (Bolinger 1978; Richards 1997; 2010; Lasnik 2014; Cortés Rodríguez 2019). This is shown by the contrast in (49).

Different authors account for this restriction in different ways. Lasnik (2007; 2014) attributes the ungrammaticality of (49a) to restrictions on extraposition. Recall that on his analysis, the first wh-remnant in a multiple sluicing construction undergoes leftward wh-movement to [Spec CP], while the second one undergoes extraposition, as shown in (50).

As shown in (51a–b), extraposition is sensitive to the DP vs. PP contrast in that PPs extrapose more easily than DPs do.

We have argued that coordinated sluicing is not derivationally related to multiple sluicing. Since on our analysis of coordinated sluicing, both wh-phrases undergo leftward wh-movement, there is no extraposition, and the absence of the preference for PPs is to be expected.

Richards (2010) accounts for the ban on multiple wh-DP remnants in multiple sluicing in a different way. As stated in Section 3.1, Richards assumes that multiple sluicing involves the structure in (52), where both wh-phrases undergo movement to [Spec CP].

Richards considers the ban on two wh-DP remnants in English sluicing to be a special case of a more general restriction on linearization that “rejects trees in which two nodes that are both of type α are to be linearized in the same Spell-Out domain” (Richards 2010: 5). He refers to this restriction, given in (53), as Distinctness.

In a multiple sluice, two wh-DP remnants cause the derivation to crash: fronting both wh-phrases to their left-peripheral positions creates the linearization statement <DP, DP>, which violates Distinctness.

Since on our analysis of coordinated sluicing the two wh-phrases are in separate clauses, they are never required to be linearized in the same Spell-Out domain. Thus, even when both wh-remnants are DPs, the illicit linearization statement is never created and Distinctness is obeyed.

The bi-clausal nature of our analysis does not in and of itself derive the availability of wh-argument coordination in coordinated sluicing, or the absence of the at-all reading. However, both of these properties follow from the presence of an E-type pronoun in the second conjunct (they), co-indexed with the trace of the wh-phrase in the first conjunct, as shown in (44b), repeated here as (54).

The presence of the pronoun in the second conjunct makes wh-argument coordination possible in coordinated sluicing by ensuring that the selectional properties of the verb are satisfied in both conjuncts; in the first conjunct, by the wh-phrase and the indefinite pronoun, and in the second conjunct, by the wh-phrase and the E-type pronoun (co-indexed with the trace of the wh-phrase in the first conjunct). Since the selectional properties of the verb are satisfied in both conjuncts, regardless of the type of wh-phrases or the type of the verb, coordination of wh-arguments is possible.

The presence of the pronoun in the second sluice also derives the absence of the at-all reading in coordinated sluicing. The at-all reading arises in coordination of wh-questions in which a wh-object that introduces one conjunct is not interpreted in the conjunct introduced by a wh-adjunct, as in the CWH in (55a). Since in coordinated sluicing the wh-object is interpreted in the second conjunct (via the E-type pronoun), the at-all reading is not available, as (56a–b) shows.

Finally, since coordinated sluicing involves coordination of two single questions, it captures the observation that coordinated sluices have only single pair readings and contrast in this respect with multiple (non-coordinated) sluices. This is shown by the contrast in (57), repeated from (29), where coordinated sluicing is unacceptable when the antecedent clause contains a distributive quantifier every and acceptable with the non-distributive some.

Our analysis makes the prediction, brought to our attention by Joe Emonds, that each of the two conjuncts should be able to undergo ellipsis independently of the other. We think this prediction is correct as long as no independent restrictions are violated. These independent restrictions include MaxElide, constraints against cataphoric dependencies, conditions on the interpretation of indefinites and/or the licensing of E-type pronouns. In the remainder of this section, we present examples that show that this prediction is borne out.

We start with examples in which ellipsis, instead of targeting TPs in the two conjuncts (as in (58a)), targets a TP in one conjunct and a VP in the other conjunct, as in (58b–c), or a VP in both conjuncts, as in (58d). All the examples with VP ellipsis are ungrammatical.1718

We attribute the ungrammaticality of (58b–d) to violations of MaxElide, which, in general terms, requires deletion of the largest possible constituent (see Fiengo and May 1994; Lasnik 2001; Takahashi and Fox 2005; Merchant 2008; Kimura 2013, among others).19 Our conclusion that (58b-d) are excluded because they violate MaxElide is corroborated by the contrast in (59a–b). The ungrammatical (59a) parallels (58b) in that the first of the coordinated sluices involves VP ellipsis, in violation of MaxElide. In the grammatical (59b), however, the sluice involving VP ellipsis contrasts with the antecedent clause, which results in the auxiliary being focused. The focused auxiliary is not part of the maximal string that can be deleted, so (59b) does not violate MaxElide even though, like the ungrammatical (59a), it involves VP ellipsis.20

We turn next to examples in which ellipsis targets a TP only in one conjunct. The (a) examples in (60) and (61) are baseline coordinated sluicing examples, in which TP ellipsis takes place in both conjuncts. In the (b) examples, TP ellipsis takes place only in the second conjunct, and in the (c) examples only in the first conjunct. Crucially, both (b) and (c) examples are grammatical. For completeness’ sake, we also include (d) examples, in which there is no ellipsis in either conjunct.21

The examples in (60) and (61) show that the two instances of TP ellipsis in multiple sluicing are in principle independent, as one can take place without the other. However, things get more complicated in (62), which shows that not all logically possible TP deletions are grammatical. What distinguishes the examples in (62) from the ones in (60) and (61) above is the fact that the wh-pronoun what, which introduces the second sluiced conjunct, has an overt correlate something in the antecedent clause. The ungrammaticality of (62b) might be taken to indicate that in this case the second conjunct cannot be deleted. However, the fact that the non-elliptical (62d) is equally ungrammatical shows that the ungrammaticality of (62b) has nothing to do with ellipsis.

The problem with the examples in (62b) and (62d) appears to stem from the presence of two instances of the indefinite pronoun something: one in the antecedent TP Some students sang something, and the other one in the first conjunct which students sang something. Either instance of the indefinite something could in principle be the correlate of the wh-pronoun what in the second conjunct. However, the two indefinites necessarily introduce two different discourse referents (Heim 1982). Thus, what may be causing the degradation of (62b) and (62d) is the fact that both TPs (the TP Some students sang something and the first conjunct which students sang something) contain the correlate something, but the two correlates are non-identical since the referents of the two indefinites are different.

There is another question related to the grammatical coordinated sluicing example in (62a), where the TP in the first conjunct is deleted (together with the TP in the second conjunct). The question is whether the non-elliptical source of the first conjunct contains the indefinite something to being with. The interpretation of singular sluices such as the one in (63a) below suggests that it does not. The most natural interpretation of (63a) is not the one in (63b), in which the sluice contains the indefinite present in the antecedent TP, but the one in (63c), in which the sluice contains a pronoun coindexed with the indefinite in the antecedent.

Kim (2010) arrives at a similar conclusion based on the examples in (64) and (65a). She first notes that in (64) the two instances of someone refer to two different individuals, and discusses the source of the sluice in (65a) in light of this observation.

Kim states that if the source of the sluice in (65a) were (65b), we would also expect (65a) to be a statement about two different individuals, one committing a crime at a certain place and the other committing a crime at a certain time. This is not what (65a) means; it asks about the time and place of the crime committed by one and the same person. This leads Kim to propose (65c) as a source for (65a).

If this reasoning is on the right track, the source for the multiple sluice in (66a) does not contain an indefinite in the first conjunct (as in (62a), repeated as (66b)), but rather a pronominal element, as shown in (66c).

However, even when the indefinite is replaced with a pronoun that can be construed as an E-type pronoun, as in (66b), the sentence is degraded if this pronoun is pronounced. This is what examples (67a–b) show.

We attribute the ungrammaticality of these examples to a cataphora constraint, which in this case prevents the pronoun it from being coindexed with the wh-pronoun what following it (Kazenin 2002, for example). We take it to be the same constraint that excludes example (68a), which contrasts with (68b), where the pronoun stands in an anaphoric relationship with the preceding wh-phrase.

We thus conclude that in coordinated sluicing ellipsis may apply to each conjunct without applying to the other conjunct(s), as long as no independent constraints are violated.

So far, we have shown that coordinated sluicing and CWHs have different properties, which we took as evidence that coordinated sluicing cannot be derived from CWHs. However, we have not addressed the question of why this should be the case: why do coordinated sluices differ from CWHs? In other words, what excludes the same source for both constructions?

If this were possible, the coordinated sluice in (69a) would be derived from the structure of CWH in (69b), and would presumably have the properties found in CWHs, which is not what we find (see the discussion of the differences between coordinated sluices and CWHs in Section 2.2).

We hypothesize that (69b) is excluded by economy. Our reasoning relies on an independently motivated assumption that operations apply only when they have an effect on pronunciation and/or interpretation (see Fox 2000).22 In the case at hand, the idea is that ellipsis can only apply if it has an effect on pronunciation. We adopt Merchant’s (2001: 60) proposal that ellipsis is triggered by an E(llipsis) feature, which instructs “the PF system to skip its complement for purposes of parsing and production.” In (69b), the E feature is located on C, and since both TP₁ and TP₂ are its complements, both have to be deleted. However, since deleting one TP (say TP₁) will already have deleted the string John sang, deleting TP₂ will have no further effect on pronunciation; such a vacuous application of ellipsis is banned by economy considerations.

In our analysis of coordinated sluicing, given in (70b), ellipsis also applies to two syntactic objects: TP₁ and TP₂, just as it does in (69b). However, each TP dominates a separate string, so both ellipsis operations have an effect on pronunciation. Thus, no ellipsis operation applies vacuously.

We next turn to a related question: why can’t CWHs be derived from the structure we posited for coordinated sluicing? What prevents the CWH in (71a) from having the structure in (71b) or (71c)?

We first consider (71b) as a possible source of the CWH in (71a). In this structure, the verb sing in the second conjunct does not contain a direct object; this forces an intransitive interpretation of the verb and yields the at-all reading of the CWH, as desired. However, if the string in (71a) were derived from (71b), it would mean that the sluicing remnant in the first conjunct – the wh-phrase what – has no overt correlate in the second conjunct, i.e., that its correlate is an implicit argument. Implicit arguments always take the lowest scope in their clause, as indicated, for example, by the fact that (72b) does not give rise to the same ambiguity as (72a) and that (73) is not ambiguous (Fodor and Fodor 1980). These examples show that an implicit argument (interpreted as an existential) does not interact with other quantifiers in the sentence; instead, it is always outscoped by them.

Given this, the structure in (71b) violates Scope parallelism (Romero 1998), which requires that the remnant of a deletion operation and its antecedent have the same scope. Scope parallelism is violated in (71b) because the wh-phrase what in the sluiced, first conjunct takes the highest scope in the clause, but its antecedent, the implicit argument in the second conjunct does not because it is outscoped by the fronted wh-phrase where. Thus, (71a) cannot be derived from (71b).

We next turn to (71c), repeated as (74), as a possible source for (71a). The structure in (74) contains a pronoun in the second conjunct that would presumably be pronounced,23 yielding an incorrect string.

Our next question is what excludes (74). We believe that (74) is ungrammatical because the wh-trace in the first conjunct, which the E-type pronoun is coindexed with, is deleted. This may be related to the condition that requires the antecedent of an E-type pronoun to be overt and salient (Evans 1977; Kadmon 1987; Heim 1990; Chierchia 1992; Elbourne 2001; 2005; Patel-Grosz and Grosz 2010; Grosz et al. 2014, among others).24 This is corroborated by the contrast in (75), where the (a) example (from Merchant 2001) contains no ellipsis in the first conjunct, and the pronunciation of the E-type pronoun in the second conjunct is licit. Our (b) example, in which the first conjunct is elided, no longer licenses the pronunciation of the E-type pronoun in the second conjunct.

However, the ungrammatical (75b) becomes grammatical if another possible antecedent for the pronounced E-type pronoun is added to the discourse, as shown in (76). Now, the preceding sentence contains the indefinite something, which serves as an alternative antecedent for the E-type pronoun it. Examples (77a–b) show that this holds more generally.2526

We conclude that the analysis in (71c) is impossible for CWHs because on such an analysis, the non-elided E-type pronoun in the second conjunct is always co-indexed with a copy of a wh-phrase that has undergone ellipsis. If this is illicit, we have an explanation for why CWHs cannot be derived in the same way as coordinated sluices.

We started with a puzzle concerning the ameliorating effect of coordination in multiple sluicing: why do the ungrammatical cases of multiple sluicing in English improve when the wh-phrases are coordinated?

We presented several arguments against the claim that coordinated sluicing is derived from coordinated wh-questions (CWHs). First, coordinated sluices allow wh-coordination to contain obligatory argument(s) of the verb, while CWHs do not. Moreover, coordinated sluices disallow at-all readings, while CWHs allow such readings. We also showed that coordinated sluicing cannot be derived from multiple sluicing: while multiple sluicing is, coordinated sluicing is not subject to the clause-mate condition. Also, unlike multiple sluicing, coordinated sluicing allows coordination of simplex DP wh-phrases. Finally, we showed, based on contrasts involving compatibility with wh-adjuncts, compatibility with implicit arguments, “mention-some” modification, and case considerations that coordinated sluicing is not derived from a coordinated cleft construction. Instead, we proposed a bi-clausal structure for coordinated sluices, which involves coordination of two CPs, with a single wh-phrase in the specifier of each CP and TP ellipsis in each CP. We justified the existence of this structure alongside the structure of CWHs by showing that the two constructions cannot share the same underlying source (either the one we posited for coordinated sluicing or the one of CWHs) because if they did, the derivation of one construction would involve a violation of a principle that is independently operative in the grammar.