1.1 The proposal in a nutshell

In this paper, I also propose an analysis of patterns of syncretism that does not presuppose a total order on a case hierarchy but which nevertheless retains case contiguity. I suggest that rather than conceiving of a case sequence as a total order, it can be thought of as a partially ordered set (or poset) such that not all elements of the case “hierarchy” need to be ordered with respect to each other (Figure 1; see also Bárány 2016; Graf 2019).

Figure 1

An example of a partially ordered set.

Figure 1 represents a set partially ordered by a subset relation (⊂; throughout, I use the symbol “⊂” to indicate the proper subset relation and “⊆” to indicate the subset relation). The nodes represent sets of features. The leftmost set, {A}, is a subset of all other sets in Figure 1, but not all sets are ordered with respect to each other by the subset relation. For example, while neither {A, Z} nor {A, B} is a subset of the other set, both are (proper) subsets of {A, B, C, Y, Z}, the rightmost set in Figure 1. Elements that are not ordered with respect to each other, such as {A, Z} and {A, B}, are called incomparable. Elements that are ordered with respect to each other, such as {A} and {A, Z}, are called comparable (Partee, Meulen & Wall 1990: 278).

Partially ordered sets can be used to account for case syncretisms. Rather than duplicating cases on a totally ordered hierarchy, a hierarchy can be “split” into branches. The elements of two distinct branches are incomparable to, that is not ordered with respect to, each other, but they are comparable to, that is ordered with respect to, other elements not on those branches. Again, {A, Z}, {A, B}, and {A, B, C, Y, Z} in Figure 1 illustrate this. This allows for maintaining contiguity between syncretic cases by not ordering them with respect to cases that intervene on totally ordered hierarchies. More concretely, rather than ordering Gujarati’s cases as in (4), repeated here, they can be ordered as in (7) to account for the actual case paradigm of Gujarati, maintaining strict contiguity of the empty set ∅ and ABS on the one hand, and ABS and DAT on the other.

(7)	Partially ordered Gujarati case sequence (to be revised)

The hierarchies proposed in this paper are an abstract representation of cases and their underlying features which are related to surface forms by spell-out rules. In this system, syncretism arises through underspecification, when one vocabulary item can spell out several sets of features. Underspecification can be part of the system as a whole (e.g. two forms being syncretic in all contexts) or the result of the application of impoverishment rules. These two sources of syncretism are not redundant, however, as only syncretism through impoverishment leads to alternations, namely differential object marking in the context of this paper.

This approach naturally models a scenario in which syntactic objects with different morphological forms show identical syntactic behaviour, because they are of the same underlying type. I will argue that this is the case for direct objects in Gujarati, Basque, and Spanish, motivating that they are associated with a single level on a hierarchy.

This contrasts with Starke’s (2017) and Irimia’s (2020) hierarchies. These capture patterns of syncretism and maintain case contiguity, but at the price of positing structural (or dependent) cases in between inherent (or oblique) ones, resulting in hierarchies that do not conform to Zompì’s (2019) universal containment. At least Starke’s (2017) hierarchy also seems to be intended as a (universal) underlying representation (Starke 2017: 1, 4, fn. 2), the levels of which are spelled out differently in different languages (Starke 2017: 5). If so, I believe the data discussed in this paper provide strong evidence against positing two distinct underlying representations of ACC. But even if one takes Starke’s (2017) and Irimia’s (2020) hierarchies to be surface representations, they do not conform to Zompì’s (2019) universal containment because they interleave structural and inherent cases.

The partially ordered hierarchies described below fare better in this respect. First, two distinct morphological forms can be associated with one underlying syntactic object. Second, this approach captures the patterns of syncretism of DOM and dative case in Gujarati, Basque, and Spanish just like approaches based on total orders (see e.g. Bárány 2018), but it also captures ERG=LOC syncretism in Gujarati, while maintaining case contiguity (avoiding *ABA patterns) and universal containment. Finally, by “branching off” certain cases, genitives can be included in partially ordered case hierarchies in a systematic way. While the hierarchies shown below are compatible with Zompì’s (2019) generalisation in (5), they can vary from language to language, based on the respective case paradigm of a language, as in Harðarson (2016).

In the remainder of this paper, I will argue in favour of partially ordered case hierarchies in more detail. The outline of the argument is as follows. The data in Section 2 indicate that morphologically unmarked and DOM objects show identical syntactic behaviour and that they behave differently from other syntactic relations, such as subjects and indirect objects, even if they are syncretic with them.

I take this to mean that both unmarked and DOM objects are direct objects. In Section 3, I therefore analyse morphologically unmarked and DOM objects as representing the same syntactic relation and being associated with the same underlying Case which can be spelled out in different ways. Finally, I show that partially ordered case hierarchies successfully account for these patterns while conforming to Zompì’s (2019) universal containment.

2.1 Gujarati

Gujarati (Indo-Aryan) is a split-ergative language with overt markers of ergative (-e), locative (-e), dative (-ne), genitive (-n+AGR), as well as DOM, spelled out as -ne, like dative (see Table 1 and Comrie 1984; Mistry 1997; 2004; Grosz & Patel-Grosz 2014; Irimia 2020). Unmarked noun phrases are often referred to as absolutive.

Gujarati also has a complex agreement system (Comrie 1984; Mistry 1997; Grosz & Patel-Grosz 2014). Addressing it in detail goes beyond the scope of the present paper, but agreement is relevant in two respects. First, it can distinguish the behaviour of different arguments marked with -ne. In contrast to Hindi–Urdu, where only morphologically unmarked noun phrases can control agreement (Saksena 1981; 1985; Comrie 1984; 1985; Mohanan 1990; 1994; Bhatt 2005; Butt 2006), morphologically marked direct objects can control agreement in Gujarati, as shown in (8).

Examples (8a,b) are in the perfective aspect, with ergative subjects (-e). In (8a), the direct object is morphologically unmarked and controls gender agreement. The verb references the object’s masculine gender rather than the subject’s feminine gender. In (8b), the proper name object Svati-ne is morphologically marked but still controls gender agreement. Ergative noun phrases never control agreement (Comrie 1984; Mistry 1997).

The suffix -ne, glossed as DOM in (8), is also the exponent of dative. In constructions with dative arguments, as in (9) and (10), the dative cannot control agreement, however, independently of aspect.

The crucial contrast lies in examples such as (8b) versus (9b) and (10). Objects with the DOM suffix -ne can control agreement, while datives with -ne cannot. Following Mistry (1997; 2004); Grosz & Patel-Grosz (2014), and in particular Irimia (2020), I take this to mean that -ne represents the syncretic spell-out of two underlyingly different syntactic objects. In addition, the unmarked object kagəL in (8a) can also control agreement on the verb, showing that morphologically unmarked objects ((8a)) and objects with DOM ((8b)) behave alike, to the exclusion of dative-marked arguments (see also Mistry 1997: 432).

The second relevant aspect of agreement is that it also distinguishes between subjects and objects. Grosz & Patel-Grosz (2014: 222) argue that Kutchi Gujarati (and potentially other varieties of Gujarati, too) have two ϕ-probes, one on T and a second, lower one on v or Asp. In (11), the auxiliary spells out agreement with the subject while the participle spells out agreement with the object. Note that it does not matter whether the object shows DOM or not, it triggers the same type of agreement, suggesting that both types of objects are in a relation with v. Indeed, Grosz & Patel-Grosz (2014: 241) conclude that DOM “appears to be connected to abstract (accusative) case licensing by v”.

In sum, Kutchi Gujarati agreement patterns show that direct objects pattern together, independently of DOM, and that both types pattern differently from indirect objects as well as subjects (see Grosz & Patel-Grosz 2014 for more detailed discussion). This is strongly indicative of a distinct type of syntactic relation (direct object) which, independently of its morphology, shows characteristic syntactic behaviour that crucially differs from that of other syntactic relations, even if their expression is syncretic.

Passivisation, another potential test for identifying syntactic relations, is not very productive in Gujarati (Pritty Patel-Grosz, p.c.), so my conclusions here rest on the agreement data. However, I am not aware of any evidence that the morphologically unmarked and DOM objects would represent anything other than direct objects, and so I conclude that they are (in line with the literature). Gujarati thus illustrates the characteristics mentioned in the introduction to this section: morphologically unmarked and DOM objects behave alike, as direct objects, and these direct objects behave differently from other syntactic relations.

2.2 Basque

Odria (2014; 2019) shows that in some southwestern varieties of Basque, direct objects are either morphologically unmarked (ABS) or appear with the case marker -ri. Odria argues that -ri is the syncretic expression of DOM and dative case based on the different syntactic behaviour of direct and indirect objects with -ri.

One such difference is an argument’s ability to control depictive secondary predicates. Odria (2014) points out that indirect objects cannot control depictive secondary predicates while direct objects can. In (12a), the ergative subject ni-k ‘I-ERG’ and the absolutive object umea ‘child’ can control the secondary predicate pozik ‘happy’, but the dative amona-ri ‘grandmother-DAT’ cannot. In (12b), in contrast, the direct object zu-ri ‘you-DOM’ can control the secondary predicate. This difference thus cannot be due to the morphology of -ri.

Other arguments for treating -ri as DOM rather than dative case come from its sensitivity to person in certain varieties and its behaviour in ditransitive constructions. Odria (2014: 297–300) shows that in Zumaia Basque first and second person direct objects are marked with -ri, (13), but third person objects are not. In other varieties, third person objects can be marked with -ri as well, as long as they are human and definite. These patterns are typical of DOM, but not of datives.

In ditransitives, where the recipient argument is marked with dative -ri, however, the same direct objects that are marked in (13) lose DOM, as shown in (14).

This behaviour of DOM objects is also found in Hindi and Spanish (Bhatt & Anagnostopoulou 1996; Ormazabal & Romero 2013; Odria 2014). Crucially, in all of these languages, it is the direct object that loses its case marker, never the indirect object. This distinguishes the direct from the indirect object syntactically and again shows that direct objects can be morphologically marked or unmarked. In addition, in varieties of Spanish, Hindi and Basque, DOM is optional in ditransitive constructions even on direct objects that would otherwise require DOM. I will not provide an analysis of this phenomenon here, but it could be captured by Richard’s (2010) “distinctness”.

In sum, the data shown here suggest that DOM objects in Basque do not pattern syntactically with dative objects but rather with unmarked absolutive objects (Odria 2014: 310). I concur with Odria’s (2014) assessment that both absolutive and DOM objects are syntactically canonical direct objects.

Thus Basque shows the same characteristic properties as Gujarati with respect to DOM and dative case. Morphologically unmarked and DOM objects that behave alike syntactically. They are direct objects whose syntactic behaviour can be distinguished from that of other syntactic relations, for example with respect to person sensitivity and being able to control secondary predicates.

2.3 Spanish

It has been argued that the marker a is the syncretic spell-out of distinct underlying structures representing DOM and dative objects, respectively, rather than a single type of syntactic structure (see e.g. Bresnan 1982; Odria 2014; Bárány 2018; López 2018; Irimia 2020; Muñoz Pérez 2020; see Manzini & Franco 2016 for a dissenting view). Odria (2014); Bárány (2018) in particular argue that not only is DOM in Spanish not dative, but that DOM patterns syntactically with morphologically unmarked direct objects.

A clear illustration of this comes from passivisation. Examples (15a–c), the passive counterparts of (3a–c), show that passivising direct objects with or without DOM is possible, (15a,b), while passivizing dative objects is not, (15c).

In addition to Bárány’s (2018) data in (15), (16) shows that a theme passive of a ditransitive is also possible (in contrast to the recipient passive in (15c)). (16) is modeled after the active examples (52) and (53) in Ormazabal & Romero (2007) in which DOM is obligatory for the direct object a los sospechosos.

Passives therefore distinguish DOM objects from dative objects and group morphologically marked and unmarked direct objects together.

Demonte (1987; 1988); Odria (2014; 2019); Bárány (2018); López (2018) provide further evidence that morphologically unmarked and DOM objects differ from DAT objects. Demonte (1987; 1988); Odria (2014; 2019) show that direct objects (with or without DOM) can control secondary predicates (like in Basque), and López (2018) shows that dative case is retained in nominalisations while both unmarked and DOM direct objects are marked by the genitive de. Finally, Bárány (2018) argues that passivisation and controlling secondary predication are not tied to thematic roles: the verb armar ‘to arm’ takes a recipient direct object which behaves just like other direct objects in that it can be morphologically unmarked or appear with DOM ((17)), control secondary predication ((18a)), and be passivised ((19)), in contrast to dative recipients in ditransitives.

Like Gujarati and Basque, Spanish shows characteristic properties of languages with DOM/DAT syncretism. The language has DOM and morphologically unmarked and DOM objects which behave alike syntactically, like direct objects. These direct objects behave differently from other, syncretic, syntactic relations.

2.4 Interim summary

In this section, my aim was to show that Gujarati, Basque and Spanish all show similar properties, characteristic of languages with DOM and dative syncretism. All have a syntactic relation that corresponds to direct objects which can be morphologically unmarked or be spelled out as DOM and in all three languages these objects show strikingly different syntactic behavior from other syntactic relations such as subjects or objects even when syncretic. The properties I discussed are summarised in Table 2.

I am not aware of any evidence that would suggest that these direct objects differ in their syntax from typical absolutive or accusative objects in ergative–absolutive and nominative–accusative languages.¹ This view is widely held in the literature. Starke (2017); Bárány (2018) refer to both morphologically unmarked and DOM objects as accusative (small and big in Starke 2017), while Odria (2014; 2019) and Irimia (2020) characterise both as being like absolutive direct objects.

In the following section, I develop an analysis that retains case contiguity and case containment while capturing both the identical syntactic behaviour of morphologically unmarked and DOM objects and their patterns of syncretism.

3.1 Modelling partially ordered case hierarchies

The starting point for my proposal is case decomposition. Rather than treating “nominative”, “ergative” etc. as atomic, it has often been suggested that these categories are bundles of features. Many analyses of this type, for example those by Bierwisch (1967); Wunderlich (1997); Müller (2002); McFadden (2004), rely on bivalent features, such as [±oblique], to distinguish nominative and accusative ([–oblique]) from dative and genitive ([+oblique]).

Caha (2009: 19–25; 2013: 1024), in contrast, proposes a “cumulative classification” of cases, in which each case in (1) is represented by a set of (abstract) features, as in (20).

If each case is a set of features, a case hierarchy can be stated as a total order of sets ordered by the subset relation (⊂). Such sets of features are straightforwardly implemented in the spell-out rules used in Distributed Morphology (DM; Halle & Marantz 1993; Halle 1997; Harley & Noyer 2003; Embick & Noyer 2007; Bobaljik 2011). This is true both when each case is spelled out by a distinct vocabulary item and when two or more cases are syncretic. Consider the two sets of spell-out rules in (21) referring to the case features in (20). In the absence of another spell-out rule referring to DAT in (20), (21a) describes a situation in which the marker -er would be inserted for both GEN and DAT. This is due to DM’s subset principle, which states that a vocabulary item, for example -er in (21a), must have a subset of the features of the terminal node it is inserted in (see e.g. Halle & Marantz 1993: 121–122). The single marker -er in (21a) thus syncretically spells out GEN and DAT. Note that no impoverishment is necessary here; the set of vocabulary items is merely underspecified. (21b), in contrast, describes two distinct markers for GEN and DAT.

Cumulative classification, as shown in (20), gives rise to a hierarchy totally ordered by the subset relation ⊂. As mentioned in Section 1, this order has been argued to be empirically inadequate: taking Spanish as an example, where a spells out both DOM and dative but de spells out genitive, the syncretism of DOM and dative violates case contiguity if DOM represents accusative.

Instead of giving up cumulative classification and ordering by ⊂, or adding several instances of accusative and dative, I propose to give up the total ordering of (20), within limits. To restrict the expressive power of the partially ordered hierarchies, I will maintain the general idea behind Zompì’s (2019) (5), namely that unmarked cases (NOM, ABS) are ordered before dependent cases (ACC, ERG), which are in turn ordered before inherent cases. More specifically, my hierarchies implement Zompì’s (2019) generalisation as stated in (22). This allows for unmarked cases to be subsets of dependent cases, but crucially also for (some) dependent cases to be incomparable to (some) inherent cases.

As for possible DOM syncretisms, this system correctly accounts for syncretism with DAT (as discussed in this paper) but also with INS (as in Kolyma Yukaghir, Maslova 2003; Keine 2010) or GEN (as in Finnish, Kiparsky 2001; Vainikka & Brattico 2014; Poole 2015). In principle, like on Zompì’s (2019) approach, DOM could be syncretic with any inherent case, although cross-linguistically DAT seems to be the most frequent choice (Bossong 1991). By maintaining case contiguity the system rules out syncretism of an inherent case with an unmarked case, unless a dependent case is also syncretic (*ABA configurations). In this respect, it is at least as powerful as Starke’s (2017) and Irimia’s (2020) hierarchies, with the benefit of conforming to Zompì’s (2019) universal containment.

Consider (23), a partially ordered hierarchy for Spanish annotated with Zompì’s (2019) categories. Since NOM is ordered before ACC and both are ordered before GEN and DAT, (23) conforms to Zompì’s (2019) hierarchy, as do all other case hierarchies I propose (see e.g. (25) below). Note finally that, again conforming to Zompì’s proposal, different cases in one group such as GEN and DAT in (23), do not have to be comparable to each other.

(23)	Partially ordered Spanish case hierarchy and universal containment

In line with the data in Section 2 and the subsequent discussion, I argue that both morphologically unmarked and DOM objects represent direct objects which typically correspond to ABS or ACC in languages without differential marking. Recall also that the cases on (23) are underlying representations, the features of which can be subject to impoverishment before spell-out.²

For Spanish, the spell-out of NOM, ACC, GEN, and DAT on the hierarchy in (23) can be analysed as follows. ACC and DAT are now contiguous, without positing two instances of each case, as GEN does not intervene between them. By assigning the cases the features shown in (23), syncretism of ACC and DAT can be straightforwardly implemented in spell-out rules.

The spell-out rules for de, the genitive, and a, the syncretic form of DOM and dative, are shown in (24).

By the subset principle, a in (24b) can be inserted for both ACC with the feature set {A, B} and DAT with the feature set {A, B, C}. {A, B} is of course also a subset of GEN with {A, B, Z}, but there is a more specific marker, de, which takes precedence over a. By giving up the total order of case sequence, this approach to Spanish ACC, DAT, and GEN retains case contiguity, that is it does not derive non-linear case syncretisms (*ABA patterns).

The same approach can account for the more complex patterns in Gujarati and (varieties of) Basque as well. Recall that Gujarati is split-ergative, while Basque is ergative. Both have morphologically unmarked ABS direct objects as well as morphologically marked DOM that is syncretic with dative. Having a morphologically marked direct object case in ergative languages is not very common; such case systems are referred to as “tripartite” because A, S, and P all have distinct morphological forms (see e.g. Deal 2010; Comrie 2013; Baker 2015). Comrie (2013) refers to Hindi–Urdu as a tripartite language because, like Gujarati and Basque, it has DOM in ergative contexts such that both the transitive subject and the object have morphological case-marking. In this respect, Gujarati and Basque differ from Spanish: Spanish only spells out one dependent case (in Zompì’s terminology), ACC. Gujarati and Basque can spell out two dependent cases, ERG and ACC. This motivates the inclusion of ABS, ERG, and ACC in the hierarchy in (25) (see Section 3.2) for further discussion).

In Gujarati, ergative and locative are also syncretic. A partially ordered Gujarati case hierarchy is shown in (25), annotated with the spell-out of each marker, its features and Zompì’s (2019) categories.

(25)	Partially ordered Gujarati case hierarchy and universal containment

In (25), not all cases are comparable, or ordered with respect to each other by ⊂, hence it represents a partial order. ERG and LOC are incomparable to DAT, while both groups are comparable to ABS and GEN. Crucially, ERG, a dependent case, is ordered before LOC, an inherent one, and DAT does not intervene between ACC and ERG, as ERG and DAT are incomparable. Therefore, no inherent case precedes a dependent case and no dependent case precedes an unmarked case.

The vocabulary items spelling out these cases are shown in (26).

Again, because of the subset principle, the marker -e, specified for {A, Z}, spells out both ERG and LOC, while the marker -ne, {A, B}, spells out both ACC (corresponding to DOM) and DAT.

The Basque syncretism of DOM and dative can be captured in essentially the same way as the Gujarati one: ACC ⊂ DAT, but both are incomparable to ERG. This makes it possible for a single vocabulary item -ri to spell out both DOM and DAT.

The present implementation of partially ordered case sequences is similar in some respects to Harðarson’s (2016) proposal that case contiguity is weak, Zompì’s (2019) proposal that classes of cases, rather than individual cases, are comparable, as well as Bárány’s (2016) and Graf’s (2019) partial orders. Harðarson’s (2016) hierarchies represent total orders, which may, however, differ across languages. Zompì’s (2019) hierarchy in (5) is universal, but refers to classes of mutually unordered cases. Similarly, Graf (2019) posits different levels on which cases are incomparable.

Partially ordered hierarchies capture the benefits of both Harðarson’s (2016) and Zompì’s (2019) proposals. GEN can appear to be in different orders with respect to ACC and DAT by being unordered relative to DAT, as in (27) (repeated from (23)).

(27)

Different vocabulary items can determine whether, for example, ACC and DAT are syncretic (as in Spanish) or ACC and GEN are syncretic (see Caha 2009 on some Russian inflection classes). Both types can be captured by the same sequence.

At the same time, partially ordered hierarchies are compatible with Zompì’s (2019) generalisations about classes of cases and syncretism in (5) and (6), in contrast to Starke’s (2017) and Irimia’s (2020) hierarchies. Consider Irimia’s hierarchy for Gujarati again (repeated from (4)):

(28) has a stretch of interleaved dependent and oblique cases and therefore does not conform to Zompì’s (5). The partially ordered hierarchy in (25), in contrast, implements Zompì’s universal containment and retains the restrictive power of Zompì’s generalisation.

An earlier version of Zompì’s proposal, based on the data in Zompì (2017), is characterised by Graf (2019: 19) as being “both too permissive and too restrictive”. Graf (2019: 20–21) instead proposes a partial order with groups of incomparable cases organised on three levels, crucially not ordering ACC, ERG, GEN, and LOC with respect to each other (note that Graf includes NOM, ABS, as well as ACC and ERG). These layers are shown in (29). Graf (2019) proposes the generalisation in (30), banning certain “parallel” syncretisms between the second and third layers of (29).³

(29)	Case layer hierarchy (Graf 2019: 20)

Graf (2019: 22) correctly points out that (29) and (30) restrict the power of partial orders. My proposed hierarchies are as permissive as Graf’s layers; they could also be supplemented by a ban such as (30).

Finally, another potential advantage of the present proposal lies in the mapping of cases on the hierarchy to their morphological expression. In the case of Spanish, a single ACC case underlies two different morphological forms of direct objects, in contrast to Starke’s (2017) two. This is advantageous, because, as Zompì (2019: 15) points out, Starke’s (2017) hierarchies both over- and undergenerate. In addition, being associated with a single underlying case makes sense in light of the syntactic behaviour of direct objects with and without DOM in Spanish.

The situation is somewhat different in Basque and Gujarati, for which I argued that both ABS and ACC can be motivated on the hierarchies. I turn to this point now.

3.2 Direct objects, accusative, and absolutive

In this section, I return to the question of the syntactic relations and the underlying case of the objects discussed in Section 2. I will argue that the relevant objects, be they morphologically marked or not, all represent direct objects and are the (potentially modified) spell-out of an underlying ACC.

The overall logic of my argument is as follows (I am grateful to two reviewers for pushing me to clarify this reasoning). First, if certain syntactic arguments show identical behaviour, it is reasonable to treat them as representing one syntactic relation. Second, if this syntactic behaviour is that of typical direct objects, it is reasonable to assume that the arguments represent that grammatical function and have abstract Case associated with direct objects (ACC). Therefore, third, if morphologically unmarked direct objects and DOM show the same syntactic behaviour, they can be classified as the same syntactic relation and as having the same abstract Case — even if DOM objects are syncretic with another case, namely DAT. I will address these points in turn.

I have interpreted the data in Section 2 as evidence that subjects (morphologically unmarked or ergative) can be distinguished from direct objects (morphologically unmarked or DOM) and indirect objects (dative) in Gujarati, Basque, and Spanish, based on their syntactic behaviour. Unmarked and DOM objects are able to control agreement in Gujarati, they control depictive secondary predicates and show sensitivity to person and animacy in Basque, and they can be passivised and control depictive secondary predicates in Spanish (Table 2). Recall also that, at least in Spanish, these properties are independent of the thematic role of the object (cf. (17), (18), (19)).

This behaviour is typical of direct objects (although there is some cross-linguistic variation; see Haspelmath 2018 on difficulties of comparison of this sort). For example, passives generally promote a direct (or primary) object to subject (Oehrle 1976; Perlmutter & Postal 1983); in languages with object agreement, direct (or primary) objects are always potential agreement controllers in monotransitive sentences (Faltz 1978; Bárány to appear). The situation with secondary predicates seems to vary more across languages. While Bárány (2018) shows that in Spanish, recipient direct objects (of the verb armar ‘to arm’) can control secondary predicates, this is not true of goal or recipient arguments in English and German in many cases (Williams 1980; Maling 2001). Nevertheless, it is clear from Odria’s (2014) data that DOM objects, even though they are syncretic with dative, behave like morphologically unmarked objects, and not like datives. Thus, depictive secondary predicates do work as a diagnostic for whether morphologically unmarked and DOM objects behave alike, as typical direct objects.

What about the (abstract) Case of these objects? In nominative–accusative languages, ACC is taken to be the abstract Case associated with direct objects (“objective” in Chomsky 1981: 170; accusative assigned by v in Chomsky 2001: 6). Legate (2008), among many others, also adopts this idea and adds that v assigns abstract Case to the same class of object in ergative–absolutive languages of the type discussed in this paper.

Linking this to the case hierarchies proposed here, I assume that v assigns to the direct object the set of features associated with ACC on the hierarchy. In NOM–ACC languages with morphological case, but without DOM, this is spelled out as ACC (e.g. in German or Hungarian). In ERG–ACC languages with morphological case, but without DOM, this is spelled out as ABS, i.e. as an unmarked case (Legate’s 2008 ABS=DEF(ault) languages). In languages with DOM, be they NOM–ACC or ERG–ACC, the underlying features of ACC can be spelled out as DOM or they can undergo impoverishment and be spelled out differently (Keine & Müller 2015), for example as unmarked case in Gujarati, Basque, and Spanish.

The association of two distinct morphological forms with one underlying Case is compatible with the identical syntactic behaviour of morphologically unmarked and DOM objects and the distinct behaviour of true dative objects, which are assigned a different set of case features.

In sum, I argued that, first, morphologically unmarked and DOM objects show the same syntactic behaviour and that this supports treating them as the same type of syntactic relation. Second, this syntactic relation is that of typical direct objects, which are generally assumed to be assigned ACC (or ABS) in frameworks adopting abstract Case. Third, I showed that the behavior of these objects distinguishes them from that of other syntactic relations, such as indirect objects, even if these are syncretic with DOM objects.

3.3 Summary

Summarising this section and the proposal, I have argued that Harðarson’s (2016) and Zompì’s (2019) arguments about case contiguity can be implemented by adopting partially ordered case hierarchies. By restricting partial orders to respect Zompì’s (2019) generalisations about classes of cases in (5) and syncretism in (6) as stated in (22), this proposal accounts for at least the languages covered by those approaches and, crucially, avoids Starke’s (2017) multiple instances of the “same” dependent case. The analysis presented here is similar to Graf’s (2019), but corresponds to Zompì’s (2019) universal containment more directly. The hierarchies are partially ordered by a subset relation (⊂). Syncretism can be modelled in the same way as on totally ordered hierarchies.