Longenbaugh’s syntactic account is based on four ingredients: feature-driven Merge, the Obligatory Operation Hypothesis (Preminger 2014), the condition of Feature Maximality and the Bobaljik-Moravcsik treatment of case.

Longenbaugh follows the assumption that certain syntactic heads are associated to a Merge operation (e.g., merger of the external argument in Spec,vP of unergative and transitive verbs). He encodes this mechanism with a special Merge feature on these heads (Longenbaugh 2019: 23). These Merge features can be satisfied either by external or internal Merge. Furthermore, he assumes that a syntactic operation must apply if it can apply. This is a widely accepted assumption in Minimalism, no matter if one assumes the Obligatory Operation Hypothesis by Preminger (ObOp, 2014) or the Uninterpretable Feature account of Chomsky (2001). The important difference between those two accounts is what happens when agreement fails: under the Chomskyan view, a derivation crashes if an agreement operation fails whereas in the ObOp frame (Preminger 2014), an unvalued feature may receive the default value without affecting the grammaticality of the sentence. If one head is associated with several requirements, there is no specific order in which those requirements have to be satisfied: they can apply in every possible order as long as the result is interpretable at the interfaces.

The relationship between movement and agreement is governed by an economy condition:

Feature Maximality gives the instruction to maximize the discharge of requirements in one established Probe-Goal relation. Thus, if a head enters into an agreement relation with another element and the probe also bears a Merge feature that the goal can in theory satisfy, it has to satisfy it. Conversely, then, if a certain syntactic element satisfies the Merge feature of a given head, it must also value the unvalued features on the given head; “agreement is therefore predicted to be associated with movement if and only if the triggering head has an independent, unrealized need to project a specifier.” (Longenbaugh 2019: 21).

The fourth and last necessary tool in his account is the Bobalijk-Moravcsik treatment of case (Moravscik 1974; Bobaljik 2008; Preminger 2014), which has two essential components. First, case is valued configurationally. Unvalued case features on DPs can be licensed either via lexical/oblique case or via dependent case. Certain syntactic heads have the ability to value the case feature of their specifier or complement, resulting in lexical/oblique case. For the other cases, case features on DPs are valued configurationally. In the presence of two DPs, the lower DP, i.e. the IA, obtains dependent case which is morphologically realized as accusative. Case valuation obtains as soon as the configurational requirement is met. The case feature of the higher DP remains unvalued which does not result in a derivational crash but in the spell-out as nominative.9

Case Accessibility determines whether a DP is a possible goal for agreement (Bobaljik 2008; Preminger 2014). This is a parametrical option for languages: some languages only allow φ-agreement with DPs without Case value, while others also allow agreement with already case valued DPs.10

Having introduced these theoretical tools, we can now turn to Longenbaugh’s detailed account of French and Italian PPA in unaccusative/passive inversion.

Longenbaugh assumes, along with more literature (Belletti 2017; D’Alessandro & Roberts 2008), that PPA is triggered by the head that introduces the external argument, v°. In Longenbaugh’s account, unaccusatives and passives bear a vP (Legate 2003; Sauerland 2003) and v° is associated with a φ-probe [φ: __ ] and a [D] (Merge) feature, just like transitive v°.11 The [D] feature on v° can either be satisfied by internal or external Merge, with the constraint on unaccusative v° that it cannot externally Merge semantically contentful DPs, i.e. it blocks the insertion in Spec,vP of arguments that are not already assigned a theta-role.12 Longenbaugh follows Richards & Biberauer (2005) and Deal (2009) in assuming that expletives are Merged in Spec,vP.

Since v° has two requirements (discharge [φ: __ ] and discharge [D]), there are two derivational options that can apply as the ordering of the operations is not fixed: first discharge [φ: __ ] and then discharge [D], or first discharge [D] and then discharge [φ: __ ]. The ordering of these derivational options crucially affects the position of the subject as well as the success of the agreement operation due to Case Accessibility, as will be sketched out below.

The first possible ordering of derivational processes after the Merge of v° (first φ, then [D]) results in the PPA with the IA and its subsequent obligatory movement to Spec,vP and Spec,TP, thus, a SV structure:

If, on the other hand, the [D] feature is satisfied first, an expletive will be merged in Spec,vP. The French expletive il is pronominal in nature and bears a case feature, thus, it is a case-competitor. Therefore, the necessary syntactic configuration for dependent case valuation of the IA is met, triggering the immediate valuation of the case feature of the lower DP. The IA is case-valued and therefore inaccessible for the φ-probe of v°. The unvalued φ-features on v° are morphologically realized with the default value [M.SG].

The Merge of a case-feature-bearing and, thus, case-competing expletive triggers dependent case valuation, making the agreement operation impossible and resulting in the default valuation of the φ-features on v°.

Standard Italian differs from French in two regards: there is no overt expletive in preverbal position, and PPA is obligatory with postverbal subjects.

Longenbaugh (2019) bases his analysis of PPA in Italian unaccusative inversion on two assumptions: firstly, Standard Italian disposes over a null expletive (Rizzi 1982; Sheehan 2006) that can satisfy the [D] feature on v° and T°; and secondly, the Italian null expletive does not carry a case feature, i.e. is not a case-competitor (as the English there expletive) contrary to the French expletive il (Rizzi 1982; Cardinaletti 1997).

Applying Longenbaugh’s system, the first derivational option (discharge φ and then [D]) results in a SV structure, as it is the case in French. But for the present purpose the second derivational option resulting in a VS structure is of bigger importance.

If after the Merge of v° the [D] feature is satisfied first, again, an expletive is merged in Spec,vP. The crucial difference to the French example is that the expletive is not a case-competitor since it does not carry a case feature. Therefore, the necessary syntactic configuration for dependent case valuation is not met: the IA is not valued with dependent case and remains accessible to the v°-probe. The φ-features on v° get valued by the IA.

Longenbaugh, thus, explains the different PPA properties in French and Italian inversion with the presence of two different kinds of expletives. While the French expletive il is a case-competitor and therefore introduces dependent case valuation of the IA, the Italian null expletive pro is not a case-competitor, i.e. no case valuation takes place. The French case-valued DP is not accessible to the φ-probe, while the Italian postverbal DP is: PPA can only obtain in the Italian case.

Concluding, the approach by Longenbaugh (2019) can account more properly for the empirical facts of Romance PPA, including optionality of PPA in French in wh-interrogatives. Furthermore, Longenbaugh’s system gives a possible new perspective to tackle the syntactic mechanisms of PPA alternation in the North-Eastern Italian dialects of Mestre and Gazzolo, as reported in section 2.

The analysis of the full agreement pattern is based on Standard Italian (Section 4.1.3.4), including a non-case competing null pro. As sketched out before, Longenbaugh (2019) bases his analysis of PPA in Italian unaccusative inversion on two assumptions: first, the existence of a null expletive in Standard Italian; and, second, the assumption, that the Italian null expletive does not carry a case feature. Assuming a non-fixed order of derivational processes for one syntactic head, there are two derivational options: discharge [D] first or discharge [φ: __ ] first. As the second option triggers the obligatory movement of the IA to Spec,vP and subsequently to Spec,TP, resulting in an SV structure, as already seen for the Standard French and Standard Italian data, I will focus on the first option.

After the Merge of v°, the [D] feature is satisfied by the Merge of the Standard-Italian expletive pro. Since pro does not carry a case feature, it is not a case-competitor. Therefore, independent case valuation of the IA does not take place and the IA is still a licit goal for the φ-probe on v°; φ-agreement takes place, while the case feature of the IA remains unvalued resulting in a VS structure in which the participle fully agrees with the postverbal subjects. The postverbal subject is spelled out with nominative case.

The analysis of the default agreement pattern is based on French (Section 4.1.3.3), including a case-competing null expletive. The Standard French expletive is pronominal in nature. Thus, it carries φ-features as well as a case feature, qualifying as a case-competitor. Again, as the second derivational option is negligible for the present purpose, I focus on the first derivational option, the immediate satisfaction of [D] after the Merge of v°. In order to satisfy [D], an expletive is inserted in Spec,vP. The peculiarity of the dialects at issue is that they do not only dispose over an expletive pro of the Standard-Italian type, but also over a null expletive of the French type which is pronominal in nature and carries φ-features and a case feature. Due to the Merge of the case-competing expletive in Spec,vP, the necessary syntactic configuration for dependent case valuation is met and the IA is assigned dependent case.13 On the basis of Case Accessibility, the IA is no longer accessible to the φ-probe on v°. The agreement operation of the φ-probe fails and the unvalued φ-features on v° are morphologically realized, according to the language-specific default value, as 3^rd person masculine singular.

Based on Longenbaugh’s (2019) account of French and Italian PPA, the North-Eastern Italian agreement alternation is analysed as the reflex of two different kinds of null expletives:

The case-competing expletive, (i), is pronominal in nature and carries φ-features and an unvalued case feature. Merge of the expletive in Spec,vP yields the necessary syntactic configuration to trigger dependent case valuation of the case feature of the IA, rendering the IA inaccessible to the φ-probe. The other expletive, (ii), does not carry a case feature and is not a case-competitor. Therefore, the case feature of the IA remains unvalued and is spelled out as nominative.

Based on these considerations, the following correlations arise: case-competing expletives appear with accusative-marked IAs and the participle exhibits default agreement. Non case-competing expletives, on the other hand, appear with nominative-marked IAs and the participle overtly agrees with the IA. Now, two questions arise:

Indeed, some Norwegian dialects dispose over two expletives: the pronominal third singular neuter expletive det and another expletive of the locative proform der, cognate to English there (Afarli 2009: 171). The following contrast regarding PPA appears in all unaccusative/passive contexts:

The expletive det correlates with (neuter) default agreement, while the expletive der correlates with PPA with the postverbal subject. Since Modern Norwegian does not mark morphological case, it is not clear which case the postverbal subject bears. Case is morphologically encoded on pronouns, but they are prohibited from expletive constructions due to the Definiteness Effect which is active in Norwegian: definite DPs cannot appear in the postverbal position in expletive constructions.

We can observe similar effects with the German (pronominal) expletive es and the (locative) expletive da:

While the pronominal expletive es correlates with an accusative marked IA and default agreement on the verb,14 the locative expletive da appears with a nominative-marked IA and the verb agrees with the IA. I chose the example with a plural DP, in order to highlight the agreement facts, i.e. the opposition between the plural full and the singular default agreement on the verb. The morphological case marking becomes more telling, if the DP is singular:

These data confirm the predictions coming from the present analysis: the different expletives show the predicted correlation. One kind of expletive (the pronominal es) appears with an accusative-marked postverbal argument and default agreement, while the other expletive (the distal locative da) appears with a nominative-marked postverbal argument and full agreement.

The same correlations show up in a null-subject language like Greek. The opposition between two kinds of expletives that we see overtly marked in Mainland Scandinavian and German, is still there, even in absence of an overt realization for them. But the predicted correlation of accusative case with default agreement and nominative case with full agreement is clearly visible in the Greek example:

These data support the proposal put forward for the dialects at issue. They show that Longenbaugh’s (2019) prediction regarding the nature of the expletive, case and agreement holds in these languages. Since the dialects of Mestre and Gazzolo d’Arcole are null subject languages, the assumed existence of two different kinds of null expletives is not far-fetched.15 As indicated in (62), this predicts that the postverbal subject is marked for nominative in a. and for accusative in b.

Since neither the variety of Mestre nor of Gazzolo is subject to the Definiteness Effect we could theoretically test whether this prediction is born out using pronouns. Unfortunately, the dialects show a syncretism in tonic 3^rd person nominative and accusative pronouns, here shown for Gazzolo:

The next question to tackle is whether the appearance of the expletives is restricted to certain lexical and/or pragmatic contexts, as the descriptive data of the dialects of Mestre and Gazzolo d’Arcole implies.

Having put in place the pragmatic and the syntactic analysis, I will now shortly tie together these two ends. As presented in Section 3.1, languages use different formal means in order to disambiguate thetic and categorical sentences. While in French the case-competing expletive il is used, Standard Italian marks thetic sentences with unaccusative verbs by exibiting an inverted order of the constituents, i.e. VS. In the latter case, a syntactic dummy expletive is inserted in the structure: the non-case-competing pro.

The two investigated North-Eastern Italian dialects cannot use the strategy of the Standard Italian type marking categorical sentences by preverbal subjects since a restriction forbids preverbal indefinites. A French-type case-competing thetic expletive compensates this lack of disambiguation by word order. In the preceding section, the different syntactic mechanisms of the insertion of either the thetic or the syntactic expletive pro were explained in detail. Due to a mechanism of case-valuation and the premise of Case Accessibility, the insertion of the different expletives triggers the appearance of the full or defective PPA pattern respectively.