2.1 Some general remarks and clarifications

The prerequisite hypothesis, as stated in (4), is phrased in descriptive terms, but is consistent with central ideas of Principles and Parameters theory (P&P). More precisely, it can be derived from one of the implicational relationships stated in the original formulation of the null subject parameter (Rizzi Reference Rizzi1982),Footnote ³ namely that the presence of null RefSs implies the presence of null NonRefSs (more on this in Section 2.2). The idea of an implicational relationship between null RefSs and null NonRefSs has been widely accepted, also in recent works (see e.g. Roberts & Holmberg Reference Roberts, Holmberg, Biberauer, Holmberg, Roberts and Sheehan2010:12), and it is corroborated by cross-linguistic empirical evidence. There is a very strong tendency for languages allowing null RefSs to also have null NonRefSs; Gilligan (Reference Gilligan1987) concludes that the implication seems to hold in a sample of more than 100 languages. In a more recent study, Nicolis (Reference Nicolis and Biberauer2008:291), who considers data from a range of Creole languages, states that the implication appears to be of an “absolute” nature.

It should be noted, though, that some (potential) counter-examples have been observed in the literature. One case is Övdalian, which allows null RefSs in the first and second person plural, but requires NonRefSs to be overtly realised (Rosenkvist Reference Rosenkvist2010:236). Other cases are e.g. Old High German, Finnish and Dominican Spanish.Footnote ⁴ In the latter languages, overt and null NonRefSs co-exist (Axel Reference Axel2007:295, 303, Hinzelin & Kaiser Reference Hinzelin, Kaiser, Mihatsch and Sokol2007, Nicolis Reference Nicolis and Biberauer2008:276–277). Whether null subject systems of this type are actually counter-examples to the implicational relationship between null RefSs and null NonRefSs depends on whether one adopts a strong or a weak version of the implication. In what I will refer to as the strong version, a language that allows null RefSs will require null NonRefs; there is, in other words, no room for overt NonRefs. In what I will call the weak version, languages with null RefSs will allow null NonRefSs, but not necessarily require them; there is, in other words, room for some overt NonRefSs. Nicolis (Reference Nicolis and Biberauer2008) adopts the weak version; he is thus able to reconcile Finnish and Dominican Spanish data with the implication.Footnote ⁵ Camacho (Reference Camacho2013:42), on the other hand, operates with a stronger version and takes data of the Old High German/Finnish/Dominican Spanish type to indicate that the implication between null RefSs and null NonRefSs does not hold universally.

In this paper, my point of departure will be the strong version of the implicational relationship between null RefSs and null NonRefSs, and, accordingly, a strong version of the prerequisite hypothesis. The claim to be tested is thus the following: a language will not only allow but will also require null NonRefSs as long as null RefSs are licit; consequently, no overt NonRefSs are found. There are two reasons why I use the strong version of the hypothesis as my starting point. First, the strong version is the one that most immediately follows from the works to be discussed in the following sections, in particular from Rizzi (Reference Rizzi1982). Second, from a heuristic point of view, it is preferable start by testing the strongest prediction; the weaker version can then be taken into consideration if the strong version turns out not to hold. Note, however, that even a strong version of the prerequisite hypothesis is compatible with certain “subject-like”, non-referential elements. Crucially, though, such elements must have some identifiable linguistic function apart from that of being a subject (from the viewpoint of mainstream generative grammar, they must do something more than value the uninterpretable φ-features of T). Vietnamese has a non-referential element nó that has been argued to encode specificity (Greco et al. Reference Greco, Phan and Haegeman2015). Non-referential ele in non-standard European Portuguese has been argued to be a type of discourse marker emphasising the illocutionary force of a sentence (Carrilho Reference Carrilho, Barbiers, Koeneman, Lekakou and van der Ham2008). Elements like nó and ele do not conflict with the implication between null RefSs and null NonRefSs if we can safely assume that they are more than, or perhaps something else than, plain NonRefSs.

The distinction between the strong and the weak version of the prerequisite hypothesis concerns the predictions made for any given language synchronically. Before we move on, one point should be clarified with regard to diachronic predictions: the prerequisite hypothesis does not state that overt NonRefSs necessarily arise in any language that loses null RefSs. However, if overt NonRefSs arise in a language, we do not expect that language to be one that (still) allows null RefSs.

We now turn to the works of Rizzi (Reference Rizzi1982), Håkansson (Reference Håkansson2008) and Faarlund (Reference Faarlund, Røyneland and Enger2012, Reference Faarlund, van Gelderen, Barðdal and Cennamo2013) to see how the prerequisite hypothesis is instantiated there.

2.2 Rizzi (Reference Rizzi1982)

Rizzi (Reference Rizzi1982) does not discuss Scandinavian in detail but is relevant by virtue of being one of the most influential works in early P&P theory. Rizzi (Reference Rizzi1982) put forth the null subject parameter, whereby the null subject properties of a language are determined by the settings of two related parametric options, rendered in (5) (see Rizzi Reference Rizzi1982:143):

1. (5)

   1. a. INFL can be specified [+ pronoun].

   2. b. INFL can be referential.

INFL is, in Rizzi’s (Reference Rizzi1982) framework, subject-verb agreement. For any subject to be null, Ref or NonRef, INFL must be specified as [+ pronoun]. INFL being specified as [+ pronoun] is a sufficient condition for null NonRefSs; null RefSs, on the other hand, additionally require a positive setting of the parameter in (5b), stating that INFL can be referential.Footnote ⁶ It follows that a language may have null NonRefSs but require RefSs to be overt; Rizzi (Reference Rizzi1982:143–144) mentions Icelandic, a variety of Dutch, and certain northern Italian dialects, e.g. Paduan, as examples of this.Footnote ⁷ Cf. example (6), from Paduan (Rizzi Reference Rizzi1982:143):

1. (6)

   

The opposite pattern, whereby RefSs can be null, but NonRefS are overt, is “excluded for intrinsic reasons (if an inflection cannot be pronominal, it cannot be referential either)” (Rizzi Reference Rizzi1982:143). The typological prediction of Rizzi (Reference Rizzi1982) is thus clear, but it also entails a diachronic dimension: we would not expect a language to develop overt NonRefSs while still maintaining null RefSs. If null RefSs are licensed, the language should also be capable of licensing null NonRefSs. Overt NonRefSs would be unnecessary, and Rizzi (Reference Rizzi1982) offers no way of reconciling them with null RefSs.

2.3 Håkansson (Reference Håkansson2008)

Håkansson’s (Reference Håkansson2008) study focuses on null RefSs in Old Swedish; it also proposes a diachronic account of how null subjects were lost. In Håkansson’s analysis, the loss of null subjects followed from a change in the status of Spec-TP (Spec-IP in his terminology).Footnote ⁸ According to Håkansson, Spec-TP changed from being an A'-position in Old Swedish to an A-position reserved for the subject at the modern Swedish stage. I will not discuss the details of the analysis here; the important point in the present context is the following: subjects, according to Håkansson (Reference Håkansson2008), can only be omitted from A'-positions. Thus, the change of Spec-TP from an A' to an A-position not only implied obligatory movement of the subject from its base-generated position in the V-domain to Spec-TP, but it also implied that subjects could no longer be deleted from Spec-TP.Footnote ⁹ Håkansson (Reference Håkansson2008:225) proposes a scenario in which the transition of Spec-TP into a pure subject position happened in three stages, summarised in (7):

1. (7)

   1. 1. Subjects of transitive verbs began to move obligatorily to Spec-TP.Footnote ¹⁰

   2. 2. The rule in 1 was generalised to all RefSs, causing movement of all RefSs from their base-generated, VP-internal position.

   3. 3. The rule in 2 was further extended in the sense that overt NonRefSs were generated in Spec-TP. This is the situation in Modern Swedish.

As is evident, overt NonRefSs do not enter the scene until the last stage, after the changes regarding RefSs are completed. Obligatorily overt RefSs can thus be seen as a prerequisite for the rise of overt NonRefSs. According to Håkansson (Reference Håkansson2008:225), the model in (7) can also be applied to Modern Icelandic: Modern Icelandic has only completed the two first stages, which is why RefSs are obligatorily overt, whereas NonRefSs are not.

2.4 Faarlund (Reference Faarlund, Røyneland and Enger2012, Reference Faarlund, van Gelderen, Barðdal and Cennamo2013)

Faarlund (Reference Faarlund, Røyneland and Enger2012, Reference Faarlund, van Gelderen, Barðdal and Cennamo2013) discusses null arguments in the history of Scandinavian and other languages. He treats null arguments as inherently silent pronouns whose presence or absence in a language is independent of the functional categories of the clause; the (im)possibility of null arguments only reflects properties of the pronominal system itself.Footnote ¹¹ Faarlund adheres to common generative terminology in calling silent pronouns pro, but as opposed to Rizzi (Reference Rizzi1982, Reference Rizzi1986) and much subsequent work, he does not assume any particular syntactic licensing conditions (like pronominal INFL).

According to Faarlund, pro is a lexical item that must be robustly represented in the primary linguistic data (PLD) to be acquired. If the frequency of pro drops below a certain threshold, it will not be picked up by children during language acquisition, and a new grammar with only overt pronouns will emerge. In Mainland Scandinavian, Faarlund argues that the frequency of pro started to drop because of the weakening of subject-verb agreement morphology: although pro was not syntactically conditioned by subject-verb agreement, the agreement morphology did promote recoverability of pro on a pragmatic level. When the agreement morphology was weakened, overt pronouns became a more preferable option for communicative reasons. This made the frequency of pro drop below the critical level, which in turn led to its loss.

Faarlund (Reference Faarlund, Røyneland and Enger2012, Reference Faarlund, van Gelderen, Barðdal and Cennamo2013) does not propose a stepwise loss of null subjects; in his account, both referential and non-referential pro were lost simultaneously in the history of Scandinavian. Thus, according to Faarlund, the loss of null RefSs was not directly a condition for the loss of null NonRefSs. Still, Faarlund’s works are relevant in the context of the prerequisite hypothesis: the frequency changes that triggered the loss of all null subjects must have started with null RefSs. This follows from the fact that null NonRefSs in Old Norwegian did not have overt counterparts. When overt NonRefSs were not a part of the lexicon, speakers cannot have chosen overt NonRefSs simply as a matter of preference, for communicative reasons.

In terms of variation between overt and null subjects, the predictions made by Faarlund’s account are, in practice, the same as those made by Rizzi (Reference Rizzi1982) and Håkansson (Reference Håkansson2008). In a text produced by a single grammar, we may expect to find null NonRefSs, although there are no null RefSs. This type of output is produced when pro is still a part of the lexicon, but the speaker opts for overt pronouns when these are readily available, i.e. in the referential contexts. We do not expect overt NonRefSs to co-occur with null RefSs. Det ‘it’ is not reanalysed as an overt NonRef until pro is gone (Faarlund Reference Faarlund, van Gelderen, Barðdal and Cennamo2013:272), and when pro is gone, null RefSs are no longer possible.

Having shown how (versions of) the prerequisite hypothesis is instantiated in some works on null subjects, I will now discuss whether it captures the situation that can be observed in Middle Norwegian.

3.1 Middle Norwegian data

Middle Norwegian (ca. 1370–1550) is, as previously mentioned, the language stage between Old and Modern Norwegian. The syntax of Middle Norwegian in many ways resembles that of Old Norwegian (Mørck Reference Mørck and Haugen2013:669): it is V2 in the sense that the finite verb seems to move to C in main clauses. Like in Old Norwegian, verb-initial declarative main clauses are rather common. In subordinate clauses, however, there is variation between the Old Norwegian word order, which in most cases means V-to-T movement (Faarlund Reference Faarlund2004), and the Modern Norwegian word order, in which the verb is commonly analysed as in situ (Vikner Reference Vikner1995:140, Vittersø Reference Vittersø2004).

I have investigated a sample of 136 Middle Norwegian charters from the Diplomatarium Norvegicum (DN). The charters date from the period 1371–1548. The documents in my sample exhibit a low degree of influence from Swedish and Danish, and many of them have a high proportion of narrative contents in addition to the usual introductory and concluding formulas (the protocol and the eschatocol). I take the view that formulaic contexts must not necessarily be disregarded as linguistic evidence (see Grøtvedt Reference Grøtvedt1961:225 and Mørck Reference Mørck2011:41); however, none of the examples discussed in this paper are formulas.

In most cases, we can safely assume that a charter is the work of one individual scribe (Wetås Reference Wetås2008:89). It can be rightfully asked, however, whether this means that the charter is a reflection of a single grammar, or I-language (Chomsky Reference Chomsky1986). The question is important, as the aim of this study is to investigate the compatibility, or incompatibility, of null RefSs and overt NonRefSs within individual grammars.

Following Kroch (Reference Kroch1989), many works in historical syntax have adopted the idea that a single speaker may have two or more competing grammars, which can all underlie the production of one individual text. I adhere to the view that speakers may have more than one grammar, and that this may result in intra-textual syntactic variation. As Roberts (Reference Roberts2007:331) and Walkden (Reference Walkden2014:24–25) point out, however, it is problematic to invoke grammar competition without identifying any functional motivation for switching between grammars. It is not random whether a bilingual speaker in a given context chooses to use, say, German or French. The competition between two grammars that are more similar, like an Old English grammar with a head-initial vs. a head-final TP (see e.g. Pintzuck Reference Pintzuck2002), is not fundamentally different; we would expect the choice of grammar in every given context to be guided by stylistic, sociolinguistic or other functional factors. The charters that I have investigated are, mostly, short documents, rarely exceeding a couple of pages, treating one specific matter. Abstracting away from the question of formulas, I find it hard to justify the idea of competing grammars being at work in such contexts, unless there is specific and independent evidence of this.Footnote ¹² My default assumption is thus that all syntactic phenomena occurring within a single charter can be derived by a single grammar.

With a few exceptions, I have only considered variation between overt and null subjects within individual charters. This leaves us with a rather limited set of relevant data, as the documents must exhibit a very specific combination of properties to qualify as evidence: not only must they contain a null RefS, which is a rather low-frequency phenomenon in Middle Norwegian (see Mørck Reference Mørck1990 and Kinn Reference Kinn2016a, Reference Kinn2016b); they must also exhibit a syntactic environment in which an overt NonRefS can potentially occur. However, although demanding much of the data, the method has an important advantage: it minimises the risk of attributing the properties of different varieties/idiolects to a single I-language.

3.2 Co-occurrences of overt, non-referential subjects and referential null subjects

My data set contains 33 instances of (the precursor of) det ‘it’, often spelled thet, that I have analysed as overt NonRefSs.Footnote ¹³ Contrary to the predictions of the strong prerequisite hypothesis, I have found that NonRef det does co-occur with null RefSs. Due to the nature of my data and methodology, the instances are too few to make meaningful statistical generalisations, but as existential evidence, my findings should be clear enough.Footnote ¹⁴ Some relevant data are rendered in the example pairs in (8)–(12). The examples labelled a contain null RefSs, whereas the ones labelled b contain overt NonRefS. The examples in each pair are taken from the same individual charter. Consider, first, example (8):

1. (8)

   

The null RefS in example (8a) is found in a subordinate clause; this shows that we are not dealing with topic drop/discourse ellipsis of the type found in Modern Norwegian (see note 1). The construction with det (spelt þet) will be discussed in more detail in Section 3.3; observe, however, that þet occurs in a post-verbal position. This means that it cannot be analysed as an expletive topic of the type found in Modern Icelandic, i.e. as an element that can only fill the preverbal position of declarative main clauses (see Section 3.3.1, Faarlund Reference Faarlund1990 and Thráinsson Reference Thráinsson2007:312).

In example (9a), the null RefS occurs in a main clause;Footnote ¹⁵ the overt NonRef pronoun thet in (9b) is found in a conditional subordinate clause:

1. (9)

   

In example (10), the null RefS occurs in a main clause. The overt NonRef thet is found in an impersonal passive construction:

1. (10)

   

In example (11a), the null RefS is again found in a main clause, as is the NonRef thet in (11b).Footnote ¹⁶ Footnote ¹⁷

1. (11)

   

Consider, finally, example (12):Footnote ¹⁸

1. (12)

   

The null RefS in example (12a) is found in a main clause. The preverbal position is occupied by a conditional subordinate clause; again, we see that null RefSs in Middle Norwegian do not obey the distributional restrictions that apply to the modern discourse ellipsis.Footnote ¹⁹ The overt NonRef thet in (12b) is found in the postverbal position of a particular type of existential construction (Faarlund et al. Reference Faarlund, Lie and Vannebo1997:1093). The construction bears resemblance to a cleft in that it involves a subordinate clause introduced by som ‘that, who’. Unlike prototypical clefts, however, the function of the construction is not to pick out and focus a referent; rather, it states (or, in this case, hypothesises) the existence of somebody. The existential nature of the sentence is underpinned by the fact that it is most naturally translated into English with there, not it.Footnote ²⁰

Having presented evidence that null RefSs and overt NonRefSs co-existed in Middle Norwegian, contrary to the strong version of the prerequisite hypothesis, I will now discuss the properties of overt NonRefSs in Middle Norwegian in some more detail.

3.3 NonRefSs with special functions?

A way of reconciling overt NonRef det in Middle Norwegian with the strong version of the prerequisite hypothesis could be to assume that NonRef det ‘it’ was not a “pure” non-referential subject before the loss of null RefSs, but rather had some other function (see Section 2.1). In this section, I will discuss that possibility. In the literature on overt NonRefSs in Scandinavian, relevant proposals have been put forth by Faarlund (Reference Faarlund1990) and Falk (Reference Falk1993a, Reference Falk1993b): Faarlund claims that NonRef det ‘it’ was initially an expletive topic, while Falk suggests that it was initially a quasi-argument only and later also a marker of the existential construction. I will argue that none of the proposals can fully account for the situation in Middle Norwegian and that the status of the prerequisite hypothesis thus remains dubious.

5.1 On the notion of parameter

The behaviour of NonRef det in Middle Norwegian is unexpected in the context of the null subject parameter of Rizzi (Reference Rizzi1982). It can thus be seen as counter-evidence against P&P theory more generally – at least P&P in its original formulation (Chomsky Reference Chomsky1981). As a consequence of this, the diachronic account that I would like to sketch here is not based on P&P in the “classical” sense. Instead, it is set in the framework of what I will refer to as modern parametric theory (see e.g. Roberts Reference Roberts, Galves, Cyrino, Lopes, Sandalo and Avelar2012), where the notion of parameter is substantially different from that developed in the 1980s.

A basic assumption of modern parametric theory is the so-called Borer-Chomsky Conjecture (BCC), according to which the locus of parametric variation is the lexicon: parametric differences are a result of the presence or absence of features on lexical items, including functional categories like C and T (Baker Reference Baker and Biberauer2008:353). Importantly, parametric options and implicational relationships are not given by UG; rather they follow from interaction of all the three factors in language design proposed by Chomsky (Reference Chomsky2005): the genetic endowment (i.e. UG), experience (i.e. the PLD) and so-called third factor principles, which are innate capacities not specific to the faculty of language.Footnote ³²

The more recent notion of parameter allows for more flexibility than Rizzi’s (Reference Rizzi1982) proposal. In modern parametric theory, the null subject properties of a language (or absence thereof) are not determined by the features of one particular lexical item, rather, they result from the featural make-up of functional categories in combination with the featural make-up of pronouns (Biberauer Reference Biberauer and Biberauer2008:50). In the following, I will argue that the featural make-up of pronouns has played a particularly important role in the history of null subjects in Norwegian, in a way that is compatible with the data presented in Section 3.

5.2 DP vs. φPs pronouns and pronoun deletion

To account for how a language develops diachronically, it is necessary to make explicit assumptions about its synchronic nature. I will therefore clarify some points regarding the analysis of null subjects in Old Norwegian before I turn to the question of diachronic change. I will focus on issues that are immediately relevant to the relationship between RefSs and NonRefSs; for extensive discussions, cf. Kinn (a, b).

As briefly mentioned in footnote 6, there are weighty reasons to assume that null subjects in Old Norwegian were not directly licensed by subject-verb agreement. First, even though both subject-verb agreement and null subjects were lost in the transition into Modern Norwegian, the relative chronology between the changes does not indicate any direct, causal relationship: the loss of null subjects basically started while subject-verb agreement was still retained (Kinn Reference Kinn2011; cf. Håkansson Reference Håkansson2008, Reference Håkansson2013 for similar conclusions regarding the loss of null subjects in the history of Swedish). Second and relatedly, Old Icelandic, which is very closely related to Old Norwegian, eventually lost null subjects without any concomitant weakening of subject-verb agreement (Sigurðsson Reference Sigurðsson1993). Third, Old Norwegian, like other early Germanic languages, allowed null objects without having any object-verb agreement (Sigurðsson Reference Sigurðsson1993, Walkden Reference Walkden2014). Fourth, in Old Norwegian, null subjects are virtually always third person and almost never first and second person (more on this below), but third-person forms of finite verbs do not have any more distinct agreement morphology than the first and second persons, as we would perhaps expect if subject-verb agreement acted as a syntactic licenser. Cf. Table 1, based on Faarlund (Reference Faarlund2004:49–53) and Spurkland (Reference Spurkland1989:124).

Table 1. Old Norwegian verbal inflections, present indicative.

The asymmetry between the first and second persons on the one hand versus the third person on the other is the point of departure of the syntactic analysis that I will assume here. Note that the division between the grammatical persons is very clear in Old Norwegian: while a preference for the third person has been observed in discussions of null subjects in other early Germanic languages (e.g. Old High German; see Axel Reference Axel2007:315), the Old Norwegian data seem to suggest something more than a quantitative tendency. As compared to third-person null subjects, across genres, first- and second-person null subjects are so rare that both the philological literature and more recent, generative works assume the existence of a grammatical rule that prevents them (see Nygaard Reference Nygaard1894: Reference Nygaard1905 and Faarlund Reference Faarlund, Røyneland and Enger2012, Reference Faarlund, van Gelderen, Barðdal and Cennamo2013); Kinn (Reference Kinn2016a:126ff) provides quantitative and paleographic evidence in favour of this view.

The question is, then, what it is that prevents deletion of pronouns in the first and second persons. I will argue that the answer can be found in the featural make-up of these pronouns.Footnote ³³

It is well known that pronouns differ in terms of syntactic category and internal structure, both cross-linguistically and within individual languages (Cardinaletti & Starke Reference Cardinaletti, Starke, Thráinsson, Epstein and Peter1996, Reference Cardinaletti, Starke and van Riemsdijk1999, Déchaine & Wiltschko Reference Déchaine and Wiltschko2002, Höhn Reference Höhn2015). One of the points that varies is whether a pronoun can function as a determiner, i.e. take a lexical noun as (a part of) its complement. Déchaine & Wiltschko (Reference Déchaine and Wiltschko2002), whose framework I am adopting, distinguish between DP and φP pronouns, of which only the first type may function as determiners.

In terms of internal structure, the crucial difference between DPs and φPs is that DPs have a D-feature that heads a D-projection, or D-layer, as illustrated in (25a). The D-feature is not present in φPs; cf. (25b):

1. (25)

   

The D-layer makes DP pronouns “demonstrably definite” (Déchaine & Wiltschko Reference Déchaine and Wiltschko2002:410); their ability to function as determiners is related to this semantic property. An example of a DP pronoun is we in English; when we functions as a determiner, in examples such as we linguists, we have the following structure (Déchaine & Wiltschko Reference Déchaine and Wiltschko2002:21):

1. (26)

   

φPs, as opposed to DPs, “lack inherent semantics”; they “simply spell out φ-features” and cannot be determiners (Déchaine & Wiltschko Reference Déchaine and Wiltschko2002:410–411).

Now, in Old Norwegian, first- and second-person pronouns exhibit DP behaviour; they function as determiners in examples like (27):

1. (27)

   

3rd person pronouns, on the other hand, do not appear in contexts like those cited in (27). When a third-person pronoun co-occurs with a noun, the noun is always definite, and I follow Faarlund (Reference Faarlund2004:89–90) in interpreting it as an apposition rather than a pronoun. Cf. (28):

1. (28)

   

As Old Norwegian third-person pronouns generally cannot function as determiners, I take it that they are φPs rather than DPs.Footnote ³⁴ In Old Norwegian, the distribution of null subjects thus seems to correlate with the DP vs. φP distinction: null subjects are almost always third person, and third-person pronouns, as opposed to first- and second-person pronouns, are φPs. This suggests a syntactic derivation that allows φPs, but not DPs, to be null. The generalisation can be formally accounted for if we assume that null subjects are derived by a version of Roberts’ (Reference Roberts, Biberauer, Holmberg, Roberts and Sheehan2010) mechanism of pronoun deletion, whereby pronouns are deleted if their features are a proper subset of the features of a Probe with which they agree. I assume that the D-feature, which is only present in first- and second-person pronouns, interferes with the required subset – superset relation and thus prevents deletion; I refer to Kinn (a, b) for details and further discussion.

Keep in mind that both the featural make-up of pronouns and that of the functional categories with which pronouns agree are language-specific. The fact that other languages allow first- and second-person null subjects does therefore not in itself undermine my account of Old Norwegian. In languages that allow first- and second-person null subjects, the internal structure of pronouns may be different, or the relevant functional categories, or both.

5.3 Spreading of the D-feature and the loss of null subjects

We now turn to the question of diachronic change. If it is correct, as I am assuming, that there is a D-feature on first- and second-person pronouns in Old Norwegian that prevents deletion, the loss of null subjects can be analysed in terms of an extension of the D-feature to new contexts. In other words, if it can be shown that the D-feature “spread” to the third person, we potentially have a formal account of how null subjects were lost. There is in fact some evidence of such a development.

In Modern Norwegian, first- and second-person pronouns may function as determiners just like in Old Norwegian. Additionally, however, there are contexts in which third-person pronouns too exhibit DP behaviour, contrary to what was argued for Old Norwegian in Section 5.2. For example, han ‘he’ and hun ‘she’ can be used as psychologically distal determiners (PDDs) (Johannessen Reference Johannessen, Solstad, Grønn and Haug2006, Reference Johannessen, Johannessen and Hagen2008a, Reference Johannessen2008b). PDDs express a certain type of deixis, namely psychological distance to persons. Typically, they occur in contexts where either the speaker or the addressee does not personally know the person referred to, or when the speaker wants to signal a negative attitude to this person. Cf. the examples in (29), from Johannessen (Reference Johannessen2008b:164–166):

1. (29)

   

PDDs cannot co-occur with the definite determiner den ‘that’, and they are therefore best analysed as DPs (Johannessen Reference Johannessen2008b).Footnote ³⁵ PDDs are not known to occur in Old Norwegian; I take them to be symptomatic of a reanalysis of the pronoun system, whereby not only first- and second-person pronouns but also third-person pronouns are DPs.Footnote ³⁶

The spreading of the D-feature to a new class of pronouns can be seen as an analogical change. In the framework of modern parametric theory, this type of change is predicted by the third factor principle Input Generalisation (IG) (Roberts Reference Roberts, Galves, Cyrino, Lopes, Sandalo and Avelar2012, Biberauer et al. Reference Biberauer, Holmberg, Roberts, Sheehan, Newmeyer and Preston2014). IG states that once a child has identified a formal feature, like the D-feature, in the PLD, he or she will have an inclination to (over-)generalise this feature to new, but similar contexts.Footnote ³⁷

The D-feature, as we have seen, is a formal feature that enables a pronoun to have determiner properties. A reanalysis from φP pronoun to DP pronoun by analogy, along the lines suggested above, need not necessarily mean that the new determiner functions arose immediately; a pronoun may be a DP without taking a noun as a lexical complement. Relatedly, nothing in principle prevents the reanalysis from φP to DP to affect NonRefSs, or a subset of NonRefSs, before RefSs. Thus, the diachronic scenario that I have sketched is compatible with the Middle Norwegian data, in which overt NonRefSs and null RefSs co-occur. It is also worth noting, however, that the Middle Norwegian situation did not last for very long; Norwegian did, eventually, end up as a non-NSL, consistently with common cross-linguistic patterns and the typological predictions of Rizzi (Reference Rizzi1982).Footnote ³⁸ Although modern parametric theory allows for the Middle Norwegian situation to occur, it also provides a motivation for the subsequent diachronic development: in a situation where the D-feature preventing deletion is present on first- and second-person pronouns, as well as on some third-person pronouns, a further generalisation of the D-feature to all third-person pronouns seems close at hand. At that stage, null subjects are lost altogether.

Returning now briefly to the prerequisite hypothesis, the following point can be noted: we have seen that the loss of null RefSs was not a prerequisite for the emergence of overt NonRefSs. The diachronic analysis that I have sketched allows us to take another step away from the prerequisite hypothesis as it was presented in the introduction of this paper: rather than being a consequence of the loss of null RefSs, the emergence of overt NonRefSs in Middle Norwegian may have been one of the language-internal factors that contributed to this change.Footnote ³⁹