Having shown how the X-bar schema matches fairly closely the results of cartographic projects, let me now turn to other typological restrictions that may be the result of the X-bar organization imposed by syntax.
Before proceeding, I should note that the pervasiveness of the X-bar schema that I am arguing for here should not be understood as a claim to the eVect that this is the sole source of hierarchy. Clearly hierarchies exist outside of syntax, and in some cases, they may be isomorphic to the X-bar schema (as in the case of gradable adjectives), not necessarily the result of ‘‘syntacticization.’’ Only comparative studies across mental modules and across species will reveal which hierarchies are independ-ently generated.
Similarly, I wouldn’t like to give the reader the impression that any triad one Wnds in language is to be analyzed as being organized along the lines of the X-bar schema. Although I think that triple manifestations of a given dimension are suggestive, there exist a few three-member sets for which I have not been able to Wnd any shred of evidence for an internal hierarchy (nesting). Take, for example, the existence of three major lexical categories ({A, N, V}), if Baker
(2003) is correct in viewing adpositions as functional items, of the three possible clause types ({Interrogative, Declarative, Exclamative}
values for ForceP/SP (Laka 1990)), or the three values for GenderP ({Masculine, Feminine, Neuter}), or the three shifters/discourse variables studied by Schlenker (2005) ({Mood, Tense, Person}).
All these may be regarded as Xat triplets. Such triplets may be the result of the fact that concepts, once digitized, can take on any of the three possible values: {+,, ø}, which will form the basis for three parallel projections, not three nested projections. Alternatively, some of them may be the result of the fact, well established in the cognitive science literature, that humans and many other species are able to chunk conceptual spaces into small groups (of three, and in some cases four), a cognitive operation technically known as subitizing (see Dehaene 1997, among others; see also Pinker 1997 on the pervasiveness of three-way divisions).
Accordingly, three-member sets in language may have multiple sources. What is special about the hierarchies examined in this chapter is not so much the fact that they involve three members, but the fact that these members organize themselves in a nested pattern. What is lacking in the context of subitization or lexicaliza-tion is the internal hierarchy imposed by, and perhaps unique to, narrow syntax (Hauser, Chomsky, and Fitch 2002).
Let me end this brief note of caution by saying that although imposing an internal hierarchy on some of the Xat triplets one Wnds may not look very promising at Wrst, one must leave open the possibility for there to be an internal structure inside the triads just listed. One of the great lessons that emerged from work in syntax over the past thirty years is that very often closer empirical scrutiny reveals subtle, but robust asymmetries where at Wrst symmetries are expected.
This may be the case for Person. While it is fairly standard to treat 3rd person as the odd one out, it is not clear whether 1st person and 2nd person should be hierarchically ordered, X-bar like. Most studies on phi-feature geometry (see, e.g., Harley and Ritter 2002) assign the same hierarchical status to both 1st and 2nd person ([+author;
participant] for 1st person, [author; +participant] for 2nd person). However, Quinn (2006) provides evidence for a 1st person >
2nd person hierarchy on the basis of Algonquian data. (Quinn’s evi-dence is particularly relevant as it comes from the complex Inverse system in Algonquian, a system traditionally thought to require a 2nd person> 1st person hierarchy (see McGinnis 2005).)
Likewise, the apparently symmetric values of Tense (Future, Pre-sent, Past) may turn out to be nested, if Baker and Travis (1997) are right in treating the values of Tense as similar to the dimensions found in the nominal domain (deWnite, indeWnite nominals), which show signs of nesting.
Finally, consider Number. It is known that the latter standardly takes on the two values {singular}, and {plural}, but it is also known that number can take on additional values like {dual}, {trial}, and {paucal}. As far as we know, number cannot take on any other value (see Corbett 2000).16 This could signal a cognitive limit, or it could be the reXex of an X-bar-like schema of the sort given in (58).
(58) X” (plural) X” (paucal)
X’ X’ (trial)
X⬚ (singular) X⬚ (dual)
If (58) is tenable, the X-bar schema could be used to make sense of typological Wndings, by imposing limits on variation.
For example, the X-bar schema may allow us to explain why macroparametric eVects are concentrated in a way that Baker (1996) captured well in this quote:
It is not clear that there are other natural language representation systems that do not Wt somewhere within the triangle deWned by head-Wrst/head-last/
adjoined, and the related triangle deWned by Case-marked/agreement-marked/uninXected. (Baker 1996: 506)
The categories head-Wrst, head-last, and adjoined are precisely the three deWning X-bar relations, once ‘‘head-Wrst’’ and ‘‘head-last’’ are
16 I thank Eytan Zweig (p.c.) for encouraging me to look at Corbett’s survey.
understood along the lines of Kayne’s (1994) Universal Base hypoth-esis, which rigidly orders heads before complements (head-Wrst), speciWers before heads (head-last).
The X-bar schema may also prove useful in the domain of verb clusters recently studied by Svenonius (2007a). Svenonius examines the known cross-linguistic orderings of sets of morphemes, corre-sponding to three hierarchically organized elements (symbolized as 1-2-3), for example, C-T-V. Svenonius arrives at the following topo-logical variations. (I reproduce Svenonius’s terms for some of these patterns right next to the sequences the terms refer to.)
(59) a. 1-2-3 ‘‘Straight’’
b. 1-3-2 ‘‘Curl’’
c. 3-2-1 ‘‘Roll-Up’’/‘‘Snowball’’
d. 3-1-2 Long-distance extraction e. 2-3-1 Constituent Fronting f. 2-1-3 Short-extraction
Pattern (59a) corresponds to the situation one Wnds with English main verbs: an undisrupted C-T-V sequence (60a). (59b) is found in lan-guages that raise V past T, like French, or German (C-V-T) (60b). (59c) corresponds to robustly head-Wnal languages like Japanese (Verb-Tense suYx-C suYx) (60c). (59d) corresponds to long-distance dependen-cies like Wh-movement (from within VP to SpecCP), or perhaps long-distance participle fronting in Slavic (the long head-movement cases analyzed in Rivero (1991) and Roberts (1993)), or V-fronting (60d).
(59e) captures instances of VP-fronting (60e), while (59f) captures instances of movement like T-to-C raising in English (60f).
(60) a. that (it) will rain
b. dass (es) regnen wird [German]
that it rain will
‘that it will rain’
c. (ame-ga) fu-ru to [Japanese]
rain-nom fall-nonpast Comp
‘that rain will fall’
d. Rain, it certainly will e. [Kiss [John]], Mary will f. Will it rain?
Of particular interest in the present context is Svenonius’s claim that the patterns in (60a–f) exhaust those that are needed to capture the range of word-order permutations attested in natural language.
Considering the range of options oVered by permutations of two elements only would not be enough to capture the cross-linguistic variation we Wnd (only two possible patterns would be expected).
More crucially, taking four elements into account would give rise to too many cross-linguistically unattested patterns (sixteen patterns).
Svenonius concludes that the possible reorderings of exactly three elements suYce to capture the space of possibilities. Svenonius’s result follows immediately if the space of possibility is deWned by the X-bar schema, which makes room for three, and only three levels of projections, occupied by elements that can be reordered by movement.