Sentence structure: a basic design

One of the core assumptions about sentence structure is that all grammars share a common basic structural design. The so-called X-bar template is made up of the head [= X] of a phrasal expansion or projection combined with its complement to form an X’ projection; the specifier, in turn, combines with the (topmost) X’ projection to form a maximal projection [= XP] (Chomsky 1995; Haegeman 1994). Complex structures are built up by combining (merging) pairs of categories. The order of the head and its complement is not fixed which accounts for cross-linguistic variation at the level of word order. Two options are associated with the head-complement parameter: the head may take a complement to the left (head-final value) or to the right (head-initial value) (cf. (3a-b) for a head-initial and head-final version of the X-bar schema). X-bar theory accounts for the common format of phrasal projections of lexical and functional categories.

Functional categories: sentence structure and grammatical processes

Following current assumptions, functional categories play a central role in the structural representation of syntactic constructions. This is in line with the traditional idea that semantic aspects of an utterance are primarily related to the elements of the open class (N, A, V, P) while elements of the closed class would determine formal aspects (Guilfoyle & Noonan 1988; Radford 1990). Roughly, to form a clause, the verb phrase (VP) is combined with the projection of the functional category INFL (for inflection), that is, the IP. Embedded and interrogative clauses are projections of the functional category C or COMP (for complementiser), that is, the CP, which takes IP as its complement.

Grammatical processes and relations. The lexical and functional structural levels that build up clauses differ with respect to the information that is relevant at each (cf. also Table 2.1). The verb phrase (VP) is the domain of the expression of thematic relations. The functional level above the VP, the inflection phrase (IP), is the level at which grammatical relations between constituents are expressed. For example, the relation between the verb and the subject is marked through verb inflection (agreement) and nominative case marking in many languages. The grammatical feature of tense is also checked at this level. Auxiliary and modal verbs are base generated in INFL. Movement processes involved in the formation of subordinated or interrogative clauses involve the CP.

Table 2.1: Structural levels and associated grammatical processes.*

*The table illustrates the main relations relevant for the present work.

Grammatical features of FCs need to be checked in the course of the derivation of a given structure to give rise to a well-formed representation at the level of logical form (LF, that is, the level that concerns the linguistic aspects of the meanings of a sentence) (Radford 1997: 70). Feature checking involves verb movement (raising) to the respective functional head, in keeping with the Head Movement constraint according to which a head category can only move to a position immediately preceding it. Table 2.2 provides an overview of the main features associated with the functional categories AGR, TNS and C. In this table, AGR and TNS appear in the place of INFL, in line with the Split-INFL hypothesis according to which features traditionally subsumed under the category INFL project their own separate phrases (cf. Radford 1997: 225). Basically, case and agreement features are checked in AGR categories, and tense in TNS. Hence, to have their features checked, verbs are moved from the VP to the head positions of these functional projections. The feature composition of C includes the feature +/- wh. This feature distinguishes interrogative from non-interrogative clauses. In interrogative sentences, wh-phrases are moved into the specifier position of the CP, and the finite verb to C so that the interrogative features can be checked. Further, C also includes c-selectional features. This accounts for the clause type selected by complementers. In English, for example, that and if select a finite clause, whereas for selects an infinitival clause.

Table 2.2: Functional categories and their main features

Cross-linguistic variation. According to the Functional Parametrisation Hypothesis languages differ with respect to selectional properties and features of FCs (Pollock 1989; Chomsky 1989; Ouhalla 1991). This variation is reflected in typological differences across languages, including variation at the level of word order (for a detailed discussion see Plaza-Pust 2000). Over the last decades, linguistic research has been dedicated to the study of properties of numerous oral languages and sign languages within the framework outlined. Similarities and differences between languages become apparent not only between oral languages but also across languages that differ in their modality of expression.

The knowledge that has been gleaned from these studies about the nature of language is not only valuable from a descriptive point of view. The definition of universal and specific properties of language systems is also relevant from a developmental linguistics perspective seeking to account for the learning task language learners are confronted with. Following this line of reasoning, we will elaborate on the properties of DGS and German within the framework sketched previously in chapters 3 and 4 respectively.