which must exist when children come to know a language, and to appreciate its power.
2.4.1 The basic design
Figure 2.2 sketches the basic design of the Language Faculty (adapted from Chomsky 1995). This overall architecture is necessary to generatesentences (syntax) and perceive and articulate thesoundsof language (phonology)16in a way which has meaning (semantics), and to use that knowledge to proclaim, exclaim, argue or beg, to interact in the world socially or otherwise (pragmatics).
Linguists differ in how they represent each of the components represented in this figure, and in how they represent the interrelation between the components, but the overall design must be accounted for in any theory of language knowledge and language acquisition.
In figure 2.2, the central component is the grammar, which provides a theory of how a language works: it relatessound(theauditory interface) andmeaning (theconceptual interface). It is the core “computation for human language” or CHL(Chomsky 1995), the essence of our “language faculty”.
2.4.2 The interfaces
This Language Faculty coordinates – or “interfaces” – with other forms of cognition.Soundandmeaningof language are both points of cognitive interfaces, acting as “modes of interpretation by performance systems” (Chomsky 1995, 171). Although they are given their “instructions” by the grammar, these
15See Larson and Segal 1995, 545f. and Pylyshyn 1999, 10f, for discussion of the term “represen- tation” as it is used here.
16In sign languages, the interfaces will involve distinct visual and motoric modalities.
24 c h i l d l a n g ua g e
GRAMMAR
(CHL) Computation for Human Language
AUDITORY INTERFACE
PHONOLOGY/PHONETICS
CONCEPTUAL INTERFACE
LOGIC, MEANING, SEMANTICS
PRAGMATICS
USE OF LANGUAGE: inference from the code to the world or the world to
the code
Basic design of the human Language Faculty
Fig. 2.2 Basic design of the human language faculty.
interfaces are “external to the computational system of language” (Chomsky 1995, 132, 168).17
The auditory interface: PF (Phonetic Form).A formalization of the interface between the computational systems and sensorimotor systems involved in audition and articulation.
The conceptual interface: LF (Logical Form).A formalization of the interface between the computational system and systems of conceptual structure and language use.
2.4.3 Levels of representation
As in figure 2.2, children must deal with several levels of representa- tion at once so that these are interrelated and susceptible to computation. Units
17A critical and profound issue in linguistics and cognitive science today concerns the interrelations between the core computational and the interface components of the Language Faculty.
SYNTAX words/morphology
phrases clauses sentences
PHONOLOGY (sound)
phone phoneme
syllable mora
SEMANTICS (meaning) arguments predicates propositions
concepts Units at each basic level of representation
in language knowledge
Fig. 2.3 Units at each basic level of representation in language knowledge.
must be discovered at leach level (figure 2.3).18 The auditory and conceptual interfaces must be formalized so they can enter into the computation required by knowledge of a language. Thus linguists study “PF” (Phonetic Form) and “LF”
(Logical Form) respectively in analyzing the interfaces ofsound andmeaning (Chomsky, 1995, 131).19
2.4.4 Relation of child language acquisition to linguistic theory We look to linguistic theory for formulation of scientifically testable, theoretically based hypotheses regarding the exact nature of the architecture of the Language Faculty and of the adult end-state, i.e., what needs to be acquired when we acquire a language. At the same time, every normal child in normal circumstances will solve the problem which all linguists are pursuing, acquiring the “true” formal computational system for any and all possible languages (even for multiple languages at a time). We can only assume that children must know
18Chomsky’sLogical Structure of Linguistic Theory(1975/1955) made this approach to the study of linguistic structure explicit. Levels of representation remain an essential component of generative grammar today, even though the exact form of levels remains debated; e.g., in current “minimalist”
theory of generative grammar, previous “deep structure” and “surface structure” levels (Chomsky 1965) do not appear (see Chomsky 1995, 188, Lasnik 2002).
19Crystal 1997a, 82–83, provides a general introduction to the notion of linguistic “levels.”
26 c h i l d l a n g ua g e
the “right” way to capture a language. We look to the child for empirical evidence regarding the Language Faculty.
2.4.5 Does the Language Faculty develop?
Every computer has an architecture built into it. Is the cognitive archi- tecture of the Language Faculty, as sketched in figure 2.1, built into the child brain and in place from the beginning, or is it in some way developmentally acquired or constructed by children? Do infants begin solely with the pragmatic components of language use, and only later attain formal knowledge of the central computa- tional system? Is development of general cognition, i.e., thinking and reasoning, and children’s understanding of the world, a necessary precursor to significant development of the formal linguistic system, and perhaps a determinant of this formal system in some way? Are the components of the Language Faculty only assembled gradually?
Figure 2.1 suggests that the organization of this Language Faculty is “inter- nally modular”; that is, the formal computational system CHL is distinct from the conceptual and auditory components, although these interact. Is this “internal modularity” in place from the beginning? Do the basic components or “modules”
of this faculty, i.e., knowledge of grammar (syntax), knowledge of the sound system (phonology) and knowledge of meaning (semantics) develop in parallel?
Is development across these areas independent? Is development across the areas linked? What are the interactions among the internal modules?20