As British linguist
Peter Hugoe Matthews noted in his review of the book, the content of
Aspects can be divided into two distinct parts: Chapter 1 is concerned with the psychological reality of language and the
philosophy of language research, and the rest of the chapters deal with specific technical details within generative grammar.
The goal of linguistic theory Competence vs. performance: descriptive adequacy In
Aspects, Chomsky lays down the abstract, idealized context in which a linguistic theorist is supposed to perform his research: "Linguistic theory is concerned primarily with an ideal speaker-listener, in a completely homogeneous speech-community, who knows its language perfectly and is unaffected by such grammatically irrelevant conditions as memory limitations, distractions, shifts of attention and interest, and errors (random or characteristic) in applying his knowledge of the language in actual performance." He makes a "fundamental distinction between
competence (the speaker-hearer's knowledge of his language) and
performance (the actual use of language in concrete situation)." A "grammar of a language" is "a description of the ideal speaker-hearer's intrinsic competence", and this "underlying competence" is a "system of generative processes." An "adequate grammar" should capture the basic regularities and the productive nature of a language. Chomsky calls this "descriptive adequacy" of the linguistic theory, in the sense that "it correctly describes its object, namely the linguistic intuition—the tacit competence—of the native speaker. In this sense, the grammar is justified on external grounds, on grounds of correspondence to linguistic fact."
Language acquisition, universal grammar and explanatory adequacy Additionally, Chomsky sets forth another ambitious goal for linguistic theory in
Aspects: that it has to be "sufficiently rich to account for acquisition of language, yet not so rich as to be inconsistent with the known diversity of language." In other words, linguistic theory must be able to describe how any normal human child masters the complexities of his mother tongue at such a young age, and how children all over the world master languages which are enormously different from one another in terms of vocabulary, word order and morpho-syntactic constructions. In Chomsky's opinion, in order for a linguistic theory to be justified on "internal grounds" and to achieve "explanatory adequacy", it has to show how a child's brain, when exposed to primary linguistic data, uses special innate abilities or strategies (described as a set of principles called "Universal Grammar") and selects the correct grammar of the language over many other grammars compatible with the same data. When sentences are directly generated by the system of grammatical rules, they are called "perfectly" or "strictly well-formed" grammatical sentences. When sentences are "derivatively generated" by "relaxing" some grammatical rules (such as "subcategorization rules" or "selectional rules" Chomsky calls these grammatically "deviant". The degree and manner of their deviation can be evaluated by comparing their structural description with that of the strictly well-formed sentences. In this way, a theory of "degree of grammaticalness" can eventually be developed. The notion of acceptability depends on various "dimensions" such as "rapidity, correctness, and uniformity of recall and recognition, normalcy of intonation". The linguist's main object of inquiry, as Chomsky sees it, is this underlying psychological reality of language. Instead of making catalogs and summaries of linguistic behavioral data demonstrated on the surface (i.e. behaviorism), a Chomsky-an linguist should be interested in using "introspective data" to ascertain the properties of a deeper mental system. The mentalist approach to linguistics proposed by Chomsky is also different from an investigation of the neurophysiological mechanisms underlying language. It is about abstractly determining the properties and functions of such mechanisms.
The structure of grammar: deep structure In
Aspects, Chomsky summarized his proposed structure of a grammar in the following way: "A grammar contains a syntactic component, a semantic component and a phonological component...The syntactic component consists of a base and a transformational component. The base, in turn, consists of a categorial subcomponent and a lexicon. The base generates deep structures. A deep structure enters the semantic component and receives a semantic interpretation; it is mapped by transformational rules into a surface structure, which is then given a phonetic interpretation by the rules of the phonological component." In this grammar model, syntax is given a prominent, generative role, whereas phonology and semantics are assigned secondary, interpretive roles. This theory of grammar would later come to be known as the "Standard Theory" (ST).
The base subcomponent The base in the syntactic component functions as follows: In the first step, a simple set of
phrase structure rules generate
tree diagrams (sometimes called Phrase Markers) consisting of nodes and branches, but with empty terminal nodes; these are called "pre-lexical structures". In the second step, the empty terminal nodes are filled with complex symbols consisting of morphemes accompanied by syntactic and semantic features, supplied from the lexicon via lexical insertion rules. The resulting tree diagram is called a "deep structure".
Comparison with the Syntactic Structures model The
Aspects model or ST differed from
Syntactic Structures (1957) in a number of ways. Firstly, the notion of kernel sentences (a class of sentences produced by applying obligatory transformational rules) was abandoned and replaced by the notion of "deep structures", within which negative, interrogative markers, etc. are embedded. This simplified the generation of "surface" sentences, whereas in the previous model, a number of successive optional transformational rules had to be applied on the kernel sentences to arrive at the same result. Secondly, the addition of a semantic component to the grammar marked an important conceptual change since
Syntactic Structures, where the role of meaning was effectively neglected and not considered part of the grammatical model. Chomsky mentions that the semantic component is essentially the same as described in Katz and Postal (1964). Among the more technical innovations are the use of recursive phrase structure rules and the introduction of syntactic features in lexical entries to address the issue of subcategorization.
Syntactic features In Chapter 2 of
Aspects, Chomsky discusses the problem of
subcategorization of lexical categories and how this information should be captured in a generalized manner in the grammar. He deems that
rewriting rules are not the appropriate device in this regard. As a solution, he borrows the idea of
features use in phonology. A lexical category such as noun, verb, etc. is represented by a symbol such as N, V. etc. A set of "subcategorization rules" then analyzes these symbols into "complex symbols", each complex symbol being a set of specified "
syntactic features", grammatical properties with binary values. Syntactic feature is one of the most important technical innovations of the Aspects model. Most contemporary grammatical theories have preserved it. ==Significance==