Linguistic Theory

Linguistic Theory Lecture 11 Explanation

How do we explain things? • In lay terms an explanation answers the question why: • A: “Why are you carrying that large heavy suitcase?” • B: “I just bought a Japanese wrist watch” • A: “What’s that got to do with the suitcase?” • B: “The watch is Japanese but the batteries are Russian”.

In science, we also want to answer the question ‘why’. But things are more difficult. • The reductionist problem: • If X explains Y, what explains X? • The only natural end to this would be to map everything back to the initial event (the big bang). • But we can’t do this – not enough evidence • Even if we could, we wouldn’t understand it and what’s the point of an explanation that you can’t understand?

Explanation in Linguistics • There are two ways that explanation comes into linguistics: • The normal one – what explains X? • A more technical one: given two theories how do we decide which one is best?

Levels of adequacy • For any set of data, there are an infinite possible grammars that capture the data • So how do we decide which one is the right one?

A demonstration of infinite possible grammars • Suppose a simple language with one word, “a” • The sentences of this language contain any number of instances of the word: • a • aa • aaa • aaaa • etc.

S  aS  Sa • This grammar will generate all and only all the sentences of this language • But so will: • S  a or S  a etc.S  aS S  Sa S  aS • Moreover so will: • S’  Sb (obligatory deletion rule)S  a Delete b at the end of aS  Sa sentence

All these grammars are distinct, but they all generate languages which have sentences made up of any number of ‘a’s • Which one is correct? • Chomsky (1965) proposed that different grammars attain different levels of adequacy: • observational adequacy • descriptive adequacy • explanatory adequacy = the highest

Observational adequacy: • a grammar which predicts all and only the grammatical sentences of a language (e.g. all of the grammars we previewed) • Descriptive adequacy: • Native speakers have intuitions about how sentences are structured: • S SS a a Sa a • A grammar which conforms to these intuitions is descriptively adequate

Explanatory adequacy • A theory which sheds light on the logical problem of language acquisition is explanatorily adequate • two descriptively adequate theories of two different languages do not amount to an explanatorily adequate theory of language if they are very disparate • if both are possible human grammars, how would a child be able to learn any one? • a theory which contributes to a coherent notion of Universal Grammar therefore is one which has explanatory adequacy

Normal Explanation • Explanatory adequacy does not in itself guarantee explanation • it is just a method to use to distinguish between different grammars and to guide research • Explanation in linguistics comes through restriction • if grammatical principles are as complex as the data, then we have description • the simpler the grammar, the more explanation • simple does not necessarily mean easy to understand • it means structurally simpler • the fewer and more general the principles the simpler

Thus, suppose we have a grammar whose principles are in a one-to-one relation with linguistic phenomena: • Here the grammar is just as complex as the data and doesn’t help us understand it any better • But if two or more of these principles can be collapsed into a more general one, the grammar is simpler than the data P1 P2 P3 etc. P1 P3 etc. Phen1 Phen2 Phen3 etc. Phen1 Phen2 Phen3 etc.

But this is a reductionist argument • We may be able to achieve more and more explanation • But we can never achieve the ultimate explanation • Perhaps this is enough • Perhaps not

The Minimalist Programme • Chomsky has argued (since 1990s) that we can achieve a greater degree of explanation • If the theory we produce is built on only absolutely necessary assumptions, then it cannot be reduced any further • What is absolutely necessary? • the set of assumptions that if they were not made, we wouldn’t have a theory of language

Suppose language is the mental system that links the part of the mind concerned with thinking and the part of the mind concerned with articulation (bodily movements) thought action language

The two interfaces have requirements for language in order for it to do its job: • the products of the linguistic system must be interpretable in the relevant ways • Suppose that is all there is • the linguistic component consists of only the things that are required to enable interpretation by the conceptual and phonetic components • if anything else is needed to account for linguistic phenomena, this will require extra explanation (and we are back to where we started)

A Minimalist Demonstration • Why do things move? • In GB there were different reasons why things move: • to satisfy the Case Filter • to bind bound morphemes • semantic reasons • But if movement is part of the linguistic system it must have a reason motivated by the output conditions (conceptual and phonetic interpretation)

Language shows a number of phenomena which involve semantically interpretable features coupled with similar features which are not interpreted • e.g. verb agreement • features are interpretable on the subject (person, number, gender) • features a purely grammatical (uninterpretable) on the verb • Presumably, uninterpretable features are a problem at the output: what would the conceptual and phonetic components do with them?

The minimalist claim is that movement serves the purpose of ‘checking off’ uninterpretable features • uninterpretable features are generated in some position (e.g. on the verb) • the verb moves to be in a certain structural relation with the subject (specifier-head) where the features of one are checked against those of the other

IPDP3.s I’ I VP • If the features check, they are deleted and therefore not present at interpretation • If the features do not check they remain and cause the structure to be uninterpretable Checking V3.s

Phrase Structure in the Minimalist Programme • The output systems require a single structure to be formed from individual words for interpretation: • how can a sentence be interpreted either semantically or phonetically (order?) if unconnected words are presented • So it is necessary to have a structure building part of the grammar

Structure building proceeds as follows: • take two words • put them together to form a new object (= ‘merge’) • choose one to label the new object (= head) loves Mary loves

The structure building process is a series of mergers which builds a structure step by step • Do we need any other principles? • how do we know which words to merge? • how do we know which one to select as head? • No other principle is needed other than that the structure that is built must be interpretable • if we merge two incompatible words, it will not be interpretable • if we choose the wrong head, it will not be interpretable • The system then distinguishes grammatical (interpretable) from ungrammatical (uninterpretable)

Linguistic Theory