Transcript Slide 1
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. •Sa S Sa • This grammar will generate all and only all the sentences of this language • But so will: –Sa S aS or • Moreover so will: – S’ Sb Sa S Sa Sa S Sa S aS etc. (obligatory deletion rule) Delete b at the end of a 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 S S a a a S 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: • P1 P2 P3 etc Here. the Phen1 Phen2 Phen3 etc. 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 P3 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) t h o u g h t language a c t i o n • 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 • IP DP3.s I’ I Checking VP V3.s • 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 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)