Linguistic TheoryLinguistic Theory

Lecture 11Lecture 11

ExplanationExplanation

How do we explain things?How do we explain things?

• In lay terms an explanation answers In lay terms an explanation answers the question why:the question why:– A: “Why are you carrying that large heavy A: “Why are you carrying that large heavy

suitcase?”suitcase?”– B: “I just bought a Japanese wrist watch”B: “I just bought a Japanese wrist watch”– A: “What’s that got to do with the A: “What’s that got to do with the

suitcase?”suitcase?”– B: “The watch is Japanese but the B: “The watch is Japanese but the

batteries are Russian”.batteries are Russian”.

• In science, we also want to answer In science, we also want to answer the question ‘why’. But things are the question ‘why’. But things are more difficult.more difficult.– The reductionist problem:The reductionist problem:

• If X explains Y, what explains X?If X explains Y, what explains X?

– The only natural end to this would be to The only natural end to this would be to map everything back to the initial event map everything back to the initial event (the big bang).(the big bang).•But we can’t do this – not enough evidenceBut we can’t do this – not enough evidence

•Even if we could, we wouldn’t understand it Even if we could, we wouldn’t understand it and what’s the point of an explanation that and what’s the point of an explanation that you can’t understand?you can’t understand?

Explanation in LinguisticsExplanation in Linguistics

• There are two ways that explanation There are two ways that explanation comes into linguistics:comes into linguistics:– The normal one – what explains X?The normal one – what explains X?– A more technical one: given two A more technical one: given two

theories how do we decide which one is theories how do we decide which one is best?best?

Levels of adequacyLevels of adequacy

• For any set of data, there are an For any set of data, there are an infinite possible grammars that infinite possible grammars that capture the datacapture the data

• So how do we decide which one is So how do we decide which one is the right one?the right one?

A demonstration of infinite A demonstration of infinite possible grammarspossible grammars• Suppose a simple language with one Suppose a simple language with one

word, “a”word, “a”

• The sentences of this language contain The sentences of this language contain any number of instances of the word:any number of instances of the word:– aa– aaaa– aaaaaa– aaaaaaaa– etc.etc.

• S S a aS S Sa Sa

• This grammar will generate all and This grammar will generate all and only all the sentences of this languageonly all the sentences of this language

• But so will:But so will:– S S a a oror S S a a etc.etc.

S S aS aS S S Sa SaS S aS aS

• Moreover so will:Moreover so will:– S’ S’ Sb Sb (obligatory deletion rule)(obligatory deletion rule)

S S a a Delete b at the end of Delete b at the end of aaS S Sa Sa sentencesentence

• All these grammars are distinct, but All these grammars are distinct, but they all generate languages which they all generate languages which have sentences made up of any have sentences made up of any number of ‘a’snumber of ‘a’s

• Which one is correct?Which one is correct?

• Chomsky (1965) proposed that Chomsky (1965) proposed that different grammars attain different different grammars attain different levels of adequacy:levels of adequacy:– observational adequacyobservational adequacy– descriptive adequacydescriptive adequacy– explanatory adequacyexplanatory adequacy == the highestthe highest

• Observational adequacy:Observational adequacy:– a grammar which predicts all and only a grammar which predicts all and only

the grammatical sentences of a language the grammatical sentences of a language (e.g. all of the grammars we previewed)(e.g. all of the grammars we previewed)

• Descriptive adequacy:Descriptive adequacy:– Native speakers have intuitions about Native speakers have intuitions about

how sentences are structured:how sentences are structured:• SS S S

S aS a a Sa S

aa a a

– A grammar which conforms to these A grammar which conforms to these intuitions is descriptively adequateintuitions is descriptively adequate

• Explanatory adequacyExplanatory adequacy– A theory which sheds light on the logical A theory which sheds light on the logical

problem of language acquisition is problem of language acquisition is explanatorily adequateexplanatorily adequate•two descriptively adequate theories of two two descriptively adequate theories of two

different languages do not amount to an different languages do not amount to an explanatorily adequate theory of language if they explanatorily adequate theory of language if they are very disparateare very disparate

– if both are possible human grammars, how would a if both are possible human grammars, how would a child be able to learn any one?child be able to learn any one?

•a theory which contributes to a coherent notion a theory which contributes to a coherent notion of Universal Grammar therefore is one which has of Universal Grammar therefore is one which has explanatory adequacyexplanatory adequacy

Normal ExplanationNormal Explanation

• Explanatory adequacy does not in itself Explanatory adequacy does not in itself guarantee explanationguarantee explanation– it is just a method to use to distinguish between it is just a method to use to distinguish between

different grammars and to guide researchdifferent grammars and to guide research

• Explanation in linguistics comes through Explanation in linguistics comes through restrictionrestriction– if grammatical principles are as complex as the if grammatical principles are as complex as the

data, then we have descriptiondata, then we have description– the simpler the grammar, the more explanationthe simpler the grammar, the more explanation

• simple does not necessarily mean easy to understandsimple does not necessarily mean easy to understand• it means structurally simplerit means structurally simpler

– the fewer and more general the principles the simplerthe fewer and more general the principles the simpler

• Thus, suppose we have a grammar whose Thus, suppose we have a grammar whose principles are in a one-to-one relation with principles are in a one-to-one relation with linguistic phenomena:linguistic phenomena:

• Here the grammar is just as complex as the Here the grammar is just as complex as the data and doesn’t help us understand it any data and doesn’t help us understand it any betterbetter

• But if two or more of these principles can be But if two or more of these principles can be collapsed into a more general one, the grammar collapsed into a more general one, the grammar is simpler than the datais simpler than the data

P1P2P3etc.

Phen1Phen2Phen3etc.

P1

P3etc.

Phen1Phen2Phen3etc.

• But this is a reductionist argumentBut this is a reductionist argument

• We may be able to achieve more and We may be able to achieve more and more explanationmore explanation

• But we can never achieve the But we can never achieve the ultimate explanationultimate explanation

• Perhaps this is enoughPerhaps this is enough

• Perhaps notPerhaps not

The Minimalist ProgrammeThe Minimalist Programme

• Chomsky has argued (since 1990s) that Chomsky has argued (since 1990s) that we can achieve a greater degree of we can achieve a greater degree of explanationexplanation

• If the theory we produce is built on only If the theory we produce is built on only absolutely necessary assumptions, then it absolutely necessary assumptions, then it cannot be reduced any furthercannot be reduced any further

• What is absolutely necessary?What is absolutely necessary?– the set of assumptions that if they were not the set of assumptions that if they were not

made, we wouldn’t have a theory of languagemade, we wouldn’t have a theory of language

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

thought

action

language

• The two interfaces have requirements The two interfaces have requirements for language in order for it to do its for language in order for it to do its job:job:– the products of the linguistic system must the products of the linguistic system must

be interpretable in the relevant waysbe interpretable in the relevant ways

• Suppose that is all there isSuppose that is all there is– the linguistic component consists of only the linguistic component consists of only

the things that are required to enable the things that are required to enable interpretation by the conceptual and interpretation by the conceptual and phonetic componentsphonetic components

– if anything else is needed to account for if anything else is needed to account for linguistic phenomena, this will require linguistic phenomena, this will require extra explanation (and we are back to extra explanation (and we are back to where we started)where we started)

A Minimalist DemonstrationA Minimalist Demonstration

• Why do things move?Why do things move?• In GB there were different reasons why In GB there were different reasons why

things move:things move:– to satisfy the Case Filterto satisfy the Case Filter– to bind bound morphemesto bind bound morphemes– semantic reasonssemantic reasons

• But if movement is part of the linguistic But if movement is part of the linguistic system it must have a reason motivated system it must have a reason motivated by the output conditions (conceptual by the output conditions (conceptual and phonetic interpretation)and phonetic interpretation)

• Language shows a number of Language shows a number of phenomena which involve phenomena which involve semantically interpretable features semantically interpretable features coupled with similar features which coupled with similar features which are not interpretedare not interpreted– e.g. verb agreemente.g. verb agreement

•features are interpretable on the subject features are interpretable on the subject (person, number, gender)(person, number, gender)

•features a purely grammatical features a purely grammatical (uninterpretable) on the verb(uninterpretable) on the verb

• Presumably, uninterpretable features Presumably, uninterpretable features are a problem at the output: what are a problem at the output: what would the conceptual and phonetic would the conceptual and phonetic components do with them?components do with them?

• The minimalist claim is that The minimalist claim is that movement serves the purpose of movement serves the purpose of ‘checking off’ uninterpretable ‘checking off’ uninterpretable featuresfeatures– uninterpretable features are generated uninterpretable features are generated

in some position (e.g. on the verb)in some position (e.g. on the verb)– the verb moves to be in a certain the verb moves to be in a certain

structural relation with the subject structural relation with the subject (specifier-head) where the features of (specifier-head) where the features of one are checked against those of the one are checked against those of the otherother

• IPIP

DPDP3.s3.s I’ I’

I VP I VP

• If the features check, they are deleted and If the features check, they are deleted and therefore not present at interpretationtherefore not present at interpretation

• If the features do not check they remain If the features do not check they remain and cause the structure to be and cause the structure to be uninterpretableuninterpretable

V3.s

Checking

Phrase Structure in the Phrase Structure in the Minimalist ProgrammeMinimalist Programme• The output systems require a single The output systems require a single

structure to be formed from individual structure to be formed from individual words for interpretation:words for interpretation:– how can a sentence be interpreted either how can a sentence be interpreted either

semantically or phonetically (order?) if semantically or phonetically (order?) if unconnected words are presentedunconnected words are presented

• So it is necessary to have a structure So it is necessary to have a structure building part of the grammarbuilding part of the grammar

• Structure building proceeds as Structure building proceeds as follows:follows:– take two wordstake two words– put them together to form a new object put them together to form a new object

(= ‘merge’)(= ‘merge’)– choose one to label the new object (= choose one to label the new object (=

head)head)

loves

Mary

loves

• The structure building process is a series of The structure building process is a series of mergers which builds a structure step by stepmergers which builds a structure step by step

• Do we need any other principles?Do we need any other principles?– how do we know which words to merge?how do we know which words to merge?– how do we know which one to select as head?how do we know which one to select as head?

• No other principle is needed other than that No other principle is needed other than that the structure that is built must be the structure that is built must be interpretableinterpretable– if we merge two incompatible words, it will not if we merge two incompatible words, it will not

be interpretablebe interpretable– if we choose the wrong head, it will not be if we choose the wrong head, it will not be

interpretableinterpretable

• The system then distinguishes grammatical The system then distinguishes grammatical (interpretable) from ungrammatical (interpretable) from ungrammatical (uninterpretable)(uninterpretable)