Download Lecture 11 - ELTE / SEAS

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a
S  Sa
• This grammar will generate all and only all
the sentences of this language
• But so will:
–Sa
S  aS
or
• Moreover so will:
– S’  Sb
Sa
S  Sa
Sa
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)