[Corpora-List] No poverty of the stimulus

[Geoffrey Sampson]

Dear Diana and others,

Well I don't think I can undertake fully to clarify what is being
argued, because like so many issues in intellectual life one thing is
leading to another, and what started when I first contributed to this
discussion as a single narrow point has in subsequent discussion been
linked to several other related but different points!  But I'll try to
go a little way.

A central proposition within the group of ideas commonly referred to as
"poverty of the stimulus" is that the experience available to a child at
the first-language acquisition stage contains only positive examples of
things that are good, or "grammatical", in the respective language, but
not also negative examples identified as bad or ungrammatical, analogous
to "*The men running is" in a linguistics textbook; and that it is
logically impossible to infer a grammar of a language exclusively from
data about positive instances without data about negative instances (so
children must have something more, given independently of experience).

One can question whether children's experience is indeed as devoid of
negative data as that proposition claims; John Sowa made very sensible
sceptical remarks on that.  But my main point is that, _even if we
accept the claim that the child's data contains only positive and no
negative information_, it CANNOT be the case that this makes it
logically impossible to infer a grammar (that is a general theory using
a limited range of principles to account for the numerous individual
observed instances), because the natural sciences routinely produce
general theories to account for empirical observations, and we know that
natural scientists _never_ observe events violating physical laws.  (I
can choose to violate the rule that says that plural subjects cannot
take the 3rd-person-singular verb suffix in English, but I cannot choose
to violate the law that says that my body will be attracted towards the
centre of the Earth at a given force.  Certainly, I can jump in the air,
but that doesn't violate the law of gravity; it just uses other equally
law-governed resources in order briefly to overcome what the law of
gravity predicts would happen if it were the only law of nature in
operation -- which it isn't.)

Mike Maxwell then changed the subject, to my mind, by arguing that
natural-language grammars are so much more complex than the laws of
physics that theory-inferring techniques which might work in the natural
sciences would surely be inadequate for formulating language grammars.
We could argue about this, but it is a quite separate issue from what is
normally called the "poverty of stimulus" argument.  This latter point
of Maxwell's is a quantitative point -- inferring theories from
positive-only data might get a certain way but can't get far _enough_ to
cope with the complexity of English, Portuguese, Chinese, etc.  To
pursue that we would presumably have to find ways of putting numbers on
how complex the theories are which could be derived in a given period of
time from positive-only data, how complex natural languages are, how
much time is available to the child, and so on.  But the "poverty of
data" argument is not about numbers at all, it is an absolute argument
which claims that there is a _logical_ impossibility about the concept
of formulating a grammar without prior knowledge based exclusively on
positive instances.  (If I were sitting among my books at home I could
quote supporters of the "poverty of data" idea to back up that statement
of how the phrase is used.)  The analogy with the natural sciences
refutes that absolute argument, which is what I thought was under
discussion when I first contributed to this thread.

I would add that I find the analogy between the scientist producing a
theory to account for observations of the natural world, and the small
child acquiring his mother tongue, a more worthwhile one than you want
to concede!  Of course there are differences.  The scientist is adult,
the child is very young.  The scientist is using a body of specialized
observations not available to most people, the child is using a type of
observations available to all members of a society.  The scientist is
theorizing about matters that are not directly crucial to most people's
lives and in some cases not really important for anyone's life, the
child is trying to achieve a skill that is crucial for virtually all
aspects of our interaction with other human beings.  These differences
are interrelated, and they are real.  But to my mind they don't
contradict the fact that the _logic_ of scientific discovery, to use
Karl Popper's phrase, is very analogous to one way of conceiving the
logic of language-acquisition (and I personally find that way of
conceiving the latter process the most plausible one).

Geoff


............................................................
     Prof. Geoffrey Sampson  MA PhD MBCS CITP FHEA

     author of "The 'Language Instinct' Debate"

     Department of Informatics, University of Sussex
     Falmer, Brighton BN1 9QJ, England

     www.grsampson.net     +44 1273 678525
............................................................


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