What I mean by productivity is linguistic productivity: roughly, the fact
that a finite human mind is capable of producing and understanding potentially
infinitely
many different linguistic expressions on equally many different occasions.
Ordinary speakers perform the miracles of productivity on the fly and without
even being
aware of it: they produce new expressions not encountered before and use
old expressions for new purposes.
The received wisdom of the last forty or so years is that recursive syntactic
rules and semantic compositionality may be the core of an explanation for
productivity. However, infinity of the set of expressions really is not
the point, and that's
why recursion can at most be part of the story and is in fact a little
misleading as a showpiece of an explanation of linguistic productivity.
The point, I
want to suggest, is projectibility: projecting properties from the known
to the unknown,
and in a fashion that other speakers can follow.
One may reasonably doubt that the familiar category-based rules will suffice
to account for processes of word formation, there are problems about the
compositionality of certain syntactic constructions and, of course, pragmatics
isn't really compositional
either. I will not touch upon most of these problems though, but I will
concentrate on problems of the context dependence of the semantic interpretation
of linguistic
utterances. I shall argue that there is no way of accounting for sentence
contents, i.e. for the truth conditions sentences have under particular
circumstances of
utterance, in a compositional a priori fashion. I shall argue that, in
addition to familiar category-based compositional mechanisms, representations
of linguistic
experience are required that cannot be formulated in terms of a denumerable
set of categories. Such representations are mapped onto other situations
of language
use via relations of similarity, and I will argue that category-based rules
are here no serious alternative - even though they are still required for
other purposes
in a theory of projectibility.