[ Pobierz całość w formacie PDF ]
ontogenetic theory needs lexical semantic representations; but it makes quite a different
sort of case from the one we've just been looking at.
The Baker's Paradox Argument
Pinker thinks that, unless children are assumed to represent eat as an action verb
(mutatis mutandis, give as a verb of prospective possession, etc.). Baker's Paradox will
arise and make the acquisition of lexical syntax unintelligible. I'll tell you what Baker's
Paradox is in a moment, but I want to tell you what I think the bottom line is first. I think
that Baker's Paradox is a red herring in the present context. In fact, I think that it's two red
herrings: on Pinker's own empirical assumptions, there probably isn't a
end p.64
Baker's Paradox about learning the lexicon; and, anyhow, assuming that there is one
provides no argument that lexical items have semantic structure. Both of these points are
about to emerge.
Baker's Paradox, as Pinker understands it, is a knot of problems that turn on the
(apparent) fact that children (do or can) learn the lexical syntax of their language without
much in the way of overt parental correction. Pinker discerns, three aspects of the
problem [that] give it its sense of paradox , these being the child's lack of negative
evidence, the productivity of the structures the child learns ( if children simply stuck with
the argument structures that were exemplified in parental speech . . . they would never
make errors . . . and hence would have no need to figure out how to avoid or expunge
them ), and the arbitrariness of the linguistic phenomena that the child is faced with
(specifically near synonyms [may] have different argument structures (1989: 8 9)). If,
for example, the rule of dative movement is productive, and if it is merely arbitrary that
you can say John gave the library the book but not * John donated the library the book ,
how, except by being corrected, could the child learn that the one is OK and the other is
not?
That's a good question, to be sure; but it bears full stress that the three components do
not, as stated and by themselves, make Baker's Paradox paradoxical. The problem is an
unclarity in Pinker's claim that the rules the child is acquiring are productive . If this
means (as it usually does in linguistics) just that the rules are general (they aren't mere
lists; they go beyond the child's data ) then we get no paradox but just a standard sort of
induction problem: the child learns more than the input shows him, and something has to
fill the gap. To get a paradox, you have to throw in the assumption that, by and large,
children don't overgeneralize; i.e. that, by and large, they don't apply the productive rules
they're learning to license usages that count as mistaken by adult standards. For suppose
that assumption is untrue and the child does overgeneralize. Then, on anybody's account,
there would have to be some form of correction mechanism in play, endogenous or
otherwise, that serves to expunge the child's errors. Determining what mechanism(s) it is
that serve(s) this function would, of course, be of considerable interest; especially on the
assumption that it isn't parental correction. But so long as the child does something that
shows the world that he's got the wrong rule, there is nothing paradoxical in the fact that
information the world provides ensures that he eventually converges on the right one.
To repeat, Baker's Paradox is a paradox only if you add no overgeneralizations' to
Pinker's list. The debilitated form of Baker's Paradox that you get without this further
premiss fails to do what Pinker very much wants Baker's Paradox to do; viz. [take] the
burden of explaining learning out of the environmental input and [put] it back into the
child (1989: 14 15). Only if the child does not overgeneralize lexical categories is there
evidence for his differentiating [them] a priori (ibid.: 44, my emphasis); viz. prior to
environmentally provided information.
Pinker's argument is therefore straightforwardly missing a premiss. The logical slip
seems egregious, but Pinker really does make it, as far as I can tell. Consider:
[Since there is empirical evidence against the child's having negative information, and
there is empirical evidence for the child's rules being productive,] the only way out of
Baker's Paradox that's left is . . . rejecting arbitrariness. Perhaps the verbs that do or don't
participate in these alterations do not belong to arbitrary lists after all . . . [Perhaps, in
particular, these classes are specifiable by reference to semantic criteria.] . . . If learners
could acquire and enforce criteria delineating the[se] . . . classes of verbs, they could
productively generalize an alternation to verbs that meet the criteria without
overgeneralizing it to those that do not. (ibid.: 30)
Precisely so. If, as Pinker's theory claims, the lexical facts are non-arbitrary and children
are sensitive to their non-arbitrariness, then the right prediction is that children don't
overgeneralize the lexical rules.
Which, however, by practically everybody's testimony, including Pinker's, children
reliably do. On Pinker's own account, children aren't conservative in respect of the
lexicon (see 1989: 19 26, sec. 1.4.4.1 for lots and lots of cases).15 This being so, there's
got to be something wrong with the theory that the child's hypotheses differentiate
lexical classes a priori. A priori constraints would mean that false hypotheses don't even
get tried. Overgeneralization, by contrast, means that false hypotheses do get tried but are
somehow expunged (presumably by some sort of information that the environment
supplies).
At one point, Pinker almost fesses up to this. The heart of his strategy for lexical
learning is that if the verbs that occur in both forms have some [e.g. semantic] property
. . . that is missing in the verbs that occur [in the input data] in only one form, bifurcate
the verbs . . . so as to expunge nonwitnessed verb forms generated by the earlier
unconstrained version of the rule if they violate the newly learned constraint (1989: 52).
[ Pobierz całość w formacie PDF ]