Language Learnability: BBS Call for Commentators

[Stevan Harnad]

Below is the abstract of a forthcoming target article to appear in
Behavioral and Brain Sciences (BBS), an international journal of "open
peer commentary" in the biobehavioral and cognitive sciences, published
by Cambridge University Press. For information on how to serve as a
commentator or to nominate qualified professionals in these fields as
commentators, please send email to:         harnad at mind.princeton.edu
or write to:          BBS, 20 Nassau Street, #240, Princeton NJ 08542
                                                  [tel: 609-921-7771]
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[Chomsky, heredity/environment, poverty-of-the-stimulus, development]

       The Child's Trigger Experience:   "Degree-0" Learnability

                         David Lightfoot
                      Linguistics Department
		      University of Maryland

A selective model of human language capacities holds that people come
to know more than they experience. The discrepancy between experience
and eventual capacity is bridged by genetically provided information.
Hence any hypothesis about the linguistic genotype (or "Universal
Grammar," UG) has consequences for what experience is needed and what
form people's mature capacities (or "grammars") will take. This BBS
target article discusses the "trigger experience," i.e., the experience
that actually affects a child's linguistic development. It is argued
that this must be a subset of a child's total linguistic experience
and hence that much of what a child hears has no consequence for the
form of the eventual grammar. UG filters experience and provides an
upper bound on what constitutes the triggering experience. This filtering
effect can often be seen in the way linguistic capacity can change between
generations. Children only need access to robust structures of minimal
("degree-0") complexity. Everything can be learned from simple, unembedded
"domains" (a grammatical concept involved in defining an expression's
logical form). Children do not need access to more complex structures.