The situated processing of situated language

Abstract

People often characterize the semantic component of a natural-language processing system as the implementation of a semantical theory. As system designers they adopt or perhaps even develop a theory of natural language semantics (frame semantics or Montague semantics, say). Then they provide a computational mechanism that derives the semantic representation used in that theory from the syntactic representation produced by a parser. That mechanism may in turn connect to the rest of a system in such a way as to ensure appropriate action by the agent. This characterization, though simple, illustrates an important point: the search is for a single semantical account that can serve simultaneously as an account of the semantics of the utterances of the language and as the semantic representation of those utterances to be used by a computer.1 There is growing evidence, however, that suggests the need for a re-evaluation of the assumption that there is, or could be, any such single account. On the face of it, one might imagine that a serious challenge could come quite simply from fundamental differences between humans (and hence, human language) and computers. After all, we might imagine that because computers and humans are different, computers could not in any robust way be endowed with anything like the human language ability. From this point of view, no matter what your account of human language is like, if it were to adequately describe full-blooded language use, it couldn't be embodied in a computer. Arguments of this type have been made of course, Searle's (1980) Chinese box argument being an especi ally familiar one. One can also imagine arguments against the direct embedding of a linguist's account in a computer coming from differences in the way linguists theorize and what seems best from an implementer's point of view. And there have been cogent arguments of this latter sort too, at least for syntactic representations (see, for example, Shieber, 1984, 1986). Finally, one can imagine limits arising from more standard practical exigencies of computers themselves, i.e., their limits on time and memory. But and this is perhaps unexpected there is also an argument