What's in a symbol: ontology, representation and language

This paper is in a form unconventional in modern journals but traditional for the discussion of foundational questions: a dialogue. It is a form that makes it possible to contrast two deeply held but incompatible views, each with its standard forms of defense, in order to seek common ground and make the diierences more precise. In artiicial intelligence, or at least in the major part of it still committed to symbolic representations, there is a long history of discussion of the origin and nature of the symbols we use in representations, symbols which normally look like words, English words in fact, but which most researchers deny are such words, since to concede that would put in question the abstract nature of the representation. In what follows, we examine our common ground and then diverge over ve speciic questions on the issue of representations. The discussion focuses on symbol use in representations of language, because there the similarity is most acute | between the representation and the represented | but the issues are general and apply to symbolic AI as such.