The term "projection" describes cases where some element of meaning unexpectedly escapes from the scope of another expression, such as a negation or conditional. For example, "John didn't see his sister" is typically understood as denying that there was an event of John seeing his sister, but not as denying that John has a sister -- even though syntactically the expression "his sister" is under the scope of the negation. An enormous range of expressions yield projection, including presupposition triggers, conventional implicature triggers, approximatives, and some inferences associated with Gricean implicatures. This project will carry out the first systematic empirical and theoretical analysis of the full range of projective meanings, to establish why projection occurs, and how subclasses of projective meaning differ. To this end, it will develop templates for diagnostic tests that can be used to study properties of projective meanings cross-linguistically, with theoretically naive consultants. The researchers will conduct detailed investigations of projective meanings in English and Paraguayan Guarani, and disseminate the techniques to fieldworkers studying other languages, through publications and workshops.
Modern linguistic semantics centers around Fregean compositionality, the way in which the meanings of parts are combined to give the meanings of larger expressions. While there has been great progress in compositional semantics, projective meaning does not obey ordinary compositional rules. Until now, there has been no uniform account of why projective meanings behave differently from ordinary content. This project seeks to explain projection, based on the working hypothesis that aspects of meaning project if and only if they are not at-issue. The notion of at-issueness is a pragmatic one, based on what questions are under discussion in a discourse. Thus the project will place a relatively little-studied pragmatic notion at the heart of work on linguistic meaning. A first area where the innovations in the project are of broad significance is in its cross-linguistic focus: a theory of human language cannot be based on one language alone, and the project will apply its empirical techniques cross-linguistically. Beyond linguistic semantics, the issues studied are fundamental to Philosophy of Language, since the work subtly redraws the boundary between Semantics and Pragmatics. Further the project is of practical significance in the field of Natural Language Processing (specifically, the subfield of Computational Semantics). Text processing systems, e.g. computer systems for automatically answering a user's questions, must take account of inferences which arise independently of standard composition. A question answering system which does not take account of what is projected will not be able to identify what the user already knows, and will not be able to identify what question needs to be answered.
