This volume contains the late J.L. Austin's examination of his distinction of performative utterances from statements, and his subsequent theory of "illocutionary forces" of utterances. It is a revised version of his famous William James Lectures, delivered at Harvard University.

This work sets out Austin's conclusions in the field to which he directed his main efforts for at least the last ten years of his life. Starting from an exhaustive examination of his already well-known distinction between performative utterances and statements, Austin here finally abandons that distinction, replacing it with a more general theory of `illocutionary forces' of utterances which has important bearings on a wide variety of philosophical problems.