This volume contains the proceedings of the first annual Philosophy Colloquium at the University of Western Ontario, which have been revised for publication. The give and take of scholarly debate is maintained by the inclusion of some of the most interesting comments from the floor, with the replies of the main speakers.

The Colloquium begins with an address on ‘Existence and Quantification’ by W.V. Quine, which is followed by three symposia: ‘Descartes’ Ontological Argument’, ‘On Events and Event-Descriptions’ and ‘Existence-Assumptions in Practical Thinking’.