The essays in the collection do not indicate, of course, the discussions they occasioned. The following is based on notes I took throughout the conference, together with comments some participants presented me with on the day. The latter have been incorporated into the discussion. For the most part, however, the reactions to the conference discussions are mine. They do not claim to summarise different points of view in a way which would always satisfy their proponents. That is one reason why I have not attributed the various voices to specific participants in the conference. Where points were repeated at different times I have not hesitated to bring them together in a single ‘voice’ where I thought this to be stylistically or philosophically advantageous. Nevertheless, the different voices are meant, hopefully, to capture the character of the philosophical exchanges which took place. Some of the participants modified or extended their papers before publication. The discussion which follows takes no account of these further developments.