R.M. Hare is one of the most widely discussed of today's moral philosophers. In this volume he has collected a number of essays, including one which is previously unpublished, which fill in the theoretical background of his thought. Each essay is self-contained, but together they give a connected picture of his views on such questions as the objectivity and rationality of moral thinking, the issue between the ethical realists and their opponents, the place in our moral thought of appeals to common convictions, and how to tell whether a feature of a situation is morally relevant.