This collection of John Mackie's papers on personal identity and topics in moral and political philosophy, some of which have not previously been published, deal with such issues as: multiple personality; the transcendental "I"; responsibility and language; aesthetic judgements; Sidgwick's pessimism; act-utiliarianism; right-based moral theories; cooperation, competition, and moral philosophy; universalization; rights, utility, and external costs; norms and dilemmas; Parfit's population paradox; and the combination of partially-ordered preferences.