In the first edition of Sex: A Philosophical Primer, Singer offered a new conception of sex, locating it within a spectrum that also includes love and compassion. He suggested that this conception improves upon the work of theorists who tend to relegate sex, love, and compassion to separate and distinct compartments. Singer further argues that sex in human beings is normally—perhaps always in some degree—a composite of the appetitive and the interpersonal, a view that becomes the basis for his later remarks about the relative value of individual sex acts, as well as their place within the aesthetic and moral dimensions of human nature. In the present, expanded edition, Singer supplements the 2001 chapters with a timely and stimulating essay that focuses upon marriage, particularly same-sex marriage. Singer maintains that questions about sex are fundamental in all thinking about the marital condition, and addresses the problem of same-sex legitimization and rights to material benefits by analyzing the nature of marriage, union, and family in their relation to sexuality and love. For first-time and seasoned readers alike, Singer's lucid new reflections will clarify current and emerging issues in the philosophy of sex. Irving Singer is professor of philosophy at Massachusetts Institute of Technology and the author of many books, among them Explorations in Love and Sex, Feeling and Imagination, and his trilogies Meaning in Life and The Nature of Love.