Henry Sidgwick was one of the most influential ethical philosophers of the Victorian era, and his work continues to exert a powerful influence on Anglo-American ethical and political theory. His masterpiece, The Methods of Ethics (1907), was first published in 1874 and in many ways marked the culmination of the classical utilitarian tradition—the tradition of Jeremy Bentham and James and John Stuart Mill—with its emphasis on “the greatest happiness of the greatest number” as the fundamental normative demand.
Sidgwick’s treatment of that position was more comprehensive and scholarly than any previous one, and he set the agenda for most of the twentieth-century debates between utilitarians and their critics. Utilitarians from G. E. Moore and Bertrand Russell to J. J. C. Smart and R. M. Hare down to Derek Parfit and Peter Singer have acknowledged Sidgwick’s Methods as a vital source for their arguments. But in addition to authoritatively formulating utilitarianism and inspiring utilitarians, the Methods has also served as a general model for how to do ethical theory, since it provides a series of systematic, historically informed comparisons between utilitarianism and its leading alternatives.
Thus, even such influential critics of utilitarianism as William Frankena, Marcus Singer, and John Rawls have looked to Sidgwick’s work for guidance. C. D. Broad, a later successor to Sidgwick’s Cambridge chair, famously went so far as to say “Sidgwick’s Methods of Ethics seems to me to be on the whole the best treatise on moral theory that has ever been written, and to be one of the English philosophical classics” (Broad, 1930: 143).
Engaging with Sidgwick’s work remains an excellent way to cultivate a serious philosophical interest in ethics, metaethics, and practical ethics, not to mention the history of these subjects. Moreover, he made important contributions to many other fields, including economics, political theory, classics, educational theory, and parapsychology. His significance as an intellectual and cultural figure has yet to be fully appreciated.