This is the first comprehensive study of the ethics of G. E. Moore, the most important English-speaking ethicist of the twentieth century. Moore's ethical project, set out in his seminal text Principia Ethica, is to preserve common moral insight from skepticism and, in effect, persuade his readers to accept the objective character of goodness. Brian Hutchinson explores Moore's arguments in detail and in the process relates the ethical thought to Moore's anti-skeptical epistemology. Moore was, without perhaps fully realizing it, skeptical about the very enterprise of philosophy itself, and in this regard, as Brian Hutchinson reveals, was much closer in his thinking to Wittgenstein than has been previously realized. This book shows Moore's ethical work to be much richer and more sophisticated than his critics have acknowledged.