Abstract
In 1977, Terence Irwin published Plato’s Moral Theory. This book, along with the work of Gregory Vlastos, has had a greater influence on the study of Plato’s ethics than anything published since. Although the present volume, Plato’s Ethics began as a second edition of PMT, it quickly became a “new book” in which none of PMT’s text reappears. Irwin declines to keep score of the specific differences between the two works and I cannot here provide a comprehensive comparison. I shall, instead, discuss in broad outline PE’s position on one of PMT’s central themes and then turn to the details of one of PE’s new arguments.