Abstract: This book is an evolution of Plato’s Moral Theory where Irwin presented for the first time his personal interpretation of Plato’s ethics. The aim of this book is to demonstrate that Plato’s rejection of Socrates’ instrumentalism is one of the key elements in the development of Plato’s philosophical perspective. The book, which is structured in 20 chapters, is a dialogue by dialogue commentary, which discusses Plato’s ethics in context of his metaphysics and epistemology. The first chapters study how in his early dialogues (Laches, Charmides, and Euthydemus) Plato interprets Socrates’ method and doctrines. Then, from chapter 6 to 9, it is illustrated how in later dialogues (Gorgias, Meno, Protagoras) Plato tries to defend and support Socrates’ theories against some possible critics. The core of the book (chapters 10 through 18) is devoted to a careful analysis of how Plato in the Republic develops his own views, moving away from the positions of his master. Lastly, in the two final chapters how the mature views of the Republic are advanced in the late dialogues (the Philebus, the Statesman, and the Laws) is examined.

Keywords: Good, Plato, Gorgias, Happiness, Instrumentalism, Meno, Protagoras, Socrates, Republic, Virtues