This is the first book-length treatment of the so-called ergon argument that makes part of the classical philosophers' attempt to ground ethics in human nature. As such the argument has attracted the attention of contemporary philosophers, especially the founders of virtue ethics. Jirsa examines closely all passages where the ergon argument occurs, at the end of Republic I and in Aristotle's ethical treatises, the Protrepticus, the Eudemian Ethics, and the Nicomachean Ethics I. The book aims to show that the ergon argument crucially refers to the activity of the soul and regarding Aristotle in particular it sets out to show how the ergon argument connects to the eudaimonia, arguing that the latter amounts ultimately to contemplation (theoria). This is a philosophically sophisticated, clearly written book that contains much that is original, even intriguing. It is essential reading for both scholars of ancient philosophy as well as for virtue ethicists.

George Karamanolis, University of Vienna, Austria

There are a handful of arguments in the history of philosophy so interesting and profound that they seem to admit of endless, fruitful consideration. The function argument of Aristotle is one of these. And there is no treatment of the argument which rivals Jakub Jirsa's for its comprehensiveness, accuracy, and soundness of insight

Michael Pakaluk, The Catholic University of America, USA

The “function” (or ergon) argument is one of the most important in all of Aristotle's ethics, and there is an avalanche of literature discussing the various versions of it in different works. Jakub Jirsa is the first scholar to offer a complete analysis of the argument in all of the ethical works where it appears, including not only the Eudemian and Nicomachean Ethics, but also Aristotle's popular lost work, the Protrepticus. The Protrepticus version, which is clearly the earliest version, is at the same time the most neglected one. By taking it very seriously, Jirsa has been able to make considerable progress on several seemingly intractable issues, and his discussion is not only the most complete but also the best that I know of. All future discussion of this central argument will have to start from his account.

Monte Ransome Johnson, University of California, San Diego, USA

This is a very interesting book which explores in a detailed way the four versions of the ergon argument: (i) Plato's Republic, (ii) Aristotle's Protepticus, (iii) Aristotle's EE and (iv) Aristotle's NE. The argument is clearly presented, and the author supports his claims with textual evidence and analysis, discussing the more important contrary positions found in the literature.

Marco Zingaro, University of São Paulo, Brazil