Saint Thomas Aquinas is an Aristotelian (few scholars would question that) and he is the most important author in the entire history of natural law theory. Yet, there is no natural law theory in Aristotle. Even the concept of person, which is so important in Aquinas’ ethics, seems to be foreign to Aristotle’s culture and thought. How can Aquinas’ ethics be said Aristotelian? How can his natural law theory? In From Aristotle to Thomas Aquinas: Natural Law, Practical Knowledge, and the Person, Fulvio Di Blasi argues that Aquinas’ concept of natural law, his personalism and his overall approach to moral theory are deeply rooted in the very heart of Aristotle’s ethics: in his concepts of practical knowledge, proairesis (moral choice), and practical syllogism, as well as in his account of the moral agency, the ultimate end and human social nature. Di Blasi goes as far as to connect Aquinas’ definition of natural law to Aristotle’s concept of proairesis.

From Aristotle to Thomas Aquinas develops a line of thought that was already sketched in Di Blasi’s previous book, God and the Natural Law. Di Blasi engages several authors and critics, including John Finnis, Martin Rhonheimer, Germain Grisez, and Robert George. The first part of the book relates to metaphysics, the concept of good and the concept of practical knowledge. The second part addresses issues in moral philosophy like the concepts of person, the ultimate end, marriage and contraception. The third part applies Aquinas’ concepts of natural law, friendship and the person to issues in political philosophy. Di Blasi outlines an ideal of political personalism and the need to recover the concepts of nature and authority in the contemporary political debate.

Every student of Aristotle’s ethics and politics, and of Aquinas’ thought will find this book extremely revealing and stimulating.