A working of primary Thomistic texts, this volume presents the systematic and unified character of Aquinas' theory of moral agency as it relates to human action. Focusing especially on the "Summa theologiae", Ralph McInerny argues that Aquinas' theory of moral action stands up to contemporary needs and remains adequate against contemporary criticism. Intended for both the scholar and the student, "Aquinas on Human Action" is the first contribution in over 20 years to expose Aquinas' thought through primary Thomistic texts. In part 1, the author examines the fundamental texts in order to demonstrate the coherence and philosphical sophistication of Aquinas' doctrine. McInerny points out that this theory of action serves as a link between natural law on the one hand, and human good or ultimate end, on the other. In part 2, he undertakes a discussion of divergent viewpoints and offers a series of relevant debates, so that the reader can place the interpretation provided in part 1 in the ongoing philosophical discussion of Aquinas' doctrine. It provides a clean line of presentation as well as an acknowledgement of alternative contributions and viewpoints of contemporary scholars.