Thomas Acquinas and Natural Law Theory

Abstract

1. Thomas Aquinas and Natural Law Theory Natural law theory like legal positivism has appeared in a variety of forms and in many guises. One of the most elaborate statements of natural law theory can be found in Aquinas who distinguished four types of law: eternal, divine, natural, and man-made. So, according to Aquinas, eternal law reflected God's grand design for the whole shebang. Divine law was that set of principles revealed by Scripture, and natural law was eternal law as it applied to human conduct. Man-made law was constructed by human beings to fit and accommodate the requirements of natural law to the needs and contexts of different and changing societies. Also, according to Aquinas, the fundamental precepts of natural law were not only ascertainable (mere mortals like you and me could and did find them out) but self-evident, i.e., they required no proof. They were, in Aquinas' terms, per se nota, known through themselves. Like his predecessor, Aristotle, Aquinas distinguished two kinds of reasoning: theoretical and practical. Human beings were capable of both sorts of reasoning. Theoretical reason was the capacity to apprehend certain truths, such as the truths of mathematics. Practical reason was the capacity to apprehend those principles guiding human conduct which tell us how we ought to live, what things we should value, what goods we should seek, and how we ought to order our lives. Like Aristotle, Aquinas believed that there were principles of practical reason and that they were no less fundamental than the principles of theoretical or speculative reason. Thus, for Aquinas, the principle of non-contradiction was as self-evident as the first and most fundamental principle of natural law ("Good is to be done and evil is to be avoided"). Like the principle of non-contradiction, the precepts of natural law were, according to Aquinas, general and unchanging. They were the same for everyone. But man-made or human law has to take the particularities of each human situation into account. Man-made law must adjust natural law to specific and often changing circumstances. Man made law is accommodating and changeable. Furthermore, there are