Stephen Louis Brock - The Light That Binds: A Study in Thomas Aquinass Metaphysics of Natural Law

The law of nature, declares Saint Thomas, is nothing other than the light of the intellect instilled in us by God, through which we know what is to be done and what is to be avoided. In his more technical moments, Thomas will distinguish a little between the minds light and natural law, the law being a set of truths, and the light being what manifests them and lets us understand them. But once lit up, the truths are also a light, showing us a path to follow. In some sense they even oblige us, bind us, to that path. Natural law is a light that binds.

The question running through the following pages is how exactly it is, for Aquinas, that the truths of natural law constitute a genuine law and carry real binding force. I shall motivate the question and survey various answers that it has received in chapter . There I shall also explain the plan of the rest. Here I would like to say something about my subtitle.

By far the bulk of Thomass writing on natural law is found in his masterpiece, the Summa theologiae . So situated, it is obviously a theological teaching. I hope that I have kept its theological character sufficiently in view. Nevertheless, as with many of the topics presented in the Summa , its treatment of natural law involves very heavy use of philosophical sources and arguments. This is hardly surprising, if indeed natural law itself is a work of the human minds natural light. For that is also philosophys proper light. I see no need to apologize for wanting to concentrate on Thomass philosophy of natural law.

Philosophy, though, has many parts. The truths of natural law, Thomas tells us, constitute the first principles of practical reason. The practical part of philosophy is moral philosophy or ethics. Metaphysics, by contrast, is speculative or theoretical, not practical. What has metaphysics got to do with natural law?

The truths of natural law are certainly not, for Thomas, the first principles of metaphysics itself. The field of metaphysics is all of reality, being itself, and its own principles are more far-reaching, and even more basic, than those that bear only on human conduct. Of course human conduct is a being tooit existsand so its principles do somehow fall within the metaphysical purview. The metaphysician can speculate about anything. But the study of human conduct in light of the truths of natural law, both in its matter and in its purpose, is surely a practical undertaking. By that very fact, natural law pertains to moral philosophy.

It is one thing, however, to study a field in light of its principles. It is another thing to study the principles themselves. In Thomass conception of philosophy, studying the principles of any field whatever is a metaphysical task. Every other part of philosophy takes the principles of its field for granted and seeks only to draw out the implications from them that make for full mastery of that field. Moral philosophy draws practical conclusions from the principles of natural law. But the fundamental treatment of all first principles, both those of metaphysics itself and those of the other parts of philosophy, whether speculative or practical, belongs to metaphysics. The mere fact that the principles are really principles and not conclusionsthe fact that they do not need to be demonstrated, in light of other principlesdoes not preclude such treatment. For instance, the principles still need to be identified. The terms comprising them need to be clarified so as to achieve and to judge the precise formulations of them. And doubts or difficulties about them can arise and need to be resolved. These are metaphysical exercises.

Moreover, if metaphysics has one primary task, it is to trace all the fields of philosophy and all of their principles back to the very first explanations or causes of all reality and all truth. This is metaphysics in its character as wisdom.

But perhaps most importantly, at least as far as this book is concerned, the very question of how Thomas thinks natural law constitutes a law is closely tied to the question of his view of its relation to God. In a sense, the whole book is an attempt to determine the meaning and drift of his famous description of natural law as nothing other than a participation of the eternal law in the rational creature. The eternal law is Gods law. If only for this reason, the perspective cannot but be heavily metaphysical.