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"It is through conscience that human beings see and recognize the demands of the divine law. They are bound to follow their conscience faithfully in everything they do."
Religious Liberty, no 2.


Letter to the TABLET 27 March 1965, pp. 22-23

by Columba Ryan OP


Fr Columba Ryan OP DEAR SIR, Fr. Lionel Keane in his article "The Ambiguity of Natural Law" rightly, as it seems to me, complains of the way some Catholic authors attribute to fallibly drawn conclusions of the natural law the infallibility proper to this law in its principles. I should agree with him that there is a tendency to be lazy in the indispensable work of clear argumentation and research needed for arriving at these conclusions. It seems at times as if Catholics were ready to say: Look, this is part of natural law, it cannot be questioned.

But of course the conclusions of reasoning, even more in the practical order than in theory, are open to questioning. Seldom do such Catholics tell us what exactly they understand by natural law, nor where to come by it: they speak almost as if all we have to do is to "look the thing up in some mysterious code embedded in our hearts, or written in the sky.

But when Fr. Keane blames this unhappy situation upon St. Thomas I cannot agree with him. It is true that St. Thomas regards the 'natural law as a "participation of the eternal law in the rational creature" (I-II:91:2). But when Fr. Keane goes on to say that this "imprint in us of the divine light" is described by St. Thomas as the natural inclination to act in a way proper to our nature he gives only part of St. Thomas's description: if this were all, then the natural law would be found in all creatures, for in all of them are there such inclinations. But in fact, according to St. Thomas in the same article, the rational creature shares in the eternal law in a special way (excellentiori quodam modo), namely in so far as he alone shares in the divine providentia, "providing for himself and others."

For St. Thomas this means that ours is a rational sharing, a sharing precisely to the extent that we use our reason and legislate for ourselves. But from this it ensues that the natural law is realised in us at different levels corresponding to the different levels of our reasoning.

In reasoning we must begin with first principles, and in the light of these reach (with all the fallibility incident upon reasoning) conclusions of greater or less universality. And when we speak of "first principles" we may mean the purely formal principles that govern any possible reasoning —principles from which, by themselves, because they are purely formal, no conclusions can be drawn. Or we may mean the quite general principles in any given field of enquiry which are not themselves able to be resolved into any antecedent principles but must be given in the primitive experience which provides the original datum appropriate to that field of enquiry.

St. Thomas's account of natural law takes account, as it seems to me, of each one of these different levels, in the context (which is that of law) of practical reason. The purely formal principle here is "that the good is to be done, the evil avoided." This, given the natural inclination of our wills, cannot be wanting in any man in reality, though he may so beguile himself with words as to think it can, just as he can so beguile himself with words as to think that in the theoretical order he can do without the principle of contradiction.

The quite general principles (first principles in my second sense) given in any quite primitive moral awareness are those principles which, as Fr. Keane notes, are referred to in I-II:94:2 under three heads: the inclination, common to all beings, to remain in being; the inclination, common to all living things, to reproduction; and the inclination, proper to human beings, to what I think may be called communication (or, as St. Thomas puts it, to know the truth of God and to live in society). Here, too, short of a total moral unawareness, these principles cannot be wanting in men, thought this is certainly not to say that all men will understand how they are to be worked out in detail, still less that all men will agree upon this. Nor should we understand, as I think Fr. Keane takes it, either that reason does not enter into each one of these inclinations when found in men, or that sexual ethics come under the second head alone and are therefore conceived by St. Thomas in a purely biological way. It is a very big part of "living in society" that men and women should enter marriage with one another, and there is nothing to exclude the moral consideration of sexual union under this head as well as under the second head.

The Augustinian-Thomist account of marriage is in terms of mutual fidelity (fides) as well as in terms of offspring (proles).
But (to continue the investigation of the different levels of reasoning and of the natural law) these quite general principles have still to be worked out in detail, or, as St. Thomas will say, conclusions must be drawn from them. And here two things must be noticed. The first is that there will be a descending hierarchy of conclusions, the more general (those immediately derived from the first principles) serving in their turn as premises for more particular conclusions.

The second is that the process of drawing conclusions is not purely deductive, i.e. an 'exercise of pure reason : it draws upon, and draws into itself, an increasing mass of information from experience. This process, as St. Thomas observes (I-II:94:4 and 6), is liable to every kind of error—mistakes of reasoning as well as mistakes of fact. And the further the process descends into detail the greater the margin of error. The more general conclusions (those to which St. Thomas refers in l-1[:95:2 in the phrase quoted by Fr. Keane) are least open to mistake, and in fact St. Thomas takes it that all men are agreed upon them. There do seem to be general standards of conduct upon which civilised men agree. But there are many conclusions where disagreement is the rule, just as it is also in the theoretical side of philosophy.

Nevertheless, where the reasoning is in fact sound, and the facts truly established, we may say of any conclusion that it does belong, at its proper level, to natural law, and is therefore the law of God reflected in men's understanding, and incumbent, did they but know it, upon all. To this extent such conclusions or moral rulings are not, as Fr. Keane would have us believe, merely man-made. Nor is St. Thomas, when he gives them natural law status, guilty of ambiguity.

One final point. When the Church declares something to be of natural law I would suggest there is an analogy to what she does when she declares that the existence of God may be known by 'reason. In the latter case she does not provide philosophers with the necessary process of reasoning: she merely says that the thing is possible, and leaves them to discover the way. So when she declares that something is of natural law, she does not provide the reasoning: she merely declares the thing to be so. The reasoning is left to us—and very ill it seems so far to have been done. In this I think I am completely at one with Fr. Keane. And because the reasoning draws upon facts, where new facts come into being, particular conclusions are subject to development or change.

Yours faithfully, Blackfriars, Oxford.