1. Aim and Scope of this Paper.—In this paper I shall try to show that “duty” derives its significance from its relation to “interest,” and that the former concept cannot be understood when taken apart from its relation to the latter. Such a doctrine is, I am aware, rejected by some contemporary philosophers; and I shall, I trust, make it sufficiently clear in the sequel why I am unable to accept their view.

I am not, however, concerned primarily with criticism of other theories. This paper represents an attempt to interpret a particular province of “the common moral consciousness” and to elicit the principles there implied. I begin by accepting the view that, like natural science, ethics has its data, and that it is the business of ethics to interpret these data which are the contents of the “moral consciousness.” In Section A I discuss various methods which may be used for the discovery of the relevant data, and suggest that initial enquiries can most fruitfully be pursued in the field of law and custom. In Section B I undertake an analysis of the principles of the law relating to promise-keeping. As a result of what is there found, it becomes necessary, in Section C, to discuss the nature of rights and their relation to interests, and, in Section D, the nature of duties and their relation to rights.

Recent results in kinematics, obtained by myself and those working with me, have convinced me that the philosophical status of physics, as it has come down to us from Renaissance days, requires reconsideration. The reason can be stated in a couple of sentences: it has been found possible to establish certain laws of physics—laws of motion, the law of gravitation, the laws known under the name of the Lorentz transformation, and some others—purely deductively, without specific assumptions, and without empirical appeals save only to the empirical awareness of something we call “the passage of time.” Yet physicists have claimed ad nauseam that the ultimate sanction for “laws of nature” is observation and experiment, that this is what distinguishes physics from other branches of exact inquiry. The contrast in these two conceptions of natural law needs no emphasis. It is the purpose of this article to attempt to clarify this confused situation.

The various discussions on morals which have recently appeared in the pages of this journal, like most modern discussions of the subject, have had to concern themselves with two antitheses, between the good and the right, and between duty and interest. As to the first, is the good what it is because it is right, or is right what it is because it is good? Or may the two be distinct, so that what is right is not necessarily good? And if it is not good, is it bad? Or do the right and the good overlap? For the second, the antithesis between duty and interest—“of course,” says one, “the two have nothing to do with one another; the more carefully we keep them apart, the better.” In rare instances, indeed, it will be allowed that my duty may coincide with my interest; but when it does so, it is felt to be shorn of half its worth. If it pays me to tell the truth, what thank have I for all my veracity?

Few philosophical controversies have been waged with greater acrimony than the controversy between the libertarians and the determinists; the vigour with which both sides of the question have been espoused is due not only to the metaphysical importance of the issue—which is indeed considerable—but more especially to its moral and religious implications. No other philosophical issues, with the exception of those pertaining to God and the immortality of the soul, are of greater ethical and theological moment. So thoroughly has the question been debated that further consideration of it may seem futile. Has not the evidence been so completely canvassed on both sides of the controversy that further discussion will be a fruitless reiteration of long familiar arguments? The free-will problem is considered by many contemporary thinkers an admittedly unsolved but completely outmoded problem to which they respond with impatience or complete indifference. This attitude toward the problem is quite indefensible since the question of the freedom of the will is one of those perennially significant philosophical issues which takes on new meaning in every age and is particularly significant in the context of contemporary science and philosophy. Recent psychology, in large measure through the influence of Freud, has achieved a more penetrating analysis of human motivation by bringing to the fore certain hitherto obscure factors which are operative in volition. The psychology of the subconscious by filling in apparent gaps in the psychological causation of volition has furthered the case for determinism.

According to tranditional philosophical terminology and to most interpretations of Cartesianism, Descartes is a dualist. This dualism is expressed in his fundamental distinction between two substances—mind and matter—and, though admitted to be full of difficulties and by many to be untenable, it has very generally been regarded as at least a clearly intelligible doctrine, consistently held by Descartes. That this is not so has been shown by Professor Boyce Gibson in his able and careful analysis of Cartesianism. The aim of the present essay is to draw attention to another difficulty that has not been sufficiently noticed; whether it is an actual one or only an apparent one due to a misunderstanding of Descartes is a question that may be left to those who read him differently and who may be able to remove one more charge of inconsistency. The general contention is that Descartes—and this point is conceded in expositions of Descartes—seeks to prove that there are material bodies, that material bodies are necessary for his own account of the physical universe, and that yet his own theory of matter as extension, even combined with motion, makes the existence of bodies (in the plural) impossible and hence any proof of such existence impossible. In fact, the employment of the idea of motion only serves to emphasize the difficulty and inconsistency of the theory.

There are, plainly, very many reasons why a controversy should be inconclusive and abortive, and yet constantly reviving. It might, for example, be one that interests only the very stupid or prejudiced; or one that interests everyone deeply, demanding an answer of everyone, yet not yielding any really decisive evidence; or the controversy might be one in which thesis and antithesis are natural expressions of opposed psychological types (“Tough-” and “Tender-minded” people); or it might be one that is commonly conducted in terms that are vague, misleading, and question-begging. In this paper I shall confine myself to the last of these reasons: the use of language which makes it extremely difficult to understand what either of the parties are really asserting, and where, if at all, they contradict each other. I hope I shall not be thought to exaggerate the importance of this familiar factor, but I hope to show that in many important controversies the best will in the world and all the patience and tolerance a man can muster are not sufficient: special training and considerable independent reflection are necessary if the debate in question is not to prove as profitless as those described by Omar Khayyam of Naishapur:

Myself when young did eagerly frequent

Doctor and Saint, and heard great Argument

About it and about: but evermore

Came out by the same Door as in I went.