William Whewell's Moral Philosophy

...I have on former occasions endeavoured to point out an analogy between the progress of the science of Morals and other sciences; and such a comparison is, I believe very far from being merely fanciful. I conceive we may especially derive instruction regarding the progress of all branches of human knowledge, by contemplating the history of a science of which the successive steps and advances can all be distinctly traced, and which has risen from gross errors, and rudiments of mere practical knowledge, through various gradations of partial truths, up to truths of the most general kind, which, now that they are thus established, appear to be self-evident. I speak of the science of Mechanics.

Now it is well know to those who have attended to the history of this science, that in the course of the last century a principle termed the Principle of Least Action, was propounded as a mode of determining the course which a body would follow moving from point to point under the influence of external agents. The import of the principle was, that the body would select such a path, and move in such a manner, that the total action which took place in consequence of the body's motion would be smaller than if the body had moved in any other line or in any other manner.

Maupertuis, the philosopher who first asserted this principle, conceived that he could establish it as a universal truth by reasonings drawn from the nature of the Deity and the rules of His operation. And if true, it undoubtedly embraced all cases of motion under all circumstances, and promised to give the solution of all mechanical problems whatever.

The truth and the meaning of this principle were the subject of a long and angry controversy; and, as is usual in such controversies, the meaning of the principle was so modified as to ensure its truth. For what is quantity of action? Many different meanings might be given to such a word: but it was found that one very simple meaning might be assigned to it which would make the Principle include many mechanical truths. And in the sequel, it was proved by Lagrange, that, with the definition which had been adopted, the principle was a universal and necessary truth in all possible combinations of bodies and motions.

Thus then the Principle of Least Action was allowed and proved to be true. But how far was it adopted as a means of solving special problems? Did it supersede other methods of dealing with mechanical questions? Did men apply it to the simple cases of mechanical action which they had to consider? Was it desirable that they should do so? Could they have done so if they had tried?

If a mathematician of Maupertuis' time had set about solving a simple problem, or almost any problem, by means of the principle of Least Action, as the best way of obtaining the solution, he would have been very unwise. The principle then was precarious, for every mechanical principle is precarious so long as it rests upon metaphysical reasonings alone, though these may, perhaps, convert known truths into necessary truths:--the principle was of doubtful meaning if true, for its real meaning was only established when its universal truth was proved. But, dismissing these objections, the method was a bad method of solution, as being superfluously and extravagantly general and complex;--introducing the consideration fo very many indefinite and entangled elements, in a case which really required but few and simple considerations. And this is not the less the case, now that the principle is demonstrably confirmed. If any mechanical calculator were to attempt to trace the path of a projectile or a planet by Maupertuis' principle of Least Action, he would be looked upon with a smile of pity by all good mathematicians. He might perhaps excite admiration in some novice, enthusiastic in his love of generalities; but the probability is, that he would fail in his attempt, and be lost in the labyrinth of symbols into which he had so unadvisedly and unnecessarily rushed.

What the Principle of Least Action is in Mechanics, the Principle of Greatest resulting Good is in Morals. No one questions its truth: every investigation has more and more firmly established its reality. But then, how hard to fix its precise meaning! What is Good? Our judgments of the nature of Good change, as our views of the tendency of all things to good expand. Is Pleasure the Good? So says the system of which we are speaking: but what pleasure? The Pleasure of a calm mind, a pure conscience, a benevolent heart: the Pleasure of a state of future happiness when all sensual delights shall have passed away? But when we have given our principle this meaning, how shall we apply it? Who can foresee how far men's actions tend to increase such good as this? Who can calculate all the effect which his actions produce by their consequences immediate and remote; by their operation on his own character and habits; by their influence in the way of example and reputation; by their fitting him for another state of existence? Can it really be true that we cannot estimate the good or evil of any of our doings, without summing the infinite series of such terms as these, which is appended to each? and each of these terms, too, depending upon actions and thoughts of other men as its elements:--all these series, each in itself involving so much that is indefinite, so much that is incalculable, all mixed and entangled, and inter-dependent in modes innumerable. If we cannot call our actions good or evil till we have performed this summation, till we have balanced against each other the postiive and the negative quantities of such a calculation, we are surely thrown upon a task for which our faculties are quite unfit: we have the tangled course of life to run, and are blindfolded by the hand which is to assign the prize.

But it will perhaps be said that we have no better means of solving the moral problem of our being; it will be demanded what other rule can be proposed for determinign the good or evil of our actions than the consideration of their consequences. If such a question were asked, we should have to reply, in the first place, that this is not the matter under consideration. Our business at present is to weight the value of the theory of morals which is based upon general expediency. If this theory can be shown to be incapable of beign rightly employed, the arguments which prove this are nto turned aside by demanding some better theory: nor would they lose their force if we were driven to acknowledge that no general theory of morals is attainable. And even if we are able to construct a sounder and better system, this must be a distinct task; and is not to be confounded with the criticism which we apply to a sytem which is held, by the objectors now under our review, to be altogether unsatisfactory and false. It would merely produce confusion and needless repetition, to quit this ground, and to mix together the discussion of several systems at once. Yet before quitting the illustration which I have just employed, drawn from the science of Mechanics, I may notice, in the slightest possible manner, the instruction which it suggests with regard to the formation of any other sciences.

The science of Mechanics was not deduced, nor could have been deduced, as we have seen, from the general Principle of Least Action, though that Principle is indisputably true. How then was this province of human knowledge so demonstrably proved, and made into so solid and extensive a system of truths, general and particular? The answer is plain. It was by the consideration, in the first place, of special problems, reasoned upon by means of principles which, in those narrower applications at least, were self-evident; and--in proportion as these limited principles were clearly seen and steadily possessed--by passing from these to others which were true because they included the partial truths at first discovered; and which were applicable to more comprehensive and complex cases:--universal principles which include all possible cases, being arrived at only through these intermediate ones:--and these very general truths being dimly and vaguely apprehended at first; and never becoming, not even at last, the best mode of obtaining practical results.

Now so far as this general description goes, I do not think it at all extravagant to expect that the history of the Science of Mechanics may be a type of the genuine course of real progress in other sciences, even in those which deal with the internal world of thought and feeling, as well as in those that regard only the external world of matter and motion. But the further prosecution and development of this view, if it is permitted to me to trace its consequences, must be the work of future years, and of a maturer study of the subject. At present I have ventured to refer to it, only because I would not seem to criticize existing systems, without any steady belief that a better may be found; or to declare a mode of proceeding to be wrong, without knowing which way to look for the right.