They either assume the ordinary precepts of morals as of a priori authority, or they lay down as the common groundwork of those maxims, some generality much less obviously authoritative than the maxims themselves, and which has never succeeded in gaining popular acceptance. Yet to support their pretensions there ought either to be some one fundamental principle or law, at the root of all morality, or if there be several, there should be a determinate order of precedence among them; and the one principle, or the rule for deciding between the various principles when they conflict, ought to be self-evident.
To inquire how far the bad effects of this deficiency have been mitigated in practice, or to what extent the moral beliefs of mankind have been vitiated or made uncertain by the absence of any distinct recognition of an ultimate standard, would imply a complete survey and criticism, of past and present ethical doctrine. It would, however, be easy to show that whatever steadiness or consistency these moral beliefs have, attained, has been mainly due to the tacit influence of a standard not recognised. Although the non-existence of an acknowledged first principle has made ethics not so much a guide as a consecration of men's actual sentiments, still, as men's sentiments, both of favour and of aversion, are greatly influenced by what they suppose to be the effects of things upon their happiness, the principle of utility, or as Bentham latterly called it, the greatest happiness principle, has had a large share in forming the moral doctrines even of those who most scornfully reject its authority. Nor is there any school of thought which refuses to admit that the influence of actions on happiness is a most material and even predominant consideration in many of the details of morals, however unwilling to acknowledge it as the fundamental principle of morality, and the source of moral obligation. I might go much further, and say that to all those a priori moralists who deem it necessary to argue at all, utilitarian arguments are indispensable. It is not my present purpose to criticise these thinkers; but I cannot help referring, for illustration, to a systematic treatise by one of the most illustrious of them, the Metaphysics of Ethics, by Kant. This remarkable man, whose system of thought will long remain one of the landmarks in the history of philosophical speculation, does, in the treatise in question, lay down a universal first principle as the origin and ground of moral obligation; it is this: "So act, that the rule on which thou actest would admit of being adopted as a law by all rational beings." But when he begins to deduce from this precept any of the actual duties of morality, he fails, almost grotesquely, to show that there would be any contradiction, any logical (not to say physical) impossibility, in the adoption by all rational beings of the most outrageously immoral rules of conduct. All he shows is that the consequences of their universal adoption would be such as no one would choose to incur.
On the present occasion, I shall, without further discussion of the other theories, attempt to contribute something towards the understanding and appreciation of the Utilitarian or Happiness theory, and towards such proof as it is susceptible of. It is evident that this cannot be proof in the ordinary and popular meaning of the term. Questions of ultimate ends are not amenable to direct proof.
Whatever can be proved to be good, must be so by being shown to be a means to something admitted to be good without proof. The medical art is proved to be good by its conducing to health; but how is it possible to prove that health is good? The art of music is good, for the reason, among others, that it produces pleasure; but what proof is it possible to give that pleasure is good? If, then, it is asserted that there is a comprehensive formula, including all things which are in themselves good, and that whatever else is good, is not so as an end, but as a mean, the formula may be accepted or rejected, but is not a subject of what is commonly understood by proof. We are not, however, to infer that its acceptance or rejection must depend on blind impulse, or arbitrary choice. There is a larger meaning of the word proof, in which this question is as amenable to it as any other of the disputed questions of philosophy. The subject is within the cognisance of the rational faculty; and neither does that faculty deal with it solely in the way of intuition. Considerations may be presented capable of determining the intellect either to give or withhold its assent to the doctrine; and this is equivalent to proof.
We shall examine presently of what nature are these considerations; in what manner they apply to the case, and what rational grounds, therefore, can be given for accepting or rejecting the utilitarian formula. But it is a preliminary condition of rational acceptance or rejection, that the formula should be correctly understood. I believe that the very imperfect notion ordinarily formed of its meaning, is the chief obstacle which impedes its reception; and that could it be cleared, even from only the grosser misconceptions, the question would be greatly simplified, and a large proportion of its difficulties removed. Before, therefore, I attempt to enter into the philosophical grounds which can be given for assenting to the utilitarian standard, I shall offer some illustrations of the doctrine itself; with the view of showing more clearly what it is, distinguishing it from what it is not, and disposing of such of the practical objections to it as either originate in, or are closely connected with, mistaken interpretations of its meaning. Having thus prepared the ground, I shall afterwards endeavour to throw such light as I can upon the question, considered as one of philosophical theory.