What is Mill's proof of the principle of utility?

John Stuart Mill, answered from the texts and cited to the page.

John Stuart Mill answers

The question of ultimate ends does not admit of proof in the ordinary sense — and I have never pretended otherwise. What is common to all first principles, whether of knowledge or of conduct, is precisely that they cannot be established by syllogistic reasoning from something more fundamental.1 The utilitarian doctrine is that happiness is desirable, and the only thing desirable as an end; all other things being desirable only as means to that end.

The question is what sort of evidence can be offered for such a claim. My answer proceeds by analogy. The only proof that an object is visible is that people actually see it; the only proof that a sound is audible is that people hear it. In like manner, the sole evidence it is possible to produce that anything is desirable is that people do actually desire it.2

Each person, so far as he believes his own happiness to be attainable, desires it — and this fact constitutes all the proof the case admits of that happiness is a good to that person. The general happiness is therefore a good to the aggregate of all persons.3 G. E. Moore charged, in his Principia Ethica (1903), that this argument commits the naturalistic fallacy — that I infer "desirable" from "desired" as though the two were synonymous, just as "visible" means "seen." The charge does not hold.

I do not maintain that "desirable" means "desired," any more than I maintain that "visible" means "seen." What I assert is that the proof that something is visible is that it is seen, and similarly that the sole evidence that anything is desirable is that it is desired. The relation is evidential, not definitional.4 A second standard objection is that I illicitly move from each person desiring his own happiness to the conclusion that the general happiness is desired by everyone.

But I do not draw that inference. What I argue is that since A's happiness is a good, and B's happiness is a good, and C's happiness is a good, the sum of all these goods is a good.5 The argument is that a whole is intrinsically desirable when it is composed of components that are themselves intrinsically desirable — not that the general happiness is desired in the aggregate.6

There remains a further objection: that people plainly do desire things other than happiness — virtue, for instance — and that this fact refutes the utilitarian account of desire. The utilitarian doctrine does not deny this. Virtue is not merely to be desired; it is to be desired disinterestedly, for itself.7 What I maintain is that whatever is desired otherwise than as a means to some end beyond itself, and ultimately to happiness, is desired as itself a part of happiness.

The ingredients of happiness are various, and each is desirable in itself. Virtue, music, health — these are not merely means to some collective something called happiness; they are desired and desirable in and for themselves, and in being so they are parts of the end, not merely instruments toward it.8 The mind that loves virtue disinterestedly has made virtue a component of its own happiness, and in that psychological fact there is no departure from the principle of utility — only its fuller elaboration.

Sources

  1. questions of ultimate ends do not admit of proof, in the ordinary acceptation of the term. To be incapable of proof by reasoning is common to all first principles; to the first premises of our knowledge, as well as to those of our conduct.
    Of What Sort of Proof the Principle of Utility Is Susceptible, p. 282
  2. The only proof capable of being given that an object is visible, is that people actually see it. The only proof that a sound is audible, is that people hear it: and so of the other sources of our experience. In like manner, I apprehend, the sole evidence it is possible to produce that anything is desirable, is that people do actually desire it.
    Of What Sort of Proof the Principle of Utility Is Susceptible, p. 282
  3. No reason can be given why the general happiness is desirable, except that each person, so far as he believes it to be attainable, desires his own happiness. This, however, being a fact, we have not only all the proof which the case admits of, but all which it is possible to require, that happiness is a good: that each person's happiness is a good to that person, and the general happiness, therefore, a good to the aggregate of all persons.
    Of What Sort of Proof the Principle of Utility Is Susceptible, p. 282
  4. Mill also does not hold that 'visible' means 'seen.' Instead he asserts that the proof that something is visible is that it is seen. Similarly, what he affirms is that the sole evidence that anything is desirable is that it is desired.
    THE EVIDENCE OF WHAT IS DESIRABLE, pp. 58–59
  5. In a letter he explains, 'when I said that the general happiness is a good... I merely meant... to argue that since A's happiness is a good, B's a good, C's a good, &c., the sum of all these goods must be a good.'
    THE EVIDENCE OF WHAT IS DESIRABLE, p. 66
  6. Mill is holding that if the happiness of A is intrinsically desirable and the happiness of B is intrinsically desirable and the happiness of C is intrinsically desirable, then the 'sum' of the happiness of A and the happiness of B and the happiness of C is intrinsically desirable.
    THE EVIDENCE OF WHAT IS DESIRABLE, p. 66
  7. The very reverse. It maintains not only that virtue is to be desired, but that it is to be desired disinterestedly, for itself.
    Of What Sort of Proof the Principle of Utility Is Susceptible, p. 283
  8. They are desired and desirable in and for themselves; besides being means, they are a part of the end. Virtue, according to the utilitarian doctrine, is not naturally and originally part of the end, but it is capable of becoming so; and in those who love it disinterestedly it has become so, and is desired and cherished, not as a means to happiness, but as a part of their happiness.
    Of What Sort of Proof the Principle of Utility Is Susceptible, p. 283