That this is the case, that the questions, What is right? what is my duty? what ought I to do? belong exclusively to this third branch of ethical enquiry, is the first point to which I wish to call attention. All moral laws, I wish to shew, are merely statements that certain kinds of actions will have good effects. The very opposite of this view has been generally prevalent in Ethics. The right and the useful have been supposed to be at least capable of conflicting with one another, and, at all events, to be essentially distinct. It has been characteristic of a certain school of moralists, as of moral common sense, to declare that the end will never justify the means. What I wish first to point out is that right does and can mean nothing but cause of a good result, and is thus identical with useful; whence it follows that the end always will justify the means, and that no action which is not justified by its results can be right. That there may be a true proposition, meant to be conveyed by the assertion The end will not justify the means, I fully admit: but that, in another sense, and a sense far more fundamental for ethical theory, it is utterly false, must first be shewn. (§ 88 ¶ 3)

That the assertion I am morally bound to perform this action is identical with the assertion This saction will produce the greatest amount of good in the Universe has already been briefly shewn in Chap I (§ 17); but it is important to insist that this fundamental point is demonstrably certain. This may, perhaps, be best made evident in the following way. It is plain that when we assert that a certain action is our absolute duty, we are asserting that the performance of that action at that time is unique in respect of value. But no dutiful action can possibly have unique value in the sense that it is the sole thing of value in the world; since, in that case, every such action would be the sole good thing, which is a manifest contradiction. And for the same reason its value cannot be unique in the sense that it has more intrinsic value than anything else in the world, since every act of duty would then be the best thing in the world, which is also a contradiction. It can, therefore, be unique only in the sense that the whole world will be better, if it be performed, than if any possible alternative were taken. And the question whether this is so cannot possibly depend solely on the question of its own intrinsic value. For any action will also have effects different from those of any other action; and if any of these have intrinsic value, their value is exactly as relevant to the total goodness of the Universe as that of their cause. It is, in fact, evident that, however valuable an action may be in itself, yet, owing to its existence, the sum of good in the Universe may conceivably be made less than if some other action, less valuable in itself, had been performed. But to say that this is the case is to say that it would have been better that the action should not have been done; and this again is obviously equivalent to the statement that it ought not to have been done—that it was not what duty required. Fiat iustitia, ruat caelum can only be justified on the ground that by the doing of justice the Universe gains more than it loses by the falling of the heavens. It is, of course, possible that this is the case: but, at all events, to assert that justice is a duty, in spite of such consequences, is to assert that it is the case. (§ 89 ¶ 2)

Our duty, therefore, can only be defined as that action, which will cause more good to exist in the Universe than any possible alternative. And what is right or morally permissible only differs from this, as what will not cause less good than any possible alternative. When, therefore, Ethics presumes to assert that certain ways of acting are duties it presumes to assert that to act in those ways will always produce the greatest possible sum of good. If we are told that to do no murder is a duty, we are told that the action, whatever it may be, which is called murder, will under no circumstances cause so much good to exist in the Universe as its avoidance. (§ 89 ¶ 3)