For such reasons, it is apparently impossible to say that a legal punishment can be just, in the full sense in which the moralist would use the words. No doubt we may say,--and we wish that we could always say,--that a man "deserves" what he has got; and that implies that we recognise as desirable some satisfaction to our sense of justice. And, of course, too, we demand that justice should be done in another sense of the word; that the case, for example, should be impartially investigated; that a man should not be punished severely because he is poor, or because he is unpopular, or let off easily because he is a private friend of the judge. Such demands mean that justice should not be perverted by applying irrelevant considerations; but they leave our previous questions untouched. The criminal law, from its nature, cannot impose equal penalties upon all men who are equally wicked; but only upon those who have made themselves liable: and that always involves elements of accident; it cannot take into account at all some of the elements upon which the depth of moral depravity essentially depends; and it is, at least, very difficult to say what specific meaning can be given to the proportion between crime and the suffering imposed upon the criminal.
If, then, the legislative action must, of necessity, be very imperfect from the moral point of view, we may try what will be the effect of dismissing the moral question altogether, or, at least, reducing it to a secondary place. We may, that is, consider crime not in so far as immoral, but in so far as mischievous. Here we have the doctrine worked out very consistently by Bentham and his followers. Pain, they said, is an evil, the only evil; pleasure, a good, and the only good. To inflict needless pain--pain which does not cause a balance of pleasure--upon any one, be he a good man or be he a bad man, is, so far, wrong. For the same reason, it is justifiable, and, indeed, right, to inflict pain, so far as it prevents some greater evil. Hence, you should punish criminals just so far as the pain which you inflict is less than the pain which you prevent. It is wrong to give a single useless pang even to the worst of men. If (according to a sentiment attributed to Bentham) a fine of five shillings would prevent a man from committing murder, it would be wrong to fine him seven shillings and sixpence. This gives a justification of punishment, in so far as deterrent. It is obviously connected with another doctrine. A man is the best judge of his own pleasures and pains. Therefore, in so far as a man's actions affect himself alone, they are not to be forbidden by the law. We may think them bad or degrading; but so long as they do not affect others, the fact that a man chooses them is a proof that they give him pleasure; and we shall, therefore, only diminish the sum of happiness by interfering. Now, it is plain that this distinction does not draw the line between what is morally bad or good. Every habit which affects a man's own character, affects, also, his capacity to fulfil his duties to others. But this theory overlooks immorality, except so far as it happens to involve certain extraneous consequences. We are, upon this showing, to punish a criminal precisely in the same spirit as we are to abate a nuisance. The thief is to be suppressed, as we are to extirpate a mischievous weed, and to be suppressed by just as much severity as is required for the purpose. The drunkard, so long as he confines himself to making a beast of himself in his own room, does his neighbours no direct injury, and must be left to enjoy the pleasure which is shown, because he chooses it, to be a pleasure to him. Of this theory, it may, I think, be said that, however imperfect, it is tolerably consistent, and, moreover, that it undoubtedly does express one legitimate end of punishment. There can be no doubt, that is, that the punishment of murderers may be rightly defended, among other grounds, at any rate, on the ground that it discourages the practice; though we may not fully agree with the famous saying of the judge, "You are not hanged for stealing sheep, but hanged in order that sheep may not be stolen". And, further, though there are various difficulties about the distinction between "self-regarding" and "extra-regarding" conduct, we must also, I think, allow, in general terms, that the fact that a man's conduct has a direct and assignable influence upon his neighbour's happiness, must always be one reason, and, frequently, the only sufficient reason, for suppressing it by legal penalties.