This applies to people’s instinctive likes and dislikes as well as to their other instincts. It is natural to men, as to other animals, to like some of their species and dislike others; but the proportion of like and dislike depends on circumstances, often on quite trivial circumstances. Most of Carlyle’s misanthropy is attributable to dyspepsia; probably a suitable medical regimen would have given him a completely different outlook on the world. The defect of punishment, as a means of dealing with impulses which the community wishes to discourage, is that it does nothing to prevent the existence of the impulses, but merely endeavors to check their indulgence by an appeal to self-interest. This method, since it does not eradicate the impulses, probably only drives them to find other outlets even when it is successful in its immediate object; and if the impulses are strong, mere self-interest is not likely to curb them effectually, since it is not a very powerful motive except with unusually reasonable and rather passionless people. It is thought to be a stronger motive than it is, because our moods make us deceive ourselves as to our interest, and lead us to believe that it is consistent with the actions to which we are prompted by desire or impulse. Thus the commonplace that human nature cannot be changed is untrue. We all know that our own characters and those of our acquaintance are greatly affected by circumstances; and what is true of individuals is true also of nations. The root causes of changes in average human nature are generally either purely material changes—for instance, of climate—or changes in the degree of man’s control over the material world. We may ignore the purely material changes, since these do not much concern the politician. But the changes due to man’s increased control over the material world, by inventions and science, are of profound present importance. Through the industrial revolution, they have radically altered the daily lives of men; and by creating huge economic organizations, they have altered the whole structure of society. The general beliefs of men, which are, in the main, a product of instinct and circumstance, have become very different from what they were in the eighteenth century. But our institutions are not yet suited either to the instincts developed by our new circumstances, or to our real beliefs. Institutions have a life of their own, and often outlast the circumstances which made them a fit garment for instinct. This applies, in varying degrees, to almost all the institutions which we have inherited from the past: the State, private property, the patriarchal family, the Churches, armies and navies. All of these have become in some degree oppressive, in some measures hostile to life.