I use the word humanitarian in the ordinary sense, as meaning one who upholds the claims of all creatures against those of humanity. They suggest that through the ages we have been growing more and more humane, that is to say, that one after another, groups or sections of beings, slaves, children, women, cows, or what not, have been gradually admitted to mercy or to justice. They say that we once thought it right to eat men (we didn't); but I am not here concerned with their history, which is highly unhistorical. As a fact, anthropophagy is certainly a decadent thing, not a primitive one. It is much more likely that modern men will eat human flesh out of affectation than that primitive man ever ate it out of ignorance. I am here only following the outlines of their argument, which consists in maintaining that man has been progressively more lenient, first to citizens, then to slaves, then to animals, and then (presumably) to plants. I think it wrong to sit on a man. Soon, I shall think it wrong to sit on a horse. Eventually (I suppose) I shall think it wrong to sit on a chair. That is the drive of the argument. And for this argument it can be said that it is possible to talk of it in terms of evolution or inevitable progress. A perpetual tendency to touch fewer and fewer things might--one feels, be a mere brute unconscious tendency, like that of a species to produce fewer and fewer children. This drift may be really evolutionary, because it is stupid. Darwinism can be used to back up two mad moralities, but it cannot be used to back up a single sane one. The kinship and competition of all living creatures can be used as a reason for being insanely cruel or insanely sentimental; but not for a healthy love of animals. On the evolutionary basis you may be inhumane, or you may be absurdly humane; but you cannot be human. That you and a tiger are one may be a reason for being tender to a tiger. Or it may be a reason for being as cruel as the tiger. It is one way to train the tiger to imitate you, it is a shorter way to imitate the tiger. But in neither case does evolution tell you how to treat a tiger reasonably, that is, to admire his stripes while avoiding his claws.