sider, however, what light biological theories of evolution throw upon the history and the practical problems of human society. The greater complexity of social life among human beings, as compared with what one finds among plants and animals, even social animals, may well suggest that biological conceptions cannot, without considerable modification, be applied to social phenomena. Biological conceptions are certainly less inadequate than mathematical, physical, or chemical conceptions; but an uncritical use of them in this connection involves a constant risk of mistaking metaphors for scientific laws. The applicability of the idea of natural selection to human society may be taken as an illustration. The question for the biologist is: What other factors than natural selection, if any, are there in organic evolution? The question for the sociologist is more complicated; for he must not assume without proof that there are no other factors in social than in organic evolution, nor that natural selection means exactly the same thing in human society that it does among plants and animals. For example, in sub-human evolution, races and individuals that have injurious customs perish by natural selection; but in human evolution, where there is consciousness and reflection, the injurious custom may be changed without the extinction of the race or individual that practises it. The natural results of natural selection are continually checked in human society. Thus the theory of natural selection, when applied to human society, sets a problem, but does not solve it. Take, for example, the case of religion. 'Religion exists everywhere among human beings; therefore it must be due to natural selection; therefore its essence is to further social utility.' Thus reasons Mr. Benjamin Kidd in his Social Evolution. But what is a 'religion' in Mr. Kidd's sense of the term? One of the problems which most puzzles the student of human history is presented by the apparently anti-social and injurious elements contained in so many of the religions of the world. This very matter has been urged as an objection to the applicability of the theory of natural selection to the explanation of social phenomena. There can be no doubt that 'in primitive conditions of society' religion is the strongest bond of social cohesion; but it is certainly not the sole bond between human beings; nor is a conservative force necessarily under all circumstances beneficial. Again, mere increase in numbers does not always mean 'social progress,' nor decrease, 'national decay,' as biological sociologists are apt to suppose.
