The chief defect of most biological interpretations of society lies in their failure to realize the extreme subtlety and complexity of the relations between human character and the environment. Man's inherited propensities are mere potentialities, part conditions of development whose concrete filling is supplied by the social environment and the individual's own experience. Through this interplay changes in the social environment can bring about changes in human behaviour in a manner independent of alteration in race qualities, and through the agency of forces differing radi cally from those which are operative in the field of biology.
Thus ( ) to the biologist the inheritance of "acquired charac ters" and its role in the evolution of species is a matter of great doubt. In social evolution it is clearly of the greatest importance. What is acquired by one generation is transmitted to the next, either as a totality or, at any rate, as facilitating reacquisition. This makes possible cumulative change inexplicable in biology. (2) In the biological field, the formation of new types by the accu mulation of small individual differences is improbable. In social matters vast changes are clearly brought about by the accumulation of small differences. (3) There is no evidence that the occurrence of one mutation in itself favours the occurrence of others in a similar direction. One of the outstanding difficulties of natural selection is to account for the appearance of correlated struc tural changes. In the human sphere, on the other hand, a new idea is an excellent stimulus to further new ideas. (4) Inventions are far more common than mutations. This obvious fact has im portant bearings upon the problem of the relation between racial qualities and social change. Enormously significant changes can be brought about in a society without involving any changes in the inherited structure of the race. (5) Social changes, unlike mutations, can often be explained as the result of co-operation, as is best illustrated from the history of science and invention. (6) Whether the chances of the occurrence of mutations increase with changes in the environment is a matter of doubt. In the case of social mutations or inventions, it can be shown that great changes and upheavals act as stimulants, and that social or cul tural advance is favoured by variability in the environmental conditions and the clash of ideas resulting from contact with new cultural elements. (7) The problem of orthogenesis or evolution
in what appears as a directed line which has so far remained a mystery to the biologist is more readily explained in social evolu tion. The effects of changes in the environment are here cumula tive and each new generation can start on the basis of what has been acquired by past generations, since the method of trans mission does not depend on the mechanism of physical heredity. (8) Finally the source of variation in social affairs is not nearly so mysterious as is the cause of mutation in biology. For in human life teleological factors are plainly operative. Changes are brought about by a process of trial and error and by deliberate effort directed to ends more or less clearly apprehended. What ever be our view of the role of mind in organic evolution, there can be no doubt of its importance in social evolution.
At this point the biologist might retort that conation and pur pose are activities centred in some mind and mind itself grows up under the conditions determined by survival value, so that in the end we are driven back to biological agencies summed up in the term natural selection. This argument, however, is based upon what appears to be an erroneous view of the role of selection. Selection is not an originative agent and mind cannot be said to be its product. Nothing is known of the ultimate source of variations and this applies to forms of mind as to other things.
The mind once arisen is, indeed, limited by biological conditions but it gradually comes to control them by a purposeful handling of the environment and in so doing modifies the conditions of its own survival. Natural selection should accordingly not be spoken of as producing improvements or as the cause of progress. It pro duces nothing, but at most only acts upon existing variations so as to secure a certain definiteness of type. In social evolution the mind operates by adapting the environment to itself rather than by adapting itself to the environment. Changes are not brought about by waiting for the appearance in the course of hundreds of generations of survivors adapted to the new situation. The efforts of the mind are directed at securing adaptation by an in crease in plasticity, more and more independent of changes in specific race qualities.