The doctrine of evolution modified this idea of method only superficially. For “evolution” was itself often understood non-historically. That is, it was assumed that there is a predestined course of fixed stages through which social development must proceed. Under the influence of concepts borrowed from the physical science of the time, it was taken for granted that the very possibility of a social science stood or fell with the determination of fixed uniformities. Now every such logic is fatal to free experimental social inquiry. Investigation into empirical facts was undertaken, of course, but its results had to fit into certain ready-made and second-hand rubrics. When even _physical_ facts and laws are perceived and used, social change takes place. The phenomena and laws are not altered, but invention based upon them modifies the human situation. For there is at once an effort to regulate their impact in life. The discovery of malaria does not alter its existential causation, intellectually viewed, but it does finally alter the facts from which the production of malaria arises, through draining and oiling swamps, etc., and by taking other measures of precaution. If the laws of economic cycles of expansion and depression were understood, means would at once be searched for to mitigate if not to do away with the swing. When men have an idea of how social agencies work and their consequences are wrought, they at once strive to secure consequences as far as desirable and to avert them if undesirable. These are facts of the most ordinary observation. But it is not often noted how fatal they are to the identification of social with physical uniformities. “Laws” of social life, when it is genuinely human, are like laws of engineering. If you want certain results, certain means must be found and employed. The key to the situation is a clear conception of consequences wanted, and of the technique for reaching them, together with, of course, the state of desires and aversions which causes some consequences to be wanted rather than others. All of these things are functions of the prevalent culture of the period.