Propaganda
cases we can effect some change in public opinion with a fair degree of accuracy by operating a certain mechanism, just as the motorist can regulate the speed of his car by manipulating the flow of gasoline. Propaganda is not a science in the laboratory sense, but it is no longer entirely the empirical affair that it was before the advent of the study of mass psychology. It is now scientific in the sense that it seeks to base its operations upon definite knowledge drawn from direct observation of the group mind, and upon the application of principles which have been demonstrated to be consistent and relatively constant.
The modern propagandist studies systematically and objectively the material with which he is working in the spirit of the laboratory. If the matter in hand is a nation-wide sales campaign, he studies the field by means of a clipping service, or of a corps of scouts, or by personal study at a crucial spot. He determines, for example, which features of a product are losing their public appeal, and in what new direction the public taste is veering. He will not fail to investigate to what extent it is the wife who has the final word in the choice of her husband's car, or of his suits and shirts.
Scientific accuracy of results is not to be expected, because many of the elements of the situation must always be beyond his control. He may know with a fair degree of certainty that under favorable cir-
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