physical scientist can make an hypothesis, test it, revise the hypothesis hundreds of times, and, if after all that, he is wrong, no one else has to pay the price. But the social scientist cannot begin to offer the assurance of a laboratory test, and if his advice is followed, and he is wrong, the consequences may be incalculable. He is in the nature of things far more responsible, and far less certain.
But more than that. In the laboratory sciences the student has conquered the dilemma of thought and action. He brings a sample of the action to a quiet place, where it can be repeated at will, and examined at leisure. But the social scientist is constantly being impaled on a dilemma. If he stays in his library, where he has the leisure to think, he has to rely upon the exceedingly casual and meager printed record that comes to him through official reports, newspapers, and interviews. If he goes out into "the world" where things are happening, he has to serve a long, often wasteful, apprenticeship, before he is admitted to the sanctum where they are being decided. What he cannot do is to dip into action and out again whenever it suits him. There are no privileged listeners. The man of affairs, observing that the social scientist knows only from the outside what he knows, in part at least, from the inside, recognizing that the social scientist's hypothesis is not in the nature of things susceptible of laboratory proof, and that verification is possible only in the "real" world, has developed a rather low opinion of social scientists who do not share his views of public policy.