This is Volume of VII twenty-two on a series on Social Theory and Methodology. Originally published in 1961, this book was written because of the author's sense of the inadequacies of a sociological tradition dominated by empiricism and positivism. The tradition of empiricism leads to attempts to settle public issues by reference to crude ad hoc generalisations. So "right-wing" facts are refuted by "left-wing" facts and vice versa, and in the argument which ensues nothing becomes clear except the value-biasses which the authors seek desperately to conceal. The tradition of positivism on the other hand fails in refusing to interpret observed correlations of fact except in terms of the natural sciences. So the sociologist often appears to have derived little more insight through his precise methods than the untutored layman is able to do through trusting to intuition and common-sense.