In social inquiries we are not dealing, usually, with distinct and separately measurable forces, but with a complex of forces no one of which can be understood or measured apart from the rest. Granting that drinking to excess is present in one-fourth the cases of poverty, other conditions will be present along with it, such as ill health, bad housing, lack of training, lack of enterprise, low wages, unwholesome work, and so on; and who shall define what part each of these plays, and how far drink is an effect rather than a cause? For the most part poverty is the outcome of a complex organic development, in the individual, his family, and his general environment. Or suppose that we are investigating the causes of insanity and find that the ancestry show traces of it in sixty per cent of the cases. Who can say in how many cases ancestral weakness would not have manifested itself without the co-operation of such other factors as alcohol, drugs, venereal disease, or nervous strain? Evidently to ascribe sixty per cent to heredity alone would be misleading, and no real understanding of the case is possible without a synthetic study of all the chief factors. Such questions are the same, in principle, as the question of the cause of the great European War. A dozen causes may be given—as the military traditions and ideals of Prussia, the commercial ambitions of Germany and England, the lack of international control, the grudge of the French regarding Alsace-Lorraine, the struggle between democracy and autocracy, secret diplomacy, the Eastern Question—all of them essential aspects of a vast and complex situation which, _as a whole_, was the real source of the outbreak. This fallacy of “the cause” is so wide-spread and so insidious that it may be worth while to consider somewhat further the theory of the matter. Everything in life is dependent upon a complex system of antecedents without which it could not have come to pass; and yet it may often be proper, from a practical standpoint, to speak of “the cause” of an event. Commonly we mean by this the exceptional or variant factor in the course of things. There is a sound and regular process of some sort which is broken in upon by something irregular and abnormal, as when a man of habitually vigorous health is seized with weakness and chills which prove to be due to an irruption of the germs of typhoid fever. Something analogous is often found in social process, as when poverty and a sequence of other ills are brought upon a normal family by a quite exceptional event, like the failure of a bank, or an unforeseeable accident, and it is right to speak of this as “the cause.”