The notion of cause used to be counted among the primary concepts of natural science, but there is a notable tendency nowadays to cut loose from a causal term, and to render the function of science one of description rather than one of causal explanation. This is pot merely a desideratum or a program, but repre sents the attitude really taken by modern sci entists in their work. A causal explanation of an occurrence X consists in a statement of certain events, A, B C, etc., which, if present, will always evoke X' as a temporal consequent. This causal explanation of X, then, involves the statement of a law according to which X occurs, but 'not every descriptive law lends itself to expression in causal terms. In the first place, a causal law in the strict sense involves a definite, irreversible, temporal order between the events it connects; in the second place, the antecedents, A, B, etc., are definite events, which either are there or are not there. Now, the laws which have been most fruitful in the expression of scientific data and the stimulation of scientific research have usually been quantitative correlations, in which the cor related terms have not necessarily stood in a unidirectional temporal relation to one another, or indeed in any temporal relation whatever.
The law of gravitation says that the accelera tion of a body of mass m with respect to a body of mass m' at a distance d from it, if the bodies start from rest and are acted on m.
by no external forces, will vary as Here the acceleration, m, and d are all contempora neous, and are all more-or-less facts, not yes or-no facts. As far as the physicist is con cerned, it is utterly meaningless to say that the cause of the attraction resides in the mass us, or the mass or in anything else whatever. In spite of these facts, the unfortunate tradition which finds its typical exponent in Mill still makes many a metaphysician lapse into causal language in his treatment of natural science.
In law, a cause is a right of suit or action; it is something for which suit may be brought i by someone against another; it includes the right of action. In practice, a cause of action comes into existence when there is such a state of facts or circumstances as will enable a per son or party having certain relations with particular persons or property to commence a suit.