§ 9 (_c_). _The Plurality of Causes._ The indefinite regress may be shown to be inherent in Causation by a different line of argument, without appealing to the principle of the continuity of time. As the reader is doubtless aware, it was a favourite doctrine of John Stuart Mill, that whereas the same cause is always followed by the same effect—in the absence of counteracting circumstances—the same effect need not be preceded by the same cause. An effect may be “produced” on different occasions by entirely different sets of antecedents. Thus death may be due either to disease or to violence, and both the disease and the violence may have very different forms, yet the result is the same, namely, death. Heat may ensue from friction, percussion, chemical combination, and so forth. This doctrine of the Plurality of Causes is an obvious result of generalisation from the important practical consideration that different means will often lead us to the same end, so that where we cannot employ one we can often fall back on another. Mill’s critics have not failed to point out that his doctrine is based on the rather illogical combination of a concrete cause with an abstract effect. He considers the “effect” in its utmost generality simply as a state or quality, _e.g._, “heat,” “death,” and rightly contends that this general state or quality may issue on different occasions from different combinations of conditions. But he fails to observe that in any concrete case this effect exists in a special form, and with special modifications corresponding to the special character of the antecedents. Death, for instance, may result from a thousand circumstances, but the total effect in each case is never mere death, but death in some one special shape. A man who is shot and a man who is drowned are both dead, but one is dead with the special symptoms of death by drowning, the other with those of death by shooting. The water will kill you and a bullet will kill you, but death with a bullet-hole does not come from drowning, nor death with one’s lungs filled with water from a gunshot. If you take cause and effect at the same level of concreteness, they are always strictly correlative. Any variation in the one must have a corresponding variation in the other, for circumstances which vary without affecting a result are by definition no part of its conditions. So far Mill’s critics among the inductive logicians. But we can push the argument a step further, and show that it leads logically to a dilemma. (1) There cannot really be more than one “cause” for one “effect”; yet (2) in any sense in which we can single out one “effect” from the rest of the contents of the universe, and assign it its “cause,” there is _always_ a possibility of the Plurality of Causes. We will consider the alternative of this dilemma separately.