PLURALITY OF CAUSES, in logic, is the view that one and the same kind of effect can be produced in different cases by different causes. This is quite distinct from the question whether the cause of an effect is as a rule a complex or multiplic ity of several or many constituent or contributory factors or conditions. Assuming the complexity of each cause, there still remains the further question whether any one of several sepa rate causes can produce the same kind of effect as another. In other words can one cause ever act vicariously for another? (Hence the alternative, and less ambiguous name, "vicarious causes.") J. S. Mill is the best known advocate of the doctrine of plurality of causes. Examples taken from daily experience seem to support the view. Many different causes can produce death for example. For most practical purposes the doctrine holds good. The whole system of substitutes, in peace and in war, is based on it. But for practical purposes many effects are sufficiently similar, although they are really very different when closely scrutinised.
The total state called death is very different according as one cause or another led to it. The holding of coroner's inquests is based on the assumption that a close examination of the state of a dead body can help to determine the precise cause of death in each case. Similarly with all cases in which details matter. The total effect produced by one kind of cause is never precisely the same as that produced by any other. So that strictly speaking the doctrine of plurality of causes is not true. But where the interest is centred in broad kinds of effect, and differences of detail do not matter much, there the doctrine holds good for all practical purposes.
See J. S. Mill, System of Logic (1875 etc.) J. Venn, Empirical Logic (1889) ; J. Welton, Manual of Logic (1896).