550 W. L, DAVIDSON : intelligence ? If we could solve this puzzle, we should accom- plish the wonderful feat of both being and not being man at the same time. We are next introduced to the principle of causality. The law of Causation what is it, and how best may it be expressed? No doubt, our answer will most likely follow the attitude we assume with regard to the notion ; but not necessarily so. The two inquiries are closely related, but they are by no means identical (any more than the import and the origin of the notion are identical) ; and only confusion results if we be not careful to separate the treatment. Suppose, then, that we accept the doctrine that a cause is the sum-total of conditions ; then the formula consistent with this position is, " Every effect has its cause". We refuse to put it in the indefinite form, "has a cause," because, on the special supposition, there can be only one cause capable of producing or more strictly of issuing in an effect ; and we express the law as an identical proposition, because effect and cause are only different aspects of the same thing. If, on the other hand, we take cause as the equivalent of agent or producer, then our principle will assume the form, "Every effect has a cause," or "Everything that begins to be is the result of something adequate to its production". The proposition is still in reality a verbal one ; but, by using the indefinite "a" or "something," cognisance is taken of the fact that there may be a plurality of causes, or that more than one cause may produce the same effect. Tautology is avoided only when we express the law in terms of antecedence ; and then our view of the notion is the first of the three above referred to. But part of the difficulty of expressing the formula has refer- ence to the causal nexus. Is the simple statement of the fact sufficient, or do we need to introduce the circumstance of neces- sity? Does "has" or "is" give the whole case, or is "must" indispensable ? This is a question that affects the principle, but has not relevance when we simply regard the notion. It may be argued indeed in connexion with genesis (to which we shall advert presently) , but its natural place is previous to that discussion ; for, as matter of fact, we find that our view of the nature and signification of the principle is more likely to determine our doctrine of genesis than our theory of genesis to shape our view of the principle. Hence again the necessity of keeping the pro- blems scrupulously apart, and of giving them a separate handling. If it be so that cause and effect are relative and correlative, then we can see at once that the necessary union is precisely that which exists between correlatives in general. It is nothing more than given the one and the other too is given : and there is no greater sense in saying, " Every effect must have a cause," than in saying, "Every height must have a hollow," or "Every parent must have a child ". It is also in place here to ask, What is the relation between
