NECESSITY. 803 is necessary, because it is implied in every argument. That any one thing does follow from any other is, indeed, not always a necessary proposition : but that, if it does follow, then, if the first be true, the second is also true, is a necessary proposition. It is logically prior to any state- ment such as : Since this, then that. And such statements are not among the least common of truths. We have, then, an answer both as to the meaning of neces- sary propositions ; and also as to the meaning of necessary connexion between propositions. The first are necessary when they are implied in a large number of other proposi- tions ; and as to the second, it is the proposition that the truth of what is implied follows from the truth of that which implies it, that is necessary. The connexion itself is not necessary, but the truth, that if it is there, then a true conclusion may be drawn, is necessary. It remains, then, only to consider the third class of entity which may be called necessary the class of things and their connexion. That, when we call a thing necessary, we mean that it is cause or effect of some other thing, is evident. The question is then of that necessity which is involved in the notion of causality. Whether there be any causes whether from the existence of one thing you can ever validly infer the existence of another is a different question. But that if there be a cause, it is necessarily connected with its effect, and that its effect is necessary, will not be questioned. The question is merely of what this necessity means. And my answer to it is, I fear, deplorably brief. For I entirely fail to see that there can be any relation between the two things, except that from the proposition ' The one exists ' there is a valid inference to the proposition ' The other existed ' or ' will exist '. If it does really follow that, since one thing exists, another has existed or will exist, what more necessary relation can be desired ? The supposed ' real ' necessity will, then, like the supposed ' ideal,' be reduced to logical necessity. There will, indeed, be a difference. The existence of one thing is certainly not presupposed in that of another : the relation between them is certainly not that of logical priority. If we are to infer the one from the other, it must be on the basis of the principle that whenever it is true that one thing exists, it is also true that some one other thing has existed or will exist. And this principle may itself be necessary, as logically prior to other propositions. But the particular causal inference always requires not only this for its premiss, but also that some one thing does exist. In this, however, there is no reason to dispute that the necessity is logical.
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