The search for causes involves showing that a thing was necessary. And this must obviously apply to the world as a whole. If it were quite obvious that the world and its existence as it is were necessary, that is, that it would be contrary to reason to think of the world, and its phenomena, and their obedience to law as non-existent, or as different from what they are, all inquiry would be at an end. This would be _the_ ultimate necessity in which all the apparent contingency of isolated phenomena and existences was firmly based. But this is far from being the case. That anything exists, and that the world exists, is for us absolutely the greatest “contingency” of all, and in regard to it we can and must continually ask, “Why does anything exist at all, and why should it not rather be non-existent?” Indeed, all our quest for sufficient causes here reaches its climax. In more detail: that these celestial systems and bodies, the ether, attraction and gravitation should exist, and that everything should be governed by definite laws, all literally “as if shot from a pistol,” there must undoubtedly be some sufficient reason, certain as it is that we shall never discover it. It is true, as some one has said, that we live not only in a very fortuitous world, but in an incredibly improbable one. And this is not affected by the fact that the world is completely governed by law. Law only confirms it. The fact that all details may be clearly and mathematically calculated in no way prevents them from being fundamentally contingent. For they are only so calculable on the basis of the given fundamental characters of the world. And that is precisely the problem: “Why do these characters exist and not quite different ones, and why should any exist at all?”
If any one should say: “Well, we must just content ourselves with recognising the essentially ‘contingent’ nature of existence, for we shall never be able to get beyond that,” he would be right in regard to the second statement. To get beyond that and to see what it is—eternal and in itself necessary—that lies at the basis of this world of “contingency” is indeed impossible. But he would be wrong as to the first part of the assertion. For no one _will_ “content himself.” For that all chance is only apparently chance, and is ultimately based in necessity, is a deeply-rooted and fundamental conviction of our reason, one which directs all scientific investigation, and which cannot be ignored. It demands ceaselessly something necessary as the permanent basis of contingent existence. And this fact is and remains the truth involved in the “cosmological proofs of the existence of God” of former days. It was certainly erroneous to suppose that “God” could be proved. For it is a long way from that “idea of necessity” to religious experience of God. And it was erroneous, too, to suppose that anything could be really “proved.” What is necessary can never really be proved from what is contingent. But the recognition of the contingent nature of the world is a stimulus that stirs up within our reason the idea of the necessary, and it is a fact that reason finds rest only in this idea.