Like theism, naturalism has a doctrine of the ultimate: of the outermost limit of being and of thought, of the source and end and matrix of everything that is. The differences between the theist and naturalist notions of the ultimate lie, not in its operations upon the world – worlds can’t do without some environing context or other – but in its character. The ultimate of the theists is intelligent, rational, omniscient, good, supremely real, and so forth; whereas the ultimate of the naturalists is stupid, chaotic, unintelligible, blind, mindless, and unreal.
How could blind vacuous chaos give rise to an ordered, rational, sentient, intelligible world? In no possible way. It takes value to make value. Naturalists are therefore driven, willy nilly, to the conclusion that despite appearances, the world is in fact not at all ordered, rational, sentient, or intelligible. Thus it – and everything in it – cannot possibly be explained, there being in the first place nothing to explain (for under the naturalist presupposition, just everything is a brute fact), and in the second place no such thing as explanation. Naturalism elides smoothly into nominalism, and skepticism; and so, to nihilism; for, one’s vision of the ultimate is one’s vision of the essential character of existence as such. What’s to keep the nothingness back, after all, if in the final analysis everything is nothing anyway?