[Guest post by Barry.]
Let me begin by saying that these remarks are extremely sketchy, just a recording of a recent whisky-fueled conversation. I have hitherto taken myself to be a naturalist, so these remarks are in the spirit of self-examination. Any help will be very warmly welcomed.
Suppose we take naturalism to be the research project whose goal is the reduction of everything to matter. Reduction is supervenience, say; or something tighter. Everything includes all the troublesome phenomena: modality, mind, normativity, maths. Matter is whatever the theoretical physicists tell us the world is made of (never mind that they consider this a deep mystery).
Now imagine some Fukuyama-esque article of the future, triumphantly announcing the end of metaphysics. In this article it will be demonstrated, compellingly, that every single recalcitrant phenomenon has been reduced. (I do not intend the term 'demonstrated' here to be factive.)
According to our putatively final metaphysics, the world is one big chunk of matter. I think this leaves us with two questions, which the naturalist lacks the resources to answer. (1) Why is the world made of this stuff, and not some other stuff? (2) Why is there this stuff and not nothing at all?
Our explanans must always be explanatorily broader than our explanandum. You cannot explain alpha with alpha; you must explain it with some beta that may include alpha. (The fact that the girl crossed the road does not explain the fact that the girl crossed the road, but it might explain the fact that the girl crossed some part of the road.) As the Aristotelians say, explanations must involve not just the 'that' but also some 'because.'
The worry is that naturalists can explain a lot in terms of matter, but they cannot explain matter in terms of matter.
Perhaps I am being childish; perhaps explanations do have to come to an end somewhere; perhaps the answer to 'why is there something rather than nothing?' is: 'there just is.' Or perhaps this isn't a meaningful question, or it is incoherent some other way. But it doesn't seem to be. It just seems hard.
And here's a possible diagnosis of the naturalist's error. The privileging of matter is just another manifestation of the human mind's craving for fixity - for an Archimedean point. And its perhaps just as misguided as the Cartesian response to this craving, or the religious.
So should we go back to old-school metaphysics? Or embrace some sort of aesthetic scepticism?
[See also: Why does the universe exist? -- RC.]