Hume vs. Gunk

Here’s an argument against the possibility of gunky time. It’s not mine; it’s Hume’s. You can find it in part 2, section 2 of book 1 of his Treatise of Human Nature. If time is gunky then each moment is gunky and so has parts. These parts would be co-existent times, and that’s absurd.

I don’t think the argument as I’ve phrased it quite works, because you can respond that if time’s gunky then there aren’t any moments, just eras. But modify it a bit: if time’s gunky then the present’s gunky, so the present has parts. Assuming that parts of times are times, that means the present isn’t all present or more than one time is present, and both of those really are absurd.

Hume adds to his argument that time must be gunky if space is, and concludes that space can’t be gunky either. I’m not sure whether that quite follows or not, but you’d expect the gunkiness of space, time and matter to stand or fall together.

So what’s wrong with the argument? Most of us think gunk’s possible, although I’ve recently written a paper arguing that the conceivability arguments for this aren’t as good as people tend to think. Maybe there isn’t anything wrong with the argument and gunk’s not possible. But if Hume was on to this 270 years ago, why isn’t it generally known?