Abstract

Milk, sand, plastic, uranium, wood, carbon, and oil are kinds of stuff. The sand in Hawaii, the uranium in North Korea, and the oil in Iraq are portions of stuff. Not everyone believes in portions of stuff.1 Those who do are likely to agree that, whatever their more specific natures, portions of stuff can at least be identified with mereological sums of their subportions.2 It seems after all trivial that a given portion of stuff just is all of its subportions combined—not by a spatiotemporal or any other substantive unifying relation, but by a mere principle of summation, a principle requiring that, if some things exist, there exists the sum, or collection, of those things.