Another FAQ from the reading group. I was fond of apples at the time:
A substance is something that bears properties but is not itself borne by anything else.
What's the difference between a substance-attribute theorist and a bundle theorist?
Substance-attribute theorists think a flower an irreducible-substance-instantiating-properties; bundle theorists, nothing more than a unity of properties. Substance-attribute theorists think there are irreducible substances; bundle theorists, that they're reducible to bundles of universals or tropes.
(Technical note: Having written this, there is a sense in which some bundle theorists substantialize first-order properties so those properties can themselves have properties.)
What is the Problem of Individuation?
To clarify . . ., recall Socrates and Plato, two red, round spots that share all their pure properties in common. The problem of individuation is the problem of offering an ontological [account] of the situation so as to specify what it is that makes the two red spots two particular, individual entities instead of one. (Universals)
Most people would use two red apples, not dots.