 Despite Lewis’s pessimism about clarifying the abstract/concrete distinction, his approach for categorizing the various proposals, when extended, is a useful one. Indeed, in what follows, we’ll see that there are a number of additional ways that categorize attempts to characterize the abstract/concrete distinction and theorize about abstract objects. Even if there is no single, acceptable account, these various ways of drawing the distinction and theorizing about abstract objects do often cast light on the questions we’ve been discussing, especially when the specific proposals are integrated into a supplementary (meta-)ontological project. For each method of drawing the distinction and specific proposal adopting that method acquires a certain amount of explanatory power, and this will help us to compare and contrast the various ideas that are now found in the literature.