But what is 'real'?

Last night, I am happy to report, I had to defend my position on abstract entities. At least, to explai it. Thinking about it, I have been attracted to ontological parsimony, along the lines of Quine. But recently I've moved to a more conservative approach. That is, I am now allowing abstract entities to exist. Numbers, for example, sets (which can be used to define numbers but which may or may not be different from them), probably concepts. In what way are such nonphysical entities real? Or, to ask it another way, the question is what would it mean for something nonphysical to exist? This is no so intelligible as it seems at first. (Isn't it wonderful that we can turn our ordinary understandings of things into serious philosophical problems?) We imagine them floating in a void, so to speak. Or we try to ignore the question. Neither of these methods of addressing the question is acceptable, though the first for trivial reasons and the second for shameful ones.

Suppose there are souls and they are nonphysical. That would mean they have no properties physical objects have. It would not make sense to ask, "Where is my soul?"–one needs to ask, "What properties can a soul have, given my substance dualism?" Suppose instead that there are numbers, and they are nonphysical. Then it would not make sense to ask where they are or their color, or whatever. (Do we have notions of nonphysical properties? Yes: logical relations, e.g., or set membership.) The problem will be to explain how we physical things access these nonphysical "abstract" entities. We are now switching to a different topic, but one derived from the original question. And the answer, it seems to me, is somewhere in McDowell's rather startling claim that physical entities have conceptual content.

Ask yourself this, then: since abstracta aren't anyplace, what does it mean to say there are some? Almost everybody accepts that existence isn't predicable, but it seems like we do it anyway, when we get into ontology. Putting that aside, there is still the question how we can understand the existence of something with no place in space-time. We must always, I think, if we envision them, think of abstracta wrong: we think of them as having the physical property of location. We misunderstand them, in other terminology. How... quaint.