 Harry Potter has one eyeball. Is that true or is it false? It might seem like a silly question, but it actually gets at a really deep point in philosophy. Do fictional characters exist? Can we say true and false things about fictional characters? There's a couple lines of thought about this. Some people say no. Some people say yes. So intuitively it seems like we can say true and false things about Harry Potter. If I say Harry Potter has one eyeball, most people, if they're not trained in philosophy, would say, no, that's false. Of course Harry Potter has two eyeballs. But if that's true, we can say that it is a false claim about a fictional character. Does that imply that Harry Potter exists? How could we say true or false things about something that doesn't exist? Then again, on the other hand, if we say that Harry Potter doesn't exist in any way, then wouldn't it seem like we could say Harry Potter has one eyeball and that's neither true nor false because it's not talking about anything? That would seem like a very odd conclusion because everybody knows what I mean when I say Harry Potter has one eyeball. Believe it or not, this question has implications on mathematics. There's a school of thought called fictionalism which treats mathematical objects, like the number three and four, like fictional characters. That's not exactly my belief, but it's actually fairly close to my own belief. So let me tell you how I would resolve this issue. I think you can say true and false things about Harry Potter, and I think that Harry Potter exists. I don't think it's possible to talk about something that doesn't exist, but we have to distinguish between mind-dependent existence and mind-independent existence, between conceptual existence and physical existence. Harry Potter exists because we're talking about him, but he exists in our heads. When I say Harry Potter, I'm not referencing some person in the world unless I'm talking about Daniel Radcliffe, which I'm not. I'm talking about a fictional character. A fictional character is an object in my head. If I were to not conceive of Harry Potter and nobody were to conceive of Harry Potter, then Harry Potter would not exist. What's nice about this is that it preserves the obvious intuition that yes, we can say true and false things about fictional characters, and it preserves the sensibility of not saying that Harry Potter exists in a physical way. But what it implies is that there is some type of existence, which is a conceptual existence, a non-physical existence, a mind-dependent existence. A lot of people aren't willing to claim that because that implies non-physical existence, dualism, dualism at least. On the other hand, I just find it very silly and a weird way of conceiving of language and metaphysics to take the only other route, which is to say that Harry Potter doesn't exist. If Harry Potter doesn't exist, then what am I referencing when I say Harry Potter? When I conceive of the character of Harry Potter with the round glasses, who is a wizard and goes to Hogwarts, that thing that I'm talking about, that you guys know I'm talking about and can clearly conceive doesn't exist? Seems like that's a weird way of conceiving of exist. Now, when I spoke with Jodie Azuni on this topic, who's a philosopher at Tufts, he essentially got around this by saying what we mean by exist is to physically exist, to spatiotemporally exist. So then he could say things like Harry Potter doesn't exist because Harry Potter is a fictional character, fictional characters don't take up space. But I just see that as kind of cheating. Let's say, if we grant him that word, we say okay, fine, Harry Potter doesn't exist. We need another word to describe the ontological status, the metaphysical status of Harry Potter. If he doesn't exist, then what does he? Because I can say true and false things about it. This is also a really convenient way of thinking when we're talking about math. The number three, does the number three exist? And we say true and false things about three, like three is a prime number. I would say, yeah, you can say true and false things about the number three. The number three exists, but it's a concept in our head. There is no physically existent number three. There is no mind independent number three. I don't believe in the platonic realm that is inhabited by a bunch of numbers. I think the three is a concept like Harry Potter. But what's unique about three, in mathematics in general, is that the concepts we come up with can directly apply to the world. So when I talk about three and the properties of three, I'm talking about a concept in my head that can directly, immediately, perfectly apply to things in the real world. If I have three cups or three chairs, then I can build a beautiful theory in my mind to try to explain those phenomena that I just can't do when I'm talking about Harry Potter. I want to add one addendum here. It sounds like when I'm talking about Harry Potter, I'm talking about one concept that multiple different people can conceive, but we're all conceiving the same concept. I don't actually think that's what's going on. I think if we want to be precise, my concept of Harry Potter, when I'm using that word and it brings something to mind, that concept is unique to my own mind. When you conceive of Harry Potter, you're conceiving of something that's independent and unique to your own mind, and it may overlap in some ways. I think this is the metaphysical status of all concepts. They're all restricted to the mind in which they are conceived, even if they have some similarities in their conception.