Sit back, relax, and let me take you on a journey. I promise it won’t take too long.
The journey begins with this question: What does it mean when you say something exists? Sometimes it means that something is out there in the physical universe. But it doesn’t always mean that. Happiness surely exists, because some people are sometimes happy; but happiness could exist even if nobody were happy, couldn’t it? Happiness could exist as an abstraction, as a possibility, even if nobody were actually happy at a specific moment in time.
Right triangles are another example. The right triangle, as a conceptual thing, has a certain kind of reality. It has properties (e.g. one of its angles is 90 degree), and you can make true statements about it (e.g. the square of the length of the hypotenuse is equal to the sum of the squares of the other two sides). These statements are true about right triangles even if no physical things in the universe have that particular shape.
So right triangles have a kind of reality, a kind of existence, that has nothing to do with whether anything in the physical universe has that shape.
What about unicorns? We can state some facts about unicorns: they have four legs, they have fur, they have a single horn in the middle of their foreheads. Some people argue that since we can state facts about unicorns, they must exist in some sense… even if it is only in the abstract sense that right triangles “exist”. This isn’t the same kind of existence, of course, as the way my car or my pet cat exists. But we can reason about them, we can imagine them, and we can talk about them as hypothetical or potential objects: as such, they have some kind of logical abstract existence.
But wait, there’s more!
Does this mean that anything that I can talk about–no matter how fantastical or imaginary–also must exist? Well, people disagree on that question. If you’re interested in this topic, the philosophers you want to read include Alexius Meinong, Saul Kripke, and Michael Dummett.
Some philosophers say yes: the very fact that you are able to speak about a concept means that the concept must have some kind of (mental) existence. Other philosophers say no: just because you can use the phrase “the square circle” or “the invisible purple donkey” doesn’t mean they have conceptual existence, because some things are logically impossible: unlike a unicorn (which we imagine could exist in some possible world), a “square circle” can’t exist by definition.
“And what if we are wrong about the definitions?” someone might ask.
“How can we be wrong about the definitions?” comes the reply, “We are the ones who created the words in the first place!”
If we can be wrong about definitions, then we have to be very careful when we claim that something “can’t exist by definition,” even something that sounds as silly as a square circle. The best illustration of this comes from a thought experiment by philosopher Hilary Putnam.
Everybody knows that all cats are mammals, right? That’s something that we say is true by definition. If I come home one day and discover that my pet cat, Skimbleshanks, is not a mammal but in fact is a Martian robot, the standard response would not be to question the truth of the definition “all cats are mammals,” but rather to say: “Oops, I was wrong, Skimbleshanks is not a real cat.”
So far, so good. But what if, by some strange twist of events, scientists discover that all cats are actually Martian robots, and always have been. If cats are by definition all mammals, and we discover that the things we’ve been calling cats are not mammals, what do we conclude? Would we conclude that cats have never existed in the history of the universe, and all of those things that we thought were cats are actually something else? Or, would we just say that we were wrong about the definition “cat”? Common sense seems to suggest the latter, but once again: philosophers will disagree on this point.
This is all important for the question of unicorns, as well. When someone says it is possible for unicorns to exist, perhaps in an alternate universe via some alternative evolutionary pathways, that is a belief that is rooted in assumptions about biology, physiology and evolution. Do we know for certain that it’s true? Do you know enough about animal genetics or physiology to know for sure?
There are many examples of things that non-experts believe they can “imagine” that are actually not in principle possible: they only seem possible because the scenario hasn’t been fully understood. For example, you probably have heard of the Doppler Effect: the fact that a siren (for example) that is moving toward you sounds higher than one that is moving away from you. You might say: “I can imagine a universe where everything is exactly the same, except that sounds aren’t influenced by the Doppler effect!” From your own subjective point of view, that may be true: You can imagine walking down the street, seeing your friends, looking at the blue sky and the green grass, and experiencing a world that is identical to this one except that the pitch of an ambulance doesn’t change depending on whether it is coming toward you or moving away from you.
But that hypothetical world you’ve created is not logically possible, even though you have created a vivid image of it in your head. The Doppler effect is the result of fundamental truths about the physics of particles and the geometry of movement. To construct a universe with no Doppler Effect would require drastic and fundamental changes to the very fabric of physics and geometry itself. A universe that is “identical to ours” except for there being no Doppler Effect is literally logically incoherent.
Back to unicorns. Am I claiming that unicorns are impossible? No: but I’m saying that you and I can sit here all day and imagine unicorns, but that is not evidence that that such animals are biologically, genetically, and evolutionarily possible. You’d need to know a lot more about science to answer that question. Which means, answering the question “do unicorns exist?” is no mere philosophical or semantic game: to give a real and proper answer to the question, you actually have to actually have a deep understanding of the physical universe. You have to have an understanding of what genetics and evolution could possibly do, which is an even more complex question than what genetics and evolution have actually done in the world as we know it.
A fairly unexpected conclusion, don’t you think, for a journey that began with the question “What does it mean to say that something exists?”
I brought you on this journey because sometimes I see people making fun of research or philosophy that they don’t understand, and I think it’s a shame. It’s anti-intellectual, and it’s close-minded. At worst, it comes across as terribly ignorant: like when Bobby Jindal called it “stupid” to spend money on volcano monitoring, just a month before a volcano actually exploded in Alaska. It has always been a problem when non-scientists (usually politicians) leaf through summaries of scientific research and try to decide what “sounds stupid” and what doesn’t; it inevitably makes the politicians look like the stupid ones in the end. Well, the same thing is true for you, when you make fun of philosophy that you don’t fully understand.
Yes, there was a woman who wrote her dissertation on the question of whether unicorns exist. And some people mocked it.
But I wanted to give you a glimpse of why philosophers find questions like this interesting, and why even a seemingly silly question like “do unicorns exist?” can be tied into very complex and deeply profound issues of knowledge, and logic, and word-meanings, and even physics. Philosophers love peeling away the onion layers of seemingly-simple questions like this because it reveals very deep and very complicated assumptions that we humans make about ourselves and our relationship to the universe around us. They demonstrate that there is a whole underbelly of assumptions, even in seemingly simple ideas and words–like “exists”–that, like the base of an iceberg, is not visible in our normal day-to-day lives but is always present, and always guiding the way we think and view the world around us.
I may not have convinced you that “do unicorns exist?” is an important question. That’s fine.
But the next time you are sitting with your friends, and they are making fun of research or philosophy that seems “obvious” or “silly” or “insignificant”–like the question of unicorns–perhaps you will take a moment to step back and ask yourself: Should I be making fun of something I don’t understand? Or should I instead take a moment to learn why there are people out in the world who find these questions so very, very interesting?