Unicorns and the Absence of Evidence

Do unicorns exist? I mean simply, do they live somewhere in the world?

Of course not, one might say. They are a mythological creature. They don’t really exist.

How can you know that? Some real creatures exist in mythology, so the fact that unicorns exist in mythology doesn’t mean that it doesn’t exist in reality. And unlike some other mythological creatures, such as the multi-headed hydra, or the six-limbed Pegasus, the unicorn has a conservative body plan, one that would not cause a person to think that it is biologically impossible. So there aren’t any reasons to think that a unicorn can’t exist. Why then would one insist that it is a mythological animal, and not an actual animal?

Well, because no one has ever seen one.

Up until 1976, no one had seen a megamouth shark, either. Did the megamouth shark not exist before 1976? Does knowledge of a creature make it real, or can a creature exist apart from our knowledge of it? Obviously, an animal exists apart from our knowledge of it, since finding an unknown creature is called a discovery, not a creation. So the megamouth shark illustrates that creatures can, and likely, still do, exist even when we have no knowledge of them. Could the unicorn be one of these still unknown creatures? The answer we would be forced to give at this point is, yes.

What I have illustrated here is the problem of absence of evidence. There is no evidence that unicorns exist, but neither is there any evidence that they do not exist. The only conclusion that can be drawn from this is that they may exist somewhere, we just don’t know where. This argument is sound, but let us go one step further. So we establish that it is possible for unicorns to exist somewhere in the world. What applications can be draw from the statement that unicorns may exist? Nothing. True, we may not be able to say definitively that unicorns don’t exist, but because we do not know if they exist, there is nothing we can say about unicorns. They may be there, but because no one has seen them, it is impossible to know about their diet, habits, longevity, or anything about them. So the absence of evidence argument is a double edged sword: if there is a lack of evidence, we can not say that something does not exist. On the other hand, with no evidence, no knowledge about a subject can exist. The result is, since no one has seen a unicorn, we act as if they don’t exist. They may exist, but since we know nothing about them, they have no impact on our lives or our knowledge.