I don't remember how I got this

untheorem idea, but I like it:

It has been postulated by my

pseudo-intellectual friends that the universe is so large and diverse that literally anything you can think of MUST exist somewhere, every

unicorn, billboard,

useless website, etc. This is a very welcome notion among

sci-fi fans.

Now avoiding the scientific aspect of this theory, I propose that we can prove it wrong inductively. I imagine that somewhere in the universe there is a person who can imagine something that does not exist. According to the theorem, this person MUST exist. Without knowing specifically what that non-existent thing is, I know that thing to be imaginable by a human, and therefore there is something that a person can imagine that does not exist somewhere in the universe, which contradicts the postulate.

There is a problem with this logic, but I'm not telling what it is. But even clean, formal logic is a slippery thing sometimes. Lewis Carroll once used it to prove that all dowagers are thistles.