Getting Existential

I think about a lot of weird things in my spare time. I swear this isn't my fault; when my mind is allowed to wander, it comes back with the strangest ideas. But one that I have continuously analyzed and wondered about is this: Is reality defined by a person's perception of it?

Perhaps I should explain. The world around you, what you see and hear and feel, what you experience through your senses--this is your reality. This is what you expect the world to be like, and if it were any different, you would probably find it extremely confusing. Your reality may insist that elephants are firmly bound by gravity, and if you saw an elephant floating by, this would be unusual. And you, like most of us (most of the time), assume that the reality which you live in is the same one everyone else experiences; but what if it isn't?

What if everyone's reality is fundamentally different from everyone else's? What if your perception of the world is nothing like the way it actually is?

For example: I perceive you as being what I think of as human (unless you are a superintelligent dog or cat sneaking onto your human's computer, in which case I commend you). My experience of you--sight, sound, smell--is based entirely on the assumption that you are human, and I believe that your existence follows all the rules human existence must. But what if this perception is inaccurate? What if you are, in fact, a very small salamander? This fact is not true in my reality--so which reality is actually real? (This also works if you flip it around: maybe you perceive me as a salamander when I am not.)

Take it a few steps further. If I say "Hello" to you, I may perceive that you also say "Hello" to me. But maybe you're not saying that; maybe you're saying "Go away" or "Sqhvuak wiejin" or something equally incongruous/in some unheard-of language. In fact, you might have heard something completely different from what I think I just said. Or maybe you're not really there at all. Maybe I just think you're there because it makes sense in my reality. Maybe the entire universe is something I'm imagining--it's not really there, but I think it is.

Maybe I'm not really here. Maybe I don't exist--I just think I do.

This is the point where you should stop thinking, or your brain might melt or implode. Therefore I leave you with my question still unresolved. What do you think?