Freespader

This may seem like a really dumb question, but I can't figure out what the answer is, so please just bear with me.

Why does a balance that is equal come out straight? If one side is tilted slightly lower than another, shouldn't it just stay that way since the masses are the same on either side, so the force down is too? I feel like the answer probably has something to do with torque, but I honestly don't know how it happens - although I also get the feeling it'll be pretty obvious once I hear it. Thanks.