Q: why don't we fall off the sides of the earth?
A: why would anything fall anywhere? actually, nevermind, why would anything be anywhere, or exist? supposing that anything that does exist is indeed somewhat biased in favor of existing (instead of non-existing).... the 'falling' (toward each other) seems to be the force of that bias. the anythings moving in relation to each other (toward, away, etc) is the only way they can feel their existence. i suppose if the anythings were truly unbiased about which way they're falling, they would not even be registered in this reality. anyway, getting back to the main point, we fall toward earth because we prefer being here instead of outer space