Well, yes. But I accept it as an axiom, because experience tells me that it usually works. As you point out, there can be no other evidence for it without invoking the principle itself as an axiom. So it seems to support my point (that it's an experiential axiom), rather than ciphergoth's (that an axiomatic approach and an experiential one are inconsistent), which is what was puzzling me.

I still can't see the point ciphergoth is making.