[y33t]

I'd say causality and entropy are contingent on the (very compelling) assumption that time is real. We could be Boltzmann Brains, or something even weirder. Do I believe that the world is terribly different from what it appears to be? No, but ultimately our perceptions of the world are merely representation held in our minds.

[TheOtherHobbes]

We could be Boltzmann Brains on drugs.

Or worse.

Presumably the probability of a brain appearing as a disordered psychiatric monster is far higher than the probability of arriving as an Earth-normal tenured cosmologist.