[pbhjpbhj]

Your second paragraph there seems to refute your position. If you can't tell physiologically then how are you telling that "most vertebrates experience mental states". You seem to be arguing for an assumed position starting from that position (petitio principii).

And I agree that physiological responses aren't the best way to show mental states. I cry sometimes for no reason whatsoever, my eyes just leak; you can't infer fear just because a creature backs away from fire, either.