Does a reductivist or 'identity' theory have to be eliminativist? Perhaps not. The theory could simply be asserting an identity. Take an early scientific discovery: the heavenly body that appears in the morning (Phosphorus) is identical with the heavenly body that appears in the evening (Hesperus). Is the theory that Hesperus = Phosphorus a reductivist theory? Nothing has been eliminated. Hesperus has not been eliminated because Hesperus is identical with Phosphorus, and Phosphorus has not been eliminated. By equal reasoning, Phosphorus has not been eliminated. So nothing has been eliminated. But is the theory reductivist? It seems to be lacking the asymmetry that we expect of a properly reductivist theory. It seems reasonable to assert that mental states are really brain states. But if this were merely an identity statement like Hesperus = Phosphorus, it would be just as reasonable to assert that brain states are 'really' mental states. Which seems odd.