Naturalism, reduction and normativity: Pressing from below (David Papineau)

David Papineau's model of scientific reduction, contrary to his intent, appears to enable a naturalist realist account of the primitive normativity involved in a biological adaptation's being "for" this or that (say the eye's being for seeing). By disabling the crucial anti-naturalist arguments against any such reduction, his model would support a cognitivist semantics for normative claims like "The heart is for pumping blood, and defective if it doesn't." No moral claim would follow, certainly. Nonetheless, by thus "pressing from below" we may learn something about moral normativity. For instance, suppose non-cognitivists like Mackie are right that the semantics of normative claims should be "unified": if the semantics of moral claims is non-cognitivist, so too is that of all normative claims. Then, assuming that a naturalist reduction does yield a sound cognitivist account of the primitive normativity, it would follow that our semantics of moral claims is cognitivist as well.