Nominalism, Naturalism, and Materialism: Sellars’s Critical Ontology
Nominalism denies the existence of abstract entities (universals, forms, species, propositions, etc.). Traditional nominalism proceeded from an empiricist epistemology that challenges the very possibility of metaphysics, whether idealist or materialist. The critique of empiricism is taken to entail the refutation of nominalism. But nominalism contains a valuable insight for naturalists: reality does not have propositional form. This is an insight that deserves to be taken up by post-Darwinian naturalists, for whom realism about abstract entities is problematic insofar as it seems to reiterate the theological presumption of a preestablished harmony between conceptual order and real order. The question is whether contemporary naturalists can take up this nominalistic insight while jettisoning the empiricist prejudices that tied it to skeptical relativism. For the claim that reality is devoid of propositional form need not require denying that we can capture aspects of reality in propositional form or that concepts have ontological purchase. The challenge is to explain both how propositionally structured thought arises within nature and how it can be used to track natural processes despite the lack of congruence between propositional form and natural order.