In the philosophical vein: Carnap's (and Quine's) views on ontology

Rudolf Carnap's essay "Empiricism, Semantics, and Ontology" (ESO) is traditionally interpreted as an expression of either the analytic/synthetic distinction or verificationism. However, Carnap's fundamental aim---the repudiation of both nominalism and Platonism---cannot be accommodated by either interpretation. I interpret ESO as a renunciation of first-philosophical metaphysics, understood as an inquiry into what there is that transcends empirical science and constrains what sorts of entities a legitimate science can countenance. Carnap saw such constraints as metaphysical prejudices dressed up as ontological insights, and wrote ESO in order to protect science from their malign influence. The repudiation of first philosophy and advocacy of the autonomy and authority of science is naturalism, in at least one sense of the term. So ESO advocates naturalism.;This is surprising, since Carnap's most famous opponent, Quine, is also the most famous advocate of naturalism. Quine thought that Carnap was tying to enjoy the benefits of quantifying over abstracta while denying their existence. This is the maneuver Quine's criterion of ontological commitment was designed to block. But Carnap's purpose was not to satisfy nominalistic scruples. It was, rather, to show that empiricism does not imply nominalism, and therefore that such scruples are superfluous. Quine, in assuming that Carnap was subject to such scruples, has painted Carnap as Carnap's own antagonist.;The verificationist interpretation of ESO also misconstrues Carnap's intent. It sees Carnap's overall philosophical project as the defense of radical empiricism and the refutation of scepticism. But the purpose of ESO is not the refutation of scepticism; it is the repudiation of first-philosophical metaphysics. Carnap was not trying to secure the epistemic credentials of scientific doctrine. He was trying to protect science from the imposition of metaphysical prejudice.;After rejecting these two interpretations and offering mine, I turn to the impact that Carnap's views would have on the realism debate in the philosophy of science. Carnap's attitude toward this debate resembles Arthur Fine's "Natural Ontological Attitude" (NOA). Fine's own exposition of NOA, however, is difficult to interpret, a situation that is improved if we set NOA within a broadly Carnapian philosophical orientation.