Is Naturalism Coherent (Metaphilosophy, Metaphysics, Philosophy of Science)

Is Naturalism Coherent? Naturalism is the philosophical orthodoxy of the late 20th and early 21st century. However, the content of naturalism is unclear. I aim to demonstrate that naturalism cannot be formulated coherently. I offer two main arguments. First, naturalism presupposes the unity of science thesis; but the unity of science thesis has come under serious attack. But even if the naturalist successfully entitles herself to the unity of science thesis, naturalism is still subject to an argument from incoherence. First, I reconstruct naturalism as the conjunction of a methodological and ontological theme. The ontological theme of naturalism states that only those things truly exist which can be accounted for by physical science. The methodological theme asserts that “philosophy is continuous with science” (Quine 1960). While this can be interpreted in different ways, it is often taken to state that philosophy should only make statements that can be countenanced by the standpoint of science. Second, I demonstrate that this common construal has the underlying tacit assumption of the unity of science. The unity of science claims that: the entities and laws of the special sciences can be reduced to a master science, commonly identified as physics. Third, I briefly rehearse two lessons from Fodor (1974) and Horgan (1993). Fodor convincingly argued against the inter-level reducibility of special science laws to the laws of physics. Horgan´s argument starts with the observation that a sensible version of reductive physicalism has to be cashed out in terms of supervenience. He then goes on to argue that no available conception of supervenience captures the reductive ambitions of physicalism. Hence, the naturalist simply cannot entitle herself to an uncontroversial notion of the unity of science that is presupposed by naturalism. However, and fourth, even if the naturalist can establish the unity of science thesis, it is subject to an argument from incoherence. I take a cue from the coherence problem of the “empiricist criterion of meaning” in logical positivism, and apply it to the naturalist doctrine. The methodological commitment states that in philosophy only those claims can be made which are countenanced from the standpoint of the natural sciences. This is the standard for philosophical practice set by naturalism. And naturalism is itself a philosophical thesis. However, both commitments of naturalism fall short of this standard. The ontological commitment states that, in effect, the only things that really exist are those entities that are accepted and posited by physics. But this claim itself does not qualify as a piece of natural science since it transcends the bounds of what natural science investigates. Similarly, the methodological commitment cannot be countenanced from the standpoint of natural science. The claim that philosophical practice should only include statements that can be countenanced from the standpoint of natural science, is itself not a statement that is countenanced by natural science. Since this standard was set by naturalism qua methodological commitment, I conclude that naturalism turns out to be an incoherent doctrine. Bibliography Fodor, Jerry (1974): “Special Sciences (or the Disunity of Science as a Working Hypothesis),” Synthese 28:2, 97-115. Horgan, Terence (1993): “From supervenience to superdupervenience: meeting the demands of a material world,” Mind 102, 555-586. Quine, Williard v. O. (1960): Word and Object, MIT Press