The quote is from Jack Ritchie's Understanding Naturalism, which I learned about from this informative review. A bit more context:
Ritchie's brand of naturalism takes a stand against analytic metaphysicians such as Armstrong, Jackson and Lewis, who appeal to science as a basis for their constructive metaphysical programs. His main claim is that if we are honest in our appeal to actual scientific practices rather than merely paying lip-service to such an aspiration, or misguidedly employing mythical or ideological conceptions of science then we will find there is, on balance, no scientific support for substantial metaphysical conclusions embodied in such prominent '-isms' as physicalism, scientific realism, modal realism and mathematical Platonism....
Ritchie's discussion does...suggest a more useful distinction, that between metaphysically inflationary and metaphysically deflationary naturalisms. Ritchie takes seriously that for the consistent naturalist there is no first philosophy. In so far as metaphysics is extraneous to actual science then the "good naturalist should . . . be suspicious of such metaphysics" (153). Ritchie's general criticism of allegedly naturalistic analytic metaphysics is that it gains an unearned cachet from presuming to follow the results and methods of the successful sciences. Regarding metaphysically inflationary naturalists, the commitment to naturalism is really just window dressing since "there is no general metaphysical picture that our best science supports" (158). The attitude Ritchie recommends for the genuine or serious naturalist is metaphysical agnosticism (cf. 104, 143, 148, 158). Like Fine's Natural Ontological Attitude, the naturalist should not take sides in the metaphysical debates between physicalists and nonphysicalists, or between "realists" and "antirealists" about theoretical posits, universals, possible worlds, numbers, and the like. Metaphysics wants to tell us how things must be, or can be, once and for all, but "science forces us to revise our conceptions of what is and is not possible, of where a concept can be meaningfully deployed and where it can't" (147). Further, it is idle speculation to try to foresee how our future science might develop. Philosophy should purge itself of scientific soothsaying. In light of these considerations Ritchie interestingly suggests a reconception of metaphysics as metaphor: "Thinking of metaphysical theories as inspirational pictures or metaphors strikes me as . . . perhaps the best way to understand how science and metaphysics relate to one another from a deflationary naturalist perspective" (158).
Ritchie's deflationary methodological naturalism takes the sciences "at face value" (109). From this perspective the "strong disanalogy" between the standards of ontological commitment of the sciences and those of metaphysically inflationary naturalists (e.g. Quine, Armstrong and Lewis) is disastrous for these metaphysical programs (109). A naturalist is enjoined to stick as closely as possible to the results and methods of the sciences. When pondering the existence of some entity scientists themselves do not rest content with considerations of indispensability and explanatory worth. They also demand the right kind of empirical confirmation. We are asked, for example, to consider the experiments of Jean Baptiste Perrin in the aftermath of Einstein's work on Brownian motion, which allowed us for the first time to "see" atoms and thereby settle widespread skepticism about their existence. Ritchie suggests that science itself is more empirically minded than many naturalists suppose. [Aside: how would this appeal to empirical support help when it comes to the existence of abstract entities such as numbers or concepts?] In general, for the deflationary naturalist there is no unified story to tell about what exists: all he can do is to endorse "the many different things that our many empirically well-supported sciences say about the world" (158)....
In Ritchie's eyes, metaphysically inflationary naturalists are not naturalistic enough by their own lights. Although they claim to be naturalists opting for a properly scientific philosophy, they actually subscribe to false or outdated or mythic views of science. To make matters worse, they have a too loose sense of what it is to follow the results and methods of the sciences. A consistent naturalism must hold more closely to the sciences -- their variety and the multiplicity of their results and methods. This is not something that can be done from the armchair. It requires adopting an empirical attitude to the sciences themselves and learning from actual scientific case histories and examples (cf. 71, 90). However, "taking science on its own terms is not something philosophers have had much practice at" (5). Studies of "the history of science refute . . . the most popular methodologies of science", namely, inductivisim and hypothetico-deductivism (81). They also undermine constructive metaphysical programs, including philosophical speculations about the relation between mind and matter, at least within a naturalistic setting.
Discuss.
