  Maddy motivates her naturalism by appeal to the “fundamental spirit that underlies all naturalism: the conviction that a successful enterprise, be it science or mathematics, should be understood or evaluated on its own terms, that such an enterprise should not be subject to criticism from, and does not stand in need of support from, some external, supposedly higher point of view” (1997, 184). One strained reading of this sentence is that naturalism's fundamental conviction by definition applies only to natural science and mathematics. A more natural reading is that it applies to any successful science whatsoever. Maddy then claims that as a matter of fact non-mathematical grounds have not impinged on mathematics. We can express this as the thesis that mathematics is autonomous.