Abstract
Many scientists and philosophers of science have argued that metaphysical naturalism and methodological naturalism represent distinct and separable philosophical commitments (see, e.g., Barnes, 2010; Bishop, 2009; Forrest, 2000; Halvorson, 2016; Parsons, 2014). Typically, the argument is that metaphysical naturalism – sometimes termed “ontological” or “philosophical” naturalism – constitutes a truth claim about the fundamental nature of reality, while methodological naturalism does not. This conceptual dichotomy makes sense insofar as metaphysics and epistemology reflect different philosophical projects. As Bishop (2009) notes, “metaphysical naturalism makes a substantive commitment to a picture of what really exists; namely only matter, energy, and their interactions” (p. 108). In such a view, therefore, there is no conceptual space whatsoever for the non‐material, non‐observable, non‐measureable, supernatural, or spiritual – at least as such things are traditionally conceived (i.e., in the spirit of Cartesian Dualism). There is, thus, no possibility for the existence of “divine beings, a spiritual reality, ultimate intelligent causes, and so forth” (p. 108). As Nielsen (1997) famously stated, metaphysical naturalism is constituted by the simple claim that there are “no purely mental substances and there are no supernatural realities transcendent to the world or at least we have no good ground for believing that there could be such realities.. .. It is the view that anything that exists is ultimately composed of physical components” (p. 402). Ultimately, then, metaphysical naturalism reflects a system in which only that which is measureable (observable) has any place and in which concepts such as purpose, meaning, agency, consciousness, and morality have no intrinsic reality.