- I claim that the triad of scientific realism (SR), representational naturalism (RN), and ontological naturalism (ON) is inconsistent, given the theses of the pervasiveness of the simplicity criterion in our scientific practices (PS) and the essentiality of reliability as a component of naturalistic accounts of knowledge and intentionality. The argument for the inconsistency proceeds as follows.
1. SR, RN and ER entail that scientific methods are reliable sources of truth about the world.
As I have argued, a representational naturalist must attribute some form of reliability to our knowledge- and belief-forming practices. A scientific realist holds that scientific theories have objective truth-conditions, and that our scientific practices generate knowledge. Hence, the combination of scientific realism and representational naturalism entails the reliability of our scientific practices.
2. From PS, it follows that simplicity is a reliable indicator of the truth about natural laws.
Since the criterion of simplicity as a sine qua non of viable theories is a pervasive feature of our scientific practices, thesis 1 entails that simplicity is a reliable indicator of the truth (at the very least, a better-than-chance indicator of the truth in normal circumstances).
3. Mere correlation between simplicity and the laws of nature is not good enough: reliability requires that there be some causal mechanism connecting simplicity and the actual laws of nature.
Reliability means that the association between simplicity and truth cannot be coincidental. A regular, objection association must be grounded in some form of causal connection. Something must be causally responsible for the bias toward simplicity exhibited by the theoretically illuminated structure of nature.
4. Since the laws of nature pervade space and time, any such causal mechanism must exist outside spacetime.
By definition, the laws and fundamental structure of nature pervade nature. Anything that causes these laws to be simple, anything that imposes a consistent aesthetic upon them, must be supernatural.
5. Consequently, ON is false.
The existence of a supernatural cause of the simplicity of the laws of nature is obviously inconsistent with ontological naturalism. Hence, one cannot consistently embrace naturalism and scientific realism.