Introduction
In his book C.S. Lewis's Dangerous Idea: In Defense of the Argument from Reason, Victor Reppert lists nine presuppositions of rational inference.
1. States of mind have a relation to the world we call intentionality, or about-ness.
2. Thoughts and beliefs can be either true or false.
3. Human beings can be in the condition of accepting, rejecting or suspending belief about propositions.
4. Logical laws exist.
5. Human beings are capable of apprehending logical laws.
6. The state of accepting the truth of a proposition plays a crucial causal role in the production of other beliefs, and the propositional content of mental states is relevant to the playing of this causal role.
7. The apprehension of logical laws plays a causal role in the acceptance of the conclusion of the argument as true.
8. The same individual entertains thoughts of the premises and then draws the conclusion.
9. Our processes of reasoning provide us with a systematically reliable way of understanding the world around us.[1]
Commenting on this list of presuppositions, Reppert writes, "It seems to me that all of these elements of reasoning are prima facie difficult to fit within the framework of philosophical naturalism."[2] Here I want to quickly sketch how I would assess one of Reppert's supporting arguments for that claim.
