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Thursday, January 29, 2004

On the Intellect (A work in progress).

Both CS Lewis and Alvin Plantinga offer criticisms of naturalistic accounts of reason suggesting that metaphysical naturalism cannot be an adequate account of reason, knowledge, and/or justification. But there is an important difference in there approach.

Plantinga is not completely hostile to naturalism and even offers natural accounts for the formation of our beliefs. But he does argue that while natural mechanisms are adequate to serve as an explanation for how we believe, they are not adequate to account for the normativity of belief that even the naturalist sometimes wants when she insists that there is a way that belifs ought to be formed (e.g. by being based on adequate evidence). To account for the the required normativity, Plantinga first describes belif forming machines in terms of there function and then accounts for their normativity in terms of a design plan for that function. A belief formation machine works "right" if and only if it works according to plan, "the way its supposed to". Nature and normativity are this wedded together. But this solution requires a Designer, namely God. So if the the naturalist also wants to have an ethic of believing, you must be a theist. There are some replies to this argument, such as that evolution is held to sufficient to to explain proper function by means of natural selection, but leave that aside for now.

Lewis' idealism needs to do more since not even nature is available to serve in an adequate account of knowledge. Lewis distinguishes between two senses of "because"; the "because" of cause and effect "The ball flew because the bat hit it", and the "because" of consequent and ground "We know 320,572,034,576 is an even number because we know that it is divisible by two without remainder", or more simply, Lewis distinguishes between causes and reasons. According to the Lewis the naturalist must identify one sense with the other.

(X) Joe understands 8 to be an even number because Joe understands that it is divisible by two if and only if there is a brain state of Joe's which is the brain state "Thinking that 8 is an even number" which is physiologically caused by another brain state of Joe's which is the brain state "Thinking that 8 is divisible by two".

According to Lewis, however, (X) is NOT what we mean when we use "because" in the consequent/ground sense according to our own consciousness of the matter. Further, Lewis might also agree that attributing reasons to a mere physical system must only be metaphorical but that any metaphorical use of a term presupposes a legitmate non-metephorical use, but if there are no instances of reasoning there could be no possible non-metaphorical attribution of ground/consequent.

Lewis' point would apply as well to Plantinga as well as the naturalist. Not that Plantinga would mind necessarily since he is trying to work with constraints that naturalists accept and they would not accept Lewis' point. To them Lewis is commiting the "Superman" fallacy. (Lois Lane knows that Superman can fly. Lois Lane does not know that Clark Kent can fly. Therefore, Superman is not Clark Kent.) CS Lewis knows that determinig brain states is physically caused. CS Lewis does not know that determining thoughts is physically caused. Therefore, determining thoughts (reasoning) is not determining brain states (causality).

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