Bruce Russell reviews Erik Wielenberg's God and the Reach of Reason

The book is in interesting and valuable treatment of the arguments of Lewis, Hume, and Russell, mostly Lewis. It does offer a response to one of the lines of argument in the AFR, and just says that Wielenberg has answered another.

I think there are plenty of difficulties in the idea that intentional mental states (or to be more specific, propositional attitudes), can evolve from non-intentional states, so long as we insist that they physical is mechanistic and closed, and that any mental state would have to supervene necessarily on the physical states. What that would mean would be that there is a set of truths at the non-intentional level that entails some truth at the intentional level. I don't think such entailments are even logically possible. Pile up the non-intentional truths as high as the ceiling, and they won't entail an intentional truth (S believes that p), necessarily. It will always be possible for the intentional state not to exist, or that multiple possible intentional states are logically consistent with the state of the physical. (For example, a world physically identical to this one could be populated with zombies). Given this, if we are in particular intentional states such as S believes that P, then there is something other than the physical that makes it the case that I am in this mental state as opposed to that one, or as opposed to no mental state whatsoever.

Russell offers an analysis of Lewis's argument that goes like this.

If S knows that P

1) S believes p
and

2) The complete cause of S's belief that P is the truth of p itself.

Hence if I believe that 2 + 2 = 4, in order to know that 2 + 2 = 4, the cause of my belief that 2 + 2 = 4 is the fact that 2 + 2 = 4, and that would be impossible given naturalism.

However, says Russell, I know I will be dead onon Jan. 1, 2100, but the truth of that belief is a future state, and can't cause me to believe that this, so on this theory of knowledge, I can't know that 2 + 2 = 4. Therefore the theory of knowledge is flawed, and hence the Lewisian AFR on which the argument is based is also flawed.

However, the case of my being dead in 92 years, the knowledge is not known directly, but is a conclusion of a principle of past-future resemblance (which Lewis actually thinks is rationally justified on a theistic world-view but not on a naturalistic one), plus evidence we have concerning human lifespans in our collective experience. Clearly some corrections and/or clarifications need to be done on Lewis's "An act of knowing thus solely determined by what is known," which Russell is surely referencing. Nevertheless, the fact that we live in a world that renders is likely that we will die before the age of 150 seems to be evident to us, and a bridge to the future fact seems possible if we grant the naturalist the resemblance principle. But how do we get a bridge from ourselves as physical beings to the fact that 2 + 2 = 4, of that arguments of the form "modus ponens" are valid.

So I don't think the objections to the AFR work that are found in this review.

I am glad to see Wielenberg's book getting some attention.