I’ve been thinking about the connection between restrictivism and the equal weight view about rational disagreement. There are different versions of the equal weight view, but the rough idea is that the existence of disagreement has a tendency to undermine the rationality of one’s belief. What’s interesting is what kind of restrictivism must be accepted to undergird this view. In particular, the revised restrictivist position discussed here won’t be strong enough. Below the fold I say why.
Here’s the revised restrictivist view:
For any body of total evidence E, proposition p, and cognitive attitude A, either taking A toward p is forbidden or not taking A toward p is forbidden.
We accept this point with the idea that it leaves an individual open not to adopt any attitude at all toward propositions that could be rationally believed.
Suppose also that one accepts some version of evidentialism where the only things that count as evidence are mental states: mentalism, for short.
Then something interesting follows about those who think that when it is part of your evidence that there are epistemic peers who rationally disagree with you, you should turn agnostic on the issue on which you disagree. Given mentalism, you must believe the peer claim for it to be part of your evidence, and once it is, the equal weighters can appeal to the restrictivist position above to explain why the only appropriate attitude one can take is an agnostic one.
But here’s an interesting result of adopting this version of restrictivism. For the peer belief to be part of your evidence, you would presumably have other evidence that supports the peer belief. So suppose you do. Suppose I have exactly the same evidence (and no other relevant information), but I refuse to adopt any attitude toward the peer claim. Then the peer claim is not part of my evidence, and hence the restrictivist position above won’t imply that I need to be agnostic in order to be rational.
The point here is that there is pressure to find a middle position between the negatively characterized restrictivist position above and a more positive one that says that every permissible doxastic attitude is an obligatory one. This strong formulation founders on Harman’s cognitive efficiency objection, but the position of the equal weighters seems to require something closer to the strong restrictivist view in order to avoid the absurd result noted in the last paragraph. Whatever else we want to say about the equal weight view, we should say this: if you and I have the same evidence regarding the peer claim, then the mere fact that you believe the claim and I don’t shouldn’t make a difference as to whether our belief in the disputed claim is rational.