Prompted partly by Olsson’s recent Against Coherence (OUP 2005), I’ve been thinking about the truth-conduciveness of coherence. There’ve been two recent claims to prove that coherence cannot be truth conducive (in Olsson, and Bovens & Hartmann’s Bayesian Epistemology).
I don’t know how many people have looked at this literature. Briefly, the claim (theorem, in fact) is that if
a) the coherence of a set of beliefs is a function of the probability distribution over the believed propositions and
b) the beliefs are formed independently of each other (i.e., when the truth-values of the relevant propositions are fixed, the occurrence of one belief doesn’t affect the probability of the other beliefs occurring),
c) there is no possible measure of the degree of coherence of a belief system on which more coherent beliefs are in general more likely to be true, ceteris paribus.
So I wonder a few things about this:
1) Is (c) incompatible with coherentism? Perhaps some coherentists would like to weigh in.
2) Should the coherentist accept (a) and (b)?
3) Lastly, I’m wondering more generally about the interpretation of claims like “x is conducive to y, ceteris paribus.” Olsson says that means: As long as you hold fixed all factors that are independent of x, an increase in x always leads to an increase in y. But I don’t think that’s right. This actually makes a big difference to the impossibility theorem.
Has anyone else thought about this?