When Fritz was here, we spent some time talking about the evidential value of agreement. We talked about the possibility of some perhaps formal results that yield something like the following: when sources of information are unreliable and independent and yet agree about some claim (regarding which they are unreliable), their agreement is evidence for the claim in question.
I’m skeptical about the epistemic value of agreement, but am interested to know what the precise principles are here that are defensible. One issue in the above principle is whether the sources have to be both generally unreliable and unreliable about the specific subject matter; another issue is the notion of independence being appealed to. And another issue is what happens when the information in the antecedent of such a principle is brought to the attention of people who take themselves to have really good evidence for the opposite point of view (that issue, of course, takes us away from the incremental issue involved in the above principle to the issue of what the total evidence confirms).