Evidentialism is the thesis that a person is justified in believing a proposition iff the person's evidence on balance supports that proposition. In discussing epistemological issues associated with disagreements among epistemic peers, some philosophers have endorsed principles that seem to run contrary to evidentialism, specifying how one should revise one's beliefs in light of disagreement. In this paper, I examine the connection between evidentialism and these principles. I argue that the puzzles about disagreement provide no reason to abandon evidentialism and that there are no true general principles about justified responses to disagreement other than the general evidentialist principle. I then argue that the puzzles about disagreement are primarily puzzles about the evidential impact of higher-order evidence -evidence about the significance or existence of ordinary, or first-order, evidence. I conclude by arguing that such higher-order evidence can often have a profound effect on the justification of first-order beliefs.Evidentialism is a widely accepted thesis about epistemic justification. A simple way to formulate it is as follows:1. Evidentialism: S is justified in believing P at t if and only if S's evidence at t on balance supports P.A more complete statement of the view adds that other attitudes -disbelief and suspension of judgment -are justified when the evidence goes against the proposition or is neutral. 1 An additional detail that will matter in what follows is that the degree of justification a person has for believing a proposition is determined by how strongly the evidence supports that proposition.
2The evidentialist view about disagreements is quite simple: people are justified in believing what their evidence supports when they are involved in a disagreement. Consider a person who believes P and learns that someone relevantly like herself (an epistemic peer) disbelieves P. The evidentialist view is that the person is justified in continuing to believe P if and only if the evidence the person has after learning of
E P I S T E M E 2009
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