“A wise man,” wrote Hume, “proportions his belief to the evidence.” This is a formulation of evidentialism – the view that a belief is rational or justified if and only if it is supported by one’s evidence. A more generalized version of evidentialism covers beliefs with various degrees of confidence, as well as other ‘doxastic attitudes’ such as disbelief, doubt and suspension of judgment (doxa is Greek for belief or opinion). It states that the rational or justified attitude to adopt with respect to a claim or proposition is the attitude that fits one’s evidence. Although evidentialism is much harder to clarify and defend than it might seem, there is no denying its prima facie reasonableness.
Evidentialism plays a key role in attacks against religious belief by the New Atheists, as it did for Hume. Belief in the existence of God or other divine realities is criticized on the ground that there is no good evidence for it. Echoing Carl Sagan and Laplace before him, we are told that “extraordinary claims require extraordinary evidence,” and we are assured that there is nothing of the sort when it comes to the divine. The upshot is that religious belief must be judged irrational, epistemically unjustified, or intellectually illegitimate, and it should be rejected. As Christopher Hitchens is fond of saying, “what can be asserted without evidence can also be dismissed without evidence.”
