 The basic idea behind the low priors argument is that, even if the agnostic is right that, when it comes to God’s existence, the evidence is ambiguous or absent altogether, what follows is not that theism has a middling probability all things considered, but instead that theism is very probably false. This is said to follow because theism starts out with a very low probability before taking into account any evidence. (“Evidence” in this context refers to factors extrinsic to a hypothesis that raise or lower its probability.) Since ambiguous or absent evidence has no effect on that prior or intrinsic probability, the posterior or all-things-considered probability of theism is also very low. If, however, theism is very probably false, then atheism must be very probably true and this implies (according to the defender of the argument) that atheistic belief is justified. (This last alleged implication is examined in section 7.)