Seeing is often a good reason for believing—when things go well. But suppose we have a case like this: Jill believes that Jack is angry, although she has no good grounds for this belief. Nevertheless, when she sees him, she sees his face as angry even though it is neutral. Is it reasonable for Jill to believe he is angry on the basis of what she sees? No, argues Susanna Siegel: her perception has been hijacked by her prior unfounded belief, and so it cannot turn around and justify that belief even if Jill thinks it does. In The Rationality of Perception (Oxford University Press, 2017), Siegel articulates a new framework for understanding how to assess the capacity of perceptions to justify. On her view, perceptions, like beliefs, can be appraised as rational or irrational, and can be inferred from beliefs. She uses her view in turn to explain when and how the influence of a prior outlook on a perceptions ability to justify that outlook can be downgraded or upgraded.