Expert Knowledge by Perception

Does the scope of beliefs that people can form on the basis of perception remain fixed, or can it be amplified with learning? The answer to this question is important for our understanding of why and when we ought to trust experts, and also for assessing the plausibility of epistemic foundationalism. The empirical study of perceptual expertise suggests that experts can indeed enrich their perceptual experiences through learning. Yet this does not settle the epistemic status of their beliefs. One might hold that the background knowledge of experts is the cause of their enriched perceptual experience – what is known as cognitive permeation – and so their subsequent beliefs are only mediately justified because they are epistemically dependent on this background knowledge. I argue against this view. Perceptual expertise is not the result of cognitive permeation but is rather the result of perceptual learning, and perceptual learning does not involve cognition in a way that entails cognitive permeation. Perceptual expertise thus provides a means of widening the scope of the immediately justified beliefs that experts can form.