Circularity, Reliability, and the Cognitive Penetrability of Perception

Several years ago, Jerry Fodor (1984) argued that the modularity of the perceptual systems was good news for epistemology. In particular, on the assumption that perceptual systems are modular in his (1983) sense of the term, they are informationally encapsulated, which means that their operation is not sensitive to the beliefs, desires, and such of the larger organism. This would allay worries about the theory-ladenness of observation; if perception is modular, what we see is not affected by what we want to see or expect to see or have been trained to see. What one observes is determined by the outputs of the perceptual modules, and modules are cognitively impenetrable (i.e., informationally encapsulated), so if different theoretical camps disagree about what they've observed, the blame lies elsewhere than observation. Recent years have seen a resurgence of interest in the cognitive penetra-bility of perception (Raftopoulos 2001, Pylyshyn 2003, Macpherson forthcoming , Stokes forthcoming). The epistemological implications of cognitive penetrability in particular have received special attention in a recent book by Athanassios Raftopoulos and paper by Susanna Siegel (Raftopoulos 2009, Siegel forthcoming). Raftopoulos (2009) starts with a set of concerns very similar to Fodor's, and the view he develops is a modified and nuanced version of Fodor's own. Raftopoulos argues that even though much of what Fodor calls observation is cognitively penetrated, nevertheless an early stage of perception is encapsulated and therefore immune to the skeptical and relativistic worries that exercise Fodor. Siegel (forthcoming) argues that if perception is not encapsulated, this causes difficulties for a commonly held epistemological view I'll call " Seemings Internalism " (SI), which holds that one's belief that x is F is prima facie justified any time it is based on one's having a perceptual experience that x is F. 1 She doesn't think that all cognitive penetration of