Fodor has argued that observation is theory neutral, since the perceptual systems are modular, that is, they are domain-specific, encapsulated, mandatory, fast, hard-wired in the organism, and have a fixed neural architecture. Churchland attacks the theoretical neutrality of observation on the grounds that (a) the abundant top-down pathways in the brain suggest the cognitive penetration of perception and (b) perceptual learning can change in the wiring of the perceptual systems. In this paper I introduce a distinction between sensation, perception, and observation and I argue that although Churchland is right that observation involves top-down processes, there is also a substantial amount of information in perception which is theory-neutral. I argue that perceptual learning does not threaten the cognitive impenetrability of perception, and that the neuropsychological research does not provide evidence in favor of the top-down character of perception. Finally, I discuss the possibility of an off-line cognitive penetrability of perception.

No abstract

Fodor has argued that observation is theory neutral, since the perceptual systems are modular, that is, they are domain-specific, encapsulated, mandatory, fast, hard-wired in the organism, and have a fixed neural architecture. Churchland attacks the theoretical neutrality of observation on the grounds that (a) the abundant top-down pathways in the brain suggest the cognitive penetration of perception and (b) perceptual learning can change in the wiring of the perceptual systems. In this paper I introduce a distinction between sensation, perception, and observation and I argue that although Churchland is right that observation involves top-down processes, there is also a substantial amount of information in perception which is theory-neutral. I argue that perceptual learning does not threaten the cognitive impenetrability of perception, and that the neuropsychological research does not provide evidence in favor of the top-down character of perception. Finally, I discuss the possibility of an off-line cognitive penetrability of perception.

In this paper I argue for the cognitive impenetrability of perception by undermining the argument from reentrant pathways. To do that I will adduce psychological and neuropsychological evidence showing that (a) early vision processing is not affected by our knowledge about specific objects and events, and (b) that the role of the descending pathways is to enable the early-vision processing modules to participate in higher-level visual or cognitive functions. My thesis is that a part of observation, which I will call perception, is bottom-up and theory neutral. As such, perception could play the role of common ground on which a naturalized epistemology can be built and relativism avoided.

The history of science shows that for each scientific issue there may be more than one models that are simultaneously accepted by the scientific community. One such case concerns the wave and corpuscular models of light. Newton claimed that he had proved some properties of light based on a set of minimal assumptions, without any commitments to any one of the two models. This set of assumptions constitutes the geometrical model of light as a set of rays propagating in space. We discuss this model and the historical reasons for which it had the head-primacy amongst the relevant models. We argue that this model is indispensable in structuring the curriculum in Optics and attempt to validate it epistemologically. Finally, we discuss an approach for alleviating the implicit assumptions that students make on the nature of light and the subsequent interference of geometrical optics in teaching the properties of light related to its wave-like nature.