According to Kepler and Descartes, the geometry of the triangle formed by the two eyes when focused on a single point affords perception of the distance to that point. Kepler characterized the processes involved as associative learning. Descartes described the processes as a “ natural geometry.” Many interpreters have Descartes holding that perceivers calculate the distance to the focal point using angle-side-angle, calculations that are reduced to unnoticed mental habits in adult vision. This article offers a purely psychophysiological interpretation of (...) Descartes’s natural geometry. In his account of perceived limb position from the Treatise on Man, he envisioned a central brain state that controls ocular convergence and thereby co-varies with the distance from observer to object. A psychophysiological law relates the visual perception of distance to this brain state. Descartes also invokes more traditional theories of distance and size perception based on unnoticed judgments, yielding a hybrid account. (shrink)

.In this paper, I address Descartes’ claims that sensory perceptions function to aid and preserve the subject in interacting with the world, and focus specifically on the ‘valence’, or agreeable/disagreeable quality, that characterizes many sensations. I show how Descartes considers this aspect of sensation to be a significant factor in the ecological role of sensory perception and I then turn to a kind of case that seems to pose a problem for this view: that of aesthetic pleasure. I consider Descartes’ (...) remarks on a particular kind of aesthetic pleasure – that found in musical consonance – and argue that his discussion of this phenomenon reveals that he distinguishes between two distinct kinds of valence – evaluative sensory valence and aesthetic valence – only one of which functions to report directly on ecological evaluation. Further, I suggest that the best way to understand the distinction between these is by appealing to Descartes’ three grades of sensory perception. (shrink)

Commentators have argued that along with adopting a mechanical view of nature, Descartes developed two innovative views concerning sensation: sensation occurs without the involvement of an entity resembling the sensation, and sensations represent features of objects but without resembling them. When Descartes is interpreted as making both of these claims, it appears that in removing resemblance from the causal process of sensation, Descartes preserves the notion that sensations represent features of objects and that he does this by introducing a new (...) conception of representation — one not requiring resemblance.It is important to recognize that the two claims are distinct. The first claim, that the physical process of sensation does not involve something resembling the qualitative content of the sensation, does not in and of itself entail anything about the representational nature of the sensation. Or rather, what it does entail is thatifsensations do represent their causes in objects, then it cannot be by presenting those causes to the mind as they exist in objects. (shrink)