Time Structure and the Structure of Perception

Our knowledge about the world grounds in perception; and a good share of it is based, particularly, on visual perception. Due to psychological and neuro-scientific research more and more details are being disclosed about the internal causal process that starts off with rather meager optical images on the retina and ends up in beliefs about the world. As philosophers, however, we must not be content with an exploration of the causal chain between those tiny optical projections on the eye’s inside and the complex, conceptually structured representation that makes up the body of our empirical knowledge. What we have to evaluate, in addition, is the epistemic quality of this process; and in this regard what matters is precisely the course of justification. The stations of this course aren’t just states of the brain, but states of the mind. Concerning the perceptual foundation of empirical knowledge, what’s of particular epistemic interest are the starting points in this course of justification: those states of the mind that are commonly called epistemically prior. Since the optical images on the retina, for sure, are merely neuronal rather than mental, they don’t qualify as epistemically prior, although they are causally prime. Within the empiricist tradition, however, there’s always been a strong appeal for pictures that do count as mental and do precede mental judgments. Those views include the extreme positions of the British Empiricists (Locke, Berkeley, Hume) who held that “all thought consists in the manipulation of either simple images derived from sense experience or complex images built up from these simple images ” (Tye 1991, p. 5). They also include the more moderate positions of the Logical Empiricists. Carnap (1928), e.g., begins his logical reconstruction of propositional knowledge with a classification of pictorially analyzable sensations.1 It is the Empiricist Priority Thesis I will question in this paper: Empiricist Priority Thesis In the course of the perceptual justification of knowledge, pictorially structured mental representation precedes conceptually structured mental representation. In my criticism I will take recourse to recent findings on the time structure of neuronal responses in the visual cortex