Sunday, February 5, 2012

The Māya Theory of (Visual) Perception

A visit recently to the Center for Brain and Cognition at UCSD by an Indian medical student has prompted me to advance a rather skeptical theory at which I have only hinted previously. It is surprising how sometimes in the course of informal conversation even a profound idea can take shape, and that was the case the other evening when Rama and some of us in the lab were actually joking about the absurd predicament that I described below under my posting "Summation," viz. that the causal theory of perception leads to empirical evidence that does not support it, but actually contradicts it.

As I have intimated previously it is not necessarily the case that classical "action-by-contact" ("billiard ball") causality is wrong, but that the causal theory of perception is wrong by invoking it, the locus classicus being The Analysis of Matter by Lord Russell. This state of affairs may/may not be related to putative non-local causality ("non-locality") in Quantum Mechanics, which it has been claimed by theoretical physics implies "action at a distance" at the quantum level, and though a number of theorists have speculated that consciousness may have a quantum mechanical basis. I say "may/may not" because the rejection of the causal theory of perception is not because it is contradicted by anything stemming from Q.M., but by the disparity between brain structure/events and the structure of visual objects, a topic of much previous discussion here already, but something that was noted by John Smythies already over half a century ago in his Analysis of Perception.

Just as Fred Hoyle thought the universe was a "put up job," much the same might be said for the (visual) world--and perhaps for a similar reason: Highly unlikely relationships between physical constants in the case of the universe, and so-called perceptual constancies in the case of the visual world. The geometrical structure of objects in visual space is usually explained in terms of a perspective projection resulting from the geometrical optics of the eyes. It is often depicted as being something like an artist using perspective to simulate depth and distance on a flat surface. But whereas the artist can compare what he sees of the world with his perspective drawing or painting, we as perceivers cannot do that with the whole of our visual world with the physical world, so the analogy does not really hold.

Perhaps it is the case that as much as departing from "veridical" perception, visual illusions and the study of them may may actually lead to understanding perception and the visual world as māya, a Sanscrit word usually translated as "illusion" but also as "projection." How apt in the case of visual perception! Could it be that it is the nature of perception to foster a belief in an objective external world, but that such a world always remains for each of us only a belief? When one doubts the existence of an external world beyond the senses, one is a skeptic or phenomenalist, but when one doubts the existence of God, one is only an atheist. Yet both involve belief or disbelief in something beyond the senses. On the one hand, "seeing is believing," yet on the other, one "doubts their senses."

The "put up job" in the case of perception may just be predictability and repeatability in the perceptual world--as it happens, the hallmarks of scientific empiricism. But how can one know a priori that this guarantees knowledge of reality, if reality is only a belief? The argument is circular. This may be the "naive faith" which Whitehead wrote science never questions.