A thread below presumes this a "given." The discussants do not phrase it correctly (IMO). Science - if it be anything at all - IS "experience". (It cannot contradict experience: but it can contradict sloppy observation, reporting and folklore masquerading as "expereince."). As is said, "Not all (things) are known (or likely ever will be)...BUT if anything CAN be known, Science alone is that which permits us to know them."

A prominent neuropsychologist, R. L. Gregory, has considered just this subject lately in an article titled "Perceptions of knowledge" (Nature, V 140 1 Mar 01) in which he points out the curious fact that vision and hearing (unlike taste and smell) give only indirect knowledge of affairs: we must "interpret" their 'images' - whereas those of taste and smell are frontline, battleground hands-on affairs as they are actually occurring.

Misinterpretation of sight and sound gives cognitive illusion. All is erected on a base of millions of years of evolutionary development. Our ancestors learned the way around (partly) the tricks of camoflauge and deceit as biological weapons; science now extends sensory input manyfold over. That science changes its paradigms at times is NOT grounds for an "equality" among ALL views of affairs: to fall for this is to follow false lights.

Illusions are not tied to object reality - the author says. Perceptions are guesses - really, predictive hypotheses - of what may be out there. But they may be wrong (ultimately) hence the never-ending quest for refinement.

He raises a further interesting issue: illusions (paradoxes, ambiguities, distortions and fictions) may correspond to errors in language (always making my ears prick up...)- he even suggests same may be the true "deep structure" for language that post-Chomskyites posit... His words: "...perceptions by past species, of lost worlds, lying deep in our vision and speech of today...".

His conclusion? "No wonder things look confusing if our mental maps are millions of years out of date."

Bernie