Field of Science

Galileo -- Smarter than you thought

It is often said of cognitive scientists that we have, as a group, a memory that only stretches back about 10 years. This is for good reasons and bad. Methods change and improve constantly, constantly making much of the literature irrelevant. Then there is the fact that there is so much new work, it's hard to find time to read the old.

This is a shame, because some of the really old work is impressive for its prescience. A recent issue of Trends in Neurosciences carried an article on Galileo's work on perception. Most people then -- and probably most people now -- conceived of the senses as passing along an accurate representation of the world to your brain. We now know the senses are plagued by illusions (many of them actually adaptive).

Galileo was on to this fact. His study of the moon proved that perceptions of brightness are constantly subject to illusion. More generally, he noted -- contrary to the popular view -- that much of what we sense about the world is in a real sense an illusion. Objects exist, but colors and tastes in an important sense do not. It's worth presenting a few of the quotes from the article:

I say that, as soon as I conceive of a piece of matter, or a corporeal substance,...I do not feel my mind forced to conceive it as necessarily accompanied by such states as being white or red, bitter or sweet, noisy or quiet, or having a nice or nasty smell. On the contrary, if we were not guided by our senses, thinking or imagining would probably never arrive at them by themselves. This is why I think that, as far as concerns the object in which these tastes, smells, colours, etc., appear to reside, they are nothing other than mere names, and they have their location only in the sentient body. Consequently, if the living being were removed, all these qualities would disappear and be annihilated.

see also:

A wine's good taste does not belong to the objective determinations of the wine and hence of an object, even of an object considered as appearance, but belongs to the special character of the sense in the subject who is enjoying this taste. Colours are not properties of bodies to the inuition of which they attach, but are also only modifications of the sense of sight, which is affected in a certain manner by light.

Marco Piccolino, Nicholas J. Wade (2008). Galileo Galilei's vision of the senses Trends in Neurosciences, 31 (11)

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