Topics Color

Question If eyes had never evolved, would LIGHT still exist (or: be manifest)? By this I do not mean: would there still be electromagnetic radiation of a certain range of wavelengths (there would, of course). Rather, I mean: in the absence of eyes, would there still be brightness, luminance, illumination (i.e. what we ordinarily call 'light')? I am aware of course that, according to physics, light simply IS electromagnetic radiation of a certain range of frequencies. However, does this mean that things are, so to speak, illuminated "in themselves"? Or, contrariwise, is it the case that, in order to get what we ORDINARILY call 'light' (brightness, luminance etc., as opposed to Maxwell's equations), we must also take into account the way that electromagnetic waves excite our rods and cones etc.? In other words, without eyes -- and, therefore, without VISIBILITY -- would the entire universe remain 'in the dark'? Does it indeed make any sense to speak of the universe being either 'dark' or 'illuminated' in the absence of vision and visibility? Or -- to speak more generally -- would there be any 'phenomena' (i.e. would anything be 'manifest'), without a subject or dative TO WHOM they appear/manifest themselves? Any suggestions for reading on this issue -- especially scientifically informed literature -- would be greatly appreciated.

Accepted:
November 30, 2006

Comments

I think you've pretty much answered your own question. You see (get it?) that light could exist even in the absence of any creatures sensitive to it. And of course in such a situation, there would be no one and nothing experiencing the light. So is anything visible? "Visible," like many English words that end in "ible," "able," "uble," or "ile," picks out what philosophers call a "disposition" -- a condition of being ready, so to speak, to cause certain things to happen, or to undergo certain changes, if certain conditions are met. Salt is soluble -- that means that if it's put into a pot of water, then it will dissolve. Waterford crystal is fragile -- if you drop it, it will break. Similarly, to call an object visible is to say that if it is illuminated, and if a creature that is sensitive to light points its sensitive parts toward the object, then the object will cause the creature to have visual experiences (by bouncing the light onto the creature's eyes in a particular pattern).

The thing about dispositional properties is that objects can have them even if and while the "activating" conditions are not being met. The salt is soluble even while it's sitting in the carton (that's why you want to store it in a dry place -- if it weren't soluble, it wouldn't matter.) And the Waterford crystal is fragile even while it's sitting on the dining table (that's why you need to be careful with it. In fact, best not to use the good crystal at all.) Similarly -- and here comes the answer to your question, finally: things in the universe can be visible even if there's no one around for them to cause visual experiences in.

Now you wanted a little science, so here's a little science. It's an interesting question, part scientific, and part philosophical, whether color is a dispositional property of things. It turns out that color perception is amazingly complicated, and that it is not just a reaction to or detection of simple physical property. The physical property of objects that comes closest to being the objective basis of color is "spectral reflectance" -- a dispositional property of surfaces to reflect incident light in different patterns of wavelengths. But there are different combinations of wavelengths that will be perceived by human beings as the same hue. So what's color? Is it just the dispostional property of producing the effect of color perception in human beings (or other perceivers)? But in that case, the set of physical structures that have the property of being, say, teal is not going to be picked out by some objective physical property they all share, but rather by reference to the "teal-effects" they produce in us. That's different than the situation is with light, and it's lead some philosophers to conclude that color is really in the eye of the beholder. I think that view is wrong, because I think a set of physical structures still has something objectively in common if they all have a common power. But there's a lot of disagreement about this whole thing.

If you'd like to learn the details of the color debate, as well as some serious color science, here are two recommendations for further reading: the entry on "Color" in the Stanford Encyclopedia of Philosophy: http://plato.stanford.edu/entries/color/ and a book called Color for Philosophers by C. L. Hardin.