Reality Is in the Eye of the Beholder (Shimon Edelman, from Life, Death, and Other Inconvenient Truths, MIT Press Reader)
If different species, or even different individuals belonging to the same species, inhabit different perceptual worlds, what can we know about what the real world is like? Clearly enough to make action possible; apart from that, not much. Amazingly, the more basic a question about that real world seems, the more difficult it is to get a definitive answer to it. Is it dark at night? The sense in which it is for us is of little concern to a bat, and of no concern to a mole. Is air thick? Not really to us, but sufficiently so for a swallow to push against during its aerial acrobatics. Is water wet? Not to a duck or a water strider. In the face of such differences, it seems silly to insist that our perceptual world is somehow privileged or that what we perceive is how things really are.
How things look and feel depends not only on who is doing the looking and feeling, but also on what action or other purpose it serves, as well as on the perceiver’s experiential history (and therefore on memory) and bodily and emotional state. I may see a rock outcropping encountered on a hike as a human face or as a battering ram, depending on where my mind was wandering as I was walking up to it (arguably, the best hiking experience requires that the hiker practice just seeing instead of seeing as).
When I am hungry, a mountain track that I am facing looks steeper than right after a meal. The prospect of jumping at six o’clock in the morning into the indoor pool, in which the water is kept cool to prevent lap swimmers from overheating, feels discomforting to different degrees, depending on whether it is summer or winter outside, as I found out, having been doing this three times a week for many years. Luckily, it helps to think about other matters while swimming. For example, anticipating how the chapter that I am working on is going to end literally warms me up: It distracts me from the initial feeling of cold and I also swim faster, so that it takes me a couple of minutes less to do my usual 3,200 yards.
As we find ourselves compelled to doubt the very notion of objective truth about what the world is like, can science help? Yes, as long as we don’t expect it to do the impossible. Whatever the world is “really” like, evolution has been clearly successful — in an endless variety of strange and beautiful ways — in coming up with effective means of dealing with it. Science, which operates on much the same principles of variation and selection, can be at least equally successful. But evolution has no use for questions of ultimate truth and scientists too are supposed to shun them. In some disciplines, they have learned to do so. Is the electron really a wave or a particle? Quantum mechanics, an epitome of theoretical and practical success in physics, rightly refuses such questions.
The complexity of the human brain greatly exceeds that of any other physical system that we know of, so that in perception science it is even more important not to waste time on arguing about absolutes. What color is this banana? Purple (it’s my favorite variety from Costa Rica), but there is no matter of objective fact about this observation, because color has no physical definition: It is entirely the construct of the observer’s visual system in its interaction with the environment. At least as far as color is concerned, things are neither as they seem, nor otherwise.
There is a philosophical tradition out there that holds this — the essential emptiness of all things — to be an ultimate truth in its own right; indeed, the only ultimate truth.