Our arguments, big and small, often boil down to a simple misunderstanding: We generally believe that there is one true reality, and that diversions from that are made in error. You're wrong, because I'm clearly right, and whatever we're arguing about really went down the way that I saw it.
In essence we tend to believe that singular events—the building blocks of reality—would play back the same way over and over if somehow we could rewatch them from an entirely unbiased television screen. And from that belief stems the idea that, because there's one true reality, there's one true right answer to anything we perceive.
That's true when we can measure and quantify something with analytical tools more rigorous and standardized than our own senses—which sometimes don't agree with the reality we've scientifically proven. (Case in point: Galileo's tribulations over the then-mindboggling and reality-busting concept of heliocentrism.)
But our day-to-day reality is far more fluid, and is shaped at the mercy of our own ability to perceive the world through the rather inexact amalgamation of stimuli recorded by our senses and processed by our brains. Therein lies the rub: Since our senses and brains and experiences and everything else we use to navigate the world are far from standardized—humans are nowhere near robots yet—it is essentially impossible, or at least very difficult, for any of us to see the world the same exact way. Reality, at least as we use it to describe the spaces and experience we're all bumbling through, is actually plural.
Color is only a construct because we mostly agree it exists as a concept.
Sometimes the effects of this are subtle: You're at a dinner party, and you're convinced that some dumbass's comment was more snide than your date thinks, which is the sum product of your differing experiences with said dumbass, your ability to read social cues, and perhaps an unbalanced gradient of self-consciousness across your date and yourself.
Other times the effects are more profound: We say the sky is blue because most humans see it as the same hue. But do we really know that it's blue? Well, sure, we've defined the light produced by electromagnetic radiation of wavelengths around 475nm as "blue," but that feels a bit like defining the rules of the game after we've already won. But in the practical sense, we can only agree that blue is more or less one range of shades because most of our eyes and brains process those wavelengths in the same way.
How about this though: We all agree that blue is the same color because we've assigned "blue" to a set series of electromagnetic wavelengths. But how do you know that blue looks the same to you as it does to someone else? His blue might look more green, but because he's always been told that color is blue, then who's to know the difference?
In fact, we don't always know. I found a 1969 study in Sociometry that addresses the very issue above. In the experiment, groups of people were shown an "objectively blue stimulus," and in some groups a pair of "stooges" (authors' word, not mine) would say that the color was actually green. Oddly enough, members of those experimental groups said that the blue object they were looking at was actually green a significantly higher proportion of the time than the control group. The study thus makes a rather profound point: If even a minority of a certain population is steadfast in projecting its perception against the common grain, it can produce an actual change in the group's reality.
So blue and green, even if they can be objectively defined, seem to be more malleable constructs than we might believe. What happens if they aren't even really constructs at all, as is the case for someone who's been fully blind since birth? The question of how blind people perceive colors is a perennially popular internet topic, and for the answer in the abstract, I like this bit from the University of Illinois' physics department:
Different wavelengths of visible light have different colors, and mixtures of light of different wavelengths have different colors. A blind person can feel the thermal energy deposited by light, and so can be convinced that light exists and carries energy. Then it is just a matter of description of what light is and its properties. I'm afraid that for a blind man this may remain abstract and unverifiable, and he may just have to take his friends' word for it all.
Still, the question itself of how blind people perceive colors lays bare our own bias towards a color-based reality. Think of it this way: We perceive and think in colors because that's what our eyes happen to give us. But if our reality was colorless, or sightless, it wouldn't be lacking, it'd just be different. As Jim Davies put it in Nautilus:
Imagine telling a goose (who doesn't know much about humans) that you can't sense Earth's magnetic field. The bird, baffled, asks, "So, what do you sense when you change the direction you're facing??"
The answer, of course, is nothing. Just as blind people do not sense the color black, we do not sense anything at all in place of our lack of sensations for magnetic fields or ultraviolet light. We don't know what we're missing.
To try to understand what it might be like to be blind, think about how it "looks" behind your head. When you look at the scene in front of you, it has a boundary. Your visual field extends to each side only so far. If you spread your arms, and draw your hands back until they are no longer visible, what color is the space that your hands occupy? This space does not look black. It does not look white. It just isn't.
At this point, it seems particularly silly to assume that Reality, capital R, is a singular thing. It's different for all of us, entirely because our imprecise, non-standardized, messy, awkward, wonderful bodies don't process stimuli in the same way. We all see things a little bit differently, and our inability to articulate that—or even accept it—is the source of all kinds of frustrations.
So here's a thought: What would happen if our perception did become standardized? If all of our senses worked the same way, and we all processed the scent of peanut butter the same way, and all liked it or didn't like it because we had the same set of processing values in our brains?
Our brains are powered by electrical stimuli, and it's not too much of a stretch to think of them as computers. The Defense Advanced Research Projects Agency doesn't have a problem thinking in those terms, and the result is DARPA's work on brain-stimulating implants that can help regulate and repair brain function. It goes beyond: In the stuff of futures we didn't expect to already be facing, DARPA is even developing "memory prosthetics," which could implant or modify memories to help someone with PTSD.
Digitizing the brain is the next step, and despite the computational and logistical problems, it seems a matter of when, not if, a Johnny Mnemonic or The Matrix-type immersion-reality technology is going to appear.
Even if it looks nothing like either of those movies, the point is we'll be jacking into a digital reality at some point. Take your pick of cyberpunk sci-fi, if you must, but there's a point that's often missed in fiction that revolves around digital reality. I think it's best typified by The Matrix because of its white-room-full-of-guns emphasis on the super action hero aspects of being able to hack a digital construct: What about all the normal-ass people in that world?
The digital world presented in The Matrix is supposed to be a perfect representation of the living world, and maybe it is, but when we start to step our toes into digital reality, there's one very real issue to face: That reality will be built on the rules of the perceived reality of whoever built it. Those normal people in The Matrix's world, the ones who've been shoved into a digital reality that isn't based on their own cognitive ruleset and allegedly haven't figured it out, would have to chafe a bit at how it all just feels not quite right.
The old adage is that a machine is only as smart as the person who makes it, and a facet of that is that any digital world we build in the near future, one that's more or less seamlessly integrated with our own brains, will be limited to the rules of perception of its makers.
So if we accept that none of our realities are exactly the same, due to the kaleidoscope of differences in all of our bodies, and accept that those differing realities produce enough friction as it is, what's going to happen when we're forced into a unified set of rules, ones we might never have known existed, for what reality actually is?
Perhaps our psyches are malleable enough to accept it for what it is, and it'll be fun as shit, just like we don't entirely freak out when playing a video game—well, most of the time. It wouldn't be entirely surprising. To bring it back to the colors, a 1997 study explored methods for digitizing colored images to simulate dichromatic color blindness for people with normal vision. It's a pretty basic computational experiment by today's standards, but this line stands out: "Although we can never be certain of another's sensations, the simulation provides a means of quantifying and illustrating the residual color information available to dichromats in any digitized image." In other words, we can't always be sure that anything is real, but we're pretty good at accepting reality for reality's sake, even if it's weird.
Or maybe we aren't. Perhaps the first person to jack in will immediately lose his or her mind to an irreparable degree, as was the case in Cypulchre, a nice book I read recently.
Then again, we are human after all, and we largely play by the same rules. It's not like DARPA's memory implant is going to force a dog or a jellyfish's reality construct into your consciousness. My guess is that being forced to play by someone else's ruleset for perception will be a bit like putting on an ill-fitting shirt: not entirely disastrous, but you might start to wonder why everyone's faces are all melty today.