What Color Is Red?

On arbitrary nature of human perception and values

Sender Spike
5 min readJan 20, 2022

Ask any Kabbalist and they will tell you that the world is a lie. Similarly, ask a Buddhist or a Vedantin and they, too, will unequivocally assert that the world as you perceive it is an illusion. And you can find the same sentiment in Plato.

It’s then quite ironic that there is an ongoing discussion that goes back to Greek philosophy and which revolves around the question, “Is the red color that I see the same red color that you see?”

I say it’s ironic but it’s actually not surprising. After all, despite the esteem in which it was (and continues to be) held and revered ever since, Greek philosophy (sans few exceptions such as Parmenides, partly Heraclitus and Plato, or Aristotelian logic) was more a self-indulgent mind masturbation than a deep insight into the nature of reality (which may also explain the ridiculous character of vast majority of Western thought which confuses impenetrable language and pompous proclamations with profundity — however, that’s beside the point).

Although it seems to me that the original question was asked as a roundabout way of inquiring about objective nature of world, let’s forgo any and all possible implications and let us focus on actual facts in relation to the original question as stated.

When we start with actual mechanics of how (not only human) vision works, few observations immediately pop out. First, electromagnetic radiation is defined by its frequency and has no intrinsic color. Second, out of the very narrow sliver of frequencies (wavelengths between c. 400 to 700 nm) that we call visible light (because it’s the range that triggers photoreceptors) human visual system then constructs an approximation of the environment.

In the words of neurophysiologist Paul King, “[t]he visible light frequency absorption and reflection patterns are detected by the eye as a primitive approximation of the true reflected electromagnetic spectrum. […] So when we “see color” what we are really doing is remotely sensing aspects of the molecular composition of object surfaces in the environment, but there is quite a bit of neural processing needed to convert detected visible light into what we perceive as surface color.” MRI scans then reveal that the neural processing associated with perceiving different frequencies occurs in different parts of visual cortex and these parts are consistently the same across all observed subjects.

Some people assume that it solves the whole riddle, yet, it still says nothing about subjective or objective nature of the cognate we call color. After all, it is quite logical that the actual processing happens in the same parts of the body. But what is the actual perception?

So, let’s move on and have a look at Adelson’s checker-shadow illusion.


If you load the image into any image editing program and use an eyedropper tool to check the colors, you will find out that both squares, A and B, have the same color. And yet, your brain interprets them as two distinct shades of gray. Still, to be completely impartial, it says nothing conclusive about whether the gray you perceive is the same gray I perceive. Where it leaves no wiggle room, however, is the observation that color perception is heavily dependent on actual context.

Thus, let’s move even further.

As Natalie Wolchover writes in an article for Live Science, “In work published in the journal Nature in 2009, Neitz and several colleagues injected a virus into the monkeys’ eyes that randomly infected some of their green-sensitive cone cells. The virus inserted a gene into the DNA of the green cones it infected that converted them into red cones. This conferred the monkeys with blue, green and red cones. Although their brains were not wired for responding to signals from red cones, the monkeys soon made sense of the new information, and were able to find green and red dots in a gray image.” These findings imply that, “Even though neurons in the monkeys’ brains were wired to receive signals from green cones, the neurons spontaneously adapted to receiving signals from red cones instead, somehow enabling the monkeys to perceive new colors.

Wolchover then continues quoting Joseph Carroll of the Medical College of Wisconsin, who was not involved in the research, commenting on the results. “The ability to discriminate certain wavelengths arose out of the blue, so to speak — with the simple introduction of a new gene. Thus, the [brain] circuitry there simply takes in whatever information it has and then confers some sort of perception.

Now this is as clear as it gets — color is a subjective construct.

And it goes even deeper because, as Berit Brogaard writes, “The variation in color categories across languages is another indicator of the variation in color vision,” and even though, “[t]o what extent linguistic variability reflects variation in color perception is a matter of debate […] an increasing number of studies seem to suggest that this might well be the case.

There you have it. Not only is the perception of color arbitrary on a physical level, it is also context dependent and there is a strong indication that it might be moldable by such “ethereal” factors as language and culture (all of which squares perfectly with what can be observed while meditating or “doing” psychedelics). Now, since vision is this pliable, one does not have to be a rocket scientist to see the arbitrary and consensual nature of human perception as such (*). Not to mention the utterly subjective essence of all value judgments such as meaning, aesthetics, or ethics.

Well, to answer the initial question, red has no color. And despite my stated reluctance to make any inferences, I must say that world is a lie, indeed.

(*) There is also e.g. a phenomenon well known to almost all musicians, one which I would call visual sound — one tweaks an EQ and hears clear changes in timbre of sound, only to find out that the EQ was switched off during the whole process and didn’t affect the sound at all.