As we live our everyday lives, we usually feel that we are perceiving the world around us as it actually is. But are we really? Consider this chart:
Drawing from Abstruse Goose
Even if our eyesight is 20/20 and we have normal color vision, the range of electromagnetic radiation we can see is limited to a tiny portion of the full spectrum. Likewise, we generally cannot hear sounds lower than 20 Hz or higher than about 20,000 Hz. Even within those visible and audible frequency ranges, we can’t perceive light or sound that is too weak, and if they are too strong they overwhelm our senses. Our senses of touch, taste, and smell are similarly limited.
Our perceptions are also limited in terms of the size of things. Without the aid of a microscope, we’re unable to see very small things. (According to this, the smallest visible object we have any chance of seeing with the naked eye is six microns (six thousands of a millimeter). There are things much smaller than that we might wish we could see – viruses, for example – but you’d have to string together about 15 of the largest known viruses to form a line six microns long.
Nor can we see things that are too big. Have you ever seen Africa? Maybe you’ve seen a bit of it, but unless you’ve been to space you haven’t seen the whole thing at once.
We can directly perceive movement only when it happens on a human timescale. The motion of an oak tree growing taller and the motion of a bullet flying past are equally imperceptible to us.
Presumably, evolution has equipped us with the ability to perceive things that tend to be most important to our survival, enabling us to find food and avoid dangerous predators, for example. Evolution didn’t bother to giving us the ability to see radio waves because nothing in the natural environment that matters to us emits them.
In an article in The Atlantic titled The Case Against Reality, cognitive scientist Donald D. Hoffman argues that our senses do not present us with an accurate representation of reality:
“The classic argument is that those of our ancestors who saw more accurately had a competitive advantage over those who saw less accurately and thus were more likely to pass on their genes that coded for those more accurate perceptions, so after thousands of generations we can be quite confident that we’re the offspring of those who saw accurately, and so we see accurately. That sounds very plausible. But I think it is utterly false. It misunderstands the fundamental fact about evolution, which is that it’s about fitness functions—mathematical functions that describe how well a given strategy achieves the goals of survival and reproduction. The mathematical physicist Chetan Prakash proved a theorem that I devised that says: According to evolution by natural selection, an organism that sees reality as it is will never be more fit than an organism of equal complexity that sees none of reality but is just tuned to fitness. Never.”
Our visual system distorts reality in various ways in order to present a view of the world that is (usually) more helpful to us than a truly accurate representation would be. Optical illusions lay bare the tricks our brains are pulling on us. They are powerful reminders that we don’t see reality as it is.
If you lay a ruler across the lines in the above checkerboard pattern you’ll see that they are perfectly straight, even though they certainly don’t appear that way.
Quoting Hoffman again:
Evolution has shaped us with perceptions that allow us to survive. They guide adaptive behaviors. But part of that involves hiding from us the stuff we don’t need to know. And that’s pretty much all of reality, whatever reality might be. If you had to spend all that time figuring it out, the tiger would eat you.
Hoffman has developed a mathematical model of conscious experience:
My intuition was, there are conscious experiences. I have pains, tastes, smells, all my sensory experiences, moods, emotions and so forth. So I’m just going to say: One part of this consciousness structure is a set of all possible experiences. When I’m having an experience, based on that experience I may want to change what I’m doing. So I need to have a collection of possible actions I can take and a decision strategy that, given my experiences, allows me to change how I’m acting. That’s the basic idea of the whole thing. I have a space X of experiences, a space G of actions, and an algorithm D that lets me choose a new action given my experiences. Then I posited a W for a world, which is also a probability space. Somehow the world affects my perceptions, so there’s a perception map P from the world to my experiences, and when I act, I change the world, so there’s a map A from the space of actions to the world. That’s the entire structure. Six elements. The claim is: This is the structure of consciousness. I put that out there so people have something to shoot at.
Here’s the striking thing about that [the external world]. I can pull the W out of the model and stick a conscious agent in its place and get a circuit of conscious agents. In fact, you can have whole networks of arbitrary complexity. And that’s the world.
I call it conscious realism: Objective reality is just conscious agents, just points of view. Interestingly, I can take two conscious agents and have them interact, and the mathematical structure of that interaction also satisfies the definition of a conscious agent. This mathematics is telling me something. I can take two minds, and they can generate a new, unified single mind. Here’s a concrete example. We have two hemispheres in our brain. But when you do a split-brain operation, a complete transection of the corpus callosum, you get clear evidence of two separate consciousnesses. Before that slicing happened, it seemed there was a single unified consciousness. So it’s not implausible that there is a single conscious agent. And yet it’s also the case that there are two conscious agents there, and you can see that when they’re split. I didn’t expect that, the mathematics forced me to recognize this. It suggests that I can take separate observers, put them together and create new observers, and keep doing this ad infinitum. It’s conscious agents all the way down.
I’m emphasizing the larger lesson of quantum mechanics: Neurons, brains, space … these are just symbols we use, they’re not real. It’s not that there’s a classical brain that does some quantum magic. It’s that there’s no brain! Quantum mechanics says that classical objects—including brains—don’t exist. So this is a far more radical claim about the nature of reality and does not involve the brain pulling off some tricky quantum computation.
The formal theory of conscious agents I’ve been developing is computationally universal—in that sense, it’s a machine theory. And it’s because the theory is computationally universal that I can get all of cognitive science and neural networks back out of it. Nevertheless, for now I don’t think we are machines—in part because I distinguish between the mathematical representation and the thing being represented. As a conscious realist, I am postulating conscious experiences as ontological primitives, the most basic ingredients of the world. I’m claiming that experiences are the real coin of the realm. The experiences of everyday life — my real feeling of a headache, my real taste of chocolate — that really is the ultimate nature of reality.
P.S. All the Light We Cannot See is the title of a fascinating novel by Anthony Doerr.