Does evolution lead us to perceive reality, or is it all an illusion?

Donald D. Hoffman is a highly respected Professor of Cognitive Science at the University of California at Irvine.  He’s developed a “formal theory of conscious agents” that he describes in a new Atlantic article—or rather in an interview with Amanda Gefter called “The case against reality“. And for the life of me I can’t figure out what the man is trying to say. I haven’t read his more formal academic work, but if they’re presenting his theory in a public place like the Atlantic, it seems that what he’s saying should be clear. Yet what I read is either unclear, or, when it’s clear, seems wrong. You should read the short interview yourself, but here are the points I take from it. It’s all a mess, and seems a bit like a gemisch of quantum woo, evolutionary misunderstandings, and postmodernism. If there’s a substantive and important point in the piece, I’ve been too dense to see it.

I’ve indented bits of the interview below. I address three claims.

1). There is no external reality. Quantum mechanics has proved that. Hoffman seems to think that because quantum mechanics has disproved local realism for some particles (that is, has disproved the claim that a photon or electron, for instance, has a certain nature and is in a certain place, regardless of whether we know it), so it has disproved local realism for everything, including macro objects. What we see isn’t reality, or even an approximation of reality: it is all illusion molded by natural selection.

Experiment after experiment has shown—defying common sense—that if we assume that the particles that make up ordinary objects have an objective, observer-independent existence, we get the wrong answers. The central lesson of quantum physics is clear: There are no public objects sitting out there in some preexisting space. As the physicist John Wheeler put it, “Useful as it is under ordinary circumstances to say that the world exists ‘out there’ independent of us, that view can no longer be upheld.”

. . . Gefter: If snakes aren’t snakes and trains aren’t trains, what are they?

Hoffman: Snakes and trains, like the particles of physics, have no objective, observer-independent features. The snake I see is a description created by my sensory system to inform me of the fitness consequences of my actions. Evolution shapes acceptable solutions, not optimal ones. A snake is an acceptable solution to the problem of telling me how to act in a situation. My snakes and trains are my mental representations; your snakes and trains are your mental representations.

We’ll get to the “fitness consequences”—the selective pressures—in a minute, but I want to document Hoffman’s view of reality, which Gefter seems to accept:

Hoffman: . . . 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.

Gefter: But if there’s a W, are you saying there is an external world?

Hoffman: Here’s the striking thing about that. 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.

Gefter: The world is just other conscious agents?

Hoffman: I call it conscious realism: Objective reality is just conscious agents, just points of view. 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.

And one more bit, showing that brains aren’t real, either:

Hoffman: The idea that what we’re doing is measuring publicly accessible objects, the idea that objectivity results from the fact that you and I can measure the same object in the exact same situation and get the same results — it’s very clear from quantum mechanics that that idea has to go. Physics tells us that there are no public physical objects. So what’s going on? Here’s how I think about it. I can talk to you about my headache and believe that I am communicating effectively with you, because you’ve had your own headaches. The same thing is true as apples and the moon and the sun and the universe. Just like you have your own headache, you have your own moon. But I assume it’s relevantly similar to mine. That’s an assumption that could be false, but that’s the source of my communication, and that’s the best we can do in terms of public physical objects and objective science.

. . . 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.

I don’t know where to begin with this. First of all, just because a subatomic particle doesn’t have an intrinsic property until we measure it, and that property is dependent on how we measure it, doesn’t mean that macro objects don’t have properties or, as Hoffman implies, don’t exist. You can, after all, measure the momentum of a car, or of a stationary chair, with great accuracy. It seems to me that Hoffman is using a form of Chopra-ist woo here: claiming not only that certain claims about quantum mechanics extend all the way up to macro objects (yes, they do, but classical mechanics is adequate for macro phenomena, and that includes existence claims), but also that those objects don’t exist outside of consciousness. In fact, Hoffman claims, like Chopra, that the only real thing that exists is consciousness:

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.

I find this problematic in several ways. If the brain is an illusion and doesn’t really exist, where does consciousness come from? After all, if we fiddle with the Object Formerly Known as the Brain, and ablate certain parts of it, or give it chemicals, then consciousness goes away. Further, all observers agree on that. Isn’t it strange, if reality is only an illusion constructed by our consciousness, that giving ketamine to a brain removes its consciousness? Why do we all still perceive the same objects then, and agree that the chemical has the same effect? Or, if the Moon is a figment of our consciousness (Chopra has maintained exactly that!), why, when some scientists observe a Rover landing on the Moon, do other scientists perceive exactly the same thing? After all, that concurrence couldn’t reflect anything molded by natural selection—our fitness doesn’t depend on Moon landings. Surely that must say something about an external reality.

But on to evolution:

2). We don’t perceive reality accurately because evolution provides us not with an accurate take on reality, but with a series of illusions that enhance our fitness [reproductive output]. Again, maybe I’m missing something, but if external reality is solely a result of our consciousness (which comes from a nonexistent brain), then why are we even subject to natural selection? That already seems contradictory, but perhaps I’m not understanding Hoffman. But what I do understand is his argument, which is flawed, why evolution gives us a take on the world that doesn’t even come close to reality:

Gefter: People often use Darwinian evolution as an argument that our perceptions accurately reflect reality. They say, “Obviously we must be latching onto reality in some way because otherwise we would have been wiped out a long time ago. If I think I’m seeing a palm tree but it’s really a tiger, I’m in trouble.”

Hoffman: Right. 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.

Now I’ll admit right off the bat that natural selection occasionally confers traits that, in some circumstances, distort reality. We may, for example, have been selected to think that we’re brighter or better than we are, because having that illusion gives us a confidence and power that might enhance our fitness. As Steve Pinker has written:

. . . beliefs have a social as well as an inferential function: they reflect commitments of loyalty and solidarity to one’s coalition. People are embraced or condemned according to their beliefs, so one function of the mind may be to hold beliefs that bring the belief-holder the greatest number of allies, protectors, or disciples, rather than beliefs that are most likely to be true. Religious and ideological beliefs are obvious examples.

. . . publicly expressed beliefs advertise the intellectual virtuosity of the belief-holder, creating an incentive to craft clever and extravagant beliefs rather than just true ones. This explains much of what goes on in academia.

. . . the best liar is the one who believes his own lies. This favors a measure of self-deception about beliefs that concern the self…

And our everyday experience with objects can sometimes mislead us when evolved traits create optical illusions, like the famous “checker shadow illusion.” Futher, we know that our sensory system is imperfect and limited by our biological constitution, so that we miss things that other creatures can see, like the ultraviolet patterns perceived by birds and butterflies. Finally, natural selection will foster our consciousness of those animals, those environmental factors, and those traits that have the highest potential effect on our fitness. But that’s not the same thing as saying that our consciousness actually molds the appearance of those organisms and traits.

But I maintain that, in general, natural selection will favor a fairly accurate take on reality (assuming there is a reality), because the more accurately we perceive nature, the higher fitness we will have. Hoffman gives one example where he says we’re selected to have illusions, but I don’t find it particularly convincing:

Gefter: You’ve done computer simulations to show this. Can you give an example?

Hoffman: Suppose in reality there’s a resource, like water, and you can quantify how much of it there is in an objective order—very little water, medium amount of water, a lot of water. Now suppose your fitness function is linear, so a little water gives you a little fitness, medium water gives you medium fitness, and lots of water gives you lots of fitness—in that case, the organism that sees the truth about the water in the world can win, but only because the fitness function happens to align with the true structure in reality. Generically, in the real world, that will never be the case. Something much more natural is a bell curve—say, too little water you die of thirst, but too much water you drown, and only somewhere in between is good for survival. Now the fitness function doesn’t match the structure in the real world. And that’s enough to send truth to extinction.

I find that baffling. Why wouldn’t the fitness function be one like this: “we want enough water to drink, and to sate our band of hominins, but we don’t want to go jumping in huge ponds of water if we can’t swim.” I think Hoffman has gotten it all backwards: our consciousness doesn’t shape external reality to increase our fitness; rather, our fitness depends on accurately perceiving external reality. There are some exceptions. I’m convinced, for example, that natural selection molds our tastes, which are qualia, to conform to what’s good for us. That’s why we like fats and sweets so much. As I’ve always said, a rotting carcass probably tastes like heaven to a vulture. But in most cases we want to see things as they are, for our fitness depends on that. If we could mold reality through consciousness to match our fitness, we would be able to see all dangerous insects as highly visible: snakes and spiders, for example, would be perceived as bright red or orange. We should be able to evolve our color-vision system to enhance our fitness. But that’s a shade on the teleological side, and we just can’t do that.

Yes, many dangerous animals are cryptic. That proves that we can’t change our perception of reality willy-nilly—that there is an external reality out there (animals often enhance their own fitness by being cryptic, so they win the perception battle!).  We can’t often mold the way we see reality to match our fitness functions.

I won’t go on, as this is already too long, but I wanted to add one more claim by Hoffman.

3). Neuroscience hasn’t progressed because neuroscientists haven’t taken into account the quantum nature of brain function and neural activity. 

Gefter: It doesn’t seem like many people in neuroscience or philosophy of mind are thinking about fundamental physics. Do you think that’s been a stumbling block for those trying to understand consciousness?

Hoffman: I think it has been. Not only are they ignoring the progress in fundamental physics, they are often explicit about it. They’ll say openly that quantum physics is not relevant to the aspects of brain function that are causally involved in consciousness. They are certain that it’s got to be classical properties of neural activity, which exist independent of any observers—spiking rates, connection strengths at synapses, perhaps dynamical properties as well. These are all very classical notions under Newtonian physics, where time is absolute and objects exist absolutely. And then [neuroscientists] are mystified as to why they don’t make progress. They don’t avail themselves of the incredible insights and breakthroughs that physics has made. Those insights are out there for us to use, and yet my field says, “We’ll stick with Newton, thank you. We’ll stay 300 years behind in our physics.”

There is by no means universal agreement that quantum-mechanical phenomena, as opposed to classical mechanics, are important on the level of brains and perception.  There are good arguments, in fact, that we can use simple classical mechanics—assuming an external reality—when doing neuroscience. At any rate, I would take issue with the claim that our failure to grasp quantum mechanics has impeded the study of consciousness, or has slowed progress in neuroscience.

If you can figure out a really important point in Hoffman’s article, do point it out below.

h/t: Peter