It's rare that I find it difficult to put down a non-fiction book because I'm so eager to read the final chapters and grasp the author's concluding arguments.
Such was the case, though, with The Case Against Reality: Why Evolution Hid the Truth From Our Eyes, by Donald Hoffman. I hadn't planned to spend so much time reading the book this morning, but I carried on until I'd read all but a technical appendix.
Hoffman's Big Idea is this: evolution selects for fitness, not truth. If a living organism perceives reality well enough to be able to pass on its genes, that's what evolution is all about. Or at least, mostly about. In shorthand, FBT, Fitness Beats Truth.
Another acronym Hoffman uses a lot is ITP, the Interface Theory of Perception. Here's a paragraph that encapsulates key ideas in the book.
Perception is not about truth. It's about having kids. Genes that fashion perceptions that help us raise kids are genes that may win the fitness game and elbow their way into the next generation. The FBT Theorem tells us that winning genes do not code for perceiving truth.
ITP tells us that they code instead for an interface that hides the truth about objective reality and provides us with icons -- physical objects with colors, textures, shapes, motions, and smells -- that allow us to manipulate that unseen reality in just the ways we need to survive and reproduce.
Physical objects in spacetime are simply our icons in our desktop.
This Big Idea strikes me as being more right than wrong. Which means that I agree with most of what Hoffman says in his engrossing book.
Still, a Publisher's Weekly review had some key words that reflect how I see The Case Against Reality. "Intriguing but overreaching treatise."
I'm a believer in objective reality. So I resonated with Hoffman's contention in all but the final chapter that objective reality exists. For example, he writes:
According to the FBT Theorem, if selection shapes perceptions, then perceptions guide useful behaviors rather than report objective truths about an independent world. Something exists independent of us, but that something doesn't match our perceptions. This feels difficult to understand because of our penchant to reify our interface.
Hoffman notes that a Maserati certainly seems real. It can be seen, and touched with eyes closed. However, Hoffman says:
It proves nothing. It suggests, but does not prove, that there is something objective. But that something could be wildly different from anything you perceive.
When you open your eyes, you interact with that unknown something and create a visual icon of a Maserati. When you close your eyes and reach out your hand, you create a tactile icon. The same is true for all the other senses.
OK, that seems reasonable.
There's an objective reality, but all sentient beings perceive it differently. We humans view reality in one fashion, while other species view it quite differently. An ant, bat, dolphin, and eagle all have their own way of looking upon the world, as would, almost certainly, aliens from a galaxy far, far away.
I certainly agree that there is no one way, or preferred way, to perceive reality. Evolution has led each species here on Earth to possess different reality interfaces, in Hoffman's language. So the icons that populate these interfaces also are going to be unique.
No two people perceive the world in exactly the same way, and certainly no two species do. Hoffman appears to be on solid ground when he says this in his Preface:
The purpose of a desktop interface is not to show you the "truth" of the computer -- where "truth," in this metaphor, refers to circuits, voltages, and layers of software.
Rather, the purpose of an interface is to hide the "truth" and to show simple graphics that help you perform useful tasks such as crafting emails and editing photos. If you had to toggle voltages to craft an email, your friends would never hear from you.
That is what evolution has done. It has endowed us with senses that hide the truth and display the simple icons we need to survive long enough to raise offspring. Space, as you perceive it when you look around, is just your desktop -- a 3D desktop. Apples, snakes, and other physical objects are simply icons in your 3D desktop.
Those icons are useful, in part, because they hide the complex truth about objective reality. Your senses have evolved to give you what you need. You may want truth, but you don't need truth. Peceiving truth would drive our species extinct. You need simple icons that show you how to act to stay alive.
Perception is not a window on objective reality. It is an interface that hides objective reality behind a veil of helpful icons.
However, Hoffman casts independently existing objective reality aside in his final chapter. I found this intellectually dubious. He spends nine chapters arguing that evolution has fashioned interfaces for determining what is useful for us, fitness-wise. So what we perceive is objective reality filtered through both a species-specific interface and our personal interface.
(A blind person, for example, has a decidedly different interface than a sighted person.)
Then, in chapter 10, Hoffman casts objective reality aside. Or at least, objective reality that is independent of conscious agents. He writes:
"But," you might object, "didn't you earlier define 'objective reality' as that which exists when no one observes? And don't conscious experiences exist only when some agent observes? Haven't you contradicted yourself when you propose conscious realism, and claim that objective reality consists of conscious agents?"
Indeed, for sake of argument, I adopted a notion of objective reality that is accepted by most physicalists. Then I used evolutionary assumptions that are also accepted by most physicalists to make the case against physicalism and its notion of objective reality.
Now that I have presented that case, I am proposing a new ontology, and with it a new notion of objective reality in which conscious agents, with their experiences and structures, are central.
Well, I think his original ontology was stronger. Somehow Hoffman ends up arguing that "Objects, shapes, space, and time reside in consciousness. If the living creature were removed, all these qualities would be annihilated."
That's a huge argument to make in the concluding pages of a book where Hoffman argued quite differently up to that point. Understand: he isn't saying that living creatures perceive space and time from their own unique evolutionary perspective. Rather, he claims that there is no such thing as space and time absent a conscious observer.
He may be right. Perhaps the universe was just sitting there doing nothing for billions of years after the big bang, waiting for conscious observers to bring it into being.
But how did conscious observers come to exist if there was no space and time for evolution to work its magic? This strikes me as a major flaw in Hoffman's replacement ontology. His final two paragraphs sound way too New Age'y for my tastes.
What is spacetime? This book has offered you the red pill. Spacetime is your virtual reality, a headset of your own making. The objects you see are your invention. You create them with a glance and destroy them with a blink.
You have worn this headset all your life. What happens if you take it off?
That said, I still hugely enjoyed his book. Again, it seems much more right than wrong. Check out his TED talk, and I think you'll agree.