Reality+: Virtual Worlds and the Problems of Philosophy

by David J. Chalmers

Today’s VR and AR systems are primitive. The headsets and glasses are bulky. The visual resolution for virtual objects is grainy. Virtual environments offer immersive vision and sound, but you can’t touch a virtual surface, smell a virtual flower, or taste a virtual glass of wine when you drink it. These temporary limitations will pass. The physics engines that underpin VR are improving. In years to come, the headsets will get smaller, and we will transition to glasses, contact lenses, and eventually retinal or brain implants. The resolution will get better, until a virtual world looks exactly like a nonvirtual world. We will figure out how to handle touch, smell, and taste. We may spend much of our lives in these environments, whether for work, socializing, or entertainment. My guess is that within a century we will have virtual realities that are indistinguishable from the nonvirtual world. Perhaps we’ll plug into machines through a brain-computer interface, bypassing our eyes and ears and other sense organs. The machines will contain an extremely detailed simulation of a physical reality, simulating laws of physics to track how every object within that reality behaves. Sometimes VR will place us in other versions of ordinary physical reality. Sometimes it will immerse us in worlds entirely new. People will enter some worlds temporarily for work or for pleasure. Perhaps Apple will have its own workplace world, with special protections so that no one can leak its latest R...

Once simulation technology is good enough, these simulated environments may even be occupied by simulated people, with simulated brains and bodies, who will undergo the whole process of birth, development, aging, and death.

One can imagine that a few curious 23rd-century simulators might focus on the early 21st century. Let’s suppose the simulators live in a world in which Hillary Clinton defeated Jeb Bush in the US presidential election of 2016. They might ask: How would history have been different if Clinton had lost? Varying a few parameters, the simulators might go so far as to simulate a world where the 2016 victor was Donald Trump. They might even simulate Brexit and a pandemic.

Narcissistic simulators might nudge the parameters so that some simulated 21st-century philosophers speculate wildly about simulations built in the 23rd century. They might be especially interested in simulating the reactions of 21st-century readers reading thoughts about 23rd-century simulators, as you are right now.

Someone in such a virtual world would believe themselves to be living in an ordinary world in the early 21st century—a world in which Trump was elected president, the UK left the European Union, and there was a pandemic. Those events may have been surprising at the time, but humans have a remarkable capacity to adjust, and after a while these things become normal.

Although simulators may have nudged them into reading a book on virtual worlds, it will seem to them as if they are reading th...

“How do you know you’re not in a computer simulation right now?”

simulation hypothesis.

Philosophy translates as love of wisdom,

Philosophers are like the little kid who keeps asking, Why? or What is that? or How do you know? or What does that mean? or Why should I do that? Ask those questions a few times in a row and you rapidly reach the foundations. You’re examining the assumptions that underlie things we take for granted.

How can we know about reality? This last question was at the heart of the challenge posed by René Descartes in his Meditations on First Philosophy (1641), which set the agenda for centuries of Western philosophy to come. Descartes posed what I’ll call the problem of the external world: How do you know anything at all about the reality outside you? Descartes approached the problem by asking: How do you know that your perception of the world is not an illusion? How do you know that you are not dreaming right now? How do you know you’re not being deceived by an evil demon into thinking all this is real, when it’s not? These days, he might approach the problem by asking the question I just asked you: How do you know you’re not in a virtual world? For a long time I thought I didn’t have much to say about Descartes’s problem of the external world. Thinking about virtual reality gave me a new perspective. It was reflecting on the simulation hypothesis that led me to realize that I had underestimated virtual worlds. In their own way, so had Descartes and many others. I concluded that if we think more clearly about virtual worlds, this might lead us to the beginnings of a solution to Descartes’s problem.

Virtual reality is genuine reality.

virtual realities are genuine realities. Virtual worlds need not be second-class realities. They can be first-class realities.

Virtual worlds are not illusions or fictions, or at least they need not be. What happens in VR really happens. The objects we interact with in VR are real.

Life in virtual worlds can be as good, in principle, as life outside virtual worlds. You can lead a fully meaningful life in a virtual world.

The world we’re living in could be a virtual world. I’m not saying it is. But it’s a poss...

VR can be much more than escapism. It can be a full-blooded environment for living a genuine life.

Each virtual world is a new reality: Reality+. Augmented reality involves additions to reality: Reality+. Some virtual worlds are as good as or better than ordinary reality: Reality+. If we’re in a simulation, there is more to reality than we thought: Reality+. There will be a smorgasbord of multiple realities: Reality+. I know that what I’m saying is counterintuitive to many people. Perhaps you think that VR is Reality−, or Reality Minus. Virtual worlds are fake realities, not genuine realities. No virtual world is as good as ordinary reality. Over the course of this book, I’ll try to convince you that Reality+ is closer to the truth.

technophilosophy. Technophilosophy is a combination of (1) asking philosophical questions about technology and (2) using technology to help answer traditional philosophical questions.

The name is inspired by what the Canadian-American philosopher Patricia Churchland called neurophilosophy in her landmark 1987 book of the same title. Neurophilosophy combines asking philosophical questions about neuroscience with using neuroscience to help answer traditional questions in philosophy. Technophilosophy does the same with technology.

At a minimum, virtual reality technology helps illustrate Descartes’s problem—that is, how can we know anything about the reality around us? How do we know that reality is not an illusion?

“How do we know we’re not in a simulation right now?”

the it-from-bit hypothesis: Physical objects are real and they are digital.

Thinking about the simulation hypothesis and the it-from-bit hypothesis—two ideas inspired by modern computers—yields the beginnings of a response to Descartes’s classic problem.

We can put Descartes’s argument as follows: We don’t know that we’re not in a virtual world, and in a virtual world nothing is real, s...

This argument turns on the assumption that virtual worlds are no...

Once we make the case that virtual worlds are indeed genuine realities—and especially that objects in a virtual world are real—we...

How do mind and body interact?

What is consciousness?

Does the mind extend beyon...

Here’s my view of these things. Our minds are part of reality, but there’s a great deal of reality outside our minds. Reality contains our world and it may contain many others. We can build new worlds and new parts of reality. We know a little about reality, and we can try to know more. There may be parts of it that we can never know. Most importantly: Reality exists, independently of us. The truth matters. There are truths about reality, and we can try to find them. Even in an age of multiple realities, I still believe in objective reality.

Is this the real life? Is this just fantasy?

Once Zhuangzi dreamt he was a butterfly, a butterfly flitting and fluttering around, happy with himself and doing as he pleased. He didn’t know he was Zhuangzi. Suddenly he woke up and there he was, solid and unmistakably Zhuangzi. But he didn’t know if he was Zhuangzi who had dreamt he was a butterfly, or a butterfly dreaming he was Zhuangzi.

A dream world is a sort of virtual world without a computer. So Zhuangzi’s hypothesis that he is in a dream world right now is a computer-free version of the hypothesis that he’s in a virtual world right now.

If Neo had thought as deeply as Zhuangzi, he might have wondered, “Maybe my old life was the reality, and my new life is the simulation”—

Maybe the red pill knocked him out just long enough for him to be hooked up to this exciting simulation.

How do any of us know we aren’t dreaming right now?

How do we know anything we experience is real?

Narada says to the god Vishnu, “I have conquered illusion.” Vishnu promises to show Narada the true power of illusion (or Maya). Narada wakes up as a woman, Sushila, with no memory of what came before. Sushila marries a king, becomes pregnant, and eventually has eight sons and many grandsons. One day, an enemy attacks, and all her sons and grandsons are killed. As the queen grieves, Vishnu appears and says, “Why are you so sad? This is just an illusion.” Narada finds himself back in his original body only a moment after the original conversation. He concludes that his whole life is an illusion, just like his life as Sushila.

Around the same time as Zhuangzi, the ancient Greek philosopher Plato put forward his allegory of the cave. In his extended dialogue, the Republic, he tells the story of humans who are chained up in a cave, seeing only shadows cast on a wall by puppets that imitate things in the world of sunlight outside. The shadows are all the cave people know, so they take them to be reality. One day, one of them escapes and discovers the glories of the real world outside the cave. Eventually he reenters the cave and tells stories of that world, but no one believes him.

Plato’s spokesman, Socrates, raises the question of whether we should prefer life inside or outside the cave.

Socrates: Do you think the one who had gotten out of the cave would still envy those within the cave and would want to compete with them who are esteemed and who have power? Or would not he much rather wish for the condition that Homer speaks of, namely “to live on the land [above ground] as the paid menial of another destitute peasant”? Wouldn’t he prefer to put up with absolutely anything else rather than associate with those opinions that hold in the cave and be that kind of human being? Glaucon: I think that he would prefer to endure everything rather than be that kind of human being.

Life outside the cave, even life as a menial laborer, is vastly better than life inside it. We can ask the same question about virtual worlds. Which is better, life in a virtual world or life outside it? This leads us to a more fundamental question: What does it mean to live a good life?

In one traditional picture, philosophy is the study of knowledge (How do we know about the world?), reality (What is the nature of the world?), and value (What is the difference between good and bad?).

Knowledge: How can Zhuangzi know whether or not he’s dreaming? Reality: Is Narada’s transformation real or illusory? Value: Can one lead a good life in Plato’s cave?

The first question, raised by Zhuangzi’s butterfly dream, concerns knowledge. I’ll call it the Knowledge Question. Can we know whether or not we’re in a virtual world?

The second question, raised by Narada’s transformation, concerns reality. I’ll call it the Reality Question. Are virtual worlds real or illusory?

The third question, raised by Plato’s cave, concerns value. I’ll call it the Value Question. Can you lead ...

Can we know anything about the world around us? Is our world real or illusory? What is it to lead a good life?

To put my cards on the table: I don’t know whether we’re in a virtual world or not. I don’t think you know, either. In fact, I don’t think we can ever know whether or not we’re in a virtual world. In principle, we could confirm that we are in a virtual world—for example, the simulators could choose to reveal themselves to us and show us how the simulation works. But if we’re not in a virtual world, we’ll never know that for sure.