When I was ten years old, I discovered computers. My first machine was a PDP-10 mainframe system at the medical center where my father worked. I taught myself to write simple programs in the BASIC computer language. Like any ten-year-old, I was especially pleased to discover games on the computer. One game was simply labeled “ADVENT.” I opened it and saw:
You are standing at the end of a road before a small brick building.
Around you is a forest.
A small stream flows out of the building and down a gully.
I figured out that I could move around with commands like “go north” and “go south.” I entered the building and got food, water, keys, a lamp. I wandered outside and descended through a grate into a system of underground caves. Soon I was battling snakes, gathering treasures, and throwing axes at pesky attackers. The game used text only, no graphics, but it was easy to imagine the cave system stretching out below ground. I played for months, roaming farther and deeper, gradually mapping out the world.
It was 1976. The game was Colossal Cave Adventure. It was my first virtual world.
In the years that followed, I discovered video games. I started with Pong and Breakout. When Space Invaders came to our local shopping mall, it became an obsession for my brothers and me. Eventually I got an Apple II computer, and we could play Asteroids and Pac-Man endlessly at home.
Over the years, virtual worlds have become richer. In the 1990s, games such as Doom and Quake pioneered the use of a first-person perspective. In the 2000s, people began spending vast amounts of time in multiplayer virtual worlds like Second Life and World of Warcraft. In the 2010s, there arrived the first rumblings of consumer-level virtual reality headsets, like the Oculus Rift. That decade also saw the first widespread use of augmented reality environments, which populate the physical world with virtual objects in games like Pokémon Go.
These days, I have numerous virtual reality systems in my study, including an Oculus Quest 2 and an HTC Vive. I put on a headset, open an application, and suddenly I’m in a virtual world. The physical world has disappeared entirely, replaced by a computer-generated environment. Virtual objects surround me, and I can move among them and manipulate them.
Like ordinary video games from Pong to Fortnite, virtual reality (or VR) involves a virtual world: an interactive, computer-generated space. What’s distinctive about VR is that its virtual worlds are immersive. Instead of showing you a two-dimensional screen, VR immerses you in a three-dimensional world you can see and hear as if you existed within it. Virtual reality involves an immersive, interactive, computer-generated space.
I’ve had all sorts of interesting experiences in VR. I’ve assumed a female body. I’ve fought off assassins. I’ve flown like a bird. I’ve traveled to Mars. I’ve looked at a human brain from the inside, with neurons all around me. I’ve stood on a plank stretched over a canyon—terrified, though I knew perfectly well that if I were to step off, I’d step onto a nonvirtual floor just below the plank.
Like many other people, during the recent pandemic I’ve spent a great deal of time talking to friends, family, and colleagues using Zoom and other videoconferencing software. Zoom is convenient, but it has many limitations. Eye contact is difficult. Group interactions are choppy rather than cohesive. There is no sense that we are inhabiting a common space. One underlying issue is that videoconferencing is not virtual reality. It is interactive but not immersive, and there is no common virtual world.
During the pandemic, I’ve also met up once a week with a merry band of fellow philosophers in VR. We’ve tried many different platforms and activities—flying with angel wings in Altspace, slicing cubes to a rhythm in Beat Saber, talking philosophy on the balcony in Bigscreen, playing paintball in Rec Room, giving lectures in Spatial, trying out colorful avatars in VRChat. VR technology is still far from perfect, but we’ve had the sense of inhabiting a common world. When five of us were standing around after a short presentation, someone said, “This is just like coffee break at a philosophy conference.” When the next pandemic arrives in a decade or two, it’s likely that many people will hang out in immersive virtual worlds designed for social interaction.
Augmented reality (or AR) systems are also progressing fast. These systems offer a world that is partly virtual and partly physical. The ordinary physical world is augmented by virtual objects. I don’t yet have my own augmented reality glasses, but companies like Apple, Facebook, and Google are said to be working on them. Augmented reality systems have the potential to replace screen-based computing entirely, or at least replace physical screens with virtual screens. Interacting with virtual objects may become part of everyday life.
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 Reality system under development. NASA will set up a world with spaceships in which people can explore the galaxy at faster-than-light speed. Other worlds will be worlds in which people can live indefinitely. Virtual real estate developers will compete to offer worlds with perfect weather near the beach, or with glorious apartments in a vibrant city, depending on what customers want.
Perhaps, as in the novel and movie Ready Player One, our planet will be crowded and degraded, and virtual worlds will provide us with new landscapes and new possibilities. In centuries past, families often faced a decision: “Should we emigrate to a new country to start a new life?” In centuries to come, we may face an equivalent decision: “Should we move our lives to a virtual world?” As with emigration, the reasonable answer may often be yes.
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. Like the nonplayer characters that one encounters in many video games, simulated people will be creatures of the simulation. Some worlds will be simulations set up for research or to make predictions about the future. For instance, a dating app (as seen on the TV series Black Mirror) could simulate many futures for a couple in order to see whether they are compatible.
A historian might study what would have happened if Hitler had chosen not to start a war with the Soviet Union. Scientists might simulate whole universes from the Big Bang onward, with small variations to study the range of outcomes: How often does life develop? How often is there intelligence? How often is there a galactic civilization?
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.
Simulators interested in the history of simulation might also be interested in the 21st century as a period when simulation technology was coming into its own. Perhaps they might occasionally simulate people who are writing books about possible future simulations, or people who are reading them! 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 about virtual worlds, it will seem to them as if they are doing so out of their own free choice. The excerpt they’re reading now is perhaps a little unsubtle in trying to convey the message that they may be in a virtual world, but they will take this in stride and start thinking about the idea all the same.
At this point, we can ask, “How do you know you’re not in a computer simulation right now?”
This idea is often known as the simulation hypothesis. It is famously depicted in the Matrix movies, in which what seems an ordinary physical world turns out to be the result of connecting human brains to a giant bank of computers. Inhabitants of the Matrix experience their world very much as we do, but the Matrix is a virtual world.
Could you be in a virtual world right now? Stop and think about this question for a moment. When you do, you’re doing philosophy.
Philosophy translates as love of wisdom, but I like to think of it as the foundations of everything. 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.
I was that kid. It took me a while to realize that what I was interested in was philosophy. I started off studying mathematics, physics, and computer science. These take you a fair distance into the foundations of everything, but I wanted to go deeper. I turned to studying philosophy, along with cognitive science to keep an anchor in the solid ground of science while I explored the foundations underneath.
I was first drawn to address questions about the mind, like What is consciousness? I’ve spent much of my career focusing on those questions. But questions about the world, like What is reality?, are just as central to philosophy. Perhaps most central of all are questions about the relation between mind and world, such as 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.
I hold that virtual reality is genuine reality. Or at least, virtual realities are genuine realities. Virtual worlds need not be second-class realities. They can be first-class realities.
We can break down this thesis into three parts:
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 possibility we can’t rule out.
The thesis—especially the first two parts—has practical consequences for the role of VR technology in our lives. In principle, VR can be much more than escapism. It can be a full-blooded environment for living a genuine life.
I’m not saying that virtual worlds will be some sort of utopia. Like the internet, VR technology will almost certainly lead to awful things as well as wonderful things. It’s certain to be abused. Physical reality is abused, too. Like physical reality, virtual reality has room for the full range of the human condition—the good, the bad, and the ugly.
In practice, the road to full-scale virtual reality is sure to be bumpy. It won’t surprise me if widespread adoption of VR is limited for a decade or two, while the technology matures. No doubt it will move in all sorts of directions I haven’t anticipated. But once a mature VR technology is developed, it should be able to support lives that are on a par with or even surpass life in physical reality.
Excerpted from Reality+: Virtual Worlds and the Problems of Philosophy. Used with the permission of the publisher, W. W. Norton & Company, Inc. Copyright © 2022 by David J. Chalmers.