Reality+: Virtual Worlds and the Problems of Philosophy

by David J. Chalmers

We can never prove we’re not in a computer simulation because any evidence of ordinary reality—whether the grandeur of nature, the antics of your cat, or the behavior of other people—could presumably be simulated.

Nick Bostrom has argued on statistical grounds that under certain assumptions, there will be many more simulated people in the universe than nonsimulated people. If that’s right, perhaps we should consider it likely that we’re in a simulation.

This verdict has major consequences for Descartes’s problem: How do we know anything about the external world? If we don’t know whether or not we’re in a virtual world, and if nothing in a virtual world is real, then it looks like we cannot know if anything in the external world is real.

Child: Do not try and bend the spoon. That’s impossible. Instead . . . only try to realize the truth. Neo: What truth? Child: There is no spoon.

“What you think you’re awakening to may in fact be another species of illusion. It’s illusions all the way down.” Here there is an echo of Vishnu: Simulations are illusions, and ordinary reality may be an illusion, too.

I think: Simulations are not illusions. Virtual worlds are real. Virtual objects really exist.

The same goes for our world. Even if we’re in a simulation, our world is real. There are still tables and chairs and people here. There are cities, there are mountains, there are oceans. Of course there may be many illusions in our world. We can be deceived by our senses and by other people. But the ordinary objects around us are real.

What do I mean by “real”?

the word “real” doesn’t have a single, ...

A virtual chair or table is made of digital processes, just as a physical chair or table is made of atoms and quarks and ultimately of quantum processes. The virtual object is different from the nonvirtual one, but both are equally real.

Narada’s life as a woman is not entirely an illusion.

Nor is Morty’s life as a football star and c...

The long lives that they experience really happen. Narada really lives a life as Sushila. Morty really lives a life a...

If we’re in a simulation, tables are real (they’re patterns of bits), and if we’re not in a simulation, tables are real (they’re something else). So either way, tables are real.

James Gunn’s 1954 science-fiction story “The Unhappy Man,” a company known as Hedonics, Inc., uses the new “science of happiness” to improve people’s lives. People sign a contract to move their life into “sensies,” a sort of virtual world where everything is perfect: We take care of everything; we arrange your life so you never have to worry again. In this age of anxiety, you never have to be anxious. In this age of fear, you never need be afraid. You will always be fed, clothed, housed, and happy. You will love and be loved. Life, for you, will be an unmixed joy.

Gunn’s sensies and Nozick’s experience machine are virtual reality devices of a kind. They are asking, “Given the choice, would you spend your life in this kind of engineered reality?” Like Gunn’s protagonist, Nozick says no, and he expects his readers to do the same. His view seems to be that the experience machine is a second-class reality. Inside the machine, one does not actually do the things one seems to be doing. One is not a genuine autonomous person. For Nozick, life in the experience machine does not have much meaning or value.

We can ask the same question of VR more generally. Given the chance to spend your life in VR, would you do it? Could this ever be a reasonable choice? Or we can ask the Value Question directly: Can you lead a valuable and meaningful life in VR?

In full-scale VR, users will build their own lives as they choose, genuinely interacting with others around them and leading a meaningful and valuable life. Virtual reality need not be a second-class reality.

Many of us already spend a great deal of time in virtual worlds. In the future, we may well face the option of spending more time there, or even of spending most of our lives there. If I’m right, this will be a reasonable choice.

Many would see this as a dystopia. I do not. Certainly virtual worlds can be dystopian, just as the physical world can be, but they won’t be dystopian merely because they’re virtual. As with most technologies, whether VR is good or bad depends entirely on how it’s used.

(1) Metaphysics, the study of reality. Metaphysics asks questions like “What is the nature of reality?” (2) Epistemology, the study of knowledge. Epistemology asks questions like “How can we know about the world?” (3) Value theory, the study of values. Value theory asks questions like “What is the difference between good and bad?”

The Mind Question: What is the place of minds in virtual worlds? The God Question: If we’re in a simulation, is there a god? The Ethics Question: How should we act in a virtual world? The Politics Question: How should we build a virtual society? The Science Question: Is the simulation hypothesis a scientific hypothesis? The Language Question: What is the meaning of language in a virtual world?

Like our three main questions, these six further questions each correspond to an area of philosophy: the philosophy of mind, the philosophy of religion, ethics, political philosophy, the philosophy of science, and the philosophy of language.

THE ANTIKYTHERA MECHANISM WAS FOUND IN A SHIPWRECK off the coast of the Greek island of Antikythera in 1901. It dates from two thousand years earlier. The mechanism is a bronze device that was originally mounted in a wooden box about 13 inches across. Superficially, it resembles a clock, with a complex system of 30 or more gears that once drove pointers and dials on the front and the back. Through painstaking analysis over the last century, researchers have discovered that the pointers simulate the day-by-day positions of the Sun and Moon in the zodiac according to the theories of the astronomer Hipparchus of Rhodes. Recently, mathematical analysis of surviving text and gear fragments has provided strong evidence that the system simulated the five known planets as well. It appears that the Antikythera mechanism is an attempt to simulate the solar system. It is the first known cosmic simulation.

The Antikythera mechanism is a mechanical simulation. In a mechanical simulation, the positions of components reflect the positions of the entities they’re simulating.

One could use it to predict a solar eclipse years in the future.

Mechanical simulations are still used from time to time. One prominent example is a mechanical simulation of the San Francisco Bay and its environs, erected in a giant warehouse taking up more than an acre just outside San Francisco. It’s a scale model, with enormous amounts of water moved by hydraulic mechanisms to simulate tides, currents, and other forces. It was built to test whether a plan for building dams on the bay would work. The mechanical simulation showed that it wouldn’t, and the dams were never built.

In the celebrated code-breaking unit in Bletchley Park (depicted in the film The Imitation Game), the British mathematician Alan Turing and other researchers built some of the first computers in order to simulate and analyze German code systems. After the war, the mathematical physicists Stanislaw Ulam and John von Neumann used the ENIAC computer to simulate the behavior of neutrons in a nuclear explosion.

Whereas a mechanical simulation is driven by physical mechanisms, a computer simulation is driven by algorithms.

Instead of using pointers and gears to reflect the positions of the planets, a modern computer simu...

An algorithmic simulation of the observed laws of planetary motion makes sure that the bits evolve in a way that reflects the positions of the planets. Using this method, we now have accurate simulations of the solar system allow...

Computer simulations are ubiquitous in science and engineering. In physics and chemistry, we have simulations of atoms and molecules. In biology, we have simulations of cells and organisms. In neuroscience, we have simulations of neural networks. In engineering, we have simulations of cars, planes, bridges, and buildings. In planetary science, we have simulations of Eart...

In the social sphere, there are many computer simulations of human behavior. As early as 1955, Daniel Gerlough completed a PhD thesis on computer simulation of freeway traffic. In 1959, the Simulmatics Corporation was founded to simulate and predict how a political campaign’s messaging would affect various groups of voters. It was said that this effort had a significant effect on the 1960 US presidential election. The claim may have been overblown, but since then, social and political simulations have become mainstream. Advertising companies, pol...

Simulation technology is improving fast, but it’s far from perfect. A simulation usually concentrates on a certain level. A population-level simulation approximates human behavior with simple psychological models, but it doesn’t usually t...

There are no useful simulations of human behavior that also simulate the atoms within the human brain.

The same goes for simulations of the whole universe. To date, most cosmic simulations focus on the development of galaxies, typically laying a mesh over an area of the cosmos that divides it into huge units (or cells). The simulation indicates how these cells evolve and interact over time. In some systems, the size of the mesh is flexible, so that cells can become smaller in certain areas for a more fine-grained analysis. But it is rare for a cosmic simulation to descend to the level of simulating individual stars, let alone planets or organisms on those planets.

Within the next century, however, we may construct reasonably accurate simulations of human brains and behavior. Sometime after that, we might have plausible simulations of a whole human society. Eventually we might simulate a solar system or even a universe, from the level of atoms to the level of the cosmos. In such a system, there will be bits corresponding to every entity in the universe being simulated.

Once we have fine-grained simulations of all the activity in a human brain, we’ll have to take seriously the idea that the simulated brains are themselves conscious and intelligent. After all, a perfect simulation of my brain and body will behave exactly like me. Perhaps it might have its own subjective point of view. Perhaps it will experience an environment exactly like the one I experience. At this p...

Some simulations are based on reality, while others are not. In his 1981 book Simulacra and Simulation, the French philosopher Jean Baudrillard distinguished four phases of simulation according to how closely they mirror reality.

The first phase is representation, which is the “reflection of a profound reality.” The last phase is a simulacrum, which “has no relation to any reality whatsoever.”

Baudrillard is talking about cultural symbols and not computer simulations, but a distant cousin of his distinction can be used to classify fo...

Some simulations (akin to Baudrillard’s representations) aim to simulate a particular aspect of reality as closely as possible, the way a map repre...

A historical simulation of the Big Bang or the Second World War aims to replicate those past events closely. A scientific simulation of water boiling aims to si...

Some simulations aim to simulate something that could happen in reality. A flight simulator usually doesn’t aim to simulate a flight that has already happened, but to simulate one that could happen. A military simulation may try to simulate wh...

Some simulations aim to simulate something that could have h...

An evolutionary simulation might simulate what would have happened if a massive asteroid impact hadn’t led to the extinction of the dinosaurs. A sporting simulation might simulate what would have happened if the Uni...

some simulations (akin to Baudrillard’s simulacra) aim to simulate worlds that bear no resemblance to reality. A scientific simulation might simulate a world without gravity. We might try to simula...

simulations are not just a guide to our actual universe. They are also a guide to the vast cosmos of possible universes. Phil...

There are possible worlds where the solar system never formed. There are even possible worlds where there was no Big Bang.

Computer simulations can help us to explore all of these possible worlds.