Reality+: Virtual Worlds and the Problems of Philosophy

by David J. Chalmers

our simulator is a sufficiently advanced artificial intelligence, perhaps it will have no trouble paying scrupulous attention to each simulation in a batch as it evolves.

Furthermore, simulations of all sorts may well have stopping criteria. Scientists and decision-makers are using these simulations to gather information, and once they have the information they need, there may be no need for the simulation. Perhaps ethics guidelines will require that each simulation be allowed to play out indefinitely—but perhaps not. So we should be aware that there’s some chance that our universe will end abruptly once a stopping criterion is satisfied.

we might give some thought to what those stopping criteria might be and how to avoid satisfying them. (The very idea of a stopping criterion is at least superficially reminiscent of the 19th-century idea of the “end of history,” associated with the German philosopher Georg Wilhelm Friedrich Hegel and a number of other thinkers. One version of this idea holds that the world is evolving to a point where it becomes conscious of its nature, which is the endpoint of history. In the naturalistic key of simulation: perhaps simulators are studying what we know, and will terminate the simulation when we become conscious that we are in a simulation.)

Does the simulation hypothesis accommodate an afterlife? It may at least make an afterlife possible.

Computer processes are portable. Simulators may be able to transfer simulated brain processes from one simulated world to another (heaven?), or even connect them to a body in the simulators’ own world (reincarnation?). Perhaps that will happen in some simulations, especially in personal entertainment simulations, and perhaps for truly exceptional beings in batch simulations. Doing this routinely for most simulations would come with many costs, however. If those costs are prohibitive, we shouldn’t hope for a simulation afterlife. On the other hand, perhaps ethics review panels for simulators will insist that no simulated being ever be truly killed. After a sim “dies” in a s...

If we ever create artificial intelligence within a simulation, it may be hard to keep it contained. For instance, if we communicate with the simulated beings, they’ll presumably become aware that they’re in a s...

And even if we don’t communicate with them, they may seriously entertain the hypothesis that they’re in a simulation, and then do their best to figure the simulation out. That would be a form of simulation theology.

We could in principle do the same thing. We could try to attract the attention of our simulator and communicate with it—perhaps by writing books about simulations, or by constructing simulations. We could try to figure out our simulation, to determine its purpose and its limits. But if our simulator is an artificial intelligence who has designed a batch of watertight simulations and isn’t paying attention, then our efforts may be in vain.

A variation on the simulation argument can be used to argue that we are probably simsims: beings in s...

Does there have to be an unsimulated simulator at the top of the chain?

It’s highly intuitive that there must be a fundamental level with unsimulated reality. The alternative is reminiscent of the old story where an audience member tells the American philosopher William James that the earth stands on the back of a turtle that stands on another turtle in turn. When pressed on the details, she says “It’s turtles all the way down.” Still, the contemporary philosopher Jonathan Schaffer has argued that there need not be a fundamental level in nature: There could instead be a never-ending sequence of levels. If Schaffer is right, this opens up at least the theoretical possibility that we are in a cosmos where it is simulations all the way up.

Does simulation theology come with any set of moral practices? Why should it?

There might well be self-interested practices. For example, potential sims might act in certain ways in hopes of being uploaded out of the simulation.

Should we worship our simulator?

It’s hard to see why. The simulator may simply be a scientist or a decision-maker in the next universe up. We may be grateful to her for creating our world. We may be in awe of the power she has over our world. But gratitude and awe alone are not worship.

We may be terrified by the power that the simulator has over our lives. Perhaps if we came to believe that our simulator was like the Abrahamic God in demanding our worship as a condition for reaching the afterlife,...

But there’s not much reason to think a simulator will have a psychology like this. And if she does, does she really deserve our worship? To paraphrase Lem’s personoid Adan 900: Any...

Even if our simulator is a benevolent being, why should we worship her? She may be working to create as many worlds as possible with a sufficient balance of happiness over unhappiness in order to maximize the amount of happiness in the cosmos. If so, we might admi...

The point here goes beyond simulation. Even if the Abrahamic God exists, with all those godlike qualities of perfection, I will respect, admire, and even be in awe of him, but I won’t feel bound to worship him.

Generalizing the point, I don’t think any qualities can make a being worthy of worship.

What could make a being worthy of worship, and why?

IN 1679, GOTTFRIED WILHELM LEIBNIZ INVENTED THE BIT. THE German philosopher and mathematician is celebrated as the coinventor (along with Isaac Newton) of the calculus.

He also designed and built one of the first mechanical calculators.

He is famous for his optimistic thesis that we live in the best of...

none of his ideas was more important than the invention of the binary number system, on which all...

In his 1703 essay “Explanation of Binary Arithmetic,” Leibniz draws inspiration from the I Ching, the ancient Chinese Book of Changes. The I Ching uses hexagrams—stacks of six horizontal lines, one under another—for divination. The hexagrams can be understood as a simple binary code based on the distinction between yin and yang. Yin is encoded as a broken line, ...

Like the I Ching, the integrated circuits in modern computers encode sequences of bits. Where the I Ching uses a broken line for 0 and an unbroken line for 1, transistors in these circuits typically use a low voltage for 0 and a high voltage for 1, or vice versa. Where the I Ching encodes just six bits at a time, computers often encode a trillion or more bits. Almost everything in modern computers can be explained in terms of the interplay of bits.

This raises the question: Is our universe like the Game of Life? Is everything in our universe ultimately a pattern of bits?

This idea is sometimes called the it-from-bit hypothesis, a label first used by the physicist John Wheeler in 1989. Wheeler may have intended something different by the phrase, as I’ll discuss later in the chapter, but the it-from-bit idea is so powerful that it has transcended his original conception. The powerful idea is that everything in the physical world around us—tables and chairs, stars and planets, dogs and cats, electrons and quarks—is made of patterns of bits.

The it-from-bit hypothesis is a wonderful thing for a philosopher—a new metaphysical idea. Some philosophers have thought reality is made of minds. Others have thought it’s made of atoms. Now ...

Metaphysics,

“What is reality made of?”—that is, what is the fundamental level of reality from which everything else derives?

According to Australian Aboriginal traditions, reality as we know it originated in the Dreaming of ancestral spirits. According to Aztec traditions, reality is grounded in a self-generating power known as teotl.

Thales of Miletus, who lived around 600 BCE, 200 years before Plato. Thales is most famous, or infamous, for the metaphysical thesis that everything is made of water. Water is the “primary principle” from which all things come to be and to which all things return. You might ask, “What about trees and rocks?” Thales seems to have thought of them as modified forms of water that would eventually return to being water. Other Greek philosophers put forward rival hypotheses. Thales’ fellow Miletian Anaximenes, who lived around 550 BCE, suggested that everything is made of air. Earlier in that century, Heraclitus proposed that everything is made of fire. Heraclitus thought the world was fundamentally about change; hence his memorable remark that you cannot step into the same river twice. But neither the water hypothesis, the air hypothesis, nor the fire hypothesis really caught on.

A much more widespread hypothesis in ancient times held that reality was made of four or five basic elements: earth, air, fire, and water, and sometimes “aether” or “void.” In Greece, the four-element earth/air/fire/water system was put forward by Empedocles around 450 BCE.

Babylonian text, the Enuma Elis, dating from sometime before 1000 BCE, recounts a cosmic history in which the world is formed by gods representing earth, wind, sky, and sea. The Indian Vedas, around 1500–500 BCE, make frequent reference to five basic elements: often earth, air, fire, water, and space (or aether or void). The ancient Chinese Wu Xing system, dating from around 200 BCE, suggested five elements in an eternal cycle: Wood feeds fire, which creates earth, which bears metal, which collects water, which nourishes wood. In modern times, earth, air, fire, and water have been decomposed into more basic components, all the way down to quarks and electrons. Two other ancient Greek ideas have worn much better. Pythagoras, who lived around 550 BCE, suggested that everything is made of numbers. The number 1 represents the origin of all things, 2 represents matter, 3 represents beginning/middle/end, 4 represents the four seasons, and so on. While the specifics of the Pytha...

An even more influential metaphysical idea is associated with Democritus, who lived around 450 BCE. He was known as the “laughing philosopher” because of his cheerful manner. He is sometimes called “the father of modern science,” though his ideas were heavily influenced by his teacher, Leucippus. Democritus and Leucippus held that everything is made of atoms: tiny, indivisible bodies that move in an infinite void. A number o...

materi...

Materialism has been perhaps the most popular metaphysical view among philosophers and scientists in recent decades. It’s often regarded as the obvious metaphysics suggested by modern science, where the aim is to support ideas with experimenta...

The biggest obstacle to materialism has always been the e...

One alternative is idealism, the theory that reality is made of minds, or that realit...

We have encountered idealism already in Berkeley’s 18th-century thesis that appearance is reality, and in the Buddhist thesis that reality is consciousness-only. Idealism can also be found in the ancient Vedas of Hindu philosophy. It plays a central role in the Advaita Vedānta school, in which the ultimate reality is held to be Brahman, a sort of unive...

The other classical metaphysical theory is dualism, the idea that both matter and mind are fundamental. Dualism holds that one cannot explain mind in terms of matter, nor can one explain matter in terms of mi...

The Samkhya school of Indian philosophy was deeply dualist: The universe consists of purusa (consciou...

In the 17th century, René Descartes became a central advocate of dualism, arguing that the world consists of matter and minds in interaction.

In Western philosophy since Descartes’s time, metaphysical theorizing has typically involved an oscillation among materialism, dualism, and idealism.

Descartes’s English contemporary Thomas Hobbes advoc...

In the 18th century, Berkeley advocated idealism, and various forms of idealism dominated German and British ...

In the 20th century, the pendulum swung sharply back to materialism, which has remained the dominan...

Even idealism has been making a small comeback in 21st-century philosophy, in part because of an upswell in discussion of panpsychism, the thesis that all matter has an element of consciousness.