The simulation hypothesis proposes that what one experiences as the real world is actually a simulated reality, such as a computer simulation in which humans are constructs.^[1][2] There has been much debate over this topic in the philosophical discourse.

Precursors include Zhuangzi's "Butterfly Dream" and René Descartes's "evil demon".^[3][4] In 2003, philosopher Nick Bostrom proposed the simulation argument suggesting that if a civilization becomes capable of creating conscious simulations, it could generate so many simulated beings that a randomly chosen conscious entity would almost certainly be in a simulation. This argument presents a trilemma:

1. either such simulations are not created because of technological limitations or self-destruction;
2. advanced civilizations choose not to create them;
3. if advanced civilizations do create them, the number of simulations would far exceed base reality and we would therefore almost certainly be living in one.

This assumes that consciousness is not uniquely tied to biological brains but can arise from any system that implements the right computational structures and processes (see Hard problem of consciousness).^[5][6]

Variations on the idea have also been featured in science fiction, appearing as a central plot device in many stories and films, such as Simulacron-3 (1964) and The Matrix (1999).^[7]

Human history is full of thinkers who observed the difference between how things seem and how they might actually be, with dreams, illusions, and hallucinations providing poetic and philosophical metaphors. For example, the "Butterfly Dream" of Zhuangzi from ancient China,^[8] or the Indian philosophy of Maya, or in ancient Greek philosophy, where Anaxarchus and Monimus likened existing things to a scene-painting and supposed them to resemble the impressions experienced in sleep or madness.^[9] Aztec philosophical texts theorized that the world was a painting or book written by the Teotl.^[10] A common theme in the spiritual philosophy of the religious movements collectively referred to by scholars as Gnosticism was the belief that reality as we experience it is the creation of a lesser, possibly malevolent, deity, from which humanity should seek to escape.^[11]

In the Western philosophical tradition, Plato's allegory of the cave analogized human beings to chained prisoners unable to see reality. René Descartes' evil demon philosophically formalized these epistemic doubts,^[12][13] to be followed by a large literature with subsequent variations like brain in a vat.^[14] In 1969, Konrad Zuse published his book Calculating Space on automata theory, in which he proposed the idea that the universe was fundamentally computational, a concept which became known as digital physics.^[15] Later, roboticist Hans Moravec explored related themes through the lens of artificial intelligence, discussing concepts like mind uploading and speculating that our current reality might itself be a computer simulation created by future intelligences.^[16][17][18]

Nick Bostrom's premise:

In physics, the view of the universe and its workings as the ebb and flow of information was first observed by Wheeler.^[43] Consequently, two views of the world emerged: the first one proposes that the universe is a quantum computer,^[44] while the other one proposes that the system performing the simulation is distinct from its simulation (the universe).^[45] Of the former view, quantum-computing specialist Dave Bacon wrote:

In many respects this point of view may be nothing more than a result of the fact that the notion of computation is the disease of our age—everywhere we look today we see examples of computers, computation, and information theory and thus we extrapolate this to our laws of physics. Indeed, thinking about computing as arising from faulty components, it seems as if the abstraction that uses perfectly operating computers is unlikely to exist as anything but a platonic ideal. Another critique of such a point of view is that there is no evidence for the kind of digitization that characterizes computers nor are there any predictions made by those who advocate such a view that have been experimentally confirmed.^[46]

Astrophysicist Neil Degrasse Tyson said in a 2018 NBC News interview that he estimated the likelihood of the simulation hypothesis being correct at "better than 50-50 odds", adding "I wish I could summon a strong argument against it, but I can find none".^[50] However, in a subsequent interview with Chuck Nice on a YouTube episode of StarTalk, Tyson shared that his friend J. Richard Gott, a professor of astrophysical sciences at Princeton University, made him aware of a strong objection to the simulation hypothesis. The objection claims that the common trait that all hypothetical high-fidelity simulated universes possess is the ability to produce high-fidelity simulated universes. And since our current world does not possess this ability, it would mean that either humans are in the real universe, and therefore simulated universes have not yet been created, or that humans are the last in a very long chain of simulated universes, an observation that makes the simulation hypothesis seem less probable. Regarding this objection, Tyson remarked "that changes my life".^[51]

Elon Musk, the CEO of Tesla and SpaceX, stated that the argument for the simulation hypothesis is "quite strong".^[52] In a podcast with Joe Rogan, Musk said "If you assume any rate of improvement at all, games will eventually be indistinguishable from reality" before concluding "that it's most likely we're in a simulation".^[53] At various other press conferences and events, Musk has also speculated that the likelihood of us living in a simulated reality or computer made by others is about 99.9%, and stated in a 2016 interview that he believed there was "a one in billion chance we're in base reality".^[52][54]

The idea that a dream could be considered a type of simulation capable of fooling the dreamer, and that perhaps even waking reality is entirely a dream, existed long before Bostrom's formulation. One of the first philosophers to question the distinction between reality and dreams was Zhuangzi, a Chinese philosopher of the 4th century BC. He phrased the problem as the well-known "Butterfly Dream", which went as follows:

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 unmistakable Zhuangzi. But he didn't know if he was Zhuangzi who had dreamt he was a butterfly or a butterfly dreaming he was Zhuangzi. Between Zhuangzi and a butterfly there must be some distinction! This is called the Transformation of Things. (2, tr. Burton Watson 1968:49)

The philosophical underpinnings of this argument are also brought up by Descartes, who was one of the first Western philosophers to do so. In Meditations on First Philosophy, he states "...there are no certain indications by which we may clearly distinguish wakefulness from sleep",^[55] and goes on to conclude that "It is possible that I am dreaming right now and that all of my perceptions are false".^[55]

Chalmers (2003) discusses the dream hypothesis and notes that this comes in two distinct forms:

• that he is currently dreaming, in which case many of his beliefs about the world are incorrect;
• that he has always been dreaming, in which case the objects he perceives actually exist, albeit in his imagination.^[56]

Both the dream argument and the simulation hypothesis can be regarded as skeptical hypotheses. Another state of mind in which some argue an individual's perceptions have no physical basis in the real world is psychosis, though psychosis may have a physical basis in the real world and explanations may vary.

In On Certainty, the philosopher Ludwig Wittgenstein has argued that such skeptical hypotheses are unsinnig (i.e. non-sensical), as they doubt knowledge that is required in order to make sense of the hypotheses themselves.^[57] Bertrand Russell has argued that the dream hypothesis is not a logical impossibility, but that common sense as well as considerations of simplicity and inference to the best explanation rule against it.^[58]

The dream hypothesis is also used to develop other philosophical concepts, such as Valberg's personal horizon: what this world would be internal to if this were all a dream.^[59]

Lucid dreaming is characterized as an idea where the elements of dreaming and waking are combined to a point where the user knows they are dreaming, or waking perhaps.^[60]

The simulation hypothesis and related themes like simulated reality have been explored in literature, film and theatre.^[61]

Simulacron-3 (1964) by Daniel F. Galouye is an early exploration of a computer-simulated city and inspired screen adaptations including World on a Wire (1973) and, later, The Thirteenth Floor (1999).^[62][63]

The Matrix (1999) popularized the idea of humanity unknowingly living inside a machine-generated virtual reality.^[64]

In Overdrawn at the Memory Bank (1983/1984), the protagonist undergoes compulsory “doppling” therapy that transfers his consciousness, and—after a mishap—his mind is kept inside the corporation's central computer.^[65]

Theatre has also treated the topic. Jay Scheib’s 2012 play World of Wires was explicitly inspired by Bostrom’s simulation argument and by Fassbinder’s World on a Wire.^[66][67]

Philip K. Dick’s short story “We Can Remember It for You Wholesale” (1966)—about implanted memories and unstable realities—formed the basis for Total Recall (1990) and its 2012 remake.^[68]

In 2025, Italian creative director and producer Giorgio Fazio released the two-track project Nothing But Simulation, thematically tied to the simulation hypothesis and paired with a generative web experience.^[69][70]

• Artificial life
• Artificial society
• Boltzmann brain
• Brain in a vat
• Digital physics
• Interface theory
• Fine-tuned universe
• Holographic principle
• Matrix defense
• Metaverse
• Mind uploading
• Subjective idealism
• Virtual reality

• Copleston, Frederick (1993) [1946]. "XIX Theory of Knowledge". A History of Philosophy, Volume I: Greece and Rome. New York: Image Books (Doubleday). p. 160. ISBN 978-0-385-46843-5.
• Copleston, Frederick (1994) [1960]. "II Descartes (I)". A History of Philosophy, Volume IV: Modern Philosophy. New York: Image Books (Doubleday). p. 86. ISBN 978-0-385-47041-4.
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• Tipler, Frank (1994). The Physics of Immortality. Doubleday. ISBN 978-0-385-46799-5.
• Lem, Stanislaw (1964). Summa Technologiae. Suhrkamp. ISBN 978-3-518-37178-7. {{cite book}}: ISBN / Date incompatibility (help)
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• Conitzer, Vincent. "A Puzzle About Further Facts". Open access version of article in Erkenntnis.
• Lev, Gid'on. Life in the Matrix. Haaretz Magazine, April 25, 2019, p. 6.
• Merali, Zeeya. "Do We Live in the Matrix?" Discover, December 2013, pp. 24–25. Subtitle: "Physicists have proposed tests to reveal whether we are part of a giant computer simulation".
• Grupp, Jeff (2021-09-01). "The Implantation Argument: Simulation Theory is Proof that God Exists". Metaphysica. 22 (2): 189–221. doi:10.1515/mp-2020-0014. S2CID 237494519.
• Laszlo, Fazekas (2026). Simulated Reality: Brain–Machine Interfaces and Transhumanism. Amazon. ISBN 979-8244192735.

• Are We Living in a Computer Simulation?—Nick Bostrom's Simulation Argument webpage