From the archive · June 23, 2026
Is this base reality?
How could you tell whether the world around you is real?
01 · Word
Simulation hypothesis
noun
The proposal that everything you experience is a simulation running on someone else's computer rather than the bottom level of reality
Examples
Ask whether we live in a simulation and you are asking an old question in silicon-age clothing.
The simulation hypothesis is unfalsifiable so far, which is why philosophers argue it and physicists mostly shrug.
Origin
The modern formulation comes from philosopher Nick Bostrom's 2003 paper “Are You Living in a Computer Simulation?” The underlying doubt is far older: Descartes' evil demon, Zhuangzi's butterfly dream, and Plato's cave all ask whether appearances are reality.
02 · Idea
Bostrom's trilemma
Bostrom argued that at least one of three statements must be true. First, civilizations almost always go extinct before they can run realistic ancestor-simulations. Second, advanced civilizations that could run such simulations almost never choose to. Third, we are almost certainly living in a simulation. The logic: if many civilizations run vast numbers of detailed simulated minds, then simulated observers would vastly outnumber real ones, so a randomly chosen observer, like you, would most likely be simulated. To escape that conclusion, you must accept option one or two.
This is the structure of Bostrom's 2003 paper. Its cleverness is that it does not claim we are in a simulation; it shows the three options are jointly exhaustive, forcing you to reject something you might have assumed: that technological civilizations survive, that they would run ancestor-simulations, and that we are not in one.
The argument doesn't say we are simulated. It says you must reject at least one comfortable assumption.
A good argument can trap you between options without telling you which one to pick.
Limits and context
The trilemma leans on contested assumptions: that consciousness can be simulated computationally at all, and that we can meaningfully assign probabilities across hypothetical observers. Many philosophers and physicists regard the hypothesis as untestable and therefore outside science; the argument is a piece of careful reasoning, not an empirical finding.
The enduring value is the method, not the verdict: reframing an unanswerable yes-or-no question as a set of exhaustive options is a reasoning trick that clarifies many debates far removed from simulated worlds.
03 · Moment
Descartes' evil demon
The Meditations on First Philosophy, published in Latin in 1641 by René Descartes
In his 1641 Meditations, René Descartes set out to doubt everything he could, to find whatever survived as certain. He imagined an all-powerful “evil demon” devoting itself to deceiving him, faking the sky, the earth, his own body, and every sensation. Under that radical doubt, the external world dissolved. But one thing held: even to be deceived, he had to exist as something doing the doubting. Hence his bedrock: cogito, ergo sum, “I think, therefore I am.”
- Published
- 1641
- Device
- The evil demon
- Bedrock
- “I think, therefore I am”
The caveat
Whether Descartes' cogito truly defeats radical skepticism has been debated ever since; critics question what exactly the “I” refers to. The historical point stands regardless: the simulation worry is old philosophy in new hardware.
Descartes' demon is the direct philosophical ancestor of the modern simulation and “brain in a vat” scenarios: a hypothetical deceiver generating a false reality. His response set the template too. You cannot verify the external world from the inside, but you can be certain of the existence of the thinker. Bostrom's simulation argument updates the demon into a computer while sharpening it into a probability claim; the question Descartes posed has simply changed costume across four centuries.
Descartes wrote of a “malignant demon” (genius malignus); later philosophers modernized the same setup as the “brain in a vat,” and technologists as the simulation.