>[!citation] >Bostrom, N. (2003). Are we living in a computer simulation? *The Philosophical Quarterly*, 53(211), 243–255. https://doi.org/cpvbhd >[!abstract] >I argue that at least one of the following propositions is true: (1) the human species is very likely to become extinct before reaching a "posthuman" stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of its evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we shall one day become posthumans who run ancestor‐simulations is false, unless we are currently living in a simulation. I discuss some consequences of this result (Bostrom, 2003). >[!tip] Significance >Bostrom argues that if future civilizations attain immense computing power, they could run numerous detailed simulations of their ancestors, termed "ancestor-simulations." If these simulated beings possess consciousness—a possibility supported by the assumption of substrate-independence, which posits that mental states can arise from various physical substrates—then the number of simulated conscious beings could vastly outnumber actual human beings. Consequently, if a significant number of these simulations are created, it would be statistically probable that we are currently living in one. > >Therefore, unless we accept that we are likely living in a simulation, we must conclude that either humanity will not reach a posthuman stage capable of running such simulations, or that posthuman civilizations will choose not to run them. This challenges the belief that future generations will inevitably run ancestor-simulations, unless we are already within one.