Link to original article

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Simulation arguments, published by Joe Carlsmith on February 18, 2022 on The Effective Altruism Forum. “If Nature herself proves artificial, where will you go to seek wildness? Where is the real out-of-doors?” – C.S. Lewis (Cross-posted from Hands and Cities. Content warning: weird.) Summary: This post examines “simulation arguments” – i.e., arguments that we should assign significant probability to living in a computer simulation. I distinguish between two types. The first type starts with our “standard story” about the world, and tries to argue that on this story, unless something prevents the creation of suitably many sims suitably like us, we’re probably sims. I think this version fails: on our standard story, none of the sims will make our observations. For example, they won’t observe the specific set of books on my bookshelf. This sort of objection feels cheatsy – and ultimately, I think, it doesn’t work on the best version of the argument. But I use a series of cases to bring out its similarity to less cheatsy-feeling cases: for example, cases in which it appears that all the sims that will ever get made are squid-people with tentacle arms. Simulation arguments, I suggest, should say the same thing about all these cases. But the “indifference principles” that classic simulation arguments rely on get confused about this. In particular, they end up having to hand-wave about which things we count as “knowing,” and/or about which “reference classes” are “admissible.” This confusion makes it seem like classic arguments require an unprincipled kind of “selective skepticism” – one that risks undermining itself. I think we do better to focus on a second type of simulation argument, which relies centrally on a claim about what sorts of priors it’s reasonable to have over “structurally similar” worlds that contain your observations. In particular, instead of saying “on your standard story, you’re probably a sim,” this version says: “if that’s your story, you should put lots of weight on these alternative, structurally similar stories, too – on priors, such stories are similarly likely, and they contain your observations, too. But on those stories, you’re a sim.” I think this second type of argument works better – and that it brings more to the table than a standard skeptical “what if.” Indeed, I think that classic formulations of the simulation argument are implicitly leaning on something in the vicinity. But bringing out the underlying assumptions about “reasonable priors” more explicitly helps to avoid the confusion that classic formulations often create. That said, Type 2 arguments raise their own questions – for example, about how the relevant notion of “structural similarity” should be understood and applied, and about serious flirtations with “epistemic pascal’s muggings.” These questions (and other heuristics) leave me wary of Type 2 arguments, too. I also discuss two further simulation arguments. The first is from Thomas (2021), who argues that we’re almost certainly sims, because conditional on being non-sims, the expected ratio of sims to non-sims is very high. I think this argument rests on learning the lesson of the classic argument in one breath, but forgetting this lesson in the next. The other argument is that even conditional on finding yourself (apparently) living in earth’s early history, finding yourself as an “unusually something” person (e.g., unusually influential, entertaining, etc) should be some kind of substantive additional update in favor of being a sim. I don’t currently see how this argument is supposed to work; and on the classic argument, it seems like Donald Trump’s credence on “I’m a sim” should be basically the same as that of a janitor in Des Moines (even if there will be many more Trump sims than janitor sims). I conclude with a few ...