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: Anthropically Blind: the anthropic shadow is reflectively inconsistent, published by Christopher King on June 29, 2023 on LessWrong.

For the purposes of this post, the anthropic shadow is the type of inference found in How Many LHC Failures Is Too Many?.

"Anthropic principle! If the LHC had worked, it would have produced a black hole or strangelet or vacuum failure, and we wouldn't be here!"

In other words, since we are "blind" to situations in which we don't exist, we must adjust how we do bayesian updating. Although it has many bizarre conclusions, it is more intuitive than you think and quite useful!

There are many similar applications of anthropics, such as Nuclear close calls and Anthropic signature: strange anti-correlations.

This actually has implications for effective altruism. Since we are so early into humanity's existence, we can infer from the anthropic shadow that humans will probably soon die out. Also see The Hero With A Thousand Chances.

More practically, the anthropic shadow should give us useful advice on how to reason about personally risky activities like driving or perhaps even aging. I have not actually seen any advice based on this principle, but theoretically there should be some conclusions you could draw.

The problem, as you probably deduced from the title, is that it is reflexively inconsistent.

Central Claim: Someone using the anthropic shadow should update their decision making to no longer use it. This can be justified with their current decision making procedure.

(This also suggests that if you used it in the past, that was probably the wrong thing to do.)

A weaker (and obvious) claim that is also sometimes called the anthropic shadow is that we do not have experience with situations in which we have died. I agree with this version, but isn't what I will be arguing against.

Note that I am not the first to notice paradoxes with the anthropic shadow. See No Anthropic Evidence for example. I have not yet seen the result about reflexive inconsistency though, hence why I am making this post.

I also introduce the concepts of "Anthropic undeath", "Anthropic angel" (how you would explain an absurdly large number of weird coincidences having to do with death), "Fedora shadow", and apply the central claim to a couple examples. To my knowledge, these contributions are novel.

Anthropically undead: ghosts are as good as gone

This section contains the most general form of the argument. (This could be mathematically formalized; I just haven't gotten around to doing it.) If it seems strange to you, a generalized version of this section might also work.

First, we establish the basic framing of how we will check if something is reflexively consistent. Imagine yourself before a catastrophe potentially happens. You are an expected utility maximizer (as all good agents should be, although this assumption can probably be weakened). You are trying to come up with a policy for your future-self to follow.

Consider the following scenario: in any situation that you would die, imagine instead that you become an agent with only one choice each time it takes an action: "do nothing". This state is still given the same utility as before (including the utility change from physically dying (a reinforcement learner would stop getting rewards, for example)), but as an agent you never stop existing. Call this unreal scenario "anthropic undeath".

Optimizing the utility of the real scenario is the same as optimizing utility in anthropic undeath, because the agent choosing "do nothing" in the anthropic undeath scenario has the same physical effect as what actually happens in the real scenario when the agent is dead. I call this the "ghosts are as good as gone" principle.

The anthropic undeath scenario has no anthropic shadow, because the agent never stops existing. Thus, the ...