In favor of anthropic reasoning

Often the ideas in my recent posts regarding anthropic reasoning and the Dice Killer thought experiment are met with skepticism. The sense is that something about the reasoning process being employing is rotten, and that the simple intuitive answers are right after all.

While I understand the impulse to challenge these unusual ideas, I think they have more going for them than might be obvious. In this post, I’ll present a basic argument for why we should reason anthropically: because doing so allows you to win!

We can see this in the basic Dice Killer scenario. (I won’t rehash the details of the thought experiment here, but you can find them at this link).

The non-anthropic reasoner saw a 50% chance of death if they tried escaping and only a 3% chance of death if they didn’t. The anthropic reasoner saw a 50% chance of dying if they tried escaping and a 90% chance of death if not. Naturally, the anthropic reasoner takes the escape route, and the non-anthropic reasoner does not. Now, how do these strategies compare?

Suppose that all of those that gets kidnapped are non-anthropic reasoners. Then none of them try escaping, so about 90% of them end up dying in the last round. What if they are all anthropic reasoners? Then they all try escaping, so only 50% of them die.

This is clearly a HUGE win for anthropic reasoning. Anthropic reasoners run a 40% decreased chance of dying! A simple explanation for this is that they’re simply taking advantage of all the information available to them, including indexical information about their state of being.

We can also construct variants of this thought experiment in which non-anthropic reasoners end up taking bets that lose them money on average, while anthropic reasoners always avoid such losing bets. These thought experiments run on the same basic principle in the Dice Killer scenario – sometimes you can construct deals that look net positive until you take the anthropic perspective, at which point they turn net negative.

In other words, if somebody refuses to use anthropic reasoning, you can turn them into a money pump, taking more and more of their money until they change their mind! This is a pragmatic argument for why even if you find this form of reasoning to be unusual and unintuitive, you should take it seriously.