Epistemic status: confused, probably missing something obvious

An explanation of the Doomsday Argument

I don’t understand why Doomsday-ish arguments aren’t front and centre when talking about existential risks. Obviously the DA is talked about, but it seems to be talked about way less than makes sense to me.

I see lots of very smart people estimating <10% probability of x-risk. Is there some obvious reason why these people don’t find the DA persuasive? If you don’t find it persuasive yourself, why is that?

My intuition says that if we’re looking at a flourishing future of trillions of humans, it seems incredibly unlikely that we’d find ourselves at the start of that timeline. Particularly when a number of ways we could kill ourselves seem to be pretty much on the horizon. When I think about it that way, I feel a visceral hopelessness.

Most of what I have been able to find has to do with arguing over the use of various sampling assumptions - is there any other more intuitive reason why people don’t talk about the DA very often? (maybe this is asking too much and I should just knuckle down and try to properly understand anthropic reasoning lol)

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No one wants to start the discussion about Doomsday Argument, because the people who understand it think: "Among all those people who will ever discuss the Doomsday Argument, what is the probability that I am one of the first ones?"



The doomsday argument says there likely won't be trillions of humans like us. It says less about whether that means extinction, or trillions of people who live unrecognizably better lives.



Note that the Doomsday Argument (or better, the underlying self-sampling assumption) is actually a counterargument to very short timelines:

By definition, we have a 95% probability of being in the central 95% of the human civilization lifespan; that means a 95% probability of human civilization lasting at least 1/39 of its past duration (and at most 39 times the same duration).

Given that civilizations with biological humans around have existed since at least 10000 years, this would give 95% probability of human civilization lasting at least another ~250 years.

(based on an old argument by Richard Gott; obviously you can play with the numbers to obtain different results, but the basic intuition is that we probably have more than a few years left)