P (A|B) = [P (A)*P (B|A)]/P (B), all the rest is commentary. Click to read Astral Codex Ten, by Scott Alexander, a Substack publication.

Ajeya Cotra’s Biological Anchors report was the landmark AI timelines forecast of the early 2020s. In many ways, it was prescient - it nailed the scaling hypothesis, predicted the current AI boom, and ...

The phrase “I see Satan fall like lightning” comes from Luke 10:18. I’d previously encountered it on insane right-wing conspiracy theory websites. You can rephrase it as “I see Satan descend to earth ...

Paul Fussell wants to talk about class. (well, wanted, past tense, it's a 1983 book, we'll come back to that later) He recognizes this might not be the most popular topic. When he tells people he's ...

You’ve probably heard AI is a “black box”. No one knows how it works. Researchers simulate a weird type of pseudo-neural-tissue, “reward” it a little every time it becomes a little more like the AI ...

Many cities have regular Astral Codex Ten meetup groups. Twice a year, I try to advertise their upcoming meetups and make a bigger deal of it than usual so that irregular attendees can attend and new ...

Seven years ago, I wrote an online serial novel, Unsong, about alternate history American kabbalists. You can read the online version here. The online version isn’t ...

…is one of my favorite parts of this blog. I get a spreadsheet with what are basically takes - “Russia is totally going to win the war this year”, “There’s no way Bitcoin can possibly go down”. Then I ...

[This is one of the finalists in the 2026 book review contest, written by an ACX reader who will remain anonymous until after voting is done. I’ll be posting about one of these a week for several ...

In 1917, some Portuguese children started seeing visions of the Virgin Mary. The Virgin told them she would enact a great miracle on a certain day in October, and a crowd of 100,000 gathered to ...

The annual prediction market conference was earlier this month. This was the year prediction markets went from an obscure hobby to a multi-billion dollar industry; from semi-illegal to having the ...

This is a guest post by Drew Housman, whose review of Dominion earned finalist status in the 2024 ACX book review contest. If you are unsuccessful for long enough on your pregnancy journey, and none ...