Astral Codex Ten

Astral Codex Ten is the long-running blog-turned-newsletter of psychiatrist Scott Alexander, the successor to his influential site Slate Star Codex. Each issue ranges across psychiatry, medicine, statistics, AI, history, and book reviews, often digging into research the mainstream press has missed and walking readers patiently through the math and methodology behind a claim.

Alexander has built one of the most thoughtful general-interest readerships on the internet — a mix of scientists, doctors, engineers, and curious laypeople drawn by his careful reasoning and unusual willingness to update his beliefs in public. Most posts are free, with a paid tier supporting the work and unlocking occasional subscriber-only essays and open threads.