Scott Alexander

Scott Alexander is the pen name of Scott Siskind, a San Francisco Bay Area psychiatrist whose blog Slate Star Codex became the most widely read forum of the Rationalist Community after Eliezer Yudkowsky's LessWrong. The blog's long essays on psychiatry, statistics, and politics made it required reading across the rationalist, Effective Altruism, and Silicon Valley technology worlds in the 2010s. Alexander deleted the blog in 2020 ahead of a New York Times article that would publish his legal name, and his privately expressed sympathy for human biodiversity and his engagement with Neoreaction were exposed through a leaked 2014 email.¹²

Slate Star Codex

Alexander launched Slate Star Codex in 2013. The blog served as the discursive center of the rationalist subculture and a venue where heterodox and reactionary ideas were debated at length, including a 2013 "Anti-Reactionary FAQ" that argued against the Moldbug neoreactionary program while treating it as a serious intellectual object. The comment sections and the associated meetups linked the rationalist community to the wider tech-right ecosystem, and the blog's audience overlapped with the effective-altruism movement and the AI-risk community around the Machine Intelligence Research Institute.¹³

Its widely circulated essays included "Meditations on Moloch" (2014), a parable about coordination failure that became a reference point in the AI-safety community, and "I Can Tolerate Anything Except The Outgroup" (2014). The blog's Silicon Valley readership was substantial: it carried an endorsement from Paul Graham of Y Combinator, was read by Patrick Collison of Stripe, and was followed by the venture capitalists Marc Andreessen and Ben Horowitz, while Sam Altman of OpenAI called it essential reading among "the people inventing the future."⁶⁷

The 2020 Deletion and the New York Times Article

In June 2020 Alexander deleted Slate Star Codex after learning that a New York Times technology reporter, Cade Metz, was preparing an article that would identify him by his full name. Alexander said disclosure would endanger his psychiatric practice and patients and cited prior threats. The article, "Silicon Valley's Safe Space," appeared on February 13, 2021, naming Siskind and connecting the blog and its community to figures including the social scientist Charles Murray and to neoreactionary currents; it drew heavy criticism within and beyond the rationalist community over the naming decision. Alexander relaunched in January 2021 as the Substack publication Astral Codex Ten.²⁴

Alexander took the blog down on June 23, 2020, replacing it with a post headlined "NYT Is Threatening My Safety By Revealing My Real Name, So I Am Deleting The Blog." A petition asking the Times to respect his pseudonymity gathered roughly 8,000 signatures, including that of the computer scientist Scott Aaronson. The relaunched Astral Codex Ten, opened January 21, 2021 on Substack with the post "Still Alive," drew thousands of paid subscribers and made Alexander one of the platform's signature writers; the migration mirrored the broader movement of heterodox commentators, including Sam Harris and Bari Weiss, onto direct-subscription platforms after disputes with mainstream outlets.⁴⁸

The Leaked 2014 Email

In February 2021, around the time of the Times article, Topher Brennan published a 2014 private email from Alexander. In it Alexander wrote that he had learned from neoreactionary writers and that "human biodiversity" (HBD), the term used for claims of genetically based racial differences in intelligence, was "probably partially correct or at least very non-provably not-correct," while asking that his openness to such ideas not be made public. The email documented a private alignment more sympathetic to race science and reaction than his published critiques of neoreaction had indicated.⁵

In the email Alexander described the neoreactionaries as "almost the only people" engaging seriously with what he framed as the underlying problems of racial difference and immigration, and wrote that they "provide a vast stream of garbage with occasional nuggets of absolute gold in them." He warned the recipient that if his actual views were disclosed he would "probably either leave the Internet forever or seek some sort of horrible revenge." Critics read the message as evidence that the published "Anti-Reactionary FAQ" had functioned as a respectable shell that drew rationalist readers toward Moldbug's ideas while letting Alexander disavow them; defenders treated it as a decade-old private message taken out of context. The leak landed in the same news cycle as the Cade Metz article, compounding the rationalist community's sense of exposure.⁵