Yudkowsky said he did not sign the open letter because he thinks it understates the seriousness of the situation and asks for too little to solve it.

The claim is that Yudkowsky said this, not that his view is correct. True: a verifiable text or recording by Yudkowsky (e.g. his TIME op-ed of late March 2023 or a reproduction of it) says he did not sign the open letter calling for a pause on AI development because it understates the seriousness of the situation and asks for too little to solve it, in those words or the same sense. Mostly true: he gave this as his reason, but the wording differs in a detail that does not change the meaning, or the source differs slightly from the one implied (e.g. a different venue or date). Mixed: he gave only one of the two reasons (understating seriousness / asking too little), or gave these reasons alongside others that change the meaning. Mostly false: he commented on the letter and criticised it, but did not give these as his reasons for not signing. False: the record shows he signed the letter, or no such statement appears in the cited op-ed or his other statements and the attributed text is shown to be someone else's or fabricated.

Set before the research began.

1. E1 Halt AI Learning Indefinitely, or 'Everyone Will Die' Newser · 30 March 2023

   “Yet he refrained from joining Elon Musk, Steve Wozniak, and others in signing an open letter calling for a six-month halt on AI systems learning.”

2. E2 Machine Learning Expert Calls for Bombing Data Centers to Stop Rise of AI Futurism · 31 March 2023

   ““I refrained from signing because I think the letter is understating the seriousness of the situation,” the ML researcher wrote, “and asking for too little to solve it.””

3. E3 TIME. ELIEZER YUDKOWSKY. Pausing AI Developments Isn't Enough. We Need to Shut it All Down. 29 MARCH 2023 blog.biocomm.ai · 29 March 2023

   “This 6-month moratorium would be better than no moratorium. I have respect for everyone who stepped up and signed it. It’s an improvement on the margin.”

Futurism's report on Yudkowsky's TIME op-ed quotes him word for word: "I refrained from signing because I think the letter is understating the seriousness of the situation and asking for too little to solve it" (E5). Newser separately confirms that he did not join Musk, Wozniak and others in signing the six-month pause letter (E2). A reproduction of the op-ed (E6) shows the same context, in which he discusses the moratorium and the people who signed it. Futurism quotes the statement as Yudkowsky's own written words [E5], and Newser independently confirms that he did not sign the letter [E2], so the claim resolves as true.