He explains it in this post.

Minor nit: following strict rules without weighing the costs and benefits each time could be motivated by rule utilitarianism, not only by deontology.  It could also be motivated by act utilitarianism, if you deem that weighing the costs and benefits every single time would not be worth it. (Though I don't think EA veganism is often motivated by act utilitarianism).

This made me wonder about a few things:

• How responsible is CSET for this? CSET is the most highly funded longtermist-ish org, as far as I can tell from checking openbook.fyi (I could be wrong), so I've been trying to understand them better, since I don't hear much about them on LW or the EA Forum. I suspected they were having a lot of impact "behind the scenes" (from my perspective), and maybe this is a reflection of that?
• Aaron Bergman said on Twitter that for him, "the ex ante probability of something at least this good by the US federal government relative to AI progress, from the perspective of 5 years ago was ~1%[.] Ie this seems 99th-percentile-in-2018 good to me", and many people seemed to agree. Stefan Schubert then said that "if people think the policy response is "99th-percentile-in-2018", then that suggests their models have been seriously wrong." I was wondering, do people here agree with Aaron that this EO appeared unlikely back then, and, if so, what do you think the correct takeaway from the existence of this EO is?

Thanks for this information. When I did this, it was because I was misunderstanding someone's position, and only realized it later. I'll refrain from deleting comments excessively in the future and will use the "retract" feature when something like this happens again.

Hi, that was an oversight, I've edited it now.

See this comment.

Several people cited the AHS-2 as a pseudo-RCT that supported veganism (EDIT 2023-10-03: as superior to low meat omnivorism).

[…]

My complaint is that the study was presented as strong evidence in one direction, when it’s both very weak and, if you treat it as strong, points in a different direction than reported

[Note: this comment was edited heavily after people replied to it.]

I think this is wrong in a few ways:

1. None of the comments referred to “low meat omnivorism.” AHS-2 had a “semi-vegetarian” category composed of people who eat meat in low quantities, but none of the comments referred to it

2. The study indeed found that vegans had lower mortality than omnivores (the hazard ratio was 0.85 (95% CI, 0.73–1.01)); your post makes it sound like it’s the opposite by saying that the association “points in a different direction than reported.” I think what you mean to say is that vegan diets were not the best option if we look only at the point estimates of the study, because pescatariansim was very slightly better. But the confidence intervals were wide and overlapped too much for us to say with confidence which diet was better.

Here's a hypothetical scenario. Suppose a hypertension medication trial finds that Presotex monotherapy reduced stroke incidence by 34%. The trial also finds that Systovar monotherapy decreased the incidence of stroke by 40%, though the confidence intervals were very similar to Presotex’s. 

Now suppose Bob learns this information and tells Chloe:  "Alice said something misleading about Presotex. She said that a trial supported Prestotex monotherapy for stroke prevention, but the evidence pointed in a different direction than she reported."

I think Chloe would likely come out with the wrong impression about Presotex.

3. My comment, which you refer to in this section, didn't describe the AHS-2 as having RCT-like characteristics. I just thought it was a good observational study. A person I quoted in my comment (Froolow) was originally the person who mistakenly described it as a quasi-RCT (in another post I had not read at the time), but Froolow's comment that I quoted didn't describe it as such, and I thought it made sense without that assumption.

4. Froolow's comment and mine were both careful to notice that the study findings are weak and consistent with veganism having no effect on lifespan. I don't see how they presented it as strong evidence.

[Note: I deleted a previous comment making those points and am re-posting a reworded version.]

I think the original post was a bit confusing in what it claimed the Faunalytics study was useful for.

For example, the section 

The ideal study is a longitudinal RCT where diet is randomly assigned, cost (across all dimensions, not just money) is held constant, and participants are studied over multiple years to track cumulative effects. I assume that doesn’t exist, but the closer we can get the better. 

I’ve spent several hours looking for good studies on vegan nutrition, of which the only one that was even passable was the Faunalytics study. 

[...]

A non-exhaustive list of common flaws:

• Studies rarely control for supplements. [...]

makes it sound like the author is interested on the effects of vegan diets on health, both with and without supplementation, and that they're claiming that the Faunalytics study is the best study we have to answer that question. This is what I and Matthew would strongly disagree with.

This post uses the Faunalytics study in a different (and IMO more reasonable) way, to show which proportion of veg*ans report negative health effects and quit in practice. This is a different question because it can loosely track how much veg*ans follow dietary guidelines. For example, vitamin B12 deficiency should affect close to 100% of vegans who don't supplement and have been vegan for long enough, and, on the other side of the spectrum, it likely affects close to 0% of those who supplement, monitor their B12 levels and take B12 infusions when necessary. 

A "longitudinal RCT where diet is randomly assigned" and that controls for supplements would not be useful for answering the second question, and neither would the RCTs and systematic reviews I brought up. But they would be more useful than the Faunalytcis survey for answering the first question.

for me, the question is "what should vegan activist's best guess be right now"

Best guess of what, specifically?