The Best of LessWrong

TracingWoodgrains traces how longtime Wikipedia administrator David Gerard went from enthusiastic LessWrong participant to its most persistent critic, using deep knowledge of Wikipedia policy to decide which sources count as "Reliable," shaping public perceptions of rationalists, effective altruists, and Scott Alexander for over a decade.

#17

shortest goddamn bayes guide ever

A Bayes' Rule guide in seven lines of all-caps pseudocode: make up some initial odds, then multiply each side by the chance of the evidence. Yeps and nopes never cross. Plus a worked example estimating the odds that the thing eating you alive in your tent is a bear.

#18

Superbabies: Putting The Pieces Together

What would it take to make a "superbaby"? Gene-editing embryos at scale isn't feasible yet, and simple embryo selection is too weak. But two recent breakthroughs, inducing meiosis in vitro and creating naive pluripotent stem cells, could enable iterated meiosis to produce embryos with extreme polygenic scores.

#25

Review: Planecrash

Planecrash is a ridiculously long fanfic co-written by Eliezer Yudkowsky, mixing fantasy, math lectures, and kink. This review argues it's worth reading for two reasons: its characters are unusually competent, and it lays out Yudkowsky's whole worldview (validity, probability, utility, coordination, decision theory) more clearly than anything else he's written.

#27

Towards a Broader Conception of Adverse Selection

Adverse selection isn't just for used car markets. Conditional on getting to make a trade, your trade probably wasn't that great: the open table, the empty subway car, the auction you won. Whenever you get a deal, ask yourself: "What do others know that I don't?"

#30

The Summoned Heroine's Prediction Markets Keep Providing Financial Services To The Demon King!

A summoned heroine builds prediction markets to help her kingdom anticipate the Demon King. The Demon King keeps buying shares in "The Demon King will attack the Frozen Fortress," then attacking the Frozen Fortress. A comedic fable about market manipulation, perverse incentives, and why prediction markets are harder than they look.

#32

Universal Basic Income and Poverty

Modern poor people have more clothes than medieval nobles, but so what? People in a world lacking oxygen could have all the fabric they wanted and still be poor. Eliezer argues a mysterious "Poverty Equilibrium" survived a 100-fold productivity increase, so he's skeptical Universal Basic Income would finally defeat it.

#37

Thresholding

The most damaging troublemakers don't cause single big disasters. Instead they "threshold": repeatedly doing things that are objectionable but just barely defensible, fighting hard against enforcement, spacing out incidents, and targeting different people. Duncan explains why most rule systems handle this badly and how to recognize and coordinate against it.

#38

There is way too much serendipity

Almost every popular artificial sweetener was discovered by a chemist accidentally tasting their research compounds. Meanwhile, thousands of drugs tasted in clinical trials yielded none. Malmesbury argues this suspicious serendipity (along with LSD's discovery) suggests chemists are constantly, unknowingly tasting nearly everything they touch.

#42

Arithmetic is an underrated world-modeling technology

Arithmetic isn't just for calculating – it's a world-modeling technology. Dynomight works through examples (a $500 million chimp study on salt, a 918-ton block to store your home's solar energy) showing how simple calculations reveal what's feasible and why. The key: ALWAYS KEEP UNITS. They catch errors and do the work for you.

#43

On Not Pulling The Ladder Up Behind You

As projects grow larger and more complex, they get harder for newcomers to take over, and successful projects can crowd out the small spaces where people used to level up. Screwtape argues we should leave ladders behind us: write down what you did, work alongside others, and protect the "minor leagues."

#44

The Online Sports Gambling Experiment Has Failed

Zvi, a former professional sports bettor, concludes that legalized mobile sports gambling has been a disaster. New studies find large increases in bankruptcies, reduced household savings, and more domestic violence. Sportsbooks profit by preying on addicts with terrible odds and constant temptation, so online betting should be rolled back.

#49

[Intuitive self-models] 1. Preliminaries

The brain's predictive learning algorithm builds generative models of the world, and, because we act on our own minds, also models of the brain algorithm itself. Steven Byrnes argues these "intuitive self-models" give rise to our experience of consciousness and free will, and explain trance, enlightenment, hallucinations, and more.

31Zac Hatfield-Dodds

A neat progress update, though largely obsoleted by more recent posts (see below). LessWrong is famously obsessed with the trainable skills and social practice of rationality, and with the prospect of very strong computer intelligence. The biological pathway to improved cognition doesn't get as much discussion, and the timelines to impact are (probably!) somewhat longer, but I remain convinced of its importance. I also strongly agree with the ethical position that [...] and from early 2026, it's nice to be reminded that induced meiosis and super-SOX for naive pluripotency were substantial breakthroughs! My impression is that we're still basically on track to start primate testing in the late 2020s, rather than having basically no idea if or when such things might be possible. On the other hand, I'm substantially more optimistic than Sarah about the causal predictive power of polygenic scores - at least in principle; don't take me as endorsing any particular predictor or even current practice in general. This is supported by two key stylized facts: 1. sibling genomes are independent-random when conditioned on the shared parent genomes. [1] This means that observing a phenotype-genotype correlation among siblings with a shared environment [2] really does tell us about causality. 2. most genes have approximately additive effects, and interaction effects are usually small and almost always positive rather than being tradeoffs! See e.g. the heatmap here. An intuition: this is because we're only considering traits which vary between currently-living humans, which are recent enough and weakly-selected-enough that they haven't reached fixation. [3] If that didn't help, ask me in person sometime because I have more thoughts this timebox is too narrow to contain. Finally, what's the state of the art in early 2026? * many of my friends with young children used polygenic screening aka embryo selection. At time of writing, Herasight is a clear leader, though choice of

14Screwtape

I am very much of two opposed minds here. The case against: This is inside baseball. This is the insidest of inside baseball, it's about a LessWrong commenter talking about LessWrong on the talk pages of Wikipedia, written by someone who cut his teeth writing by writing in the LessWrong diaspora online. Also, it's kind of a bad look for LessWrong to prominently feature an argument that a major detractor of LessWrong is up to shady epistemic nonsense. Like, obviously people on this forum are upvoting this, we're mostly here because we like LessWrong and this says good things about the forum. The case for: If this was about any other online community - if Gerard had been skewing the Wikipedia sources to make the My Little Pony fandom look bad, or to Streisand effect some weird theory and associated ban decision made on the War Thunder forums - I would highly upvote it without any qualm. That's because this is an excellent highlighting of two important topics: how knowledge production works in the modern internet, and how deception can be hidden by spreading edge-case decisions around in a lot of different places. What Wikipedia calls a reliable source and how Wikipedia writes about things informs a lot of the internet. (Less now with the rise of LLMs, but still a lot.) My answer to "What do you think you know and how do you think you know it" often included "I think I know it because I just read it on Wikipedia." Seriously, I live in Boston, and I think Boston has a population of about six hundred thousand people because that's what Wikipedia says. A detailed examination of the how that particular sausage gets made seems pretty good! As for deception. . . look, I know my interests these days. But I still like having this as a thing to point to. How would you spot this, on the ground and as it's happening? How would you point it out to someone else once you'd spotted it? At so many points of interaction, other Wikipedians might look and go "eh, seems like a judge

18L Rudolf L

"Yudkowskianism" is a Thing (and importantly, not just equivalent to "rationality", even in the Sequences sense). As I write in this post, I think Yudkowsky is so far the this century's most important philosopher and Planecrash is the most explicit statement of his philosophy. I will ignore the many non-Yud-philosophy parts of Planecrash in this review of my review, partly because the philosophy is what I was really writing about, and partly to avoid mentioning the mild fiction-crush I had on Carissa. There is a lot of discussion within the Yudkowskian frame. There is also a lot of failure to engage with it from outside. There is also (and I think this is greatly under-appreciated) a lot of discussion across AI safety & the rationality community, from people who have a somewhat fish-in-the-water relation to Yudkowskianism. Consciously, they consider themselves to be distanced from it, having retreat from pure Yudkowskianism to something they think is more balanced and reasonable. I think these people should become more aware of their situation, since they lack the deep internal coherence of Yudkowskianism, while often still holding on to some of the certainty and rigidity that comes with it. I hope my post has done its bit here. Perhaps strangely, the longest section of my review is on the political philosophy of dath ilan. I think this is something where Yudkowsky is underrated. A clear-eyed view of incentives & economics is very rare, and combined with Yudkowsky's humanism, I like the results. Governance sci-fi is criminally neglected, outside Planecrash, Robin Hanson, and the occasional book like Radical Markets. (It's also interesting that Nate Soares tells his story of working on reforming our civilization's governance, and building a rationality curriculum to that end, only to in the process of research for that stumble across The Sequences, "halt, melt, and catch fire", and then pivot to alignment. I wonder if all rationalist-y governance-idealists end up p

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