LessWrong (Curated & Popular)

Every so often it slips. It seems I am writing a book, but I can’t remember why. Somehow, the sentences are supposed to perform that impossible, intimate task: to translate my inner world into another. Yet they sit there so quiescent and small. How could an arrangement of words do anything, let alone reduce that ultimate threat to which it is all supposedly connected: the looming god machines? I look again at the monitor in which the words are contained and suddenly what once felt so raw and powerful deflates into limpness. Why would anyone listen to me, anyway? Have I said anything new? Or is too weird—the strangeness in my head failing to find handholds in other minds? And it floods, these pieces of doubt. Each one flitting by almost unnoticeably, but in the background they build.

Then sometimes the flood abates as quickly as it came. The world is made of scary stuff: we really may all die, and I really might not be capable of reducing or even much affecting that terrifying threat. Yet somehow this has little to do with the words on the page. The outcomes matter—they do—but that isn’t where the motivation [...]

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First published:
February 4th, 2026

Source:
https://www.lesswrong.com/posts/fnRqyuceyLuZRFFbZ/solemn-courage-1

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Nagoro, a depopulated village in Japan where residents are replaced by dolls. In 1960, Yubari, a former coal-mining city on Japan's northern island of Hokkaido, had roughly 110,000 residents. Today, fewer than 7,000 remain. The share of those over 65 is 54%. The local train stopped running in 2019. Seven elementary schools and four junior high schools have been consolidated into just two buildings. Public swimming pools have closed. Parks are not maintained. Even the public toilets at the train station were shut down to save money.

Much has been written about the economic consequences of aging and shrinking populations. Fewer workers supporting more retirees will make pension systems buckle. Living standards will decline. Healthcare will get harder to provide. But that's dry theory. A numbers game. It doesn’t tell you what life actually looks like at ground zero.

And it's not all straightforward. Consider water pipes. Abandoned houses are photogenic. It's the first image that comes to mind when you picture a shrinking city. But as the population declines, ever fewer people live in the same housing stock and water consumption declines. The water sits in oversized pipes. It stagnates and chlorine dissipates. Bacteria move in, creating health risks. [...]

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First published:
February 14th, 2026

Source:
https://www.lesswrong.com/posts/FreZTE9Bc7reNnap7/life-at-the-frontlines-of-demographic-collapse

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Based on a talk at the Post-AGI Workshop. Also on Boundedly Rational

Does anyone reading this believe in Xhosa cattle-killing prophecies?

My claim is that it's overdetermined that you don’t. I want to explain why — and why cultural evolution running on AI substrate is an existential risk.
But first, a detour.

Crosses on Mountains

When I go climbing in the Alps, I sometimes notice large crosses on mountain tops. You climb something three kilometers high, and there's this cross.

This is difficult to explain by human biology. We have preferences that come from biology—we like nice food, comfortable temperatures—but it's unclear why we would have a biological need for crosses on mountain tops. Economic thinking doesn’t typically aspire to explain this either.

I think it's very hard to explain without some notion of culture.

In our paper on gradual disempowerment, we discussed misaligned economies and misaligned states. People increasingly get why those are problems. But misaligned culture is somehow harder to grasp. I’ll offer some speculation why later, but let me start with the basics.

What Makes Black Forest Cake Fit?

The conditions for evolution are simple: variation, differential fitness, transmission. Following Boyd and Richerson, or Dawkins [...]

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Outline:

(00:33) Crosses on Mountains

(04:21) The Xhosa

(05:33) Virulence

(07:36) Preferences All the Way Down

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First published:
February 13th, 2026

Source:
https://www.lesswrong.com/posts/tz5AmWbEcMBQpiEjY/why-you-don-t-believe-in-xhosa-prophecies

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TLDR: Recently, Gao et al trained transformers with sparse weights, and introduced a pruning algorithm to extract circuits that explain performance on narrow tasks. I replicate their main results and present evidence suggesting that these circuits are unfaithful to the model's “true computations”.

This work was done as part of the Anthropic Fellows Program under the mentorship of Nick Turner and Jeff Wu.

Introduction

Recently, Gao et al (2025) proposed an exciting approach to training models that are interpretable by design. They train transformers where only a small fraction of their weights are nonzero, and find that pruning these sparse models on narrow tasks yields interpretable circuits. Their key claim is that these weight-sparse models are more interpretable than ordinary dense ones, with smaller task-specific circuits. Below, I reproduce the primary evidence for these claims: training weight-sparse models does tend to produce smaller circuits at a given task loss than dense models, and the circuits also look interpretable.

However, there are reasons to worry that these results don't imply that we're capturing the model's full computation. For example, previous work [1, 2] found that similar masking techniques can achieve good performance on vision tasks even when applied to a [...]

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Outline:

(00:36) Introduction

(03:03) Tasks

(03:16) Task 1: Pronoun Matching

(03:47) Task 2: Simplified IOI

(04:28) Task 3: Question Marks

(05:10) Results

(05:20) Producing Sparse Interpretable Circuits

(05:25) Zero ablation yields smaller circuits than mean ablation

(06:01) Weight-sparse models usually have smaller circuits

(06:37) Weight-sparse circuits look interpretable

(09:06) Scrutinizing Circuit Faithfulness

(09:11) Pruning achieves low task loss on a nonsense task

(10:24) Important attention patterns can be absent in the pruned model

(11:26) Nodes can play different roles in the pruned model

(14:15) Pruned circuits may not generalize like the base model

(16:16) Conclusion

(18:09) Appendix A: Training and Pruning Details

(20:17) Appendix B: Walkthrough of pronouns and questions circuits

(22:48) Appendix C: The Role of Layernorm

The original text contained 6 footnotes which were omitted from this narration.

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First published:
February 9th, 2026

Source:
https://www.lesswrong.com/posts/sHpZZnRDLg7ccX9aF/weight-sparse-circuits-may-be-interpretable-yet-unfaithful

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Cross-posted from Telescopic Turnip

Recommended soundtrack for this post

As we all know, the march of technological progress is best summarized by this meme from Linkedin:

Inventors constantly come up with exciting new inventions, each of them with the potential to change everything forever. But only a fraction of these ever establish themselves as a persistent part of civilization, and the rest vanish from collective consciousness. Before shutting down forever, though, the alternate branches of the tech tree leave some faint traces behind: over-optimistic sci-fi stories, outdated educational cartoons, and, sometimes, some obscure accessories that briefly made it to mass production before being quietly discontinued.

The classical example of an abandoned timeline is the Glorious Atomic Future, as described in the 1957 Disney cartoon Our Friend the Atom. A scientist with a suspiciously German accent explains all the wonderful things nuclear power will bring to our lives:

Sadly, the glorious atomic future somewhat failed to materialize, and, by the early 1960s, the project to rip a second Panama canal by detonating a necklace of nuclear bombs was canceled, because we are ruled by bureaucrats who hate fun and efficiency.

While the Our-Friend-the-Atom timeline remains out of reach from most [...]

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Outline:

(02:08) Microwave Cooking, for One

(04:59) Out of the frying pan, into the magnetron

(09:12) Tradwife futurism

(11:52) Youll microwave steak and pasta, and youll be happy

(17:17) Microvibes

The original text contained 3 footnotes which were omitted from this narration.

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First published:
February 10th, 2026

Source:
https://www.lesswrong.com/posts/8m6AM5qtPMjgTkEeD/my-journey-to-the-microwave-alternate-timeline

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