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Gwern Branwen · Gwern.net
How one person finds out what's true — and keeps the answer from evaporating along with the internet

2009–present · 440+ text files, 4.3m+ words · still updating (changelog runs through June 2026) · the hinge is May 2020, "The Scaling Hypothesis": before it, a self-taught researcher outside every institution; after it, the person who saw it coming from outside the labs · this page is based on 13 pieces read in full, spanning January 2009 to May 2026

The most complete resource on the internet about whether a memory game called dual n-back can raise your IQ took ten years to write. One person wrote it. Pull out the body text and it runs to nearly sixty thousand words.

At the top of that document, the author has stamped himself with this:

certainty: unlikely

The person who wrote the FAQ is also the person who demolished it. In 2009 he read in Wired that the game raised fluid intelligence and was genuinely shaken — IQ is one of the hardest things about a person to push upward — so he started tracking every study. By 2012 he noticed that nobody had done a meta-analysis on the question, so he did one himself. The finding: the studies showing an effect were almost all studies whose control group did nothing at all. Give the control group something to train on and the effect collapses. What had been measured was not intelligence going up; it was that people who had just trained on something try harder on the post-test.

Then he left the FAQ up. He didn't delete it. He just added the stamp.

What he's been wrestling with

Gwern Branwen is a pen name. The person under it has been hearing-impaired since birth, learned much of his vocabulary from books and still mispronounces words because of it, lives on a Patreon bringing in $900–1,000 a month plus some early Bitcoin — under $12,000 a year — keeps a cat, and when he sat for a long interview in 2024 his one condition was no audio and no video. No PhD, no lab, no grant, no peer review, no credential vouching for him.

The question he has not put down in seventeen years grows straight out of that situation: how does a person like that find out whether something he actually cares about is true? And once he's found out, how does he keep the answer from evaporating along with the rest of the internet?

Two enemies: self-deception, and forgetting. Every answer he gives is counterintuitive.

Answer one: never start

The odd thing he noticed is that blog posts are almost all disposable.

most blog posts are the triumph of the hare over the tortoise. They are meant to be read by a few people on a weekday in 2004 and never again, and are quickly abandoned…(But isn't that sad? Isn't it a terrible ROI for one's time?) "About This Website"

His fix isn't to work harder. It's to abolish the act of starting:

So this suggests a solution: never start. Merely have perpetual drafts, which one tweaks from time to time. And the rest takes care of itself. ibid.

So every page on his site carries a date range instead of a publication date (the "About" page reads 2010-10-01 to 2024-08-30 — fourteen years, 5,083 days), plus a completion status, a confidence tag, and an importance score out of 10. Every year that appears in the body text carries a small superscript telling you how long ago that was — because he isn't writing for you, this year. He says the real intended reader of these pages is:

my future self, who is intelligent and interested, but has forgotten. ibid.

Answer two: first calculate whether the experiment is worth running

He tried a near-infrared light therapy supposed to sharpen cognition. He used it on and off for over a year, ran the numbers, and found it correlated strongly with his daily self-ratings — effect size 0.455, not small. Most people would have posted a recommendation.

He asked the opposite question: might the good days be causing the usage? So from August 2014 to March 2015, 167 days, he flipped a coin at noon every day to decide whether to use it. The effect size fell to 0.07. He gave the LED away.

Better still is how he decides whether to run an experiment at all. For fish oil he wrote out the arithmetic: power × prior × benefit − cost of experimentation = (0.20 × 0.30 × 540) − 41 = −9. Negative, so he didn't run it. The reasoning is cold: he was already taking fish oil and already believed in it, so a underpowered experiment returning "no effect" wouldn't be strong enough to change his behavior anyway.

Answer three: everything is correlated, so correlations are nearly worthless

This is his most original idea and his least fun one. Past a certain sample size, any two variables you measure will be statistically significantly correlated:

If you fail to reject the null hypothesis with p < 0.05, you simply haven't collected enough data yet. "Why Correlation Usually ≠ Causation"

So he went and compiled every pairing he could find, across medicine, economics and psychology, where an observational study was later followed by a randomized trial — and checked whether the observational study called it right. Verdict: the best correlational research barely beats a coin flip.

Then comes his own explanation: reality is a dense causal graph. Every variable is wired to several others, so the number of indirect paths that carry information grows far faster than the number of direct causal edges you could actually push on. Any correlation you happen to observe is therefore very unlikely to sit on a direct edge. And our intuitions were formed in a sparse world — catching a ball, walking through a door — which is why we underestimate confounding systematically rather than randomly. His prescription is a sentence turned inside out: the question should never be whether it's ethical to run a randomized experiment here, but whether it could possibly be ethical not to.

Answer four: we are already living in the scaling world

In May 2020 the GPT-3 paper landed and, in his words, "appears to have sunk almost without a trace."

The good part is that he had been the loudest skeptic of this very idea. From 2004 to 2010, reading the people who claimed that enough compute would summon the right algorithm, he thought it was magical thinking — algorithms are hard, you can't just buy a pile of computers and expect intelligence to fall out.

What changed him wasn't a flash. It was a decade of drips: datasets kept getting bigger, models kept getting bigger, GPUs went from one to eight, convolutional nets kept eating new domains. He describes noticing, over and over, that the world was starting to look more like their world than like his. GPT-3 was the crucial test: if scaling were bogus, the paper should have been unimpressive. He got to the few-shot learning chart on the second page — we are living in the scaling world.

Then he opened Twitter and found everyone saying this proved how badly scaling worked, since it wasn't even state of the art. One of the most-cited AI essays of the decade began like this:

That made me so angry I had to write all this up. Someone was wrong on the Internet. Dwarkesh Patel interview, 2024

All four answers are really one answer. A person without a lab has exactly two assets. One is willingness to go deeper than anyone thinks the question is worth — of his most popular pages he says anyone could have compiled them, and that if he did anything meritorious it was "simply putting more work into them than someone else would have." The other is time. For an institution time is the enemy: grants end, papers must ship. For him it's the only source of compound interest. In his 2020 essay there's a question about whether some enormous multimodal agent might eventually appear. Next to that line today sits an annotation:

[Roughly, yes. —Editor 2025-10-19]

His five-years-later self came back to grade his five-years-earlier self, in the margin of the original sentence, without deleting a word of it.