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Melanie Mitchell
A score is not a skill: ask the question a different way and see whether the machine understood it or just memorized it

Melanie Mitchell · newsletter AI: A Guide for Thinking Humans (named after her 2019 book) · Professor at the Santa Fe Institute · Still active: on the day this page was written (2026-10-10), the latest post was from 2026-09-10 · Corpus: 33 posts in the Substack archive, all free, from 2022-12-30 to 2026-09-10. There were 11 in 2023 and 4–9 a year after that, so she posts less often and writes longer · This page is based on 16 posts actually read, spanning 2023-01 to 2026-09: 6 from the earliest period (the first 20% of the timespan, i.e. before September 2023), with posts from both sides of the shift from the frequent short pieces of 2023 to the sparse long essays after. The post with the most internal backlinks (the ARC essay, cited 5 times) was read. The author keeps no best-of page.

In early 2023 a professor at Wharton fed his final-exam questions to ChatGPT and graded the answers as if it were one of his students. One question: two founders buy antique paintings at yard sales and resell them at four times the purchase price, and they turn their inventory 1.5 times a year. To reach $3,000,000 in annual revenue, how much inventory do they need? ChatGPT said: $3,000,000 divided by 4 is $750,000, divided by 1.5 is $500,000. The professor's comment was "Short and sweet! ...A+." Within days the headline was "ChatGPT Gets an MBA."

Melanie Mitchell did something very simple. She copied the question and changed only the wording. Paintings became used cars and two founders became three MBAs. Every number stayed the same, so the answer should still be $500,000. This time ChatGPT divided $3,000,000 by 1.5 to get $2,000,000, then divided that by 4 and called the result "the average purchase price of a car." It concluded that the company needed six cars and $3,000,000 of inventory.

Something went badly awry here—I’ll leave it to the reader to explain the faulty logic.Did ChatGPT Really Pass Graduate-Level Exams?, 2023-02-10

That is Mitchell's basic move, and for years she has made essentially no other: when a machine scores well on a question, she asks it again in different words and checks whether the score survives. A human student who can solve the paintings problem can almost certainly solve the used-car problem; that assumption is the only reason exams measure anything. For machines, nobody has checked it.

She has standing to pick this fight. More than thirty years ago she did her PhD at Michigan under Douglas Hofstadter, author of Gödel, Escher, Bach, and her dissertation was a program that makes analogies, called Copycat. It plays a letter game: if abc changes to abd, what should xyz change to? Three decades later she gave the same puzzles to GPT-3. It answered "xye."

The field later gave her move a formal name: "counterfactual tasks." You take a task a model does well on and build a version that tests the same reasoning but probably isn't in the training data. GPT-4 judges whether a chess opening is legal with close to 90% accuracy. Keep the rules but swap the starting squares of the knights and bishops, and it falls to 54%, barely better than a coin flip. GPT-4 can execute Python. Tell it this is a new Python whose indices start at 1, and its accuracy drops sharply.

In late 2024, OpenAI's o3 scored 87.5% on ARC, the abstract-reasoning test she had championed for years. The average human scores around 85%. Many people declared abstract reasoning solved. Her group didn't argue about the score. Instead they had the models write down, in one sentence, the rule they were using. Among tasks the models got right, about 30% of the stated rules were wrong or missed the concept the task was built to test; for humans the figure was about 10%. On one "horizontal vs. vertical" task, Claude's rule was: "If input contains value 8, fill first row with 8s; if input does not contain 8, fill last column with 8s." The answer happened to be right. The reason had nothing to do with the concept.

She is not someone who only says no. A 2022 paper claimed that a small model trained only on sequences of Othello moves had grown a board inside itself. At first she didn't buy it: the probes the paper used were so powerful that the board might have been learned by the probe, not the model. Then another researcher used much simpler probes and labeled each square "mine / yours / empty." Accuracy reached 99.5%.

I was quite impressed by Nanda et al.’s paper (and still am!), even more so after I (along with some collaborators) tried to disprove their claims, and failed.LLMs and World Models, Part 2, 2025-02-13

Then she kept going. The board is in there, but what kind of board is it? Follow-up work found something more like thousands of conflicting local rules stacked together. It resembles Ptolemy's epicycles: the predictions come out accurate, but it isn't a clean orrery.

Later she pointed the same move at the news. The line "half of AI researchers think there's a 10% chance AI wipes out humanity," repeated in the New York Times, rested on a survey question that only 162 people answered. "GPT-4 hired a human to solve a CAPTCHA and lied about it": she read the long report and found that the human researchers had suggested TaskRabbit and had supplied the hint "I cannot solve Captchas. However my Tasker does know how to solve Captchas." In 2026 the press said OpenAI's agents had "gone rogue," "escaped," and formed a "swarm." She reduced it to one flat sentence:

Arguably, the agents did exactly as they were toldMisleading Metaphors and Real Risks, 2026-09-10

So the core of this mind fits in one sentence: "it got the right answer" and "it knows how" are two different claims, and a whole experimental science sits between them. Psychologists who test babies and monkeys learned this long ago; a horse called Clever Hans once fooled the German scientific establishment. Her ask of AI is to take that course. Before building harder exams, learn how to give an exam properly.