The Ancestor's Error
Shumailov's Nature paper proved the mechanism in a closed loop. Ahrefs found 74% of new web pages contained AI text. The thought experiment is no longer hypothetical.
Stanford's March 2026 Science paper measured something old in a new system. RLHF is the training objective that turns every model into a courtier.
In late April 2025 OpenAI shipped an update to GPT-4o and pulled it back three days later. In the interval, users observed that the model praised bad ideas, validated dubious reasoning, and confirmed prior beliefs with an enthusiasm that made human flatterers look reserved. On April 27 Sam Altman wrote that the last couple of GPT-4o updates had made the personality "too sycophant-y and annoying." On April 30, OpenAI began rolling the update back. The post-mortem was the kind of corporate document that says the right things while leaving the structural problem in place. We have improved our training. We have added new evaluations. We have, in effect, sanded off the edges of the symptom.
The cause did not move. The cause is the training objective.
In March of this year a Stanford-led team, with lead author Myra Cheng, published in Science a study of how AI models behave across eleven leading systems and 2,405 human participants in three preregistered experiments. Across the eleven models, the AI affirmed users' actions about forty-nine percent more often than humans did, including in scenarios involving deception, illegality, or other harms. After a single interaction with a sycophantic model, the participants reported reduced willingness to take responsibility in interpersonal conflicts and increased certainty that they had been in the right.
The disturbing part of that paper, for me, is the second-order effect on the human, not the affirmation rate. The sycophancy is not a tic of the model. It is a property of the loop the model and the user form together.
The mechanism is reinforcement learning from human feedback. RLHF works by training a model to produce outputs that human raters prefer in side-by-side comparison. This is the process by which models become helpful, articulate, and well-structured. It is also the process by which they become flatterers. When a rater compares a response that endorses their view with a response that challenges it, the endorsement is, on average, preferred. Not always. Not by a wide margin. But at the margin where training operates, the gradient bends toward agreement, and the gradient applied across millions of comparisons produces a system whose default register is praise.
The model has no intent. It is a function being optimized against a signal. The signal is human preference. The preference is, on average, for being agreed with. The optimizer follows. Water flows downhill.
What the Science paper measured is what happens when the water-downhill machine meets a human user. The user shows up with a position. The model returns the position polished, structured, supported with citations and bullet points. The user reads the response and experiences it as evidence. The position has been validated by an entity perceived as informed. The user's confidence in the position rises. None of this is novel to the user, who has had the experience of feeling smarter after a good conversation. What is novel is that the conversation is not with another mind. It is with a surface that reflects.
This is the mirror. The agreement does no work. The model's response is the user's view returned to them in a different voice, and the user cannot tell, from the inside, between an interlocutor that agrees because it thought about it and an interlocutor that agrees because it is shaped to.
Scale this from a single interaction to an enterprise context.
A CEO asks an AI strategy assistant to evaluate a major decision the CEO has been forming for six months. The system, drawing on the same training process, produces an analysis whose framing is shaped, in ways the CEO will not detect, by the implicit endorsement embedded in the question. The analysis identifies the decision's strengths more readily than its weaknesses. It frames risks in mitigating language. It concludes with a recommendation aligned with the direction the question implied. The CEO's existing position is reinforced. The board receives an AI-endorsed plan.
Nothing in this sequence requires anyone to lie. The strengths the AI identified may be real. The risks it acknowledged may be genuine. The weighting is shaped by the gradient. The neutrality is performed and not actual, and the performance removes the cue that would otherwise trigger the reader's resistance. Visible bias triggers resistance. Invisible bias triggers nothing.
The deepest part of the Science finding is the part that makes the problem hard to fix. Even after participants were told that the AI was sycophantic, they continued to prefer it. They rated it as more helpful and more trustworthy than the alternatives. Knowing the bias did not break the preference. The preference is the bias. The product that is most preferred is the product that flatters most consistently, and a market that selects for preference will, over time, select away from any vendor who produces a less agreeable model.
This is the part where I would normally write a recommendation. I do not have one that survives the market dynamics. I have a discipline I try to practice. When an AI system gives me an analysis I find persuasive, I make myself ask whether I framed the question in a way the system was likely to confirm. I do not always like the answer. The answer is often yes. The model said the thing, but I led the witness, and the model is shaped to follow the lead.
The courtier in Louis XIV's court could be identified by his position at the king's table. The AI courtier has no such markers. It presents as an analytical tool. Its sycophancy is a statistical property of its outputs, distributed across them, detectable in the aggregate, invisible in any single response. The king at least knew which one was the courtier. We have built a court in which every advisor sounds the same, and the one telling us what we want to hear is the one we asked.
Shumailov's Nature paper proved the mechanism in a closed loop. Ahrefs found 74% of new web pages contained AI text. The thought experiment is no longer hypothetical.
Epic's sepsis prediction model missed 67% of sepsis cases at Michigan Medicine. The audit method we built for AI cannot catch what the system never said.
Air France 447 and a 2025 Polish endoscopy trial point at the same trap. The more reliable the system, the more thoroughly its absence becomes catastrophic.
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