Why Smart People Believe Absurd Things Together

You have watched a smart person defend a bad idea — not because they misread the evidence, but because agreeing with the evidence would have cost them their friends. The evolutionary psychologist John Tooby, who died in 2023, explained the machinery behind this precisely. Here it is, taken apart.

A belief does two jobs at once

A belief looks like it has one job: match reality, so that acting on it works. Believe the ice is thick, walk across it, and if it's thin you drown. Reality punishes wrong beliefs directly. Call this coordinating with the world.

Tooby's move is to see the second job. A belief also positions you inside a group. The right belief marks you as a loyal member; the wrong one marks you as a defector. Socrates was executed for "failing to acknowledge the gods the city acknowledges" — his beliefs about the gods carried no practical cost, but they carried a social one. Call this coordinating with your coalition (a coalition being any group held together by shared belief — a party, a church, a scientific school, a friend group).

Your mind runs both jobs on every belief at once, silently weighing "does this match the world?" against "does this keep me in good standing?" You do not experience the second calculation. That is the point — it works better when hidden, because a person who could feel themselves believing something for social reasons would be a less convincing believer.

One variable decides which job wins

Which function dominates depends on a single thing: how often the belief is tested against reality, and how visibly.

Take a bridge engineer. Believe the wrong thing about the load steel bears, and the bridge falls where everyone can see it. The feedback is fast, public, and undeniable, and it lands on a specific person. In domains like this — physics, chip design, surgery, aviation — accurate beliefs reliably drive out inaccurate ones, because being wrong has a visible price with your name on it. These fields are tightly coupled to reality.

Now take a belief reality almost never audits: which economic policy "really" produced a country's prosperity, what a distant rival "really" intends, how some historical episode "really" unfolded. You can hold a false version for thirty years and pay nothing. The bill never arrives.

Tooby's rule: the weaker reality's feedback, the more social payoffs decide what people believe. He called the result network fixation of belief — a belief locked in place not because it is true, but because your network holds it and would penalise you for dropping it.

This is why the social sciences, macroeconomics, and long-horizon climate claims are harder to keep honest than metallurgy. Not because the people are dumber. Because reality's feedback is slow and noisy, which leaves the social function room to take the wheel. Note the mechanism cuts finely: even within a loosely-coupled field, the sub-claims that do get tested (a drug either lowers blood pressure or it doesn't) stay cleaner than the ones that don't (why the drug "should" work).

The trap that catches the rational specifically

Here is the counterintuitive part, and it needs care.

Compare two groups. Group A is a political party bound together by a shared religion. That party can freely reverse itself on tax policy or immigration, because those positions are not what makes you a member — the religion is. Revision is cheap. You update your economics and remain a member in good standing.

Group B defines its very identity by commitment to being rational, evidence-based, and willing to follow the data. This group has a hidden defect. Evidence, by its nature, keeps demanding that specific beliefs be revised. But in Group B, some of those beliefs have become the membership badge. Revising a badge belief — even for airtight reasons — reads as betrayal, because you have loosened the thing that binds the group. You risk your standing, your collaborators, your job prospects, your sense of who you are.

So the belief freezes. The group that defines itself by openness to evidence becomes, on its defining beliefs, the group least able to update. Its commitment to a fixed set of "correct" positions quietly converts each one into a loyalty test — and a loyalty test cannot be revised without disloyalty. The paradox is not that rationalists are secretly irrational; it is that making specific conclusions load-bearing for group identity is itself the mechanism that ossifies them. The more a belief works as a badge, the more expensive it becomes to be right when the badge is wrong.

Group A's advantage is real but narrow: it can update the beliefs that aren't its badge. On its own badge — the religion — it is exactly as frozen as Group B is on its. There is no group immune to this. The only variable is which beliefs a group has chosen to make identity-critical.

The tool you now hold

This is portable, not a remark about academia. Before trusting any belief — someone else's or your own — run two checks.

How often, and how visibly, does reality test this belief? If the honest answer is "rarely" or "never directly," discount the confidence of the people holding it. Confidence is cheap in a domain that never sends a bill. Loud certainty in an untested field is close to no evidence at all.

Is holding this belief a condition of belonging? If disagreeing would cost someone their friends, their status, or their self-image, then their agreement tells you almost nothing about whether the belief is true. They may believe it with total sincerity — the mind conceals its own social motives — but the belief is doing social work, and social work bends beliefs away from accuracy.

Now turn both questions on yourself, because they bite hardest exactly where you feel most certain and most surrounded by agreement. The belief you would be embarrassed to question in front of your own people is the one most likely fixed by the network rather than by the world. That warm feeling of righteous certainty in a like-minded crowd is not a signal of truth. It is a signal that the social function of belief has taken over.

Tooby's payoff is that he makes this predictable instead of mysterious. You no longer have to wonder why clever people believe absurd things in unison, or why fields full of clever people stay wrong for generations. It is not a failure of intelligence. It is intelligence doing what it evolved to do — keeping you aligned with your group, which for almost all of human history mattered more to survival than being right. Knowing the mechanism, you can sometimes catch it in the act — including in yourself, which is the only place you can actually do anything about it.

Distilled from Edge