Bayesian Updating: How to Change Your Mind Correctly

Bayesian updating is the disciplined practice of revising your beliefs as new evidence arrives — starting with a reasonable prior, then adjusting it in proportion to what you learn. Poker players do it instinctively, narrowing an opponent's range street by street, and the same method sharpens thinking everywhere.

Start with a prior, then update

A Bayesian thinker begins with an initial estimate (the "prior") based on what they already know, then updates it as evidence comes in. In poker, your prior is the opponent's preflop range; each action — a bet, a check, a raise — is new evidence that narrows and reshapes that range. By the river, you've updated through several rounds of information into a sharp read.

Update in proportion to the evidence

The key discipline is how much to move. Strong evidence should shift your belief a lot; weak evidence only a little. The two failure modes are anchoring (refusing to update when the evidence is strong) and overreacting (lurching on weak or noisy evidence). Good updating threads between them — exactly the balance a good poker read requires.

Why it matters off the table

Most beliefs should be provisional, held at a confidence level and revised as the world reveals more. People who can't update cling to first impressions and outdated views; people who overreact chase every headline. The Bayesian middle — change your mind in proportion to the evidence — is how you stay accurate over time.

Avoid confirmation bias

The enemy of good updating is confirmation bias: counting only the evidence that supports what you already believe. Honest updating weighs the evidence that contradicts you too — the river card that doesn't fit your read, the fact that undercuts your thesis.

The takeaway

Form a prior, then update it in proportion to the evidence — no anchoring, no overreacting, no ignoring what you don't want to see. It's how poker players read hands and how clear thinkers keep their beliefs in line with reality.