Concept
Hindsight Bias
Hindsight bias is the tendency, once an outcome is known, to believe we saw it coming all along, quietly rewriting our memory of what we expected so that the past looks more predictable than it was.
Daniel Kahneman draws on a study by the psychologist Baruch Fischhoff. Before President Nixon's visits to China and the Soviet Union in 1972, people estimated the likelihood of several possible outcomes. Asked afterwards to recall their estimates, they remembered giving higher odds to the events that had happened and lower odds to those that had not. Once the outcome is known, System 1 rebuilds the story around it, and the earlier uncertainty, which was real, drops out of memory. Kahneman treats this as a core part of the illusion of understanding: if the past seems to have been knowable, the future seems knowable too, and confidence grows. It also distorts how decisions are judged. When an outcome is bad, people blame decision makers for missing signals that only became clear later; when a reckless bet pays off, they praise it as foresight. Kahneman calls the judging of a decision by its result outcome bias, and notes that it pushes professionals towards defensive, bureaucratic choices. The reliable defence is a record made in advance: what you expected, how confident you were and why, written down before the result has a chance to rewrite it.
A real-life example
When a furniture retailer in İstanbul closed its new online channel after a year, the board agreed the failure had been obvious from the start. Nihan, the manager who had led the channel, opened the decision memo from the original meeting. It listed the same risks the board now called obvious, each one judged unlikely at the time by the very people now calling it obvious, and it recorded a near-unanimous vote in favour. The review that followed asked what they could have learned earlier, not whom to blame.
How to use it
- 1Before an important decision, write down what you expect to happen, how confident you are and why.
- 2When the outcome arrives, compare it with what you wrote, not with what you now remember thinking.
- 3Judge a decision by the information available when it was made, not by the result that followed.