The Field Guide › Article
A deep dive into the Local Rationality Principle: 'people do reasonable things given their goals, knowledge, understanding of the situation and focus of attention at a particular moment.' It is not a claim that a decision was objectively correct, but a claim about perspective — when an action looks irrational, that's a signal we're judging from the wrong vantage point, usually an outsider's view enriched by hindsight. The concept stems from Popper (1963) and builds on Simon's bounded rationality, but goes further: it drops the idea of full rationality altogether, so there is no hidden correct decision waiting to be found, only decisions that made sense locally. Central to the 'new view' of safety (HOP, Safety Differently, Safety-II, resilience engineering, human factors), it reframes investigations from who failed to what failed, and treats people as the solution rather than the problem. The article is explicit that local rationality is inseparable from power: in steep gradients, silence, workarounds and rule-bending are often locally rational, even when later cast as failures to speak up. It carefully distinguishes sense-making from morality — understanding why an action made sense doesn't absolve intent or remove accountability (the Harold Shipman case shows malevolent intent can hide behind apparent local rationality, so intent must be examined, not assumed). The US Airways 1549 'Sully' case illustrates hindsight bias: simulated returns to LaGuardia only succeeded until a realistic 35-second decision delay was added, after which the plane crashed. Includes practical guidance for applying the principle in retrospectives and investigations, framing it as an ethical stance, not just a technique.