The actions of hunter-gatherers have limited causal reach. A shot that misses its target might mean sudden death for the hunter or warrior whose shot it was, but the consequences of that particular error for the tribe or troop are likely to be absorbed into the flow of events and make only a small difference to the outcome of the hunt or the battle. With the advent of large-scale social and technical systems like airlines, container shipping, global financial markets, irrigation agriculture, power grids and research hospitals humans came to know man-made disasters. A single erroneous action can be the starting point for a butterfly effect that propagates upward through the levels of the relevant system until it makes the difference between cure and death, between ubiquitous electricity and power blackout, between wealth and bankruptcy or between victory and defeat; in general, between normality and disaster. The unacceptable consequences of disasters make it imperative to understand the dynamics of error correction in individuals, social systems and entire societies.

The constraint-based theory of learning from error put forward in Chapter 7 describes the inner mechanics of a single learning event, the correction of a single fault in a single person's cognitive skill.