The theory was developed by Nassim Nicholas Taleb to explain:

• The disproportionate role of high-profile, hard-to-predict, and rare events that are beyond the realm of normal expectations in history, science, finance, and technology.
• The non-computability of the probability of the consequential rare events using scientific methods (owing to the very nature of small probabilities).
• The psychological biases that blind people, both individually and collectively, to uncertainty and to a rare event's massive role in historical affairs.

The black swan theory or theory of black swan events is a metaphor that describes an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight. The term is based on an ancient saying that presumed black swans did not...