In its simplest form, a Black Swan event refers to an unexpected event that catches people by surprise and has a profound impact. These events are typically rare, unpredictable, and deviate from the norms and expectations of a given system or environment.
The history of the Black Swan Theory - or the Theory of Black Swan Events - dates back to a Latin expression of the 2nd-century by Roman poet Juvenal, when he would characterize something as: “rara avis in terris nigroque simillima cygno”
This Latin expression translates to “a rare bird in the lands and very much like a black swan”. Originally when this phrase was first used, it was thought that black swans did not exist.
The term "Black Swan" was popularized by the writer and scholar Nassim Nicholas Taleb to describe such unforeseen events that have far-reaching consequences. These events can disrupt financial markets, economies, political landscapes, or any other complex system, often leading to paradigm shifts and reshaping the way we perceive and understand the world.
According to Taleb, Black Swan events generally follow three attributes:
A Black Swan is an outlier. It is beyond that of regular expectations and as a result, nothing in the past could have predicted it.
It always carries an extreme or significant impact.
A Black Swan event, despite being an outlier and unpredictable, will certainly have a rational explanation concocted after its first occurrence, making that type of event explainable and predictable.
Examples of previous Black Swan events as described by Taleb, are the rise of the internet, the personal computer, the dissolution of the Soviet Union, and the September 11, 2001 attacks.