Black Swan theory tells us that things happen that were
previously thought to be impossible—or never thought of at
all. This is not the same as saying that sometimes things
happen against one-in-a-million odds, but rather that things
never imagined do come to pass.
The idea of the Black Swan was popularized by risk
analyst Nassim Nicholas Taleb in his bestselling books
Fooled by Randomness (2001)^1 and The Black Swan
(2007),^2 but the term goes back much further. Until the
seventeenth century, people could only imagine white
swans because all swans ever seen had possessed white
feathers. In seventeenth-century London it was common to
refer to impossible things as “Black Swans.”
But then the Dutch explorer Willem de Vlamingh went
to western Australia in 1697—and saw a black swan.
Suddenly the unthinkable and unthought was real. People
had always predicted that the next swan they saw would be
white, but the discovery of black swans shattered this
worldview.
Black Swans are just a metaphor, of course. Think of
Pearl Harbor, the rise of the Internet, 9/11, and the recent
banking crisis.
None of the events above was predicted—yet on
reflection, the markers were all there. It’s just that people
weren’t paying attention.
As Taleb uses the term, the Black Swan symbolizes the
uselessness of predictions based on previous experience.
Black Swans are events or pieces of knowledge that sit