What Is A Black Swan Event?

And there’s more out there than just black swans. Here be dragons . . .

Matt J Weber 🦢
5 min readSep 1, 2021


In 2nd century Rome, there were no black swans. No one in western Europe had seen anything other than a white swan. It was just assumed black swans just didn’t exist.

And so when a Roman poet described something as “a rare bird in the lands and very much like a black swan,” he didn’t mean black swans were rare birds. He meant they were impossible.

This became a common saying and generally referred to things that just could not happen.

But then black swans actually happened.

In 1697, over a thousand years after a roman declared them impossible, Dutch explorers in Australia stumbled upon black swans. Lots of them.

This is in itself a Black Swan event.

A Black Swan event is an event so rare and unusual that its appearance takes us by complete surprise. They can be disasters like a financial crash or great scientific advancements or the discovery of a flock of black birds. Either way, they are unprecedented and unpredictable. At least until they happen.

For something to be classified a Black Swan event it has to fulfill three requirements.

1.) It has to be an outlier. That is, it is outside the realm of our expectation. It is a surprise.

2.) It has to have a major effect.

3.) In hindsight, it is predictable. We can pinpoint and study the chain of events that led to the creation of the Black Swan. In other words, it isn’t just random.

The 9/11 attacks were a Black Swan event. The 2008 financial crisis was a Black Swan event. World War I, the collapse of the Soviet Union, the rise of the internet, the 2004 Indonesian Tsunami — all Black Swans.

Human history is full of black swan events. Even things that don’t happen — but we were very certain would happen — can be considered Black Swan Events. Because the absence of an event can be just as significant — or catastrophic — as something that does happen.

But not every disaster is a Black Swan. For instance, the Covid-19 pandemic is not a Black Swan event. Scientists…