Unexpected things happen, but humans don’t like to think about unexpected things happening. We are much more comfortable thinking about linear events and higher-probability events, tending to plan for those. In 16th Century London, there was a common expression to describe impossible events: a black swan. At the time, they were presumed to not exist because the historical data (limited to Europe) showed that all known swans were white. This all changed when European explorers reached Western Australia, whereupon they found black swans.
Reflecting on the discovery, the philosopher John Stuart Mill observed how “no amount of observations of...