I received an early lesson in caution after boldly predicting that John Lindsay would win the White House in 1972. Even stronger lessons were provided over the years by the appearance of a hugely influential factor in Presidential elections: the Black Swan.

The term comes, not from that Natalie Portman ballet movie, but from a best-selling book in 2007 by Nassim Nicholas Taleb that examines our persistent “ability” to ignore the potentially huge effects of unlikely, random events. Given what happened a year later–when we woke up on a mid-September day to find the financial universe on the brink of collapse–the book seemed prescient. In political terms, “Black Swans” have shown up often enough to make even the boldest soothsayer hold his tongue.

Think back to 1960, when Republicans could still compete for the black vote, and when an influential figure like Martin Luther King Sr. endorsed Richard Nixon out of concern about a Catholic in the White House. Then, on October 25, King’s son was arrested on a bogus parole-violation charge and transferred to a rural state prison where, his family feared, his life might be endangered. After John Kennedy called King’s wife, and Robert Kennedy called the governor of Georgia (and after Richard Nixon’s efforts to have the Justice Department intercede were ignored), King was released, and his father announced he was transferring his “suitcase full of votes” to Kennedy. On Election Day, black voters were crucial to Kennedy’s razor-thin margins not just in Illinois (8,000 controversially counted votes), but also in Michigan, New Jersey and Missouri.