In Shakespeare’s Julius Caesar, a soothsayer warns Caesar to “beware the ides of March.” The recommendation was perfectly clear: Caesar had better watch out. Yet at the same time it was completely incomprehensible. Watch out for what? Why? Caesar, frustrated with the mysterious message, dismissed the soothsayer, declaring, “He is a dreamer; let us leave him.” Indeed, the ides of March turned out to be a bad day for the ruler. The problem was that the soothsayer provided incomplete information. And there was no clue to what was missing or how important that information was.
Like Shakespeare’s soothsayer, algorithms often can predict the future with great accuracy but tell you neither what will cause an event nor why. An algorithm can read through every New York Times article and tell you which is most likely to be shared on Twitter without necessarily explaining why people will be moved to tweet about it. An algorithm can tell you which employees are most likely to succeed without identifying which attributes are most important for success.