The Facebook campaign started out with a constructive and seemingly innocent goal: to encourage people to vote. And it succeeded. After comparing voting records, researchers estimated that their campaign had increased turnout by 340,000 people. That’s a big enough crowd to swing entire states, and even national elections. George W. Bush, after all, won in 2000 by a margin of 537 votes in Florida. The activity of a single Facebook algorithm on Election Day, it’s clear, could not only change the balance of Congress but also decide the presidency.
