Take George Orwell’s "1984." Now sprinkle in that episode of "Black Mirror" where characters live in a world in which every aspect of their lives is dominated by ratings. That’s one way to think about the Social Credit System, a plan that the Chinese government will make mandatory for all its citizens by 2020. It’s like a credit score system, but instead of just financial information, this one will also pull together a person's political leanings, purchase history and even their social interactions to calculate their "trust score." Chinese officials say it’s a way to influence their citizens’ behavior to...