One night in the mid-1990s when I was working as a journalist in Beijing, I went out to dinner with some Chinese friends. I had just finished reading a book called "The File" by the British historian Timothy Garton Ash. It's about what happened in East Berlin after the Berlin Wall came down and everybody could see the files the Stasi had been keeping all those years. People discovered who had been ratting on whom—in some cases neighbors and co-workers, but also lovers, spouses and even children. After I described the book to my Chinese dinner companions—a hip and artsy intellectual crowd—one friend declared: "Some day...