As I write this, the No. 1 “most read” story on the Washington Post’s website is its investigation into the college years of Scott Walker, headlined: “As Scott Walker mulls White House bid, questions linger over college exit.” Most of the time, you don’t need to read such a story to know what it’s about: for Republicans, every silly comment or stunt in their teenage years is in the public interest, and for Democrats the same investigative practice is racist, racist, racist. (Though in 2016 it will be sexist, sexist, sexist.) But there is one aspect of this story that...