One of the problems with the social sciences is that just because you know what something is, doesn’t mean that you can count it. The classic case of this is pornography: we all know what pornography is, but defining it precisely enough to legislate it or to measure it is extremely difficult. Which is why a Supreme Court justice once said about pornography that, while it may be hard to define, ”I know it when I see it.”

It’s not just pornography. Justice, democracy, freedom, oppression, tyrann...