Economist Arnold Kling passes along his father Merle Kling's "three iron laws of social science":
1. Sometimes it's this way, and sometimes it's that way.
2. The data are insufficient.
3. The methodology is flawed.
That sounds about right. Kling is building off of Tyler Cowen's first law:
There is something wrong with everything (by which I mean there are few decisive or knockdown articles or arguments, and furthermore until you have found the major flaws in an argument, you do not understand it).
This also sounds about right.
Of course, I have never met an economist, social scientist, or even political pundit who wouldn't agree with these laws in the abstract. At the same time, I have rarely met an economist, social scientist, or — especially — political pundit who acts, most of the time, like he really, in his heart of hearts, believes these laws are true. I am no exception, of course.
Cowen is, in my experience, an exception, at least when it comes to following his own law.
And while we're talking laws, Cowen also recommends Edward Tufte's "grand truths about human behavior." Grand truth No. 1:
It's more complicated than that.