That's It, Exactly

Why is it that many economists (epitomized by Paul Krugman) seem not to understand the principles of economics? That is, why do they consistently favor government intervention in economic affairs (e.g., heavy handed regulation of the drug industry, government as the single payer in a universal health insurance plan)? Here's why, according to Arnold Kling, writing at Tech Central Station:

My sense is that even for the best students, mathematical constructs in economics tend to go into short-term memory. The really important lessons of economics can be forgotten, if they are even learned in the first place, in a class where students are graded on their ability to manipulate diagrams as opposed to their ability to apply economic reasoning.

Some economists seem completely lost without their mathematical tool kit. Unable to explain economics in plain English, they stoop to the novice level, or even lower. I put Paul Krugman in this category....

Many economists are considered "good" economists because of their command of mathematics and statistics -- not because they truly understand the principles of economics.