How Hard Is It?

Brad DeLong is in a somewhat ungentlemanly tussle with Jason Koznnicki over the relative difficulty of, well, relativity.  Brad quotes Richard Feynman discussing "what we teach our physics students in the third or fourth year of graduate school."  He might have recalled the received account of education in economics. "We" (="they") "teach the same thing in One-A, 100-A and 200-A--it takes three times to get them to believe it."