Why are we treating it as a derivative, and what's the slope? Do we have proof it's not zero? Let's say Johnny and Kareem both study poli-sci at Harvard. When Johnny graduates with his gentlemanly C's, his dad puts in a word with his golf buddy and it's off to Wall Street. Kareem shoots his resume off through online portals but no one bites. He goes to law school and takes on even more debt. Johnny's sister, Sally, passes the bar on her third try and is hired by a white-shoe law firm. Et cetera.