. . .Start with Goolsbee’s tacos. Derivatives are financial contracts that derive their value from some other factor. Asked by POLITICO how he’d explain them to a layperson, Goolsbee said it’s like betting on an NBA game. You could bet on the final score, or you could take a coupon from Taco Bell offering a free taco if the home team scores more than 100 points. “That offer is a derivative,” Goolsbee said — a financial bet that pays off only if some external event comes true.

“And you can trade that, because it has value,” said Goolsbee, who had a knack as a professor at the University of Chicago for breaking down finance-speak into plain English.

At stake in the current debate is how many derivatives — which are private, undisclosed deals — should be forced onto public exchanges, where regulators can see which banks have a hand in which deals. That was one of the reasons why the Crash of ’08 was so severe — no one knew exactly who owed what to whom in the $450 trillion derivatives market, and that froze the entire financial system.