Jonathan Gruber: It's really easy to take potshots at economics and say, oh, it's got these problems. But the fundamental idea of economics still applies in lots of places, not just the person with the street cart. He argues that as you get higher and higher in the economic stratosphere, what floats your boat is now very different. And once I make the leap, he says, I can't go back. The whole idea of economics, where that utility, the function itself, right, what gives you what makes my heart saying is now suddenly different. This is fundamentally changing of the preference function.