Usefulness depends on tractability.

The world is changing. We're not really proceeding on a stationary basis.

One thing I learned from meteorology is that being an actual science was no guarantee of exactness.

One way of looking at Impossibility Theorem is that we proposed some criteria for what a good system should be: what is it you want from a voting system, and impose some conditions. And then ask: can you have a voting system that guarantees that?

The health care provisions are presumably for individuals. And whoever pays for them, whether it's paid by the individual, state, whatever, the value is an individually based value. It has nothing to do with employment.

There is a bit of a problem with the match between derivative securities markets and the primary markets. We have long ago instituted principles, essentially high margin requirements, to prevent certain instabilities in the stock market, and I think they're basically correct. The trouble is that there's a linkage, let's say, between something like the stock market and the index futures markets, and the fact that the margin requirements are very different, for example, played some role in the October '87 crash.

Economics in college was very poor; I was not very impressed with it. I actually wanted to study statistics. I discovered mathematical statistics as an undergraduate and was fascinated with it.