I was early regarded as having unusual intellectual capacity. I was an omnivorous reader, and I added to that a desire to systematize my understandin… - Kenneth Arrow

We don't have much time left. We are moving towards temperature increases of around two degrees Celsius, which is going to have consequences in the tropics, and we will lose things like glaciers. That's not a theory; it's happening right now. It's not a prediction; it's happening right now. But you just sightsee near those glaciers. But the glaciers are a big source of water. And on the questions of water, in California we store our water in a snowpack. When that's gone, the rain will be the same but it won't accumulate. With warming temperatures the snowpack will not work. It might be possible to substitute with dams, but that's complicated. This is conjoined with a big energy problem and I think that we really have to encourage development in this area. Just waiting for technological improvement won't work. We need to encourage it.

Traditional welfare economics shows that there are certain of these combinations that will be preferred by all the voters, which permits us to eliminate the others without too much discussion. However, there will always remain an irreducible kernel of possibilities among which the choice rests on a combination or aggregation of individual ethical attitudes about distribution.

Certainly, there is no general principle that prevents the creation of an economic theory based on other hypotheses than that of rationality.