Speaking very broadly, almost any human action involves choice; the external environment delimits a range of possible actions at any given moment but… - Kenneth Arrow

Among economic phenomena which have in some way been tied up with the existence of uncertainty, three classes may be distinguished: (1) those which by their very definition are concerned with uncertainty; (2) those which are not related to uncertainty by definition but nevertheless have no other conceivable explanation; (3) those whose relation to uncertainty is more remote and disputable.

To conclude, then, we must in a general theory take as our unit a social action, that is, an action involving a large proportion or the entire domain of society. At the most basic axiomatic level, individual actions play little role. The need for a system of public values then becomes evident; actions being collective or interpersonal in nature, so must the choice among them. A public or social value system is essentially a logical necessity.

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.