This is very good.

The way economists and similar social science types look at it is that people vary in their discount rates, i.e., in the extent to which they discount the future. (And this might be rational. For a brute example, suppose you’re 70 years old and your life expectancy is very short: why should you care about 20 years down the road?)

Of course, that raises a follow-up problem: what to do when people do rationally have discount rates different from one’s own, but you have to make a collective decision?