Public policymakers and political pundits tend to focus on problems — understandably, because if things are going right they aren’t thought to need attention. Yet positive developments can teach us things as well, when, for reasons not necessarily clear, great masses of people start to behave more constructively.

One such trend is the better behavior of the young Americans of today compared to those 25 years ago. Almost no one anticipated it, the exception being William Strauss and Neil Howe in their 1991 book Generations, who named Americans born after 1981 the Millennial generation and predicted that “the tiny boys and girls now playing with Lego blocks” — and those then still unborn — would become “the nation’s next great Civic generation.”