Commentary: Why a former secretary of defense says we don't need a draft or mandatory public service

In a country worried about its own internal divisions, public figures are increasingly calling for a return of the military draft, or at least some kind of mandatory national service. Wouldn't it be good, they often reason, to reinforce for today's young people the sense of common cause that animated the Greatest Generation? Universal service is a commendable effort to deepen citizenship that should appeal to all Americans. But a closer look at these ideas suggests deep flaws.

The math of military conscription is illustrative.

Every year, about 4 million Americans turn 18. But the military needs to recruit only 250,000 per year. While