Let’s admit it: America has become a land of strangers. Even before headphones, PCs and smartphones — all of which were heralded as breakthroughs in human communication but have turned out to be instruments of further isolation — we had begun disconnecting from one another.

More and more, we have chosen to reside near and associate, almost exclusively, with people who look the same as we do, live the same as we do and think the same as we do. Polls tell us that today’s Americans do not know their neighbors as well as their parents knew theirs, and that Americans trust each other less than did earlier generations. In spite of all the public posturing about celebrating diversity, we Americans have increasingly self-segregated into our own social and political comfort zones and demographic niches.

To be honest, I grew up, went to school, played ball and worked with people who were very much like me. That all changed for me and millions of my male contemporaries when each of us received a “personal” letter from the president of the United States that began: “Greeting: You are hereby ordered for induction into the Armed Forces of the United States…”

Because, more than 56 years ago, I was able to avoid being drafted into the Army by first enlisting in the Marine Corps, I got to live with and serve with Americans who were entirely different from me — different faiths, races, backgrounds, languages and outlooks. But at Parris Island and thereafter, we all learned that Marines take care of their own, that they take care of their fellow Marines before themselves, that you can depend on the Marine next to you and that other Marines must be able to depend on you. Unlike in the vaunted private sector, loyalty, Marines understand, goes both up and down the chain of command. I never saw combat, was never fired at, but the Marine Corps bonded and connected us, in shared service, to something much larger and greater than ourselves: our country.

Even though I still believe it was a mistake, our nation ended the draft in 1973. For almost 16 years — which is longer than the Civil War, both World Wars and the Korean War combined — Americans in military service have been fighting and dying in Afghanistan. Fourteen years ago, American troops were first sent into combat in Iraq. But all the sacrifice and all the suffering in those wars has been done by just 1 percent of Americans. When some gasbag self-proclaimed patriot on a talk show or at a congressional hearing demands that we send “more troops” (or worse, “more boots”), does he not realize that we are sending — time and time again — the very same troops who were just there a few months ago?

Contrary to Ayn Rand, we all do owe much to each other and to our country. And mandatory two-year national service — civilian or military — is imperative to help us understand the responsibility, as well as the rights, of citizenship and build our connections with our fellow citizens. Two years, with no deferments and no exemptions. We could choose to serve in the Peace Corps, Marine Corps, police corps, teacher corps or another civil-service organization. But of this I am sure: Universally shared service would make us all better Americans and our country a better America. The alternative: a place where we do not know each other or why America really is exceptional.

— Mark Shields is a columnist with Creators Syndicate.