When historians of the future try to explain how the United States ended up electing Donald Trump to the presidency, they will likely point to many contributing factors — rising economic inequality; the spread of identity politics; the role of technology in amplifying voices outside the mainstream media; and, of course, the growth of negative partisanship and ideological polarization.

I also suspect that when these imagined historians dig a little deeper, they'll fasten onto a change in America's civic life that has functioned as an important but little-noted catalyst for some of the most pernicious tendencies in our politics: the abolition of military conscription in 1973.

Those of us who have come of age in the era of the all-volunteer military find the idea of a draft close to unthinkable. You mean when kids should be contemplating college or a first job, they'll need to decide whether to enlist in the service of their choice or take their chances in a lottery that could place them on the front lines of a war zone somewhere overseas? Against their will? How barbaric! How unacceptable!

That this is how so many of us respond to the thought of conscription is a testament to the potency of two ideas.

The first is the cynical notion behind Richard Nixon's drive to end the draft in the first place. Nixon promised to close down the draft as part of his campaign for president in 1968. He did so because he suspected that ending it would fatally undermine the anti-Vietnam War protest movement that was stirring up unrest on college campuses across the country. Eliminate the threat of conscription, Nixon surmised, and young people would stop caring about the war.

It took until 1973 for the draft to be eliminated completely (for the first time since just prior to U.S. entry into World War II). By then America's combat role in Vietnam was nearly over, so Nixon's hypothesis never received a proper test.

Yet subsequent history provides ample vindication of his suspicion. For all the opposition occasionally voiced by pundits in response to the brief and largely successful Persian Gulf War, the interminable war in Afghanistan, and the disastrous Iraq War (not to mention the numerous smaller military engagements pursued by presidents over the past 40 years), we've seen no sustained widespread expression of anti-war sentiment since the early 1970s — no doubt in part because the vast majority of Americans know they will never be compelled to serve in the armed forces. It's hard to get too worked up about a war if it never directly touches your own life or the lives of your friends and family. (With less than 1 percent of the population serving at any one time, most Americans fall into that category.)

And that leads to the second idea that has been vindicated by the end of the draft: individualism. It's not for nothing that conservatives call economist Milton Friedman the "father of the all-voluntary military." It was Friedman who popularized the view in the 1970s that military conscription is a form of slavery in which free individuals are coerced into sacrificing their freedom, and sometimes their very lives, for collective enterprises they often personally reject. The premise of this view — that individual freedom is and ought always to be the highest value in political life, overriding all public goods — was endorsed by Ronald Reagan's presidential campaign and seemingly vindicated by his two-time triumph at the ballot box.

After eight years of presidential speeches and policies that reaffirmed this individualistic outlook, both parties had come around to it, rendering the reinstitution of any form of conscription — for military or non-military public service — unimaginable. Offer people salaries, scholarships, and skills in return for their service and enough individuals would make a market decision to join up and fill the ranks of the armed forces, leaving those who make a different choice free to live their lives however they wish. Isn't that what America should stand for?

Of course other eras in the country's history have taken very different views of the relative worth of public purposes. As a result, they enjoyed more social cohesion than we do today, when a tiny fraction of the population gets habituated into an ethic of military virtues (courage, honor, sacrifice for the common good) while the rest of us live our lives immersed in a world oriented toward the self-interested (or at most family-centered) pursuit of money, pleasure, and social status. That clash in moral outlook understandably fuels resentment among members of our warrior class, which increasingly defines the common good for which they fight in terms of the (disproportionately Southern, rural and ideologically conservative) values that prevail in the regions of the country from which they hail.

Nothing builds social cohesion like a call for shared sacrifice — just as nothing inspires a breakdown in social cohesion like the perception that the sacrifice is borne by only a few while the vast majority takes it for granted (and consistently makes decisions about going to war while thoroughly insulated from its true costs).

Thankfully, the country has no need for a standing army much larger than the one that is currently filled by volunteers. That means any reinstitution of conscription would probably end up sending very few draftees into battle. Most could take up assignments behind the lines, or opt to take part in a mandatory stint of stateside national service instead, contributing to infrastructure projects and other public works in those rural and urban areas that have been most neglected in the post-Reagan era of rampant individualism. Think of it as a domestic branch of the Peace Corps — or a greatly expanded version of the all-volunteer AmeriCorps program.

Likely? Not very. Possible? Of course it is. But only if we begin to rein in our individualism and learn to recognize once again the considerable personal and political rewards of contributing to something bigger than ourselves.