Once upon a time, social­ists run­ning for pres­i­dent in the Unit­ed States had to explain that while they had no chance of actu­al­ly win­ning an elec­tion, their cam­paigns were aimed at ​“edu­cat­ing” vot­ers — about socialism.

Win or lose, his campaign nevertheless is proving highly educational for Americans perplexed by the meaning of 'socialism.'

As a suc­cess­ful politi­cian twice elect­ed to the U.S. Sen­ate and show­ing very respectable num­bers in most pres­i­den­tial pri­ma­ry polls, how­ev­er, Bernie Sanders needs no such excuse. He assures vot­ers that he is run­ning to win and there is no rea­son to doubt him. But win or lose, his cam­paign nev­er­the­less is prov­ing high­ly edu­ca­tion­al for Amer­i­cans per­plexed by the mean­ing of ​“social­ism.” Or as Sanders some­times spec­i­fies, ​“demo­c­ra­t­ic social­ism,” or the even milder ​“social democracy.”

Since the advent of the Cold War, and even before then, the mul­ti­far­i­ous mean­ings of the S‑word were hid­den behind the ide­o­log­i­cal and cul­tur­al defens­es erect­ed against com­mu­nism. The Sovi­et dic­ta­tor­ship and its satel­lites claimed their author­i­tar­i­an way was the only true social­ism — and con­ser­v­a­tives in the West seized that self-serv­ing claim to crush argu­ments for social jus­tice and pro­gres­sive gov­er­nance. Amer­i­can politi­cians of both par­ties embraced the blur­ring of social­ism with com­mu­nism, reject­ing both.

But that nar­row def­i­n­i­tion of social­ism was always wrong. To accept it meant to ignore fun­da­men­tal real­i­ties, both con­tem­po­rary and his­tor­i­cal — such as the bol­ster­ing of the West­ern alliance by Euro­pean democ­ra­cies that called them­selves social­ist or social demo­c­ra­t­ic, all of which had adopt­ed pro­grams, such as uni­ver­sal health care, denounced by Amer­i­can politi­cians as steps on the road to Com­mu­nist serf­dom. Decades lat­er, of course, those same coun­tries — includ­ing all of Scan­di­navia, France, Ger­many, the Unit­ed King­dom — remain demo­c­ra­t­ic, free and open to business.

As for the Unit­ed States, Sanders might recall that this coun­try once had a thriv­ing Social­ist Par­ty, which elect­ed may­ors in cities like Mil­wau­kee and even sent two of its lead­ers, Mil­wau­kee’s Vic­tor Berg­er and New York’s Mey­er Lon­don, to Con­gress. Their move­ment enjoyed not only elec­toral vic­to­ries but also a strong record of munic­i­pal reform and recon­struc­tion. They built sew­ers to clean up indus­try’s lega­cy of pol­lu­tion; they built pub­lic hous­ing; they ensured deliv­ery of pub­licly owned, afford­able water and pow­er; and they cleaned up local government.

But between the tri­umph of the New Deal and the dev­as­ta­tion of McCarthy­ism, the polit­i­cal space for Amer­i­can social­ism vir­tu­al­ly van­ished. Before they were rel­e­gat­ed to the mar­gins, how­ev­er, the social­ists strong­ly influ­enced the direc­tion of Amer­i­can social policy.

Long after the var­i­ous social­ist par­ties had fad­ed, their heirs con­tin­ued to serve as the nation’s most insis­tent advo­cates for reform and jus­tice. Social­ists (and yes, com­mu­nists), were among the lead­ing fig­ures in the civ­il rights, labor, and wom­en’s move­ments. It was a remark­able 1962 book by the late, great demo­c­ra­t­ic social­ist Michael Har­ring­ton, The Oth­er Amer­i­ca, that inspired Pres­i­dent Kennedy and his broth­ers to draw atten­tion to the con­tin­u­ing shame of pover­ty in the world’s rich­est nation. When Ronald Rea­gan warned in 1965 that Medicare was a hall­mark of ​“social­ism,” he was­n’t far from the mark — except that 50 years lat­er, that pop­u­lar pro­gram has lib­er­at­ed old­er Amer­i­cans, not enslaved them.

Now Bernie Sanders has tak­en up the old ban­ner in a polit­i­cal atmos­phere where more vot­ers — and espe­cial­ly younger vot­ers — are recep­tive to calm debate instead of hys­ter­i­cal redbaiting.

Cer­tain­ly Hillary Clin­ton, what­ev­er her view of Sanders’ ide­ol­o­gy, under­stands social democ­ra­cy: When her hus­band was pres­i­dent, the demo­c­ra­t­i­cal­ly elect­ed social­ist lead­ers of West­ern Europe were his clos­est inter­na­tion­al allies. In her first book, It Takes A Vil­lage” she high­light­ed many of the same social ben­e­fits in France, Ger­many and the Scan­di­na­vian coun­tries that Sanders dis­cuss­es today.

So Clin­ton knows very well that ​“social­ism,” as her pri­ma­ry rival uses that term, is no fright­en­ing­ly alien world­view, but mere­ly anoth­er set of ideas for orga­niz­ing soci­ety to pro­tect and uplift every human being.

It is long past time for the rest of the Amer­i­can elec­torate to learn that, too.