In a letter to the Buffalo News last week, a reader asked an unintentionally comic question: “What will it take to defeat the communist/socialist/Islamic terrorist sympathizers Hillary Clinton and Bernie Sanders?” You read and hear such delusional far-rightist rhetoric around the internet, talk radio, and in public spaces like coffee shops. (I’ve encountered it in such places more than once.)

The delusional anger spurring this kind of language is almost simultaneously fascinating and disturbing. Does anyone with even a ghost of a chance of being judged sane in a court of law believe Clinton is any of those things? But Sanders, Clinton’s rival for the Democratic presidential nomination, must be a socialist, right? He’s often referred to himself as a “democratic socialist.” In the public media, it became almost requisite to refer to the US Senator from Vermont as “the self-described democratic socialist.” In the last nine months, it’s also become a very handy tool for mainline commentators to question, and very frequently to disparage his credibility as a candidate and, of course, his ideas. Respectable centrist critics operate less stridently and absurdly than the looney American Right, but their efforts to intellectually isolate and to undercut Sanders’s campaign are more serious, and potentially more effective. When, in a recent column for Time magazine, veteran neo-liberal political maven Joe Klein mechanically acknowledged Sanders’s “admirably substantive campaign,” he quickly went on to deplore “the problem ideologues have. They see the world theoretically.” This functions as a kind of effete red-baiting. “Ideologue” is the key word. Sanders, Klein complained, “posits a binary system of oppressor (billionaires) and the oppressed (the rest of us).” He wants to claim “rights” on our behalf, so that, for example, “health care is a right, not a privilege.” (Imagine.)

But the answer to the question about Sanders’s socialist credentials is more complicated, and more important than it may seem. It entails much more than quibbling, erudite distinctions in terminology. It turns out to involve the nature of his challenge to the prevailing political-economic regime, and the viability of his proposed programs.

What do people, including Sanders, mean by “socialist?” The term has a long and increasingly obscured history. In the Oxford Guide to Philosophy (2002 edition), contributor D. W. Haslett wrote that fundamentally, it’s “an economic system that features state ownership of the means of production and control of investment.” That’s certainly what Karl Marx meant when he projected a socialist future, but history has worn away at the practical relevance of that meaning, and Haslett tells us that the word is now used to name a number of very different movements and beliefs.

Sanders comes out of the social democratic tradition, which has long influenced, and maintained relationships with, mainstream liberalism. For well over a century, social democrats have sought to correct capitalism’s more dangerous results and tendencies. A great deal of the contours and content of American social and political life owe their existence to leftist, social democratic agitation and demands: Social Security, Medicare, protection of labor unions and employee rights, restrictions on child labor and civil rights legislation. All of these and a lot more represented often grudging attempts by political and economic elites to damp down unrest and protest organized by the American Left. Sanders is not only well within that tradition, he’s very much in sync with American political history.

Writing in The Nation last November, DeWitt Clinton Professor of History at Columbia University Eric Foner pointed that out, and said that “the most successful [American] radicals have always spoken the language of American society and appealed to some of its deepest values.” Hillary Clinton, trying to dismiss her surprisingly successful challenger’s relevance, sniffed, “This isn’t Denmark,” thereby joining in spirit Klein’s snide evasions.

What is the supposedly radically unrealistic program Sanders espouses? It includes: doubling the federal minimum wage; raising income taxes on the very richest to Eisenhower-era rates; a Wall Street transaction tax to pay for public college education; loans to employees who want to buy a stake in their employers’ companies; and extending Medicare to provide all Americans with health care. Is this agenda doable? Maybe, maybe not. But it is certainly not in opposition to American values and history.

Foner, in his 1998 book, The Story of American Freedom, reminded us that Franklin D. Roosevelt, in his 1941 State of the Union address, proposed “Four Freedoms” Americans deserved, including “Freedom from want.” (The other four freedoms were: of speech, from fear, and of worship.) Four years later, Foner noted, in Roosevelt’s “Second Bill of Rights,” he called for guarantees of education, employment, medical care, a decent home, and more. Over seventy years ago.

And yet Sanders is often treated as exotically strange, and patronized by conventional media figures and politicians. CNN’s Anderson Cooper, at the first Democratic debate in October, asked Sanders, “You don’t consider yourself a capitalist?” as if he couldn’t get his head around the idea of Sanders’s candidacy and ideas.

Meanwhile, the respectable opinion-mongers have sprung into action to deride those ideas. The New York Times columnist and economics Nobelist Paul Krugman, along with others in his profession, has hammered at the Medicare proposal, charging that its cost assumptions and other numbers can’t work. But Buffalo State College economics professor Ted Schmidt wrote in an email that Krugman and company weren’t just waging war on Sanders’s healthcare proposal: “It was an attack on the impact of Sanders’ entire economic plan.” Regarding their assault on a Sanders’s advisor’s assumption of a 5.3 percent economic growth rate, Schmidt wrote, “the ‘esteemed’ economists did not attempt to evaluate his assumptions; they simply threw the baby out when they saw the 5.3% number.”

In his 1938 memoir, The Road to Wigan Pier, English writer George Orwell wrote, “To the ordinary working man, socialism does not mean much more than better wages and shorter hours, and nobody bossing you about.” Allowing for historic differences and distance, Sanders’s appeal, and his active appeal to voters, aren’t fundamentally much different.