Few things are as lethal for the healthy conduct of democratic politics as a crisis of legitimacy.

As far back as the Classical Era, Aristotle argued that a state’s legitimacy hinged on the stability created by distributive justice, which is to say, the equitable distribution of society’s material rewards according to individual merit.

More recently, the German political philosopher Jurgen Habermas has identified what he calls a “legitimization crisis,” which occurs when the state structures legally endowed with administrative powers “do not succeed in maintaining the requisite level of mass loyalties” allowing them to exercise those powers. Among the results, he argues, are incoherent policies and a paralyzing loss of political will. For a quick education on what a crisis of legitimacy can entail, take a look at the bloody civil war now convulsing the Arab world.

Even so, we here in the United States now have two candidates seeking the presidency who have built their campaigns around triggering just such a crisis.

The seeds of an American crisis of legitimacy were sown by inattention to the worsening levels of income inequality, wage stagnation and underemployment, along with the loss of public faith in institutions from the press to the church to politics. The latter’s situation was made still more wretched in the public eye by hyper-partisanship and the consequent paralysis of legislative government.

From the start, this is the poisoned soil that Donald Trump and Bernie Sanders have tilled. Both have called into question the legitimacy of institutions fundamental to our democracy. Both have attacked the national government as captive to entrenched Wall Street interests to the detriment of ordinary Americans.

Both have savaged the structures and practices of their own parties as rigged and unfair. To listen to Donald and Bernie, the economy, government and the national parties are all conspirators in a kind of shell game designed to cheat the American people out of a decent life and a say in their own destiny.

How can such a system be anything but illegitimate?

Rather than giving their loyalty to such a conspiracy, Trump proposes that the voters give it to him. In place of the corrupt parties and dishonest government, the failed Casino operator offers a kind of American “Putinism” centered on self-evidently unbalanced personality.

The Brookings Institution’s Robert Kagan has shrewdly identified the Trump agenda as nothing less than neo-fascism.

Kagan wrote in a May 18 column for The Washington Post: “The entire Trump phenomenon has nothing to do with policy or ideology. It has nothing to do with the Republican Party, either, except in its historic role as incubator of this singular threat to our democracy. Trump has transcended the party that produced him. His growing army of supporters no longer cares about the party—because it did not immediately and fully embrace Trump.

“Because a dwindling number of its political and intellectual leaders still resist him, the party is regarded with suspicion and even hostility by his followers. Their allegiance is to him and him alone. And the source of allegiance? We’re supposed to believe that Trump’s support stems from economic stagnation or dislocation. Maybe some of it does. But what Trump offers his followers are not economic remedies — his proposals change daily. What he offers is an attitude, an aura of crude strength and machismo, a boasting disrespect for the niceties of the democratic culture that he claims, and his followers believe, has produced national weakness and incompetence.

“His incoherent and contradictory utterances have one thing in common: They provoke and play on feelings of resentment and disdain, intermingled with bits of fear, hatred and anger. His public discourse consists of attacking or ridiculing a wide range of ‘others’ — Muslims, Hispanics, women, Chinese, Mexicans, Europeans, Arabs, immigrants, refugees — whom he depicts either as threats or as objects of derision. His program, such as it is, consists chiefly of promises to get tough with foreigners and people of nonwhite complexion. He will deport them, bar them, get them to knuckle under, make them pay up or make them shut up.”

As if on cue, Trump—the night before accepting the endorsement of the National Rifle Association—bellicosely dismissed the possibility that his hostility to free trade and plans to abrogate such agreements might cause economic chaos. “Who the hell is afraid of a trade war,” he sneered, presumably because all real men with concealed weapons permits (yes, he has one) relish a good scrap.

On the other side of these contested aisles, Sanders turns out to be Trump in a sort of lacey left-wing drag—precisely the vainglorious jackass his most severe Democratic critics always have insisted he was. The Vermont socialist goes on about a wish list of ill-defined policy goals—single-payer healthcare, breaking up the big banks, reregulating the financial industry–to which a lot of us might subscribe, if they were attainable, which they’re not. Sanders now goes on and on about his “movement,” which has become little more than a backdrop against which he can enact his now tiresome ego theater.

He may insist that it’s all about the people, but at this point it’s really all about Bernie.

He, too, trades in corrosive allegations of the political system’s illegitimacy: The primary system is corrupt and rigged; the Democratic National Committee is a front for Hillary Clinton’s campaign; his supporters are being cheated by their state parties. Worse, he continues to churn his backers up with the claim that the nomination still might be won, when in fact it cannot be. Functionally, he’s out of the race, but like the unwanted brother-in-law in your back bedroom just refuses to leave.

The worst part of all this is that his allegations on institutional illegitimacy—on Wall Street, at DNC headquarters—have inflamed his already frustrated an politically immature followers. The violence, attempted intimidation and death threats at last weekend’s Nevada Democratic convention are ample evidence of that.

On Friday, Politico published a series of comments on the Sanders campaign from Democratic insiders across the country. A Nevada Democrat — who, like all respondents, completed the survey anonymously — told the publication:

“After experiencing first-hand the madness of the [Nevada state] convention and seeing the aftermath where we still have yet to see Sanders doing anything to quell the fire, I’d say we are in for a rough ride in Philly,” said a Nevada Democrat — who, like all respondents, completed the survey anonymously.

“Most Democratic insiders pinned the blame on Sanders, the independent Vermont senator, arguing he has inflamed his supporters by giving them the unrealistic impression that he can pass Clinton in the delegate count.

“Bernie is doing great damage right now by giving his most ardent supporters the illusion that he can win, and impression that if he doesn’t it’s because the system was rigged or they were robbed,” said a Colorado Democrat. “Much of what we are seeing in Nevada happened in Colorado at our convention, although on a much smaller scale – booing anyone other than Sanders, near violence in the hallways, and a sense that if anything didn’t go their way it was because the system was rigged.”

Trump and Sanders have incited their supporters to violence in this campaign and they’re worse damage by promoting the notion that our flawed, but functional democracy does not deserve the loyalty of its people.

Two childish egos playing with political matches are putting us all in peril.