Can Donald Trump and the populist leaders of Europe do us some good? They do what populists have always done: play on fears, especially of those not defined as "our" people; exaggerate social breakdown; identify centrist and liberal governments as out of touch and corrupt, and point to a cosmopolitan, snobbish and self-interested elite with no respect for "the people."
This is their time. But could they also help, even unwittingly, the societies they aspire to govern?
Most of the research suggests not. A recent study from Harvard - not an institution loved by populists - contends that in both the United States and Europe, the 1970s shift away from class politics in rich countries to "post-material values" sparked a cultural backlash, especially among white, older, less-educated men - call them the "Wolems" - who "actively reject the rising tide of progressive values, resent the displacement of familiar traditional norms, and provide a pool of supporters potentially vulnerable to populist appeals."
Wolems fear marginalisation (many already experience it) and often haven't the time left in their lives to make fundamental changes. More than economic inequality, cultural distaste powers them. Where they live is no longer the America, the France or the Poland in which they believed they were raised - and the social and cultural revolutions in their native society has rendered them, the core native stock, outside the pale. They are the minority now.
In the past, populism had many toxic characteristics. The Ku Klux Klan extended its venom from black Americans to Jews and Roman Catholics. In the mid-1920s, the Klan and its allies helped push Congress to pass strict annual quotas that limited immigration to the United States from eastern and southern Europe to a few hundred immigrants a nation. The quotas weren't lifted until 1965. Trump's demonisation of Mexican immigrants as rapists and criminals dips into this turgid pool. A Washington Post fact check er found, however, no evidence to support the view that Mexican immigrants committed more crimes than native-born Americans.
In Europe, populists see Muslims as the dangerous aliens of choice, given that terrorist attacks on the continent are usually perpetrated in the name of militant Islamic groups. While centrist politicians struggle to protest that the large majority of Muslims abhor the attacks, the fear of violence has made the National Front's Marine Le Pen one of the most popular politicians in France and pushed the socialist government into endorsing ridiculous bans on "burkinis" - full body coverings for Muslim women bathers - bizarrely condemned as "provocative" by former President Nicolas Sarkozy.
These characteristics don't seem to make for benign legacies. But populism is the cry of part of a community - in some cases and places, nearly all of a community - that believes itself wounded. Its rallying point is that the labor of local workers is undercut by immigrants, who weaken communal bonds by refusing to respect them. A flood of cheap goods, the product of free trade agreements, eviscerates local manufacturers. The liberal cosmopolitan elite that forms the government enacts laws that enforce tolerance of sexual and ethnic minorities, who are not part of "us."
But populism is rooted in the same word as "people." The movements based on it express a popular protest - and protests are necessary in democracies. Bernie Sanders' pitch was based on populist disgust at economic inequality and corporate greed - and though he had few financially realistic policies, his passionate advocacy struck chords and pushed rival presidential candidate Hillary Clinton to acknowledge that globalization measures she championed had hurt millions of Americans.
Populists in the past did the same as Sanders, and changed policy. The Peoples' Party of the 1890s advocated greater state intervention to help the "plain people" of the United States. Although the party had a short life, its opposition to exploitation became part of both Republican and Democratic agendas at the turn of the century. Even the party's campaigns against the employment of foreign labour, usually backed by labor unions and often with racist overtones, led to better wages and conditions for workers.
In the United Kingdom, where what Brexit means is still being worked out, the government is investigating a long-overdue plan to expand medical training to reduce the National Health Service's dependence on foreign doctors and nurses who may face post-Brexit barriers on non-British labor.
What might Trump's benign legacy be? It is likely to be one in reaction to his policies and behavior, rather than learning from it. Some men, who indulge in "locker room talk" about sexual conquests, may be thinking again: Few things are a better prompt to change than seeing one's own ugly image in a mirror provided by another's actions. The insults Trump offered in July to the patriotic family of Captain Humayun Khan, killed in Iraq, should in their grossness, have caused those attracted to his anti-Muslim diatribes to reconsider.
Similarly, though his policies on immigration were couched in more insults, the status of millions of undocumented workers in the United States needs to be addressed. His proposal to reduce or eliminate tax loopholes for the superrich - if sincere, given that he's one of them - is appropriate at a time when the Panama Papers teach us how large these loopholes are.
Trump and his European comrades have ranged from right to left across the spectrum, as populists tend to. In doing so, they touch issues that needed airing, express resentments that need a voice. Populist parties and champions, the US historian Richard Hofstadter remarked, are like bees: Once they sting, they die. Trump will not die. My own bet is that he will found a populist-right TV channel.
Populism can descend through several circles of hell into fascism and Nazism. Yet, it can also be a cry of despair, of frustration, an appeal for help couched in the language of rejection and aggression. Democrats can beat populists, and usually have, by attending to what underlies the surface ugliness. That's likely to happen in the United States. We in Europe must hope we have politicians able to face down the challenge, too.
John Lloyd co-founded the Reuters Institute for the Study of Journalism at the University of Oxford, where he is senior research fellow. Lloyd has written several books, including 'What the Media Are Doing to Our Politics'. He is also a contributing editor at the 'Financial Times' and the founder of 'FT Magazine'.