ONE more note on the Herman Cain campaign : obviously, the campaign is the latest example of the recurrent temptation in American politics to turn to non-politicians, usually businessmen, to fix the political mess, clean up Washington, and so forth. Most attention focuses on whether Mr Cain is serious , or has any chance of winning; political scientist Hans Noel says it's very unlikely, Nate Silver of FiveThirtyEight says his polling data is anomalous so it's hard to say.

But to me, the interesting historical question here is whether turning to non-politicians to fix political messes has ever, in fact, worked. The only non-politician candidate I can think of who became a successful president was Eisenhower, and he was drafted not to clean up a mess in Washington but to end the war in Korea. Few non-politicians have been elected; in relatively modern history, only Herbert Hoover had no electoral experience, though he was hardly a Washington novice, having served two terms as commerce secretary. In any case, we all know how well he turned out. Further back, William Howard Taft had never run for anything, but he'd been in both of Teddy Roosevelt's cabinets and was hardly viewed as an "outsider", and his term was politically disastrous for the GOP. Then further back you've got General Ulysses S. Grant, whose administration was a corrupt mess. General Zachary Taylor's administration was clumsy and fortunately brief. And most non-politician white-knight candidates never make it that far. Most recently, we have examples like General Wesley Clark, who failed to go anywhere in the 2004 Democratic primaries; Ralph Nader, who got 2% of the vote in 2000; and Ross Perot, who won 19% in 1992 and 8% in 1996. In perhaps the purest white-knight candidacy in American history, Horace Greeley got creamed in 1872, went insane, and died before the votes were counted.

John Sides wrote a few days ago about a paper by political scientists Joseph Uscinski and Arthur Simon, "Prior Experience Predicts Presidential Performance", that bears this out. They find that presidents who were "outsiders" when they ran had significantly lower ratings on three dimensions in the C-SPAN Survey of Presidential Leadership.

Outside of the presidency, we have a few recent examples of non-politician white knights elected to major executive office in the United States. Arnold Schwarzenegger was a wreck as governor of California. Jesse Ventura had an ignominious term as governor of Minnesota. The only successful example I can think of is Michael Bloomberg as mayor of New York City. Mr Bloomberg is finally outstaying his welcome, but he's accomplished a tremendous amount, and winning three terms in office is a success in itself.

How about internationally? Broadly speaking, non-politician white knights can be broken down into four categories: business executives, entertainment celebrities, family members of prior politicians, and military officers. There are a lot of examples of military officers coming to power in a wave of enthusiasm, but usually in coups, not elections, and they don't generally end well. Entertainment celebrities don't seem quite as politically advanced outside the US, apart from former Philippines boxer/actor/president Joseph Estrada, who was ousted in a popular uprising over corruption. As for family members of prior politicians who lack political experience themselves, Sonia Gandhi has been surprisingly long-lived as head of India's Congress Party, but this mainly suggests the continuing strength of familial clan power. Thailand's Yingluck Shinawatra looks set to have a more typical failed term.

And so we come to the businessmen. Two potential recent success stories suggest themselves: Ms Shinawatra's brother Thaksin, the telecom billionaire who built the political machine she inherited, and Silvio Berlusconi. Both men ended up wrecking their countries' political systems, but are also transformative figures who succeeded by their own lights in accomplishing many of their goals, and who continue to enjoy the rabid, emotional support of many, perhaps a majority, of their countrymen. If I had to suggest a possible factor uniting these two businessmen-turned-leaders, it would be that both of them came from businesses that were in fact highly politicised and closely tied to government. Mr Berlusconi was the dominant media tycoon in northern Italy; he both understood how to use domination of the corporate media landscape to influence politics, and had already built political alliances in order to gain concessions for TV station ownership and mergers. Mr Thaksin built his fortune by buying up part of the electromagnetic spectrum sold off by the Thai military in the 1990s and parlaying it into a major mobile telephony company. To win the spectrum concession, he used the ties he had built through his service in the country's powerful national police. Both men thus had substantial experience in political coalition-building and had already created significant patronage relationships which they carried into their government roles.

A final example of a non-politician white knight who has enjoyed considerable success in office might be Vladimir Putin, who had never run for electoral office before Boris Yeltsin appointed him prime minister in 1999. Mr Putin's subsequent success at building a dominant political machine and consolidating control over Russian media and public opinion suggests that a career in the KGB provides both the background training and the patron-client relationships needed for success in executive politics.

Overall, then, I'd say there's evidence that a white-knight candidate can succeed in executive office if he comes either from a government-dominated business sector such as telecoms where lobbying and politics are a major part of the business, or if he has been a senior officer in the secret police. White-knight leaders' terms, if politically successful, probably lead to tremendous increases in corruption, clientelism, and centralised executive power, and to bitter political polarisation. White-knight leaders generally end their terms refusing to relinquish power, and embroiled in legal difficulties or popular uprisings. So I'm not generally optimistic about the idea of electing non-politicians to fix the mess in Washington. How about you?

(Photo credit: AFP)