Daniel W. Drezner is a professor of international politics at the Fletcher School of Law and Diplomacy at Tufts University and a regular contributor to PostEverything.

Does this Romanian waiter expect a gratuity for his service at the end of the meal he is serving? That may be a function of  how many Romanians visit the United States. (Octav Ganea/AP)

Ezra Klein made a rather provocative claim in Vox on Tuesday asserting that, because structural forces have increased the rate of polarization and gridlock in Washington, more and more Beltway folk were listening to political scientists who study American politics.  I’m not sure that Klein had any data to back this up except for this sentence:  “Young political journalists I talk to know a lot more about political science and how to use it to inform their reporting than they did when I came to town.”  But when political scientists are under periodic attack for myriad reasons, it would be churlish not to welcome good news assertions like this one. 

We here at Spoiler Alerts share a similar ethos, in pointing out how certain truisms in political science persist no matter how much pundits scream that this time is different.  But even Spoiler Alerts craves research that is new and interesting. Which brings me to the most interesting paper I saw presented at last week’s slightly singed American Political Science Association annual meeting.

It’s about gratuities.

See, Americans are far and away the biggest tippers on the planet, but gratuities as a social practice do exist in much of the globe — and the tipping rate has varied over time.  What explains the pattern of tipping across the world?

Ed Mansfield’s paper, “The Political Economy of the Itching Palm:  An Analysis of Tipping Norms” examines the global diffusion of a trend that nobody seems to like very much: leaving gratuities for restaurant service. Indeed one of the fascinating things about this paper was learning that the campaign against gratuities is almost as old as the norm of leaving gratuities itself. Indeed, according to Mansfield:

Frustration over tips grew to the point that a series of legislative efforts were made to restrict gratuities in parts of the U.S. In 1910, Congress authorized fines against waiters who accepted tips in Washington, DC restaurants. In 1909, Washington became the first state to enact a law prohibiting tipping altogether. Mississippi and Arkansas followed suit in 1912 and 1913, respectively. In 1915, Iowa, South Carolina, and Tennessee passed anti-tipping legislation, and Illinois, Nebraska, and Wisconsin actively considered measures that would have banned gratuities. All of these laws, however, were quickly repealed, either because they were deemed unconstitutional or because they were so widely ignored that it made little sense to keep them on the books.

Why do I find this an interesting topic?  Because Mansfield uses tipping as an example of a social norm and wants to know what determines its global spread. Unlike some other norms — human rights, democratic elections, Washington Consensus economic policies — the U.S. government has little incentive to use punishments or inducements to spread the norm of tipping.  This is almost a pure example of Joseph Nye’s concept of soft power — getting other countries to want what Americans want (or, in this case, feel ambivalent about but do anyway) without using carrots and sticks.  In other words, this is an example of a custom or social norm that spreads through learning and emulation.

Mansfield looks at cross-national variations in average tipping rates (as determined by a consensus of travel books) at two different points in time (1982 and 2010) to figure out what explains the variation in gratuities.

His main finding:

From an international perspective, my findings reveal that tipping rates are influenced by the extent of travel to the U.S. I have argued that such travel stimulates the spread of American culture and norms, including tipping habits. My results also suggest that these habits have not spread because of American travel to foreign countries or other features of American culture and business. The act of interacting with Americans and experiencing American tipping habits while foreign individuals tour, work, and study in the U.S. seems to be an especially potent source of the diffusion of American tipping norms.

So, for all the talk about waning U.S. hegemony these days, it turns out that the United States is still popularizing practices that Americans feel ambivalent about at home.

What’s equally interesting is what doesn’t explain the variation in tipping across countries.  Mansfield included measures for national income, economic inequality, worker conditions, the size and strength of a country’s social safety net, and the size of a country’s service sector.  None of these variables were significant.

This is a great example of a political science paper that uses what seems like a small topic to ask a big question about the diffusion of norms in the world, and then devises an interesting and empirically imaginative way to measure and test that question.  More please.