The medieval period in Europe saw the real flowering of the carnivalesque, and they didn't just do it for fun. From the "Feast Of Fools," in which priests put on their robes backwards and sang drunken, insulting songs, to entire weeks in which "Lords Of Misrule" caused chaos, the essence of the carnival spirit was about turning a very strict order of life upside down. Medieval Europeans existed in strict hierarchies with a lot of control by the state and church, and carnival periods meant they were briefly released from all those rules. In the words of Claire Tancons, carnivals were "a medium of emancipation and a catalyst for civil disobedience," in which peasants could boss around their masters without consequences.

They were also, according to literary theorist Mikhail Bakhtin, all about rebellion through satire and fun. Bakhtin argues that carnivals "built a second world and a second life outside officialdom," in which ordinary people felt free to skewer elites through mockery:

"Civil and social ceremonies and rituals took on a comic aspect as clowns and fools, constant participants in these festivals, mimicked serious rituals such as the tribute rendered to the victors at tournaments, the transfer of feudal rights, or the initiation of a knight. Minor occasions were also marked by comic protocol, as for instance the election of a king and queen to preside at a banquet 'for laughter's sake' (roi pour rire)."

In a highly-regulated world, this was about the only form of protest available to people of low status, and they used it to the fore. It could be a full-blown "anti-feudal, anti-clerical demonstration against public discourse," and the elites couldn't do anything about it. Public rowdiness and humor would continue to be part of the political and moral arsenal of Europeans even as carnivals stopped being so important; skimmingtons, a riotous procession involving an effigy of a local person who'd done something wrong, were a part of English village life up until the early 20th century.

One of the most famous theories about why this was allowed is called the "safety-valve theory." If people were allowed to vent their frustrations about oppression on certain days, about everything from the feudal system to sexism to the lords in charge, they'd be more likely to behave the rest of the year. Some critics disagree, though; they see the safety-valve idea as basically a reinforcement of the status quo, meaning that after carnival's riotous fun everything just goes back to normal, while in reality, carnivalesque protests have made some genuine social changes — as we'll see.

Carnival is, as we've seen, "a celebration by the weak of their power when, for a brief moment, they reverse the usual hierarchies," and that's a pretty powerful political moment. But is it still a viable form of social protest these days, when we're not in a feudal environment ruled by kings?

The answer seems to be yes. For one, carnivals these days are often about celebrations of identity in response to racism and homogenization. The samba enredo, a genre of samba where complex dances are performed by dance schools during the Carnaval celebrations in Rio, actually has a strong political purpose, because it celebrates the place of Afro-Brazilians in Brazilian society. Notting Hill Carnival in the UK serves a similar purpose: it's all about highlighting the contributions of immigrant communities, particularly West Indian ones, to the culture of the area, and doing it in a colorful, brilliant way.

Is that the new role of carnival in modern democracies, instead of critiquing specific practices and turning the world topsy-turvy? It's an interesting question. Carnival, political theater expert Dr. Cami Rowe explains, "has historically been successful in highly stratified societies," and there are thinkers who believe that carnival isn't the best way of dealing with problems in liberal democracies, where everybody, in theory, has a say. But Rowe points out that many people don't feel all that represented or safe in modern America (women of color, for instance, or transgender people, or immigrants, or the mentally ill). For them, there still remain many hierarchies that need to be busted up, and carnival is a good place to do it.

A lot of the argument about modern carnivals, Rowe notes, is around whether their protests can do any lasting political good. Should we leave them to their music and their dancing, and focus the political work of public protest on marches and demonstrations?

It turns out that the line between a march and a carnival isn't all that well-defined, and that carnival-marches in the past have had some real political consequences. During the Second Republic in Spain, carnivals had a tendency to "escalate into insurrection" among the public, according to Professor Warren Shapiro, which is probably why both de Rivera and Franco banned them. In 1849, a carnival masquerade on Ash Wednesday in France turned into an overtly political event, with "The Garbage Cart Of The Reactionary Press" and a man dressed as the French President blindfolded riding backwards on a donkey. And in modern history, various anti-fascist organizers across the UK in the 1970s organized carnival-protests like Rock Against Racism, which were a mix of carnival and demonstration, and took a massive "Militant Entertainment Tour" on the road around Britain. In 2008, 30 years afterwards, the Rock Against Racism concerts were seen to be a major catalyst for the drop in support for far-right politicians in the late '70s. (Maybe we need to organize a Rock Against Racism now.)

Is a carnival like other forms of political protests? There's disagreement about this: carnivals, some political thinkers argue, are all about subverting the usual order with satire and lampooning, while marches and demonstrations try to push forward concrete political change. But, as we've seen, there's a massive overlap: the 1996 protests against the electoral fraud of Slobodan Milosevic in Serbia were apparently characterized by a strong carnival atmosphere, complete with singing and dancing in the streets and city-wide chanting. And the Women's Marches around the world in January had a slightly carnivalesque atmosphere, if only expressed by brilliant and cutting signs. Carnival doesn't mean that things aren't serious. On the contrary, it means that fun can be a political weapon, too.