In the last decade, societies in which corruption used to be treated as a fact of life developed a strong intolerance to official thievery and ousted once-untouchable politicians. In Brazil and India, Russia and Spain, people took to the streets to denounce corruption by the powerful.

And too often those in power were also leaders of traditional political parties. When such leaders are caught stealing, it becomes another stain on parties, whose prestige and allure have been steadily waning. These days, political parties are seen not as natural habitats for idealists but for fast-talking and often hypocritical opportunists and careerists.

The disdain for politics as usual — and therefore for parties locked in the status quo — is intense, widespread, global. This is why anti-politics, the rejection of traditional politics and its practitioners, is such a popular instinct today.

The case of Tiririca vividly illustrates why. In 2010 Francisco Everardo Oliveira Silva, known professionally as Tiririca the clown, ran for a congressional seat in Brazil, campaigning in costume. His message was honest and straightforward: “I don’t know what a representative in Congress does, but if you send me there I will tell you.” He also explained that his goal was “to help people in need in this country … but especially my family.”

At the time, it was easy to dismiss Tiririca’s run as an extreme anti-political gesture that could happen only in a rowdy young democracy like Brazil’s. But not for long. The sentiment that propelled Tiririca to victory is similar to that which drove the political success of the comedian Beppe Grillo in Italy, or that of Mr. Trump, a reality TV show host.

Both men were able to undermine the power of dominant parties. While Mr. Grillo’s Five Star Movement sought to displace Italy’s political machine by positioning himself as a radical outsider, Mr. Trump took on traditional politics as a radical insider, staging a hostile takeover of the Republican Party.