Since Roman times, virtually every type of government that holds competitive elections has experienced some form of populism—some attempt by ambitious politicians to mobilize the masses in opposition to an establishment they depict as corrupt or self-serving. From Tiberius Gracchus and the populares of the Roman Senate, to the champions of the popolo in Machiavelli’s sixteenth-century Florence, to the Jacobins in Paris in the late eighteenth century, to the Jacksonian Democrats who stormed nineteenth-century Washington—all based their attempts at mass mobilization on appeals to the simplicity and goodness of ordinary people. By the mid-twentieth century, populism had become a common feature of democracy.
But then, during an extended period of spectacular economic growth stretching roughly from the aftermath of World War II to the late 1970s, the political establishments of most Western democracies managed to banish their populist rivals to the innocuous fringes of political discourse. On the right, populists occasionally made incursions at the local or regional level but inevitably failed to gain traction in national elections. On the left, the countercultural protest movements of the 1960s and 1970s challenged the status quo but didn’t secure institutional representation until their radicalism had subsided.
As the political scientists Seymour Martin Lipset and Stein Rokkan famously observed, during the postwar years, the party structures of North America and western Europe were “frozen” to an unprecedented degree. Between 1960 and 1990, the parties represented in the parliaments of Amsterdam, Copenhagen, Ottawa, Paris, Rome, Stockholm, Vienna, and Washington barely changed. For a few decades, Western political establishments held such a firm grip on power that most observers stopped noticing just how remarkable that stability was compared to the historical norm.
Yet beginning in the 1990s, a new crop of populists began a steady rise. Over the past two decades, populist movements in Europe and the United States have uprooted traditional party structures and forced ideas long regarded as extremist or unsavory onto the political agenda. The influence of populists has been especially