Not a program.
A frame: the people vs. the elite.

That thinness explains a lot. Because populism supplies the moral framing but not the policy, it can pair with almost any program. What stays constant is the storyline: a unified, decent people has been betrayed by a corrupt establishment, and a leader or movement arrives to give the people their voice back. The power of the frame is that it feels true whenever institutions really have failed ordinary people — and its danger is that it treats “the people” as single and unanimous when real societies never are.

Left-wing populism draws the elite in economic terms and reads politics as the many against the moneyed few. Right-wing populism draws it in cultural terms — a cosmopolitan establishment of politicians, journalists, and experts — and frequently fuses with nationalism, adding outsiders and immigrants to the list of those set against “the real people.” The two can sound like opposites, but the grammar is identical: a pure us, a corrupt them, and a demand that the us finally rule.

The word traces to the 1890s, when the American People's Party rallied farmers against banks and railroads; Latin America gave it a second home in the mass movements of the twentieth century. But the deeper root is older and more respectable: the democratic idea of popular sovereignty, and behind it Rousseau's general will — the conviction that legitimate authority flows from the people as a whole. On the spectrum of the -isms, populism is the point where that Rousseauian strand turns radical: it takes the noble premise that power belongs to the people and hardens it into the claim that there is one true people with one will, which a movement can voice directly — without the mediation of parties, courts, or compromise.

That is exactly where it collides with liberal democracy, and the collision is worth stating plainly rather than taking sides on. Liberal democracy assumes the people are plural — many interests, permanent minorities, institutions that check even the majority. Populism assumes the people are one. When a movement claims to be the sole voice of the real people, opponents can be recast not as fellow citizens but as enemies of the people, and the courts and press that constrain the majority can look like obstacles to democracy rather than parts of it. Critics such as Jan-Werner Müller argue this anti-pluralism is populism's defining risk. Defenders answer that populism is often the only force that takes real grievances seriously when establishment politics has stopped listening. Both can be true at once, which is why the phenomenon is so hard to judge in the abstract.