“Populism” isn’t really a term of art or science. At best it means any popular movement or opinion that conflicts with the center-left consensus. More often it’s used just to label any bit of ignorant demagoguery whatsoever. (The fact that the word “populism” is mostly just a smear word doesn’t prevent it from being used in the vast netherworld of social science literature, of course.) Until at least the 80s dictionaries did not include the generic term “populist”, but defined the term to mean either an American Populist or a Russian Narodnik.
The generalized use of the word as a throwaway insult seems to be an function of the transformation of the left-center into an administrative elite after WWII. Richard Hofstadter’s books, among others, provided an intellectual rationale for the smear, and they are still heavily used in indoctrinating young American wonks, but his portrait of the Populists and Progressives is polemical, not based on primary research, and presentist (he thought Joe McCarthy was a populist). A case could be made that the American Populists were not populist in the current sense of the term, even though the term traces back specifically to them.
A neutral definition of populism allowing for both benevolent and malign forms might be OK, but I don’t see anyone using it that way. Historically, both in the US and in Europe a lot of the energy behind progressive movements was populist (e.g. “obrerismo” in leftist labor movements), but the administrative left today seems to be committed to an anti-populist , gradually-retreating defensive holding action preserving their positions of influence, with The People serving as the enemy.
Anti-popular politics in the Democratic goes back a long way; the era of popular politics only lasted from about 1890 to 1941, with dwindling aftershocks up until 1968, and even during that era there was fierce internal resistance. After WWII anti-populist ideology got big boosts from the Straussians, from Adorno and the critical theorists, and from the neoliberals (on whom see Mirowski’s “Road From Mont Pelerin”.) Hofstadter was watered-down pop-Freudian Adorno.
The root anti-populist argument is simple: Hitler was a populist, and look what happened. Another reading of the same data might argue that Germany in 1918 was so hierarchical and authoritarian that it couldn’t make the transition to democracy or even liberalism. (Adorno seems to have been crushed by German labor’s refusal to obey its wise Communist leaders). Mayer’s “They Thought They Were Free” describes Germans who had at least passively accepted Naziism: for them the Nazis were like urban political bosses in the US, who helped out people who needed help when none of the established authorities were willing or able to do anything. During the 20s and early 30s the German churches, vanguard left parties, and conservative parties, as well as the Austrian economists, the Straussians, and the Schmittians were all firm in their belief that The People should be seen and not heard and that The People existed to serve the State, the Church, the Party, or the Market, and not the other way around.
Hitler of course was no better, but he successfully exploited a weak spot in the existing authoritarian establishments in order to replace the lot of them with a single new authoritarian establishment.
(A response to this Crooked Timber post, which casually uses the term “populism” as a smear word.