The philosophers of the Frankfurt School practiced a technique called negative dialectics, where concepts are defined as much by what you can't say about them as what you can. Appropriately, the Frankfurt School has ended up defined by what you can't say about them.

You can't say that they invented a new form of left-wing thought called Cultural Marxism. This would be (according to Wikipedia) the Cultural Marxism conspiracy theory, a "far right anti-Semitic conspiracy theory that misinterprets Western Marxism, especially the Frankfurt School, as being responsible for modern progressive movements, identity politics, and political correctness". You're not supposed to dub them a transitional stage between Communism and postmodernism. You're not allowed to speculate that a lot of the academic humanities, as they're practiced today, descend from the Frankfurt School's brand of critical theory. You're not supposed to think of them as the point where the muscular pro-technology leftism of the early 1900s shattered into the pessimistic degrowth leftism of the present.

Art is long, life is short. Most of us only manage to not do a few things in our limited span on Earth. But the Frankfurt School managed to not invent so many movements - to not be involved in so many of the crucial ideological shifts of the past century - that they caught my attention. Who were these people? What other aspects of our culture might we be unable to say they were involved in? For answers, I turned to the classic history of the group, Martin Jay's The Dialectical Imagination.

The basics are simple enough: the School was founded in Frankfurt in 1923. It attracted great philosophers like Max Horkheimer, Theodor Adorno, and Herbert Marcuse. When the Nazis took power in the early 1930s, the mostly-Jewish Frankfurters fled to America, where friendly locals helped them continue their work in affiliation with Columbia University. Mid-century Americans were suckers for sophisticated European intellectuals, and when the rise of fascism and World War II started dominating headlines, the German-Jewish Frankfurters were natural experts to help Americans process the situation. By the end of the war, they were firmly established as thought leaders. Some - including Horkheimer and Adorno - returned to Germany to rebuild its intellectual culture from the ruins; others stayed in America and remained relevant through the 60s and 70s.

But figuring out what the Frankfurters believed is more complicated. Forget about the thin line between universally-acknowledged fact and fascist conspiracy theory. The School itself was famously coy, worrying that if they explained themselves too clearly, people would caricature their beliefs and integrate them into the existing capitalist system. Even when they did speak "clearly", it was in the sort of German philosophical register where "the negation of the negation" is a totally normal thing to say.

Having only read a single book on them, I will no doubt fall into all the failure modes that they and their successors warned us against. But here are the analogies, intuition pumps, and parables that I found helpful.

https://www.astralcodexten.com/p/book-review-the-dialectical-imagination