This is from Benedict Beckeld, at Quillette (via Maggie's Farm):
The Frankfurt School of social theory began about a century ago, in the Weimar Republic. It consisted in the main of a group of rather anti-capitalist, Marxist-light gentlemen who embraced oikophobia (the hatred or dislike of one’s own cultural home), and who were understandably disillusioned by the carnage of World War I. Our interest today is mainly historical; of its earlier members, such as Ernst Bloch, Walter Benjamin, Max Horkheimer, Herbert Marcuse, and Theodor Adorno, really only Adorno is still read with a measure of seriousness outside of academia. The Frankfurt School popularized historicism—the belief that reflection itself is a part of history, which is to say that earlier thoughts are historically conditioned by the circumstances in which the thinkers lived, and should be seen in that light; and that what passes for “knowledge” is marred by the historical time and place in which that knowledge appeared. (This idea was present already in the second part of The Communist Manifesto.) The insights that a more positivist outlook claims to be certain, based on sensory data, historicism will consider uncertain and necessarily bound by subjective value judgments. A part of this view is the concern—and the French postmodernists will pick up this point—to identify, isolate, and thereby exorcise every sort of domination that any group might have held over any other group. They wanted to find the particular reasons why someone in the past had thought in a particular way, reasons that were to be found mainly in external factors. Essentially, the Frankfurt School endeavored to establish a “value-free” social science, that is, the erasure of any sort of prejudice among philosophers and sociologists. Since Western civilization was monomaniacally seen as the history of dominations by various groups over one another—which meant that individual actors had to be viewed as purely nefarious oppressors—it followed quite naturally that much of the West was ready for the garbage heap. Not only were the workers and the poor oppressed by the rich, but the rich in turn were, along with everyone else, oppressed psychologically by Christian sexual mores and by the overall familial hierarchy of Western civilization. This is why, to many of the school’s members, not only smaller fixes had to be implemented here and there, but the whole edifice had to be brought down (which was itself ultimately a morally positivistic effort). With the rise of Nazism in Germany, many Frankfurt scholars moved to New York, and thereby gained a broader audience of impressionable college students....
And see Linda Kimball's now classic article, "Cultural Marxism."