Herbert Marcuse (1898-1979), a member of the Frankfurt School, was a major figure in the New Left movement of the 1960s. He was also a major figure in the development of Cultural Marxism, more commonly known as political correctness. Marcuse invented the concept of “partisan tolerance,” that is, tolerance for leftist ideas and intolerance of all others. Partisan tolerance has evolved into political correctness, censorship, and curtailment of Free Speech 1st Amendment rights.
Herbert Marcuse and Saul Alinsky introduced a more pragmatic, but also more virulent form of Marxism into America academia, facilitated this self-destruction by creating a new "proletariat" of "victim groups," the bedrock of identity politics, pitting one gender against another, one race against another, one age group against another. In 1965, Marcuse and Alinsky introduced the concept of "partisan tolerance" into political parlance, which has mutated into the deadly pathogen called "political correctness"—a tolerance for evil and a stigmatization and ultimate persecution of righteousness and God's Laws.
According to Andrew Breitbart, unable to find a disgruntled proletariat, Marcuse found another dividing line that could be exploited to exacerbate social strife and dismantle societal structures—namely “victim groups,” the bedrock of identity politics. In An Essay on Liberation, Marcuse's primary thesis was that potential revolutionaries such as university students, African Americans, the ghetto populations, the alienated, the asocial, and the third world could take the place of the proletariat. 
Attempting to build a new proletariat to build a socialist revolution on, he preached that women are victimized by men. Creating a sense of exploitation, he stoked tension between white and nonwhite Americans, homosexual and heterosexual, championing the downtrodden transgender population. Breitbart maintained that Marcuse’s mission was “to dismantle American society by using diversity and ‘multiculturalism’ as crowbars with which to pry the structure apart, piece by piece.” Marcuse and Alinsky continually incorporated the best weapons to effect the assault on the structures of American society, maximizing the tension between victim and oppressor.
His infamous essay Repressive Tolerance is the definitive blueprint for the "political correctness" movement.
Many radical activists were influenced by Marcuse, such as Norman O. Brown, Angela Davis, Charles J. Moore, Abbie Hoffman, Rudi Dutschke, and Robert M. Young. Marcuse later expressed his radical ideas through three pieces of writing. He wrote An Essay on Liberation in 1969, in which he celebrated so-called "national liberation movements" such as that of the Viet Cong, which inspired many radicals. In 1972 he wrote Counterrevolution and Revolt, which argues that the hopes of the 1960s were facing a counterrevolution from the right. He published his final work The Aesthetic Dimension in 1979 on the role of art in the process of what he termed "emancipation" from "bourgeois" society.
Marcuse realized that America is a nation uniquely unburdened by a class structure, at least in the way most European nations are defined along incredibly strict stratifications of class distinction, down to how one’s class can be identified almost immediately just by one’s accent.
In America, the boundless upward mobility afforded by a republic based on the rights of the individual as opposed to the privileges of a special class, are how a prairie lawyer like Abraham Lincoln could become president, or how Barack Obama, the biracial son of a single mother, could do exactly the same thing. Fomenting a class war was clearly not going to work in a country where even the idea of class distinctions was frowned upon by the majority. Social strife was to be exacerbated so that established societal structures could be dismantled. Marcuse found another dividing line that could be exploited to exacerbate social strife and dismantle societal structures—“victim groups.”
He is infamous for promoting the false idea that the fascists and Nazis were sexual repressives and adhered to a strict moral code (when in reality, the Nazis actually were bohemians and sexual perverts).
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