The following sentence is the beating core of Marxist/Hegelian dialectics.
"Thus Hegel, in so far as he sees the positive significance of the self-referring negation (through an alienation mode), conceives man's self-estrangement, alienation of being, loss of objectivity and reality [...]"
"self-referring negation" is, of course, the the liar's paradox. You can find self-reference in any language or mathematical system.
Classical logicians knew of paradoxes but sought to avoid them.
Modern philosophy (from Hegel onward) embraces paradox.
Hegel developed a number of arguments to show freedom is slavery and slavery is freedom. Marx spewed forth reams on the notion that if we negate the foundations of western civilization and new workers paradise would spring forth from the paradoxical wreckage of culture.
Many years ago, I launched in on a project to demonstrate that Marx was simply using variations of the self-referential paradox to spew forth self-negating nonsense.
I was delighted to find Marx himself admitting that his writings are nothing more than a twist on the liar's paradox.
Classical philosophers (such as the US Founders) worked to avoid paradoxes. Modern philosophers have a tendency to build paradoxes into the foundation of their thinking.
Once you have a self-referential paradox couched in your belief system, you have a way to make anything you want to believe true.
Anyway, I was totally delighted to find Marx admitting that his work is just a long convolution of the liar's paradox. This quote was from page 189 of Eric Fromm's "Marx Concept of Man," which includes an English translation of Marx's "Critique of Hegel's Dialectical and General Philosophy."