How Epistemically Corrupt Was Classical Marxism?

Sergio: communism had a strong sense of objective reality anchored in the belief that humans are capable of discovering universal truths. Communist ideology held science and mathematics in the highest regard, even though it often distorted the former for doctrinal reasons. Early anti-Marxists often attacked them for making blanket ad hominem arguments against bourgeois history and bourgeois economics. They also believed that only the proletariat was naturally predisposed to know the truth while bourgeois people could only arrive to it by re-education,. This was complete lunacy as far as I'm concerned and led in the end to an incompetent and deeply corrupt political elite.