1) it’s contentious in Popper’s field itself on whether this criterion is right (it is generally accepted today that he is wrong) and
2) it’s contentious on whether Popper even understands Marx’s theory of history, which is where his criticism comes from, and
3) even if we decide by fiat that the predictions made by Marxism are unscientific, that does not preclude it from being a source of knowledge, or prevent Marxism from being imported as a normative political or ethical framework.
The whole “not true Marxism” thing usually comes from the mouths of people who’ve never read Marx, let alone explicitly non-Marxist thinkers who were influenced by Marx. In other words, the kinds of people who have never given this serious thought at all, but have likely watched some YouTube videos or read a couple articles. There is really no such thing as “true Marxism”. Marxism in practice has ranged from the USSR to Zapatista, which are very different from one another, but they are both no more “truly Marxist” than the other. The only person who could decide that is probably the guy himself, who is long dead.
>This never discourages the critical thinkers in the humanities, which leaves me unimpressed with the critical thinking skills of it.
If nuance and actual engagement with primary source material (as opposed to whatever it is you’re doing) does not count as “critical thinking”, then I strongly believe we cannot have any further discussion here.
STEM has had many false theories (like the sun revolves around the earth). The virtue of STEM is when the facts contradict the theories, the theories get revised, even if the old guard has to die off before the corrected theory replaces it. With Marxism, however, the facts get re-written to conform to Marxism, rather than the other way around.
One of the beauties of the scientific method is it tests the predictions a theory makes. If the predictions come true, the theory is validated. If the predictions don't pan out, the theory is false.
A famous example is Einstein's Relativity theory predicted that gravity bends light. Einstein became world famous when decades later, this bending was observed.
Marxist theory also makes predictions, but none of those predictions pan out. This never discourages the critical thinkers in the humanities, which leaves me unimpressed with the critical thinking skills of it.