The key point is: Once reason has been “killed,” then there is no basis for rational argument. So you can look for all the sources, all the facts, all the proofs you want to; but it really won’t do you any good in the end. Dealing with doctrinaire ideologues, you must always be prepared for the situation in which the “goalpost” will be constantly moved. Marx made it very clear: Inconvenient facts are always to be disregarded; and all questioning of “the system” is strictly prohibited.
WRT the discussion between the two of you - I'd like to remind you and the Lurkers that no one on the linked thread replied to my post of evidence for Marx relying on or exploiting Darwinism to promote his agenda. It was post 120 there, but the bottom line is this Google search of the Marxist website:
To be candid, I won't be impressed by what Marxists say. I don't care if they claim they are the heirs of Isaac Newton and Alexander the Great. They can't be relied upon for accurate information.
To me, the best way to deal with the issue is: (a) to observe the chronological sequence of Marx's publications, compared to the comparatively late appearance of Darwin's Origins in that chronology; and (b) to ask ourselves what in the world is there about mutation and natural selection that has anything to do with the labor theory of value, the dictatorship of the proletariat, "to each according to his needs," etc. I'm a reasonably bright fellow, and I see no connection at all.
It's true that BB found one footnote in the final work by Marx, referencing Darwin. It was, I believe, on a trivial point about the division of labor (an old concept even by the time Darwin was in school), and although it's dazzling that she found it, it's not very persuasive.
And to slay any lingering doubts ... yes, I respect Darwin's work; yes, I think the theory of evolution is good science; and no, I'm not an admirer of Marx. I'm very much a free-market Republican conservative. I'm pretty sure that's the overwhelming position of all 355 people on my evolution ping list. Not commies. Not socialists. Not leftists. Not that many self-declared atheists either (although mostly religious, they're probably not of the fundamentalist -- six-day creation -- persuasion). They're conservative people who like science. And that ain't bad.