Niall Ferguson asserts that Marx is inerrant. Seriously in response to an argument about the origin of the US middle class he wrote
F: Fact checked and--oh no! I really did get that wrong. It was the government that created the middle class, as well as the Golden Gate Bridge! Remind me to tell Karl Marx about this. It will come as news to him that, contrary to his life's work, the superstructure in fact created the base. "
Uh professor Ferguson, it may be true as you assume that Karl Marx was absolutely right about everything, but uh those of us who care about data would like some evidence. The fact that Marx said something doesn't mean it is correct. I don't know how to break this to you but he was human.
Also, I really hate to be the one to bring you the news, but he's dead so you can't tell him.
Over on that side of the Atlantic (actually over on this side of the Atlantic too) "Marx wrote p" is not considered proof that p is true. Hows about you ask your colleagues in the Harvard history department if they agree that Marx is infallible (is prof Womack still around ? If so, tell me his response which I'm pretty sure would be "no").