Imagine that you read the following paragraphs and had to state your impression:

"The transportation, however, that forms the substance of value, is homogeneous transportation, expenditure of one uniform transportation capacity. The total transportation capacity of society, which is embodied in the sum total of the values of all commodities produced by that society, counts here as one homogeneous mass of transportation capacity composed though it be of innumerable individual units. Each of these units is the same as any other, so far as it has the character of the average transportation capacity of society, and takes effect as such; that is, so far as it requires for delivering a commodity, no more time than is needed on an average, no more than is socially necessary.

[…] When I state that coats or boots stand in a relation to linen, because it is the universal incarnation of abstract transportation, the absurdity of the statement is self-evident. Nevertheless, when the producers of coats and boots compare those articles with linen, or, what is the same thing, with gold or silver, as the universal equivalent, they express the relation between their own private transportation and the collective transportation of society in the same absurd form.”

You would probably conclude that the author of those paragraphs is mentally ill or a charlatan who used a bunch of sciencey-sounding words to produce an incomprehensible mess. Perhaps, you would think that the infamous Deepak Chopra has stopped musing about quantum healing and for some reason got interested in price formation.
You would be surprised to know that I created the paragraphs in question just by slightly modifying two key paragraphs from vol. I of Marx’s Das Kapital:

"The labour, however, that forms the substance of value, is homogeneous human labour, expenditure of one uniform labour power. The total labour power of society, which is embodied in the sum total of the values of all commodities produced by that society, counts here as one homogeneous mass of human labour power, composed though it be of innumerable individual units. Each of these units is the same as any other, so far as it has the character of the average labour power of society, and takes effect as such; that is, so far as it requires for producing a commodity, no more time than is needed on an average, no more than is socially necessary.

[…] When I state that coats or boots stand in a relation to linen, because it is the universal incarnation of abstract human labour, the absurdity of the statement is self-evident. Nevertheless, when the producers of coats and boots compare those articles with linen, or, what is the same thing, with gold or silver, as the universal equivalent, they express the relation between their own private labour and the collective labour of society in the same absurd form.
The only changes I made to the original were to replace the word “labor” with “transportation”, the words “labor power” with “transportation capacity”, and the word “producing” with “delivering”. In fact, my modified paragraph probably makes somewhat more sense then the original because various kinds of transportation are much more similar to one another than various kinds of labor are."

Marx’s quote is crucial in that it was supposed to form the foundation for the whole edifice of his labor theory of value and the theory that capitalists hiring workers engaged in exploitation. Marx needed to find the universal equivalent that he believed was embodied in the exchanged goods and wanted labor to be that equivalent but the fact that labor is very diverse was inconvenient, thus Marx tried to circumvent it through the meaningless term “abstract labor”. Interestingly, more than two thousand years before Marx, Aristotle realized that the idea of any kind of universal equivalent was absurd and thus came agonizingly close to realizing that exchange never involved equalization.

I was reminded of Marx’s “abstract labor” charlatanism because of the heated discussion that erupted recently about the seemingly outsized attention Marx attracts from the university faculty in the U.S.. One type of reaction to this finding was that while Marx was wrong and his ideas led to enormous damage and suffering, he was a serious thinker, and we should engage him instead of banishing him.

From my perspective, there are thinkers who are so extremely muddled that their ideas are beyond the pale, and Marx is certainly one of them. Not just because of the “abstract labor” nonsense but also because of his use of the dialectical metaphors as if they were exactly true. Bourgeoisie never was the antithesis of the feudal nobility, having some interests that are opposed to someone else’s doesn’t make you and your opponent logically contradicting phenomena.

One can object, however, that if Marx’s ideas were what was recently aptly termed “pseudo-profound bullshit”, lots of intelligent people would not have considered and would not to this day continue to consider them worth grappling with.

However, that would be underestimating the human capacity for condoning and explaining away irrationality. It is true that, as the research on pseudo-profound bullshit has shown, in normal contexts, more intelligent people are significantly less receptive to it. But in those cases, they are not motivated to. Marx clearly was deeply hostile to capitalists’ hiring workers, probably because it erroneously seemed to him that it made them less self-directed than the Medieval artisans (who were, in fact, stiffled by a myriad of minute rules that could not be changed). His followers probably had similar motivation. Finally, at some point, Marx became so influential that it became impolite to doubt his intellectual credentials.

If anything, human history is filled with even more stark examples of very smart people trying to rationalize absurd, meaningless ideas because they mattered to them and (or) were widely considered to be respectable. It is sufficient to mention the Christian idea of the Trinity. There is no comprehensible way of interpreting what it might mean that one being has three distinct simultaneously existing personalities but it has not stopped legions of theologians and philosophers from trying and deceiving themselves that they succeeded.

The right response to such cases is not to politely pretend that smart people disagree about things. Instead, the humanity will be much better off if the susceptibility of even the most intelligent humans to rationalization of absurdities when they are dear to them were as widely acknowledged as possible. Marx’s ideas are a good place to start.