As David Harvey has pointed out, countless mainstream economists are often quick to denounce Marx's theory of value as so much mystical claptrap, with its elusive and unscientific claims, and then they turn around and act as if the invisible hand of the market exists, and pour over economic models that assume preposterous things like market equilibrium and perfect information in order to carry out their economic inquiries.
If you do look at the theory of value, yes, value is indeed a metaphysical thing, but so are so many other intellectual products, which happen to be useful for investigating all sorts of phenomena through a rational lens.
What you see with the theory of value is the construction of a sort of machine, with all sorts of moving parts that exist on their own and work in relation to each other, but which remain elusive if you try to locate them in the real world. You see concepts like value as socially necessary labor time, and surplus value, which take on more significance as the whole metaphysical project of Capital is elaborated. And the further the project is elaborated, the greater explanatory value is derived, up to a certain point.
Much of Capital is built in order to reveal capitalism as something destructive, so the entire project is a metaphysical outgrowth of that conviction. And then on the other hand, you have classical economics, which is meant to naturalize and stabilize capitalism, which is a project that is increasingly seen as necessarily obstructive of certain realities.
But such is the case with any intellectual project: the more you reveal in one direction, the more that you obstruct in another, and what you reveal and obstruct is related to your convictions and what you are trying to prioritize, which has real world effects.
There are of course certain problems with this. The three volumes of Capital are huge, gigantic even. The amount of ground that Marx is covering, and the resolution he is trying to cover the ground in, is staggering, and even then, the project was only partially complete.
So this had to be seen as an event: Marx, upon becoming opposed to capitalism, and having to surmount the constructed intellectual arguments of bourgeois economists at the time, and then suffering through a series of misfortunes, found himself in a library going through a shit ton of books and putting his own project together.
The size and scope of this project can be attributed to the intensity of the work, and how much time Marx had for intellectual coherence, with his death putting an end to the project altogether. A mountain rises in the image of upward movement, and then is halted by the natural limits of gravity and upward energy.
This is a work that is always going to be vulgarized. One can retort that "you don't understand Marx," but then who can really? To construct a sufficient response to such a work would take the kind of intellectual intensity and energy that Marx himself put into the project.
And with each project comes the mass production of countless books of great size to house all of the material, which requires the felling of fields upon fields of trees, and the marshaling of industrial and commercial infrastructure to produce and distribute it, and then we don't even take account of its dissemination over the Internet.
And so the process begins again, with all of those other authors over the course of history clamoring to respond. One can climb a mountain to gain a view of the landscape certainly. This is one of the things that mountains are great for. But one should always be aware of what one is doing, lest one wants to become a mountain onself. There is only so much room for so many mountains: they take energy and space to form, and only so much life can take place on them.
