DeLong is like some guy sitting in a bar in Brooklyn, who picks out of a hat a topic he must speak on extemperaneously - "Which theology is more correct - that of the Sunni or Shi'ite Muslim?"
DeLong: "Shi'ite? Sounds like alotta SHIT to me! I'll pick the sunny one - anyday".
Carl: "Yaa, right on! I think there is something to his conclusion!"
I have only read some short MR and a few other (Ernst Mandel) overviews of Marxian economics, and am only one third through Capital V. 1, yet it is quite apparent to me that by virtue of this, I already know 100 times more about Marxism and Marxian economics than Mr. DeLong does. Which means I know next-to-nothing, next to DeLong who knows absolutely nothing.
Marxism is all about the *historical* process of capitalism. The type of economics DeLong practices is completely *ahistorical*. Yet through DeLong's ignorance of this, he claims Marxism is ahistorical, which it's not, and then condemns ahistorical economics - which is exactly the type of economics DeLong practices. One should ask DeLong how the origins of wealth fit into HIS economic analysis. Of course they don't, and for a very good reason.
DeLong's entire piece is just total nonsense. It reminds me of an Isaac Asimov story where people could put speeches into a computer and it would excise everything but the content of what was said - with one person's speech put in outputting nothing, e.g. just being BS from beginning to end. DH mentioned the transformation problem, and thus there was only one sentence in all of that nonsense that actually said something instead of saying nothing or setting up strawman arguments (and falsely attributing them to Marx) and then knocking them down. DeLong alludes to the transformation problem but doesn't go into it, I doubt he knows much about it, or Marx, or much about the classical economists (Ricardo etc.) that some professor didn't teach him. The same goes for Krugman (well, as far as Marx goes anyhow).
As far as the transformation problem, people may have wasted time on it but I don't think it's a waste of time or nonsense. Just like Marxism, the development of Marxism is social - physicists don't have to worry about people taking Isaac Newton as canon, in fact, Einstein proved he was wrong about certain things. Nonetheless Marxism is a social science, and fears of left and right swings have caused people to treat Marxism as canon, and not a developing science. To paraphrase Chomsky, QM'ers don't say they're studying Planckism, but like Christians, people calling themselves scientific socialists have no problem calling themselves Marxists. When scientific socialists begin fearing the dumping parts of Marx overboard as something that will either swerve the boat left or right, as opposed to considering whether it is true, then we are in the realm of faith and religion, not science.