Via Chris, on Twitter (I hope I’m not preempting him here), an Open Letter from a Keynesian to a Marxist by Joan Robinson, and “Zombie Marx”, an essay by Mike Beggs. Here is Robinson, writing in 1953:

I was a student at a time when vulgar economics was in a particularly vulgar state. … There was Great Britain with never less than a million workers unemployed, and there was I with my supervisor teaching me that it is logically impossible to have unemployment because of Say’s Law. Now comes Keynes and proves that Say’s Law is nonsense (so did Marx, of course, but my supervisor never drew my attention to Marx’s views on the subject). … The thing I am going to say that will make you too numb or too hot (according to temperament) to understand the rest of my letter is this: I understand Marx far and away better than you do. (I shall give you an interesting historical explanation of why this is so in a minute, if you are not completely frozen stiff or boiling over before you get to that bit.) When I say I understand Marx better than you, I don’t mean to say that I know the text better than you do. If you start throwing quotations at me you will have me baffled in no time. In fact, I refuse to play before you begin. What I mean is that I have Marx in my bones and you have him in your mouth. … suppose we each want to recall some tricky point in Capital, for instance the schema at the end of Volume II. What do you do? You take down the volume and look it up. What do I do? I take the back of an envelope and work it out.

And here is Beggs:

There are generations of economists who would call themselves Marxists, or admit Marx as a major influence, who have … engaged with other strands of economic thought and folded them into their worldview, have worried little about dropping from their analyses those aspects of Marx’s argument they believed to be wrong or unhelpful, and have felt no need to pepper their writing with appeals to authority in the form of biblical quotations. But in each generation, there are others who have defended an “orthodox” Marxian economics as a separate and superior paradigm, which can only be contaminated by absorbing ideas from elsewhere. … If we are to engage in these ways with modern economics, what, if anything, makes our analysis distinctively Marxist? It is the two-fold project behind Capital as a critique of political economy: first to demonstrate the social preconditions that lie beneath the concepts of political economy, and especially their dependence on class relationships; and second, to demonstrate these social relations as historical, not eternal. These two strands of Marx’s thought are as valid as ever. The way to apply them today is … is to deal not only, not even mainly, with economic high theory, but also with the applied economics produced every day in the reports and statements of central banks, Treasuries, the IMF, etc., and ask, what are the implicit class relations here? Why are these the driving issues at this point in history? What are the deeper social contradictions lying behind them? The pursuit of a separate system of economics as something wholly other from mainstream economics isolates us from the political and ideological space where these things take place: better, instead, to fight from the inside, to make clear the social and political content of the categories. A side effect is that we learn to think for ourselves again about how capitalism works, to be able to answer the kinds of question DeLong raised against Harvey, no longer lost without the appropriate quotation.