> Then he is either using "model" as a mere (and not too good) synony
> for "abstraction" or he is wrong. Models as used in economics havd
> no place in Marx.
Some assumptions in those models have no place in Marx, because Marx made different assumptions.
Anyone attempting to make sense of capitalism will single out some factors as more important than others and draw relationships between whatever they find relevant. They have a simplified sketch with interrelated parts. For the sake of rigor and clarity, they render the sketch in some specialized language. Call the final product whatever you like, but they have built a model.
As for all that math, Barkley Rosser said:
I would also like to point out that having equations does not necessarily equal "math" and not having equations does not necessarily mean "not math." Math involves the ideas and their nature.
Thus, John Chipman has argued (sorry, no cite) that John Stuart Mill invented nonlinear programming in his chapter on exchange rates in one of the later editions of his Principles of Political Economy. He did so strictly using words in a verbal description. But, there is no question, he laid out a rigorous (and correct) mathematical argument. Also, while she generally said bad things about using math(s), Joan Robinson's growth theory models were generally mathematically rigorous, even if usually described strictly in words, although she would sometimes resort to figures or graphs, which is getting a bit more overtly mathy.
OTOH, there is a lot of fake or lousy math out there in econ that is not really math, that is really obfuscation and sometimes even wrong, irrelevant to what it is supposedly modeling or explaining, and so and so forth. There are equations, but the variables in them are meaningless, and there is no empirical content. They may even be made to look fancier and more complicated than they are with, unnecessary changes in variables, and so forth. Such things are not really math, even though they may look like it (and I am especially aware of this today, as I just finished writing a negative referee report on a paper of exactly this sort, with incoherent variables and even outright incorrect math).
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Shane