Mosley's work that you mentioned earlier - or anyone's work - on a specific national economy such as the USA is totally irrelevant, because the theory isn't meant to predict anything on the level of any national economy (any more than on the level of a firm or industry), but rather on the level of the total, i.e. international, economy.
As far as Mattick is concerned, I mean his last work, Marx and Keynes.
Moseley goes at great pains to explain how the statistical data has to be adjusted to approximate Marxian categories and overcome this. You can disagree with the way he does that or with the whole idea of it (and explain why you disagree, ideally by engaging directly with his arguments), but I don't think it's correct to dismiss him out of hand.
That Marx's theory of value can be difficult to grasp says nothing about its empirical relevance. Nor do its conceptual difficulties (value & price etc.), which I admit it has, at least on some interpretations. A serious argument against the empirical validity of Marx's critique would be e. g. the problem of the money-commodity, which is central to his whole analysis of money, but post-1971 it seems nowhere to be found.



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And so another LTV discussion begins, another great monument to its lack of clarity.
Jura - tbh I don't know the Mattick thing you're referring to. But in general, I'd note that many Marxists who describe changes in the world economy explicitly don't do so on the basis of the LTV - Robert Brenner, etc, or dress up standard economics in Marxist verbiage. Mosley's work that you mentioned earlier - or anyone's work - on a specific national economy such as the USA is totally irrelevant, because the theory isn't meant to predict anything on the level of any national economy (any more than on the level of a firm or industry), but rather on the level of the total, i.e. international, economy.