JG also disrupts neoclassical micro economics. JG ends neoclassical notions of market efficiency and market optimality and even of the neoclassical idea of the market itself. JG is not anti-market rather it entails a different concept of the market and the same holds for the notions of efficiency and optimality. Not sure whether the ideas of efficiency and optimality and the market that would complement the JG have been worked out in the literature. JG often discussed in terms of Post Keynesian macro economics but it constitutes an equally serious blow to orthodox micro. For one, with the JG, one is no longer able to speak of the the return to labour being a function of its marginal product. So what does determine the return to labour? In my opinion, it is ideas of social justice that do, at least at the wage floor. Yet, though it may be ethical ideas that are here determinate, the wages so established will not be inefficient, again, in my opinion.
Furthermore, the commitment to the JG takes one away from a purely procedural notion of the vindication and concept of markets. The JG says the validity of the market market/the economy is not due to it being a fair choice mechanism. The JG implies that the reasons for a market or economy being valid will have to both concrete and substantive, for example, it provides individuals the opportunity to earn their own livelihood. It follows from this that the JG also implies that the true concept of the market or economy will have to be both concrete and substantive. All the big names in the political theory of social justice since Rawls want to see both the normativity and the very concept of the economy as having to do with the fairness of choice procedures, regarding which, according to the political theory mainstream, neoclassical economics provides an adequate concept. The JG is a way of bringing to the foreground the mistakenness of this approach.