In 1989 Castoriadis says something clear and bright (in The Castoriadis Reader, p. 412):
Where there is capitalism, there is no genuine market, and where there is a market there can be no capitalism.
We spend the next few paragraphs wondering why, and Castoriadis doesn’t really give a full explanation (claiming he has done so elsewhere), but the gist of what he would say is I think contained in this passage on the next page:
An autonomous society [his political goal] will instaurate a genuine market, defined by consumer sovereignty (not mere freedom). It will decide democratically the overall allocation of resources (private consumption/public consumption, consumption/investment), aided by a technical device (the ‘plan factory’ [which he discusses elsewhere in the reader]) subject to its political control, which will also help to assure general equillibrium. Finally, it is inconceivable that it would institute the self-government of collectivities at all levels of social life and would exclude it in collectivities dealing with production. Self-management of production by the producers is but the realization of democracy in the domain in which individuals spend half their waking life.
So, some combination of 1) distributed, immanent, market-like decision-making as a way to allocate resources, 2) a very democratic institution of experts for economic planning to assist that allocation, and 3) autogestion in production.
Eugene Holland’s theoretical experiments with “free-market communism” are similar in that they suggest that we can recover the idea and practice of the market as an anti-capitalist (or pro-communist, or pro-democratic) strategy. But I am aware of very few others on the left who, like Castoriadis and Holland, refuse to abandon the market to capitalism and set about thinking a non-capitalist market instead. Typically in our thinking, precisely as with neoliberals, ‘the market’ is identical to a capitalist economy.
Path to the Possible 