Ah, yes, this assumption comes from the logic employed by apologists for capitalism. Behold a right-libertarian egoistic individualist reductionistically dismiss the social-relational nature of human beings and their existence, their social morality, and their capacity for altruism and heroic solidarity as a herd mentality! What a bleakly atomizing & alienated, materialistic & spiritually-philistine “libertarian” lebensphilosophie in which every man is an island entire of itself, cut off from the continent of humanity, untouched by and unwilling to reach out to his/her neighbor, and interested only in being a wealth-overaccumulating junior capitalist.
Capitalism is the organisation of social labour as value, so it necessarily reduces all social production to a single, homogenised abstract, exchange value, and present all social products as packets of value first, and as heterogeneous objects of utility only secondarily. Apologists for capitalism, taking as their axiom that greed and egoism embodies some universal, tranhistorical rationality, assume that any rational form of social production will likewise hinge on a homogenising abstraction. The possibility of such a reduction can thus be employed as a test to determine whether any given historical system is rational. But if the axiom is not valid, and it’s not self-evident that it is, then the test doesn’t function, and that line of criticisms becomes void. Got a response, gotlucky?