Might Marx's argument in Das Kapital be less about justice and exploitation than it is about disenfranchisment? I specifically mean his analysis of work, the falling rate of profit, and movement of 'capital' with commodity fetishism.
I think this is usually claimed to fall under the word "exploitation", and that Marx or Marxists are looking for better "justice".
But I was looking again at some Rosa Luxemborg quotes, and her opposition to Trotsky.
when it comes to a suffrage law which provides for the general disfranchisement of broad sections of society, whom it places politically outside the framework of society and, at the same time, is not in a position to make any place for them even economically within that framework, when it involves a deprivation of rights not as concrete measures for a concrete purpose but as a general rule of long-standing effect, then, it is not a necessity of dictatorship but a makeshift, incapable of being carried out in life. This applies alike to the soviets as the foundation, and to the Constituent Assembly and the general suffrage law.
She seems to be arguing against "disfranchisement", and that, even in a socialist transition phase, exclusion from both the economy and society amounts to a "general rule of long-standing effect" that does not respond adequately to the demands of the state.
There is also this very famous quote (in the same chapter) about 'justice':
Freedom only for the supporters of the government, only for the members of one party – however numerous they may be – is no freedom at all. Freedom is always and exclusively freedom for the one who thinks differently. Not because of any fanatical concept of ‘justice’ but because all that is instructive, wholesome and purifying in political freedom depends on this essential characteristic, and its effectiveness vanishes when ‘freedom’ becomes a special privilege.
Was this just due to an argument with Trotsky, one that should not be abstracted from opposition to the Bolsheviks, or can socialists think about disenfranchisement without recourse to 'justice'? Especially given the recent populisms.