>>2649158I think it's highly situational, historically contingent but a general contradiction might between various left-wing ethics like opposition to all forms of social privilege, non-domination (not being told what to do), and then becoming institutionalized whether that's a communist bureaucracy several decades after winning power or liberal NGOs in capitalist countries that absorb new social movements.
It's like "the reaction within the party." New privileges can grow out of historical development while the left degenerates, and then ideology gets turned around and redeployed to maintain those new privileges. In the communist case that really came to a head in 1968 in Prague, while in China there was a left-wing attack on rightists in the party. A certain core part of what makes the left what it is, as I see it, is a lack of sacred feelings towards any existing historical situation because social relations are flexible and it's possible to change them.
I'm not saying it's simply a case of the left coming to power is what causes this and so any left-wing party that does is bad. That's too simplistic.