All elements of both the base and the superstructure are riddled with inherent contradictions, and not just under capitalism (e.g. artistic vision vs market demand) but under socialism and communism as well (e.g. vision of one artist vs another's). You cannot expect these things to be without contradictions, for the movement that results from the dynamic of contradictions is what keeps them going at all. Sometimes these contradictions are even desirable: You will gain stability and predictability by solving the contradictions, but in e.g. art and culture you need them to keep things interesting. Even things like mathematics, which are at first glance pure and free of any (logical) contradictions, have at their bottom statements that are true but not provable, as suggested by Gödel's incompleteness theorem; and on a higher level there is also the ever-present (didactic) contradiction between mathematical truth and "common sense".