I'm looking for an English expression as I'd like to form a special interest group on the international level. In French, the expression is écrivain engagé. This is along the lines of "literature of commitment" which is defined as follows:
"Literature of commitment" is the act, for a writer or artist, to formulate commentary or criticism, even though he is supposed to write up a dissertation with beauty being the only objective, this commentary being a way to serve a human ideal. This concept is opposed to that of art being carried out solely for artistic purposes and mostly developed around the twentieth century.
I've come across "committed writer" but the hits on Google seem to indicate that it isn't used in the same fashion. George Orwell is the kind of writer we're thinking of here.