This is such an important point that it needs to be emphasized. Large chunks of the humanities and social sciences operate under a completely different epistemology. This epistemology rejects reason. And I don't mean that as a jab, I mean it literally rejects the philosophical concept of Reason itself.
Everything is about ideology. It has at it's core the notion that there is no objective truth, and that any assertion of truth is merely the application of power of one group over another. Under this epistemology, lying, contradiction, hypocrisy, fallacy, and rhetoric are all acceptable and even encouraged.
Dig a little in to post-structuralism, postmodernism, critical theory and deconstruction and so much of the Social Justice movement will make sense. You'll start to find very little about Social Justice is about social justice.