There is a difference between teaching what to think and how to think.
When to teach what to think:
1. A student mixes up the concept of non-diegetic and offscreen sound. He or she is wrong. I explain why he or she is wrong.
2. A student believes that Thomas Jefferson's sexual relationship with his slave involved no problematic power dynamics. I explain why he or she is wrong.
So far so good. These strike me as objective truths. Now:
3. A white student uses the phrase "discover" to describe his or her experiences in a non-white culture. Some of my colleagues would describe this word as indicative of a colonial tradition, what we call Columbusing (Definition: Something doesn't exist until white people learn about it.) I might see the word as a fairly innocuous term. For my colleagues this student must be taught to see what lies behind the word "discover." I see their point, but I'm not sure. My colleagues are teaching what to think, because they think they are teaching objective truth.
4. We are reading a sixteenth-century work of political philosophy. A student, perhaps influenced by ideas from another class, complains about having to read work by a cisgendered, white, heterosexual male. The words "cisgendered" and "heterosexual" would have meant nothing to this author, I explain to the student. The word "white" would have meant something very different. But I don't know if I'm talking past the student. I don't know if I'm telling him or her what to think.
5. A student, perhaps of Jewish background, perhaps with family who died in the Holocaust, is uncomfortable with calling the killings of American Indians a form of genocide, as he or she feels that it might force him or her to redefine the experiences of his or her own family. I think this student is objectively wrong. I think it's clear that the killings of American Indians over a period of centuries constitute genocide. Still, I'm not sure if by explaining my argument, which I consider to be objective truth, I'm telling the student what to think.
I try to teach my students "how" to think, and I suppose part of teaching the "how" and not the "what" is to treat the ideas in 3, 4, and 5, and as many others as possible as debatable. My students may walk out of my classroom with the same bad politics as they had when they walked in, but at least they may have the tools required to explore arguments and come up with smarter ideas of their own, outside my classroom, in "real life."