So I enlisted an African-American faculty member in my department to argue in favor of eugenics while I argued against; halfway through the debate, we switched sides. We were modeling for the students a fundamental principle of a university education, as well as civil society: When you’re forced to engage a position you strongly disagree with, you learn something about the other perspective as well as your own. The process feels unpleasant, but it’s a good kind of stress — temporary and not harmful to your body — and you reap the longer-term benefits of learning.