Look at the Disagreements to Understand a Topic

From Sapiens:

If, say, a Christian really wants to understand the Muslims who attend that mosque down the street, he shouldn’t look for a pristine set of values that every Muslim holds dear. Rather, he should enquire into the catch-22s of Muslim culture, those places where rules are at war and standards scuffle. It’s at the very spot where the Muslims teeter between two imperatives that you’ll understand them best.

This is also a good way to understand the limits of (e.g. academic) understanding of a particular topic within its field: look how far the consensus goes, and at what points do debates take place.