People often defend the version they announced longer than the version they privately believe.

Saying something aloud gives it a second life that has nothing to do with whether it is true. The private view can change quietly, but the announced one has your name attached, and abandoning it looks like being caught out rather than like thinking. So people go on arguing some distance past their own doubt.

Watch for that gap in yourself: a position you keep defending with more heat than belief. When someone else is in it, give them a way out that costs them nothing. Agree with the reasonable part, change the subject, let them move without an audience.