I find it helps a lot when you're telling someone they're wrong first tell them how they're right. Typically there's some agreement with a difference of either

I find it helps a lot when you're telling someone they're wrong first tell them how they're right. Typically there's some agreement with a difference of either an underlying core axiom or some other tradeoff that the two people are weighing differently. Pointing out the pieces you agree on helps the other person relax a little and open up when thinking about their position.