Are they really your friends if they can't handle a disagreement or unwilling to listen to your different point of view?

Besides that - how can we really flesh out an idea if we are unwilling to ever be wrong or except that our friend might be incorrect? There are a ton of things that I said that ended up not being right...

If someone is getting heated about a particular subject I just say, 'Agree to disagree. We can move on to other topics until another time.'