I've always told people that many of the best conversations with folks have started out with "Chuck I think you are wrong and here's why ..." This is especially useful when you are "important" (like someone's boss) because getting honest feedback when you are the boss can be nearly impossible at times.

Steve Bourne (yes that Bourne) told me once that you should try to cultivate people who could give you a different view on the world, That is helpful stuff but you do have to also get people to be honest. That is hard to do if they think you're 'hot headed' or likely to shoot the messenger.