The discussion should be polite !
I'm 35 years old and I met enough people in my life. I think everyone has the right to share his opinion about things. The idea should be respected if it's not causing harm.
The most important is to discuss politely. We all can be right or wrong because we are people. Noone is perfect that's for sure.
I have three diploma and I participated in a lot of conferences. The thing that nobody likes is when people start to call each other with names. In Russian it's called ''transition to personality''. It's when you start to discuss the person himself but not his/her idea.
I can participate in any kind of debate unless the other side will not start to discuss me. In this case I just stop that and move to something else. I don't have time to waste in a discussion that will lead to a conflict. I think that's the best way to be friendly and to not offend anyone.