The problem I've seen in recent times (especially during this election period) is that a lot of people get into debates unnecessarily. They will tell the counterparts how awesome their ideas are, and point out the proof here and there--all of those things. And then the counterparts, of course, will do the same, until it becomes a back and forth debate.
This is very problematic, and I can think of two main reasons.
First is the intention. Very rarely one goes into a debate to have a better understanding or simply just to listen to the other side, let alone to be interested in what the other side has to say. When people go into a debate, most of them go into it to crush their opponents. So even when they are defeated, the first thing that comes in mind is how to come back with a response or to get a back up, instead of listen to the argument that defeats theirs and say "you know what, you're right. I agree with what you said" -- not in a million years. I guess debates just create that sense of pride within the heart of those who are involved.
The second reason why it is so problematic is because what some people think are good is actually formed by their particular understanding. Now the question is, isn't it possible that one's understanding is incorrect? Definitely. Unfortunately, not many can maintain the attitude to keep that in mind--to be aware that they can, too, make mistakes.
If only each of us can, first and foremost, set the intention right whenever we have a convo with people who have different opinions, and then consciously remind ourselves that our understanding is limited and might be wrong, I believe that alone can make the world a lot better place.