I think there is a difference between having a discussion and having an argument. You are in a discussion if you are actually open to change and seeking a better understanding. You are in an argument if you are just out to change the other side. An argument is a fight so knowing when to argue is critical to winning the fight. The challenge, I think, is that often people get themselves into a discussion when the other side is having an argument with them and don't realize it. That seems like a point this article is really driving at towards the end. The missing advice though is that if you recognize the other side is just going to be in an argument and not switch to a discussion then you probably need to back out.