First, we must realize that those that oppose us also believe in their cause. In fact, there may a dozen sides. But when someone is fervently telling you that a trail should be closed, it's many times because they really believe they're in the right. The mistake that some of us make it to let tempers rule the outcome of a meeting or a planning effort. That, in nearly ALL cases is a mistake.
Heads get much more done.
The point is maintain the high ground as much as you can. Keep a level head and think one step ahead of your opponent. To do this you must remain objective and not get caught up in the emotional side of the argument. And you need to really figure out just where your opponent is coming from, so you can devise the right counter-strategy. Again, realize that most of them really believe in their cause as much as we do.