How to deal with someone who's so argumentative that they could "Start a fight in an empty room"

I have known a few people like that over the years. Honestly, the best thing to do is avoid them. That’s not always an option though. They may be a family member, coworker, boss or customer. That means that you're going to have to learn how to interact with them effectively.

When someone is so defensive that they attack even the slightest suggestion that their opinion may be uninformed, misguided or outright wrong, you’ll never avoid direct confrontation 100% of the time.

However, how you frame your interactions with them can go a long way to reducing the frequency. These high conflict personalities tend to view other people as being “against them” in some way. They are hyper-sensitive to criticism. This mindset leads them to take a defensive stance against these perceived enemies. High conflict people are quick to assign blame and aren’t always self aware enough to really understand the impact of their behaviour on others. The ensuing confrontations lead to an escalation of conflict that draws in others as everyone seeks to find supporters of their “position”. Reputations are formed and a cycle of confrontation begins.

If you can develop a relationship with them where they don’t feel that you’re an enemy, or are against them, they’ll be much less sensitive and more open to what you have to say. To start building this relationship, be sure not to directly tell them they’re wrong, even if you believe that they are. Validate their opinion, even if you don’t agree with it and ask questions that require them to think more deeply about why they feel the way they do. Avoid criticism about them as individuals (their values and sense of self). This will almost certainly be perceived as an attack. Focus instead on situational factors like the context of the dispute or the words said. Asking them questions that force them to consider the other side's point of view can also be useful. However, there may be a tendency for them to focus more on what they believe the person's motives are, or generalize about their personalities, rather than being objective about what that person might really need in this situation. Still, it may be well worth a shot.

I’ve has great success by being very intentional about not aligning myself against these folks. I haven’t always been on their side either. Taking a neutral position is fine. The key is for them to not view you as being against them. Earn their trust and respect and they’ll treat you better than they do many other people. And, when you do choose to take a contrary position, their opinion of you will soften their attack. Or so you hope!