"In a political debate you feel like the other side just doesn’t get your point of view, and if they could only see things with your clarity, they would understand and fall naturally in line with what you believe. They must not understand, because if they did they wouldn’t think the things they think. By contrast, you believe you totally get their point of view and you reject it. You see it in all its detail and understand it for what it is – stupid. You don’t need to hear them elaborate. So, each side believes they understand the other side better than the other side understands both their opponents and themselves."
This is asymmetric insight, and many psychological studies have shown this is true. Read about it here.