  In the piano case there is probably nothing important riding on the question of what to do in the face of disagreement. But in many cases our disagreements are of great weight, both in the public arena and in our personal lives. You may disagree with your spouse or partner about whether to live together, whether to get married, where you should live, or how to raise your children. People with political power disagree about how to spend enormous amounts of money, or about what laws to pass, or about wars to fight. If only we were better able to resolve our disagreements, we would probably save millions of lives and prevent millions of others from living in poverty.