Put yourself in their shoes. How you see the world depends on where you sit. People tend to see what they want to see. Out of a mass of detailed information, they tend to pick out and focus on those facts that confirm their prior perceptions and to disregard or misinterpret those that call their perceptions into question. Each side in a negotiation may see only the merits of its case, and only the faults of the other side’s.
The ability to see the situation as the other side sees it, as difficult as it may be, is one of the most important skills a negotiator can possess. It is not enough to know that they see things differently. If you want to influence them, you also need to understand empathetically the power of their point of view and to feel the emotional force with which they believe in it. It is not enough to study them like beetles under a microscope; you need to know what it feels like to be a beetle. To accomplish this task you should be prepared to withhold judgment for a while as you “try on” their views. They may well believe that their views are “right” as strongly as you believe yours are. You may see on the table a glass half full of cool water. Your spouse may see a dirty, half-empty glass about to cause a ring on the mahogany finish.
– Roger Fisher and William Ury from ‘ Getting to Yes’