Appeasement- Europe made a clear treaty that Germany could not invade certain areas. Germany did. Europe did nothing about it. The politicians did nothing, and people suffered. The world went to war.Negotiating- Tony Blair had talks with his biggest enemy in Ireland, Gerry Adams. A Treaty was written up and there has been peace ever since. There was no longer a reason to fight. The politicians did everything and it is now up to the people to decide what they want.
When people negotiate it is because two forces of equal strength cannot gain an upper hand. When people set out to appease, it is because they fear the other side is too strong to deal with in open confrontation. Europe was still too wearied from World War I to stand up to a surging Germany. Germany, on the other hand, was too humiliated to let the failure of the first war be its legacy.
The U.S. and Soviets negotiated during the Cold War. I think this has to do with the fact that both sides could back up their talk, and each side perceived that the other would in fact do so. I would think that appeasement comes into play when one side doesn't think the other would back up its talk with force if need be.
I think appeasement is simply negotiation through or because of fear or cowardice. True negotiations come from a position of strength and a willingness to back up negotiations with strength. In a sense, Clausewitz is entirely correct that
War is a continuation of politics by other means
, but he also says that war is a last resort. Appeasement comes when politicians will not stand on their principles. The root of appeasement is always either fear or cowardice.