Why did the western powers follow a policy of appeasement even though it srrmed to encourage more aggression?

The Western powers followed a policy of appeasement despite the fact that it encouraged aggression because these countries were trying to avoid another World War at all costs. Countries like Great Britain and France were heavily involved in World War I and suffered severe infrastructure damage. It took years for these countries to rebuild to their previous state. The last thing they wanted to do was get involved in another war that would ruin their countries infrastructure and result in the loss of thousands of soldiers.