Persuasion, to a large extent, involves convincing people to accept our assumptions as probably true. Similarly, exposing questionable assumptions in someone else's argument is an effective means for preparing the audience to accept your own contrary position. Most of us think that we make our decisions based on rational thought. However, Aristotle points out that emotions such as anger, pity and fear, and their opposites, powerfully influence our rational judgements. Due to this fact, much of our political discourse and much of the advertising we experience is directed toward moving our emotions.
Anger is a very powerful motivating force.
The recent breakup of Yugoslavia into separate countries provides many examples of the power of this kind of rhetoric. Yugoslavia was created after the second world war out of several smaller states, including Croatia, Serbia, Bosnia-Herzgovenia, and Slovenia. Within each state there were ethnic and religious minorities with long histories of conflict. While Yugoslavia was under the control of the Soviet Union, these conflicts were kept in check by military force. With the collapse of the Soviet Union, new political structures were necessary, and political opportunities arose for the ambitious.