What an agent decides to do should depend on its preferences. In this section, we specify some intuitive properties of preferences and give some consequences of those properties. The properties that we give are axioms of rationality from which we prove a theorem about how to measure these preferences. You should consider whether each axiom is reasonable for a rational agent to follow; if you accept them all as reasonable, you should accept their consequences. If you do not accept the consequences, you should question which of the axioms to give up.