Aristotle's Topics is about dialectic, which can be understood as a debate between two people or the inner debate of one thinker with himself. Its purposes range from philosophical training to discovering the first principles of thought. Its arguments concern the four predicables (definition, property, genus and accident). Aristotle explains how these four fit into his ten categories, and in Book 1 begins to outline strategies for debate, such as the definition of ambiguity. Alexander's commentary on Book 1 discusses how to define Aristotelian syllogistic argument, why it stands up...