In the parlance of our times, an argument means a disagreement, and disagreements are often nothing more than people contradicting each other over and over again, and rarely lead to truth. But in philosophy, an argument means a series of premises that justify a conclusion. For example, Aristotle, who lived over 2000 years ago, invented a deductively valid argument known as a syllogism, which we still use today:

P1: All humans are mortal.

P2: You are a human.

C: Therefore, you are mortal.

This argument is valid because if the premises are true, the conclusion must be true. We will discuss the rules of validity and soundness, as well as several different kinds of arguments, including: deduction, induction, and abduction. As always, send your comments and questions to