ABSTRACT
This chapter begins with the elements of reasoning. Every philosophical issue involves argument, and it wants to be sure all students are familiar with the concepts of premise, conclusion, validity, and soundness, so that these terms can be used throughout the course. The key idea, which requires emphasis because it is counterintuitive, is that a valid argument can have false premises and a true conclusion. The chapter emphasizes the difference between necessary and sufficient conditions and provides further examples. It shows an example of how necessary and sufficient conditions may be muddled: Confusing necessary and sufficient conditions is a common mistake in reasoning. The final step in teaching necessary and sufficient conditions is the hardest to grasp, yet essential to understanding the relationship of the two concepts. Before presenting it, the chapter alert students to the challenge it presents with an additional twist.
