Chapter 4 covers how to assess an argument for formal validity and how to criticize an invalid argument in natural language. We begin by showing how to use truth tables to assess the validity of arguments in sentential, and then, after a brief introduction to the logic of sets, show how to use the shortcut method to assess validity quickly. With this account of validity in hand, we show the student how to read an argument in English and to demonstrate that it is invalid, and then turn to a deeper discussion of negation.

Formal topics:

• Truth tables
• Validity
• Sets and set notation

Informal topics:

• How to rebut inferences

Supplementary topics:

• Logic circuits
• Zeno's paradoxes
• Puzzles