Many people think mathematics is the study of arithmetic, algebra, and geometry. Although they may realize that mathematical thinking is logical, they are surprised that mathematicians view logic itself as a branch of mathematics. This short chapter is an introduction to that subject.

Logic is introduced in the first two sections through simple examples of what are essentially parlor games. The rest of the chapter treats the liar paradox and Aristotelian syllogisms. These syllogisms are the basis for most everyday applications of logic.

5.1 Think of the possibilities

5.2 What's my number?

5.3 The liar paradox

5.4 Subject and predicate

5.5 Syllogisms