Introduction

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Subsection 1.4.1 Introduction

Logic is the study of valid argument (proof) structures (i.e., arguments that preserve truth).

It lets us construct and understand good arguments.

Activity 1.4.1.

In his classic novel, Catch-22, Joseph Heller clearly describes the Army’s rules for getting a mental health discharge. There are two:

To get a discharge, you’ve got to be crazy and you’ve got to request the discharge.
If you request a mental health discharge, you’re clearly not crazy – any sensible person would make exactly such a request.

From these two rules, we can reason logically and conclude that it’s not possible to get a mental health discharge.

Try proving this yourself.