Critical Thinking by Example

Example 5.3: An argument with a missing premise and missing conclusion.

Background: Local government officials are considering changing the legislation to make all elective abortions illegal. Smith wrote a letter to the editor in support of changing the legislation. Jones responds with her own letter to the editor, a single sentence: Argument: “If the government makes all elective abortions illegal, we will live in a less just society.”

This single sentence is best understood as an argument with a missing premise: “We don’t want to live in a less just society”; and a missing conclusion: “The government should not make all elective abortions illegal”. We would standardize it thus:

MP1: We do not want to live in a less justice society.
P2: If the government makes all elective abortions illegal, we will live in a less just society.
MC: The government should not make all elective abortions illegal.

Chapter 6: Relevance

Material covered in this chapter 6.1 Twelve fallacies of relevance.

With a good argument, it is possible to answer “yes” to each of these questions:

1. Assuming that the premise set is acceptable, is the premise set relevant to the conclusion?
2. Assuming that the premise set is acceptable, does the premise set provide sufficient support for the conclusion?
3. Is the premise set acceptable?
A bad argument is one which answers “no” to one or more of these questions. In this chapter we will examine arguments where the answer to question 1 is “no” by examining twelve fallacies of relevancy:

6.1 Twelve Fallacies of Relevance