Critical Thinking by Example

Material covered in this chapter

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  7.1 Sufficiency and deductive and inductive arguments
  
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  7.2 Fallacies of Sufficiency
  

Recall that we said that with good arguments 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?
With bad arguments it is not possible to answer “yes” to each. In this chapter we will examine arguments where the answer to question 2 is “no”.
It is important to emphasize that in evaluating whether a premise set is sufficient to warrant the acceptance of a conclusion, we assume that the premise set is acceptable. In other words, to say that the premise set is sufficient is to say that, if true, the premise set provides good reason to believe the conclusion.

7.1 Sufficiency and Deductive and Inductive Arguments

Arguments are often divided into two types: deductive and inductive. With deductive arguments, the intention is to make the conclusion certain given that the premises are true. With inductive arguments, the intention is to make the conclusion probable, given the premises are true.

Example 7.1: Example of a deductive argument.

All humans are less than 8ft tall. Socrates is a human. So, Socrates is less than 8ft tall.