p art one reasoning

© 2012 Wadsworth, Cengage Learning

What Is Critical Thinking? What Is Critical Thinking? What Is Critical Thinking? What Is Critical Thinking?

p. 109Exercise 5.1:Exercise 5.1:

Critical ThinkingCritical Thinking


I. Reasoning: I. Reasoning: InductionInduction vs. vs. DeductionDeduction I. Reasoning: I. Reasoning: InductionInduction vs. vs. DeductionDeduction

Inductive arguments go from specific observations to general conclusions

Deductive arguments go from broad generalizations to specific conclusions


I. Reasoning : I. Reasoning : Relevance and AdequacyRelevance and Adequacy I. Reasoning : I. Reasoning : Relevance and AdequacyRelevance and Adequacy

Two things are required to judge the soundness of an argument:

Relevance AdequacyLook at an example:

“I don’t see why all students haveto take an introductory writingcourse. It’s a free country. Students shouldn’t have to take courses they don’t want to take.”

Is the statement “It’s a free country relevant? What does living in a free country have to do with courses that community college students are required to take? Nothing.

Now look at this example:

“Everyone taking Math 100 failed the test last Friday. I took the test last Friday. Therefore, I will probably get an F in the course.”

How many tests are left in the course? What other assignments figure into students’ grades? The information present may not be adequate to predict an F in the course.


I. Reasoning: I. Reasoning: Analyzing ArgumentsAnalyzing Arguments I. Reasoning: I. Reasoning: Analyzing ArgumentsAnalyzing Arguments

Sound or Unsound?

Is it Relevant?

Is it Adequate?

Is it Logical?

“ ”The aim of argument, or of discussion, should not be victory, but progress.Joseph Joubert, French moralist


I. Reasoning: I. Reasoning: Assessing AssumptionsAssessing Assumptions I. Reasoning: I. Reasoning: Assessing AssumptionsAssessing Assumptions

Assumptions are things youtake for granted, and theycan limit your thinking.

Understand your ownassumptions and see anargument in new ways.

“One day Kerry celebrated her birthday. Two days later her older twin brother, Harry, celebrated his birthday. How could that be?”

Think! What assumptionsare you making about this puzzle? “ ”What we need is not the will to believe, but

the will to find out. Bertrand Russell, British philosopher, logician, and mathematician


I. Reasoning: I. Reasoning: Considering ClaimsConsidering Claims I. Reasoning: I. Reasoning: Considering ClaimsConsidering Claims

Generally speaking, be wary of claims that:

are supported by unidentified sources

(“Experts claim . . . ”). are made by a person or company who stands to gain

(“Brought to you by the makers of . . .”). come from a a single person claiming his experience as

the norm (“I tried it and it worked for me!”). use a bandwagon appeal (“Everybody’s doing it.”). mislead with statistics (“over half” when it’s really only

50.5 percent).© 2012 Wadsworth, Cengage Learning


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Simple vs. Simple vs. Complex Complex

Reasoning Reasoning

Simple vs. Simple vs. Complex Complex

Reasoning Reasoning

p art one reasoning

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