Use Critical Reasoning Skills to Evaluate Written Material
Recognize Stated or Implied Assumptions on which the Validity of an Argument Depends
An argument consists of:
a list of premises (hypotheses), and
a conclusion that is supposed to be drawn from the premises.
The premises can be facts or opinions. If a premise is a false fact, then the conclusion may not be true regardless of the strength of the logic used to reach it. Similarly, if a premise is not an acceptable opinion, then the quality of the logic cannot make the conclusion acceptable. Consequently, the first step in determining the strength or weakness of an argument is to decide upon the quality of its separate premises.
The conclusion of a strong argument must follow logically from its premises. The list of premises may have no flaws, but the argument is weak if those premises do not lead logically to the conclusion.
Some classic and common weak arguments are described below. The reader who is familiar with this list is well-prepared to spot most of the weak arguments that will be found in reading passages.
• Faulty cause and effect: The premise used as the cause is not sufficient to guarantee the conclusion (effect).
For Example: "She passed the test because she wore her lucky charm" has "she wore her lucky charm" as a premise and "she passed the test" as an unwarranted conclusion.
• Non sequitur: The conclusion is an illogical result of the facts stated.
For Example: "People who get cancer drank milk as children" illogically makes a connection between "people who get cancer" and "people who drank milk as children."
• Begging the question: The writer makes an assertion of fact that has not been established.
For Example: George Washington was a communist.
• Circular logic: A premise is rephrased as the conclusion which means the argument has gone nowhere.
For Example: The bookstore ran out of texts for the course because there are too many students in the class.
• Hasty generalization: The reasoning or argument is extended beyond the specific evidence cited.
For Example: All federal politicians are corrupt.
• Either/Or: The reader is expected to choose one of two extreme choices while offered no other possibilities.
For Example: Thinking people will choose either democracy or communism.
• Faulty analogy: Insufficient or inappropriate comparisons are made in an attempt to prove a point.
For Example: That politician is a flea hopping around on the issues.
• Argument to the person (argumentum ad hominem): The passage attacks a person rather than the person’s opinions or issues.
For Example: This instructor can’t be trusted because he was a hippie at one time.
• Argument to the people (argumentum ad populum): Appeals are made to the feelings or emotions of the reader rather than the other side of the argument.
For Example: When you see the American flag passing by, you won't think that it may pass out of existence if you vote for me.
• Bandwagon appeal: The passage claims that everyone believes or does whatever his/her argument is.
For Example: Everyone agrees that Cadillacs are great this year and now is the time to buy one.
• Red herring: Irrelevant is used in an attempt to divert attention from a weak argument.
For Example: The voters will want to vote against Joe Brown because they remember what happened in the ’60s.
Which of the reasons listed above makes the following argument weak?
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