Lesson - Logical Flaws

Logical Flaws 

Writers develop and propose arguments and positions concerning their topics.  Arguments consist of premises, or points, and a conclusion that is supposed to be based on those points.

When Analyzing an Argument, you will apply critical reasoning skills to evaluate what you read.

The following is a list of common weak arguments.  Being able to identify these common logical flaws will help you analyze positions and arguments.  In addition, you should learn to articulate the fallacies made in these common logical flaws when you see them.


Weak Arguments

  • Faulty cause and effect: The premise used as the cause is not sufficient to guarantee the conclusion.

Example: "He golfed his best game because he wore his lucky hat." The premise, "he wore his lucky hat" does not warrant the conclusion given.

  • Non sequitur: This term is Latin for "it does not follow." The conclusion is an illogical result of the facts stated.

Example: "More Americans have heart disease than any other national group. This has led researchers to believe that heart disease is the result of speaking English." The connection between heart disease and language is illogical.

  • Begging the question: One or more of the premises used to construct an argument is an assertion that itself is arguable. Or, the conclusion is stated as a fact without its validity being established.

Example: Roberta was the most beautiful contestant and therefore was favored to win the pageant.

  • Circular logic: A premise is rephrased as the conclusion which means the argument has gone nowhere.

Example: The supermarket ran out of milk because too many people bought milk at once.

  • Hasty generalization: The reasoning or argument is extended beyond the specific evidence cited.

Example: All federal politicians are corrupt.

  • Either/Or: The reader is expected to choose one of two extreme choices while offered no other possibilities.

Example: He will either have to leave the state to find a job or go on welfare.

  • Faulty analogy: Insufficient or inappropriate comparisons are made in an attempt to prove a point.

Example: Some say we should outlaw crop chemicals that adversely affect people. Cars hurt and kill people, but we don't outlaw them.

  • Argument to the person (argumentum ad hominem): The passage attacks a person rather than the person's opinions or issues.

Example: Jane's proposal about zoning is ridiculous. She was audited and fined for her tax return in 2008.

  • Argument to the people (argumentum ad populum): This argument appeals to the masses -- everybody's thinking it so it must be true!

Example: Dykson is the leader in the polls, so he must be the best candidate.

  • Bandwagon appeal: A type of argumentum ad populum, everybody's doing it so it must be good!

Example: Everyone jaywalks here so it must be safe.

  • Red herring: A deliberate attempt to divert a process of inquiry by changing the subject.

Example: I should not have to pay a fine for reckless driving. The police and court system should be spending their time with the real dangerous criminals and not harassing a decent citizen like me.



On the GRE, it is not necessary to identify the name of the logical flaw in an argument.  Rather, recognize and describe the problem with the thinking and reasoning of the writer in your critical analysis.