What is a Fallacy?

A fallacy is a defect in an argument that makes it invalid.  Whenever you are writing an essay it is important to make sure that the points being made do not fall into this category.  Fallacies are problematic for students because it brings the credibility of a paper down.  This is critical especially when writing a persuasive paper.  Below are examples and explanations of common fallacies from The Brief Penguin Handbook by Lester Faigley.

  • Begging the Question--People who take 8:00 AM classes are crazy because no sane person would choose to get up that early. The fallacy of begging the question occurs when the claim is restated and passed.
  • Either-or-- Either Fraternities must be forced to cancel all parties, or the university will never be able to control its underage drinking problem. The either or fallacy suggests that there are only two choices in a complex situation. Rarely, if ever, this is the case. (In this example, the writer the ignores the fact that some students under 21 drink when they are not at a fraternity party.)
  • Hasty Generalization--My folks wouldn't let me go to the movies last night, and they wouldn't let me stay up to watch TV either. They never want me to have any fun. A hasty generalization is a board claim made on the basis of a few occurrences.
  • Non sequitur--Janet Jackson's "wardrobe malfuction" during the 2004 Super Bowl shows how far contemporary morals have sunk. A son sequitur ties two unrelated ideas. In case, one person's behavior is not indicative of society's morals.
  • Post hoc fallcy-- The stock market goes down when the AFC wins the Super Bowl in even years. The post hoc fallacy assumes that things that follow in time have a casual relationship.
  • Slippery Slope--If the government were to legalize a gateway drug like marijuana, there would be a huge increase in the use of hard drugs like cocaine and heroin. The slippery slope fallcy maintains that one thing inevitbly will cause something else to happy.
  • Bandwagon appeals--Since all the power hitters in baseball use steroids, I'll have to use them too if I want to be able to compete. This argument suggests that every is doing it, so why shouldn't you?
  • Name calling-- A writer (or speaker) who finds it difficult to attack an opponent's arguments may attack the opponent on personal issues. An ethical speaker will focus on the issues rather than demean an opponent.

(Brief Penguin Handbook pp.49-51)

-TCB/ZDF