Nathan Gilbert

Logical Fallacies

Just some examples I wanted to keep around for posterity. I originally saw this posted on Usenet
many years ago.

Fallacies that result from errors in induction

• Overstatement: An unqualified generalization.
  Examples:
  "My English teacher never gives A's."
  "Almonds are good for the heart; everyone should eat 2 handfuls of almonds every day."

• Hasty Generalization: Stating a conclusion based on too little evidence or ignoring some
  evidence.
  Examples:
  "Running must be bad for your heart. Look what happened to Florence Joiner."
  "My little Yamaha motorcycle never gave me problems. Yamaha motorcycles are the best."

• Stereotyping: Giving the same characteristics to everyone in a group.
  Examples:
  "Used-car salesmen can't be trusted."
  "Utah State graduates are all nerdy."
  "Southern Utahns are all right-wing conservative fanatics who refuse to pay taxes and want to
  destroy the environment."

• Forced hypothesis: Reaching a conclusion that is not supported by the evidence or is
  unnecessarily complicated.
  Example:
  "Jerry and Kim live next door to each other, so they must be really good friends."

• Non sequitur: Conclusions not logically derived from preceding reasoning.
  Example:
  "Al Gore is a wonderful father, so he would have made a great president."

• Slippery slope: Asserting that X should not happen because it will inevitably lead to Y
  and Z, which are terrible.
  Examples:
  "Utah should not legalize parimutuel betting on horse races because that will only lead to
  gambling on other sporting events and finally to casino gambling."
  "We should never allow families to have doctors disconnect the respirators and feeding tubes
  of brain-dead patients. If we do, pretty soon we will be asking doctors to kill people with
  Alzheimer's disease."

• False dilemma: Asserting only two options exist when more are available.
  Example:
  "You either support the war in Iraq or you are a traitor to your country and an enemy to
  freedom."

• False analogy: Comparing two things with differences too great to justify the comparison.
  Example:
  "There are 10,000 deaths from alcohol poisoning to 1 from mad-dog bites in this country. In
  spite of this, we license liquor but shoot the dogs."

• Post hoc: From the Latin "after this, therefore because of it," assigning a cause-effect
  relationship where none exists.
  Example:
  "A black cat ran across my path on the way to work this morning, and sure enough, I got a flat
  tire on the way home."

Fallacies that result from ignoring the issue

• Begging the question: Assuming part or all of your argument is true without support.
  Examples:
  "The federal government should not subsidize development of alternative-fuel automobiles
  because gasoline is the cheapest and cleanest fuel."
  "We should give every American the right to have assault weapons in their home because we know
  that a nation where citizens have assault weapons will be safer."
  "We know that our police are never involved in bribery, dishonesty, or abuse of the law
  because the police report said so."

• Red herring: Introducing an irrelevant side issue to divert attention.
  Example:
  "Mary Gordon shouldn't be elected to the school board because she doesn't have any children in
  public schools."

• Straw man: Misrepresenting an opponent's view and attacking the misrepresentation instead.
  Example:
  "Environmentalists are trying to save the spotted owl because they want to run American
  loggers out of business."

• Ad hominem: Attacking the person making the argument rather than the argument itself.
  Example:
  "You're too young to understand the importance of this issue."

• Argument ad Misericordiam ("Argument to Pity"): Using emotional appeal instead of logic.
  Examples:
  "I know my paper is late, but I had the worst pimple on my nose for a week. Please don't mark
  it late."
  "Janice, you have to marry me! If you don't, I will be the most miserable person alive."

• Common practice: Arguing that something is acceptable because "everyone is doing it."
  Examples:
  "Don't worry about using your older brother's research paper; half the kids in the class are
  doing it."
  "Dad, I can't live without a cell phone and a laptop. All the kids have them now."

• Argument ad populum: Appealing to the beliefs of the masses.
  Example:
  "Republican candidates are the choice of red-blooded Americans who believe in traditional
  American values."

• Argumentum ad Baculum ("Appeal to Force"): Using threats or force to persuade.
  Example:
  "If you don't support this policy, you're unpatriotic and will face backlash."