Logical fallacies are errors in reasoning that undermine the logic of an argument. In any discourse where you are trying to support a statement with logic and evidence, avoiding these pitfalls is important as they will undermine the strength of your argument.
An example of a VALID argument where valid premises support the conclusion:
Whichever team scores the most points wins the game. Red team scored more points than Blue team. Therefore, Red team wins the game.
Faulty arguments occur when either the premises are incorrect. In the example above, not all games are won that way. If you were playing Uno, the winner of the game would be the one who scored the fewest points overall. Faulty arguments can also occur when the conclusion does not follow the premises.
Example: Cats are very good pets. Penny is a good pet. Therefore, Penny is a cat.
For each of the fallacies below, read the example and then create an example of your own. Be prepared to share with the class.
1. Ad Hominen - This translates as "to the man" and refers to any attacks on the person advancing the argument, rather on the validity of the argument or the evidence.
Example: Charles is a terrible person, therefore anything Charles says must be wrong.
2. Association (Guilt by) Fallacy - This occurs when a source is viewed negatively because of her association with another group who is viewed negatively.
Example: Rex is a member of the Dog Lovers Club, and last year one of their members was suspended for abusing a cat. Rex must want to hurt cats.
3. Argument from Ignorance - This occurs when an idea that has not been proven false must likely be true.
Sometimes, the idea may be beyond the realm of truth, as in the case of many religious arguments. This type of argument will often ask the person to "prove a negative" which can be difficult to do.
Example: Since we haven't been able to prove that the moon is not inhabited by little green moonmonsters, then it must be true that they exist there.
4. Band Wagon - The basic fallacy of democracy, that popular ideas are necessarily right.
Example: (1919) Most people don't believe that women should be allowed to vote, therefore it must be the right decision.
5. False Dichotomy - This fallacy relies on the argument of a person to suggest there are only two choices. Often there are other options not included in the statement.
Example: If you don't approve of a raise in taxes to help the school, then you are against education.
6. Straw Man - This occurs when the arguer sets up a version of the opponent's position and then attacks that, rather than the actual position. The original argument is misrepresented.
Example: Amy believes that that schools should provide birth control and sex education. Rory responded that he is shocked that Amy believes that it is okay for teens to have sex.
7. Red Herring - In this case, the arguer goes off in a different direction that distracts the argument from the original point.
Example: Clara states that everyone knows that vaccines cause autism, when Missy disagrees, Clara brings up a case where doctors were wrong about the cause of malaria.
8. Appeal to Authority - This is where someone in authority is quoted or used to support the argument. This also can apply to other types of "appeals" such as celebrity or the common folk, or even an anonymous source.
Example: My 6th grade teacher told me that blood is blue and it turns red when it hits the air, therefore blood must be blue.
9. Slippery Slope - This occurs when a person proposes that one change will inevitably lead to another, like a domino effect. Usually the effect is something bad or undesirable.
Example: If students do not have a dress code then they will wear outragous things, and some might come to school naked.
10. The Gambler's Fallacy - This occurs when a person feels that a random event can be predicted by previous outcomes.
Example: The coin has been heads twice, so the next flip is most going to be tails.
*The Fallacy Fallacy occurs when an arguer assumes that a claim is wrong because the person making the claim was guilty of fallacy. Just because the person was bad at arguing doesn't necessarily make the claim incorrect.