Types of Logical Fallacies

slippery slope

In a slippery slope argument, a course of action is rejected because, with little or no evidence, one insists that it will lead to a chain reaction resulting in an undesirable end or ends. The slippery slope involves an acceptance of a succession of events without direct evidence that this course of events will happen (ex. legalizing prostitution is undesirable because it would cause more marriages to break up, which would in turn cause the breakdown of the family, which would finally result in the destruction of civilization)

tu quoque

The tu quoque fallacy occurs when one charges another with hypocrisy or inconsistency in order to avoid taking the other's position seriously (ex. Mother: You should stop smoking. It's harmful to your health. Daughter: Why should I listen to you? You started smoking when you were 16!)

non sequitur

a conclusion does not follow logically from what preceded it (ex. if someone asks what it's like outside and you reply, "It's 2:00,")

appeal to pity (ad misericordiam)

a fallacy in which someone tries to win support for an argument or idea by exploiting his or her opponent's feelings of pity or guilt (ex. You should not find the defendant guilty of murder, since it would break his poor mother's heart to see him sent to jail)

accidental fallacy (dicto simplicter)

a general rule or observation is treated as universally true regardless of the circumstances or the individuals concerned (ex. Exercise is good. Therefore everybody should exercise.)

false dilemma

a statement falsely claims an "either/or" situation, when in fact there is at least one additional logically valid option (ex. You are for us, or you are against us)

appeal to ignorance

a statement must be true if it cannot be proven false — or false if it cannot be proven true (ex. No one can actually prove that God exists; therefore God does not exist)

post hoc ergo propter hoc

after this, therefore resulting from it: used to indicate that a causal relationship has erroneously been assumed from a merely sequential one (ex. Every time that rooster crows, the sun comes up. That rooster must be very powerful and important!)

ad hominem

an attack to the character of the person carrying an argument (ex. A: "All murderers are criminals, but a thief isn't a murderer, and so can't be a criminal." B: "Well, you're a thief and a criminal, so there goes your argument)

bandwagon (ad populum)

believing something is true or acceptable only because it is popular (ex. You believe that those who receive welfare should submit to a drug test, but your friends tell you that idea is crazy and they don't accept it. You decide to change your position based on their beliefs)

two wrongs

collection of assumptions and a conclusion, that suggest it's okay to do something wrong if someone has done a similarly wrong thing first. It's often a way of claiming that your actions are justified because of what others have done or do (ex. Jimmy stole Tommy's lunch in the past. Therefore, it is acceptable for Tommy to steal Jimmy's lunch today)

straw man

fallacy based on giving the impression of refuting an opponent's argument, while actually refuting an argument that was not presented by that opponent (ex. The time has come also to say that we need to expand Medicare to cover every man, woman, and child as a single-payer, national healthcare program)

begging the question (circular reasoning)

fallacy in which a claim is made and accepted to be true, but one must accept the premise to be true for the claim to be true (ex. God is real because the Bible says so, and the Bible is from God)

red herring

fallacy that is an irrelevant topic introduced in an argument to divert the attention of listeners or readers from the original issue (ex. When your mom gets your phone bill and you have gone over the limit, you begin talking to her about how hard your math class is and how well you did on a test today)

hasty generalization

making a claim based on evidence that it just too small. Essentially, you can't make a claim and say that something is true if you have only an example or two as evidence (ex. my brother likes to eat a lot of pizza and French fries, and he is healthy, I can say that pizza and French fries are healthy and don't really make a person fat)

false analogy

the objects may have some similarities, but they do not both have property X (ex. Joan and Mary both drive pickup trucks. Since Joan is a teacher, Mary must also be a teacher)

equivocation

when a key term or phrase in an argument is used in an ambiguous way, with one meaning in one portion of the argument and then another meaning in another portion of the argument (ex. I have the right to watch "The Real World." Therefore it's right for me to watch the show)

fallacy of composition

when an individual infers that something is true of the whole because it is true of part of the whole (ex. This tire is made of rubber, therefore the vehicle of which it is a part is also made of rubber)

dogmatism

when one doctrine is pushed, often intensely, as the only acceptable conclusion and that that belief is beyond question (ex. a feminist view is the one and only way to look at literature)

appeal to doubtful authority

when one uses ideas or concepts of an inexperienced person to support one's argument (ex. A commercial claims that a specific brand of cereal is the best way to start the day because athlete Michael Jordan says that it is what he eats every day for breakfast.)