logical fallacies

sweeping generalization Argument: Cutting people is a crime. Surgeons cut people, therefore, surgeons are criminals. Argument: It is illegal for a stranger to enter someone's home uninvited. Firefighters enter people's homes uninvited, therefore firefighters are breaking the law. exception

hasty generalization Argument: Every person I've met has ten fingers, therefore, all people have ten fingers. argues from a special case to a general rule

irrelevant conclusion argument: Billy believes that pigs can fly, therefore pigs can fly. personal consideration; popular sentiment; fear; conventional propriety; arouse pity; diverts attention away from a fact in dispute rather than addressing it directly

affirming the consequent/ denying the antecedent Argument: If people have the flu, they cough. Torres is coughing. Therefore, Torres has the flu. Argument: If it rains, the ground gets wet. The ground is wet, therefore it rained. Denying the antecedent Argument: If it is raining outside, it must be cloudy. It is not raining outside. Therefore, it is not cloudy. draws conclusion from premises that do not support that conclusion by confusing necessary and sufficient conditions

begging the question Argument: Aspirin users are at risk of becoming dependent on the drug, because aspirin is an addictive substance. premises assume conclusion

false cause Argument: I hear the rain falling outside my window; therefore, the sun is not shining. Argument: It rained just before the car broke down. The rain caused the car to break down. Argument: More cows die in the summer months. More ice cream is consumed in summer months. Therefore, the consumption of ice cream in the summer months is killing cows.

straw man Person A: Sunny days are good. Person B: If all days were sunny, we'd never have rain, and without rain, we'd have famine and death. Therefore, you are wrong. 曲解对方的论点

equivocation All heavy things have a great mass; Jim has a "heavy heart"; therefore Jim's heart has a great mass. 一词多义

apophasis and argument by innuendo For example, a job reference that says a former employee "was never caught taking money from the cash box" In this example the overly specific nature of the innuendo implies that the employee was a thief, even though it does not make (or justify) a direct negative statement. implicitly suggesting a conclusion without stating it outright.

amphiholy The position of the adverb "only" in a sentence starting with "He only said that" results in a sentence in which it is uncertain as to which of the other three words the speaker is intending to modify with the adverb. ambiguity of grammatical structure

fallacy of composition acceptable: all the parts of the car are in the garage, therefore the car is in the garage. problematic: all the musicians in a band are highly skilled, therefore the band itself is highly skilled. from each to all

division The university (the whole) is 700 years old, therefore, all the staff (each part) are 700 years old". all to each

proof by verbosity accent: he is a fairly good pianist figure of speech: the sailor was at home on the sea rhetorical techniques

misplaced concreteness billy is a good tennis player. therefore, billy is good, that is to say a morally good person.

nothing is better than eternal happiness. eating a sandwich is better than nothing. therefore, eating a sandwich is better than eternal happiness.

paradox "This statement is false" "The following sentence is true." "The previous sentence is false." "What happens when Pinocchio says, 'My nose will grow now'?" "Numbers are infinite, however there are more fractions than whole numbers."