LOGICAL FALLACIES DR LORI MILLER HARROWING LOGIC INFORMAL

LOGICAL FALLACIES DR. LORI MILLER

HARROWING LOGIC

INFORMAL LOGICAL FALLACIES • A "fallacy" is a mistake or an error in reasoning. • Our concern here is with informal or every day errors in reasoning, which we call “logical fallacies. ” • There are, of course, types of mistakes other than mistakes in reasoning. For instance, factual mistakes are sometimes referred to as "fallacies". • However, today’s lesson is specifically concerned, not with factual errors, but with logical ones. • An informal fallacy is an error in reasoning that does not originate in improper logical form, which study belongs to the domain of philosophy. It comes from an error in thinking things through logically.

SWEEPING GENERALIZATIONS • A sweeping generalization is an unqualified general statement. • It disregards exceptions and considers no qualifications. • “Dicto simpliciter” • “Exercise is good. Therefore, everybody should exercise. ” • Correction: Add qualifiers

HASTY GENERALIZATIONS • Like the overgeneralization but sneaky because the claim offers proofs, but too few instances are provided to justify a logical conclusion. • “Hypothesis Contrary to Fact” • “Becky can’t speak French, Pete can’t speak French, and the teacher can’t speak French, so nobody in Spanish class can speak French. ” • Correction: qualify terms in conclusion

FALSE PREMISES LEAD TO IRRELEVANT CONCLUSIONS Red Herring Arguments • Simply speaking, a red herring argument diverts attention away from the claim itself, avoiding an analysis of its merits. • Red herring arguments lead to irrelevant or false conclusions. Logical fallacies are “red herring” arguments when they engage in disputing the premises or arguing about the logistics or processes involved.

IRRELEVANT CONCLUSIONS False Cause • A fallacy of false cause illogically attributes the cause of something to another; in Latin this is a “non sequitur” • “Post hoc” • Let’s not take Bill with us to the game. Every time he goes with us, we loose. • Every time I sit in that booth, the waitress brings me cold coffee.

MORE FALLACIES LEADING TO IRRELEVANT CONCLUSIONS • Appeals to authority • We know pigs can fly because Mr. Bailey, an expert in the field, believes it is possible. • Ad hominem • George is a liberal who believes taxes should be raised. We should never follow liberals. Therefore, taxes should not be raised. (“Poisoning the Well. ”) • Bandwagon • Everybody who is cool drinks Coke, so you have to drink Coke if you want to be cool. • Appeals to loyalty • John questions the minister’s claim that all good Christians donate 10% of their money to the church. The minister never lies so anyone who agrees with John is surely going to hell.

ILLOGICAL PREMISES • Contradictory Premises • Begging the Question If God can do everything, then He can create a stone too heavy for Him to lift. • Problem: no argument exists when Aspirin users are at risk of becoming dependent on the drug because aspirin is an addictive substance. the premises are contradictory. This is simply untrue on its face. When people have the flu, they cough. Pedro is coughing, so he must have the flu. • Problem: there are other reasons that cause coughing, like asthma. One premise here is false. • Problem: Demonstrates the conclusion by means of premises that argue the conclusion. If you accept the premise, there’s no need for the conclusion. • Also called “Circular Reasoning”

FALSE ANALOGIES • We use analogies to suggest a relationship exists between unlike things. These are “false” or fallacious when the analogy itself is inaccurate or misleading. • Problem: • “The model of the solar system is similar to that of an atom, with planets orbiting the sun like electrons orbiting the nucleus. Electrons can jump from orbit to orbit; so we should study ancient records for sightings of planets jumping from orbit to orbit. ” [wiki]

MORE LOGICAL FALLACIES • Straw Man Fallacy • Loaded Question A straw man argument is an informal fallacy based on misrepresenting an opponent's position so as to more easily refute it Person A: Sunny days are good. Person B: If all days were sunny, there’d be no rain. Since we need rain, you’re wrong. A loaded question implies in its asking a fact that is not in evidence. “When did you quit cheating on exams? ” “Did you stop beating the dog in your training sessions? ”

EMOTIONAL FALLACIES • Appeals to Pity These arguments divert attention away from the conclusion by offering reasons that attempt to get the hearer to feel sorry for the speaker. Claim: I’m not guilty of speeding. Premises: My mom is sick, my dog just died and I can’t afford a ticket. Fallacy: Ad miserecordium

EMOTIONAL FALLACIES • Appeals to Fear These arguments divert attention away from the conclusion by offering reasons that threaten the hearer with an undesirable outcome. • “All penguins are mammals. Disagree with me and your research funding will be delayed or cancelled. ” • “There is only one religion. Disagree with me and your bedroom will be rented out to a stranger and you will be homeless. ”

SUMMING UP • Logical fallacies occur when we have not thoroughly examined the basis of our thesis claims. • Types of fallacies include sweeping or hasty generalizations, using false premises, red herring, straw man, and loaded question fallacies, false analogies, illogical appeals to authority, ad hominem attacks, bandwagon appeals, and appeals to loyalty, pity, and fear. • Solutions include identifying your assumptions (premises), qualifying your claims, and re-thinking or even giving up emotion-based conclusions.

WORKS CITED • “Logical fallacies, ” Wikipedia. March 24, 2013. • “English 1 b Logical Fallacies DLA. ” WRC web page. Moreno Valley College. March 24, 2013.