Intro to Logic Chapter 3

32 terms by sj126

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Fallacy

error in reasoning, defect in an argument, AKA as a non sequiter: "does not follow"

Formal Fallacy

can be detected by mere inspection or form.

Informal Fallacy

requires some analysis of content.

Fallacies of Relevance

a group of informal fallacies that occur because the premises of an argument are irrelevant to the conclusion

Appeal to Authority (fallacy of relevance)

believing something solely on the fact that an expert says it is true, so therefore it must be. both an indirect and direct approach, the direct is easier then the indirect approach.

Appeal to Popularity (fallacy of relevance)

the majority believes something, so then someone may believe it as well.

Appeal to traditional wisdom (fallacy of relevance)

what was in the past, will work now "it's always been this way" mentality.

Ad Hominem "to the man"

arguments against a person but not their arguments. this is often viewed as a personal attack.

Type of Ad hominem: Abusive (fallacy of relevance)

Attack of character ex: saying Obama is an idiot but not really caring about what he believes in/basing your idea of him off that.

Type of Ad hominem: circumstantial (fallacy of relevance)

disregarding someone's argument because of someone's situation that makes them appear bias

Type of Ad hominem:tu quoque (fallacy of relevance)

just cause you don't follow that advice then I wont. Ex: dad asks his kids to eat their veggies, but on his plate there are still veggies, the kids are committing Tu Quoque.

Emotional Appeals

trying to get to someone by tapping into their various emotions, force, fear, pity, vanity.

Fallacies of Ambiguity

fallacies that have more then one meaning

Vagueness

no precisely defined meeting. Example: Hot (temperature) some may think that 75 is hot, while others may think 80 is, it is an unclear definition since everyone has a different view of what is hot.

Equivocation

using a word that shifts its meaning in the context of some argument. Ex: only man is rational, no women is a man, therefore no woman is rational (which isn't a sound argument but does use "man" to mean two different things.

Composition

attribute is wrongly transferred from parts to whole. example: pizza pieces are triangles therefore the pizza is a triangle (while it's true of each part being a triangle but the pizza as a whole is a circle)

Division

attribute is wrongly transferred from whole to parts. Ex: the average GPA for CMU students is 2.9, so therefore an individual's GPA is a 2.9. While it is a true of the students as a whole, it is not necessarily the truth for an individual student.

Composition and Division

a predicate (property) applies distributively if it applies to each and every member of a group or collection but not necessarily to the group or collection itself. Ex: Fleas are small, this flea is small so all of them are small. a predicate (property) applies collectively if it applies to a group or collection as a group or collection but not necessarily to each member of the group ex: fleas are numerous, but one flea isn't numerous, all of them are as a whole.

appeal to unqualified authority (fallacy of weak induction)

arguer cites untrustworthy authority.

Appeal to ignorance (fallacy of weak induction)

premises report that nothing is known or proved, and then a conclusion is drawn. "you can't prove x" so therefore it is not x. ex: i've never seen him drink so therefore he doesnt.

Hasty generalization ( aka hasty generalization, fallacy of weak induction)

conclusion is drawn from an atypical sample. You have the right kind of evidence but not enough of it.

False Clause (aka questionable cause, fallacy of weak induction)

conclusion depends on nonexistent or minor casual connection. A happens, B happens, A caused B. Ex: I stepped on the bricks outside Warrnier Hall and then I failed my exam, because I stepped on the bricks, I failed.

Slippery Slope (fallacy of weak induction)

conclusion depends on unlikely chain reaction. A leads, to b, which leads to C, D, and E. therefore one can conclude not to do A. Ex: having "sleepovers" leads to to kisses, which leads to moving in clothes, leads to snuggles, leads to touching, leads to sex, which leads to the creation of a human being. meaning do not do A then the slippery slope won't occur. SLIPPERY SLOPES HAVE A WEAK LINK AND PROBLEM WITH COMPLEX PROBABILITIES. THE DIMINISHING LIKELIHOOD OF ULTIMATE CONCLUSION AS COMPLEXITY OF ARGUMENT INCREASES

Weak Analogy (fallacy of weak induction)

conclusion depends on defective analogy. x has properties a, b,c,d, y has properties a, b,c. So therefore Y has property D. Ex: I am taking this class in IT building and it is math like, long, hard, confusing, and boring. I am taking another class in the fall that is in the IT building so it must be math like, long, hard, confusing, and BORING (since it is property D).

Sweeping Generalization ( aka: Accident,fallacy of relevance)

general rule is applied to a specific case it was not intended to cover. Any "all" statement Ex: All women are lousy drivers, Sarah is a woman, therefore she is a lousy driver.

Straw Man (fallacy of relevance)

arguer distorts opponent's argument and then attacks the distorted argument. misrepresentation of argument and atack on the person. this an argument you can poke holes in (which is why its called straw man)

Missing the point (fallacy of relevance)

arguer draws conclusion different from that supported by premises.

begging the question (Fallacies of presumption)

arguer creates the illusion that inadequate premises are adequate by leaving out a key premise by restating the conclusion as a premise, or by reasoning in a circle.

Complex Question (fallacy of presumption)

multiple questions are concealed in a single question,and the presumptions are built in. Ex: Do you believe in that idiotic health care plan?

False dilemma (aka false Dichotomyfallacy of presumption)

"either..or" statement hides additional alternatives. Either you support nuclear weapons and want a war, or you don't because you want peace.

Suppressed evidence ((fallacy of presumption)

arguer ignores important evidence that requires a different conclusion.

What makes an analogy weak

the comparison involves either irrelevant similarities, relevant dissimilarities. Ex: Japanese kill whales for food, display, etc. Americans kill cows for the same purpose. U.S. breeds cows, Japan just kills the whales as they see them, whales are endangered Cows arent.

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