Logical Fallacies Flashcards
Ad ignorantium
Appeal to ignorance. Arguing on the basis of what is not known and cannot be known. If you can’t prove something is true then it must be false.
Ad hominem
Attacking the person.
Ad verecundiam
Appeal to authority. This fallacy tries to convince the listener by appealing to the reputation of a famous or respected person.
Amphiboly
A fallacy of syntactical ambiguity where the position of words in a sentence or the juxtaposition of two sentences conveys a mistaken idea. Ambiguity in word placement. Jim said he saw Jenny walk her dog through the window.
Appeal to emotion
In this fallacy, the arguer uses emotional appeals rather than logical reasons to persuade the listener. The fallacy can appeal to various emotions including pride, pity, fear, hate, vanity, or sympathy.
Argument from stretched analogy or false analogy
An unsound form of inductive argument in which an argument relies heavily on a weak analogy to prove its point. This car must be great, for, like the watches in the world, it was made in Switzerland.
Begging the question
An argument in which the conclusion is implied or already assumed in the premises. Also said to be circular argument. Of course the Bible is the word of God. Why? Because God says so in the bible.
Slippery slope
A line of reasoning that argues against taking a step because it assumes that if you take the first step, you will inevitably follow through to the last. This fallacy uses the valid form of hypothetical syllogism, but uses guesswork for the premises. We can’t allow students any voice in decision making on campus; if we do, it won’t be long before they are in total control.
Common belief
“Bandwagon” or appeal to popularity. This fallacy is committed when we assert a statement to be true on the evidence that many other people allegedly believe it.
Past belief
A form of common belief fallacy. The same error in reasoning is committed except the claim is for belief or support in the past. We all know women should obey their husbands. After all, marriage vows contained those words for centuries.
Contrary to fact hypothesis
This fallacy is committed when we state with an unreasonable degree of certainty the results of an event that might have occurred but did not.
Division
This fallacy is committed when we conclude that any part of a particular whole must have a characteristic because the whole has that characteristic. I am sure that Karen plays the piano well, since her family is so musical.
Composition
We conclude that a whole must have a characteristic because some part of it has that characteristic. The Dawson claim must be rolling in money, since Fred Dawson makes a lot from his practice.
False dilemma
“Either/or” fallacy or false dichotomy.
Assumes that we must choose one of two alternatives instead of allowing for other possibilities; a false form of disjunctive syllogism. America, love it or leave it.
Equivocation
This fallacy is a product of semantic ambiguity. The arguer uses the ambiguous nature of the word or phrase to shift the meaning in such a way as to make the reason offered appear more convincing.
Hasty generalization
A generalization accepted on the support of a sample that is too small or biased to warrant it. All men are rats! Just look at the louse they married.
Post hoc, ergo propter hoc
After this, therefore caused by this. A form of the false cause fallacy in which it is inferred that because one event followed another it is necessarily caused by that event. Mary joined our class and the next week we all did poorly on the quiz. It must be her fault.
Inconsistency
A discourse is inconsistent or self contradictory if it contains, explicitly or implicitly, two assertions that are logically incompatible with each other. Inconsistency can also occur between words and actions. A woman who represents herself as a feminist, yet doesn’t believe women should run for congress.
Non sequitur
It does not follow.
The premises have no direct relationship to the conclusion. This fallacy appears in political speeches and advertising with great frequency. A waterfall in the background and a beautiful girl in the foreground have nothing to do with an automobiles performance.
Questionable cause
Non causa pro causa
Not the cause of that.
Form of false cause fallacy occurs when the cause for an occurrence is identified on insufficient evidence. I can’t find the checkbook; I am sure that my husband hid it so I couldn’t go shopping today.
Red herring
Diversionary and important to recognize.
This fallacy introduces an irrelevant issue into a discussion as a diversionary tactic. It takes people off the issue at hand; it is beside the point. Many people say that engineers need more practice in writing, but I would like to remind them how difficult it is to master all the math and drawing skills that an engineer requires.
Slanting
A form of misinterpretation in which a true statement is made, but made in such a way as to suggest that something is not true or to give a false description through the manipulation of connotation. I can’t believe how much money is being poured into the space program (suggesting that ‘poured’ means heedless and unnecessary spending.
Straw man
This fallacy occurs when we misrepresent an opponent’s position to make it easier to attack, usually by distorting his or her views to ridiculous extremes. This can also take the form of attacking only the weak premises in an opposing argument while ignoring the strong ones. Those who favor gun control legislation just want to take all guns away from responsible citizens and put them into the hands of criminals.
Two wrongs make a right
When we try to justify an apparently wrong action by charges of a similar wrong. The underlying assumption is that if they do it, then we can do it too and are somehow justified. Supporters of apartheid are often guilty of this error in reasoning. They point to U.S. Practices of slavery to justify their system.
Far-fetched hypothesis
A fallacy of inductive reasoning that is committed when we accept a particular hypothesis when a more acceptable hypothesis, or one more strongly based in fact, is available. The African American church was set afire after the civil rights meeting last night; therefore, it must have been done by the leader and the minister to cast suspicion on the local segregationist.
