Presentation is loading. Please wait.

Presentation is loading. Please wait.

LOGICAL FALLACIES. What’s a logical fallacy and why should you care? It’s poor logic partly consisting of overgeneralizations and assumptions. The presence.

Similar presentations

Presentation on theme: "LOGICAL FALLACIES. What’s a logical fallacy and why should you care? It’s poor logic partly consisting of overgeneralizations and assumptions. The presence."— Presentation transcript:


2 What’s a logical fallacy and why should you care? It’s poor logic partly consisting of overgeneralizations and assumptions. The presence of logical fallacies may weaken a writing project. When you’re developing an argument, your points should follow in logical order and make proper conclusions. When you’re refuting a counterargument (procatalepsis), it’s useful to point out logical fallacies as weak points in your opponent’s argument.

3 Fallacies can refer to… a kind of error in an argument, a kind of error in reasoning (including arguments, definitions, explanations, and so forth), a false belief, or the cause of any of the previous errors, including what are normally referred to as "rhetorical techniques".

4 Why learn logical fallacies? To point them out when an opponent uses one or offer reasoning if you use them. Make you look smart. Impress judges. To remove an argument from the table, not just weaken it. To know when you are using them and prepare for your opponent’s argument, rather than being taken off guard.

5 How do you point them out? State the name of fallacy in Latin and English, making sure to use the phrase “logical fallacy.” Explain what the fallacy means and why it is wrong, but do it without sounding pedantic ~ smarter than everyone else. Give a really obvious example of why the fallacy is incorrect, preferably an unfavorable analogy for your opponent’s case. Point out why the fallacy matters.

6 Common Fallacies

7 Argumentun Ad Antiquitatem The argument to antiquity or tradition. Argument that a policy, behavior or practice is right or acceptable because “its always been done that way”. Ex: “Every great civilization in history has provided states subsidies for art and culture.” Try to avoid it; if you do use it, give a reason why it should be considered.

8 Argumentum Ad Hominem Argument directed at the person. Attacking the character or motives of a person who has stated an idea rather than the idea itself; can also be an attack on the source of information. Ex: Richard Nixon was liar and a cheat. Also occurs when the person has something to gain from the policy. Ex: Bill Gates talking against antitrust legislation

9 Argumentum Ad Ignorantiam Argument to ignorance. Assuming something is true simply because it hasn’t been proven false. Example: Global warming is true because nobody has demonstrated conclusively it is not. Whomever has “burden of proof” (usually affirmative) has to be careful in using this fallacy. Ex: Prosecution who says that no alibi means guilty vs. defense saying prosecution didn’t prove case so defendant is not guilty.

10 Argument Ad Logicam Argument to logic. Assuming that something is false simply because proof that someone has offered for it is invalid. AKA Straw Man Argument. Burden of proof determines whether it is fallacy or not. Ex: If affirmative team fails to provide sufficient support for its case, the burden of proof dictates they lose the debate even if there exists other arguments not presented that could have supported the case.

11 Argumentum Ad Misericordian Appeal to pity. Ex: Think of all the poor, starving people in Ethiopia. How can we not help them? This doesn’t mean you can’t argue for something like aid to Ethiopia, but it does mean that you can’t just use emotional pleas.

12 Argumentum Ad Nauseam Argument to the point of disgust or repetition. Trying to prove something by saying it again and again. Stating a main point over and over again instead of real arguments. Make sure you SUPPORT your main points.

13 Argumentum Ad Numerum Argument to numbers. Attempt to prove something by showing how many people think that it’s true. Ex: 70% of all Americans support restrictions on access to abortions.

14 Argumentum Ad Populum Appeal to people or to popularity. Trying to prove something by showing that the public agrees with you. Narrowly designates an appeal to the opinions of people in the audience. Ex: You should turn to Channel 8. It's the most watched channel this year.

15 Argumentum Ad Verecundiam Argument to authority. Someone tries to demonstrate the truth of a proposition by citing some person who agrees, even though that person may have no expertise in the given area. Ex: Quoting Einstein on politics.

16 Circulus In Demonstrando Circular argument. Someone uses what they are trying to prove as part of the proof of that thing. Always illegitimate but hard to spot. Ex: A couch is a sofa. A sofa is a davenport. A davenport is a couch.

17 Complex Question Question that implicitly assumes something to be true by its construction. Ex: The majority of black Americans live in poverty, but do you really think that self-help within the black community is sufficient to address their problems? Only a fallacy when used for something that hasn’t been proven.

18 Cum Hoc Ergo Propter Hoc With this, therefore because of this. Usually called cum hoc. Mistaking correlation for causation - because two things occur simultaneously, one must be a cause of the other. Ex: Gypsies live near our low-yield cornfields. Therefore, gypsies are causing the low yield.

19 Dicto Simpliciter Sweeping generalization. Making a sweeping statement and expecting it to be true of every specific case; stereotyping. Example: Women on average are not as strong as men and less able to carry a gun; therefore, women can’t pull their weight in a military unit.

20 Either – Or / False Dilemma Asserts that a complex situation can have only two possible outcomes and that one of the options is necessary or preferable. Ex: Either go to college or forget about making money.

21 False Analogy An analogy points out similarities in things that are otherwise different. A false analogy claims comparison when differences outweigh similarities. Essentially, it’s comparing apples and oranges!

22 Nature, appeal to Assuming that whatever is natural or consistent with nature is good or that whatever conflicts with nature is bad. Fairly rare, but usually seen in environmentalist argument.

23 Non Sequitur It does not follow. Stating as a conclusion, something that does not strictly follow from the premises. Ex: Racism is wrong, therefore, we need affirmative action.

24 Petitio Principii Begging the question. Assuming, when trying to prove something, what it is that your are trying to prove. Very similar to circular argument. Occurs when a question has been asked before in the discussion, then a conclusion is reached on a related matter without the question having been answered. Ex: Person 1: He is mad right now. Person 2: How do you know? Person 1: Well, because he is really angry.

25 Post Hoc Ergo Propter Hoc After this, therefore because of this. Assuming that A caused B simply because A happened prior to B. Ex: Most rapists read pornography when they were teenagers; obviously, pornography causes violence toward women. Similar to cum hoc ergo prompter hoc.

26 Red Herring Introducing irrelevant facts or arguments to distract from the question at hand. Ex: The opposition claims that welfare dependency leads to higher crime rates; but, how are poor people supposed to keep a roof over their heads without our help? It is not fallacious to argue that benefits of one kind may justify incurring costs of another kind.

27 Reductio Ad Absurdum Useful in creating a comic effect. Assumes a claim for the sake of argument, derives an absurd or ridiculous outcome, and then concludes that the original assumption must have been wrong as it led to an absurd result.

28 Slippery Slope Not always a fallacy. Argument that says adopting one policy or taking one action will lead to a series of other policies or actions also being taken without showing a causal connection between the advocated policy and the consequent policies. Ex: If we legalize marijuana, the next thing you know we’ll legalize heroin, LSD and crack cocaine.

29 Tu Quoque You too. Defending an error in one’s reasoning by pointing out that one’s opponent has made the same error. Ex: They accuse us of making unjustified assertions, but they asserted a lot of things, too.

Download ppt "LOGICAL FALLACIES. What’s a logical fallacy and why should you care? It’s poor logic partly consisting of overgeneralizations and assumptions. The presence."

Similar presentations

Ads by Google