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Recognizing problems in reasoning.  An error in reasoning.  Fallacies may be applied intentionally or may show faulty logic or a weakness in an argument.

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Presentation on theme: "Recognizing problems in reasoning.  An error in reasoning.  Fallacies may be applied intentionally or may show faulty logic or a weakness in an argument."— Presentation transcript:

1 Recognizing problems in reasoning

2  An error in reasoning.  Fallacies may be applied intentionally or may show faulty logic or a weakness in an argument.

3  Recognizing fallacious arguments allows you to avoid falling into rhetorical traps and being convinced too easily.  Understanding how others construct arguments helps us to make informed choices about products, political candidates, leaders, even friends.  Understanding fallacies helps you to strategically employ them in your own rhetoric to argue more persuasively.

4  Formal—an argument that is deductively invalid.  Deductive reasoning –general to specific; theory- hypothesis-observation-confirmation  Informal—an argument that does not prove inductively probable.  Inductive reasoning—specific to general; observation-pattern recognition-hypothosis-theory

5  1 : a deductive scheme of a formal argument consisting of a major and a minor premise and a conclusion (as in “every virtue is laudable; kindness is a virtue; therefore kindness is laudable”) 2 : a subtle, specious, or crafty argument 3 : deductive reasoning ( Merriam- Webster’s Online Dictionary)  Valid: (1) All men are mortal. (2) Socrates is a man. Therefore: (3) Socrates is mortal.

6 Valid: (1) All men are mortal. (2) Socrates is a man. Therefore (3) Socrates is mortal. Invalid: 1) Some men are green. 2) Socrates is a man. Therefore 3) Socrates is green.

7 Examples  "How can you argue for vegetarianism when you wear leather shoes?“  "In order to maintain a civil debate, I will not mention my opponent's drinking problem.“  "If you weren't so stupid you would have no problem seeing my point of view."  “The advocates of this idea are the worst kind of sloppy thinkers. They are fanatical adherents who already have their minds made up.” Non-Examples  “Although I disagree with my opponent on abortion, I understand that she feels deeply about the issue and respect that.”  “My opponent’s drinking is irrelevant; what matters is that his view is incorrect.”  “He is certainly an intelligent man with well thought-out views, I just happen to hold very different views.

8  An attack on a person or that person’s character (ethos) rather than on the argument itself

9 Examples “Everyone is selfish; why should you feel guilty for seeking your own happiness when that's what everyone else is doing, too?” “Fifty million Elvis fans can’t be wrong!” “The majority of people like soda. Therefore, soda is good.” "Bill, I know you think that 1+1=2. But we don't accept that sort of thing in our group. “ Non-examples “If everyone else jumped off a bridge, would you do it, too?” “I don’t care how many records Elvis sold, I find his music boring.” “1+1=3? What a unique way of looking at it!”

10  Assumes that popularity or growing popularity of an idea proves the value of that idea

11 Examples " We must have a death penalty to discourage violent crime". "Active euthanasia is morally acceptable. It is a decent, ethical thing to help another human being escape suffering through death." "Why must you always take positions that are so unscientific?“ "My new method of conducting analysis is the most valid because it is the only one capable of such validity, the only one that has ever approached such validity, and the only one that is so completely valid.” Non-examples “Statistics show that in 45 % of cases, death row inmates have been wrongly convicted.” “My new method of analysis has proven accurate in 85 % of test cases—higher than any other known method.” “The method you used does not rely upon empirical data or facts—why did you choose that method?”

12  the truth of the conclusion is assumed by the premises  The name of this fallacy comes from the fact that the fallacious argument either; A) Does not truly answer the question posed or B) raises further questions which the arguer fails to answer  Also known as “circular reasoning”

13 Examples “You may think that he cheated on the test, but look at the poor little thing! How would he feel if you made him sit it again?” ”I know your car isn't working right. But, if you had gone to the store one day earlier, you'd not be having problems. “ “I know I forgot to deposit the check into the bank yesterday. But, nothing I do pleases you.” "I think there is great merit in making the requirements stricter for the graduate students. I recommend that you support it, too. After all, we are in a budget crisis and we do not want our salaries affected.“ Non-Examples “It seemed he cheated on the test— five other students claimed they saw him do it.” “I forgot to deposit the check yesterday because I had to work late and then my car broke down.” “We should make graduate requirements stricter to make sure students are adequately prepared for the real world.”

14  Derives name from fox hunting, specifically from the practice of using smoked herrings, which are red, to distract hounds from the scent of their quarry  Use of an irrelevant or unrelated argument to distract an audience or speaker

15 Examples  "My new sport psychology intervention works! I chose the player with the lowest batting average based on the last game from each of the teams in our amateur baseball league. Then I gave each of them my 5-minute intervention. And almost all of them improved their batting average in the next game!“  "President Johnson raised taxes, and then the rate of violent crime went up. Johnson is responsible for the rise in crime."  Grading this exam on a curve would be the most fair thing to do. After all, classes go more smoothly when the students and the professor are getting along well.“"  “Roosters crow just before the sun rises. Therefore, roosters crowing cause the sun to rise.” Non-examples I studied hard for three weeks before the final, so I passed it with an 88. “President Johnson raised taxes, so there were many anti-tax petitions and protests across the country.” “Grading the class on a curve would ensure that grades were distributed evenly, giving everyone a fair shot at assessment.”

16  From the Latin “post hoc, ergo propter hoc”, or “after this, therefore because of this”.  Assumes that because B occurs after A, A caused B.

17 Examples "Senator Johnson says that we should not fund the attack submarine program. I disagree entirely. I can't understand why he wants to leave us defenseless like that.“ "Those who believe in behavior modification obviously want to try to control everyone by subjecting them to rewards and punishments.“ “Senator Johnson’s opposition to the North American Free Trade Agreement amounts to nothing but opposition to free trade.“ “Al Gore's support of the discussion of sexual orientation issues on Ellen is dangerous: he advocates the exposure of children to sexually explicit materials, which is wrong.”

18  Attacking something that was never said nor directly implied; exaggerating the claims of an opponent to make the claims appear weaker.

19 Examples The lab rat wasn't killed, it was sacrificed. The death of innocent bystanders is collateral damage. The technical support specialist told me my computer has an issue since I can’t even turn it on. It’s not that I don’t believe in God, I am merely Skeptical of his existence. Non Examples “Let’s not mince words here—killing a rat in any situation is still killing.” “The technical support person told me there is a broken jack connecting the power supply to the motherboard.” “I am an agnostic—I am not sure if I o or do not believe in God.”

20  Definitions and examples adapted from:    nks/fallacies.pdf nks/fallacies.pdf   

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