LOGIC AND CRITICAL THINKING by Karey Perkins

1. LOGIC AND CRITICAL THINKINGby Karey Perkins

2. RHETORICAL APPEALS: USING LOGOS, ETHOS, PATHOS • LOGOS = LOGIC and REASON= Soundness of facts, evidence, statistics, and reasoning; soundness of authority’s statements outside self; well-documented evidence • ETHOS = Credibility and reliability of writer him/herself; character and reputation of the author • PATHOS= EMOTION = Appeal to needs, values, and attitudes; uses the emotional power of language

3. ?? ACME's new dihydro-cesium detonation process By combining cesium and dihydro-oxide in laboratory conditions, and capturing the released energy, ACME has promised to lead the way into the future. Our energy source is clean, safe, and powerful, according to laboratory tests. In 20 tests conducted over a period of 5 years, no pollutants were released into the atmosphere. The world will soon have an excellent source of clean energy. ACME is currently working toward a patent on our process. Our scientists are exploring ways to use the process in cars, houses, airplanes, and almost anything else that needs power. ACME batteries will be refitted with small dihydro-cesium reactors. Once the entire world is powered by ACME’s generators, we can all relax and enjoy a much easier life.

4. ?? Acme Gizmotronics, the company that you've trusted for over 100 years, has recently entered the World Wide Web! Now you can purchase our fine products through the Internet. Our quality gizmos, widgets, and thingamabobs can be shipped to you within minutes. All come with the famous lifetime guarantee that makes Acme the company that the world depends on for its gizmo needs.

5. ?? CESIUM-BASED REACTOR KILLS! A baby turtle breaks free from the leathery shell of its egg, catching its first glimpse of its first sunrise. It pauses a moment to rest, unaware of the danger that lies so close to it. As the tide comes in, approaching the nest, it also approaches a small pile of metal: cesium. The water draws closer and closer, the turtle unsuspecting of the danger. Finally, the water touches the cesium. The nest is torn to bits in the resulting explosion, destroying even more of an endangered species. Why does this happen? One name: Acme. (Examples from: The Art of Rhetoric: Learning How to Use the Three Main Rhetorical Styles. Available at: (http://www.rpi.edu/dept/llc/webclass/web/project1/group4/ ))

6. SUCCESSFUL ARGUMENTSpersuade the reader by means of: • Clear premises and conclusions • Evidence, not unsupported claims and appeals to emotions • Consideration of the other side • Consideration of audience to whom argument is given • Use appropriate tone and diction • Avoidance of logical fallacies

7. Argument: The Toulmin Model • Claim: Main point or central message; thesis statement • Support: Data, evidence, reasons, details • Warrant: Underlying assumptions implied but not stated. Reader infers assumptions. Warrants are based on: • Authority: respect for credibility and trustworthiness of source • Substance: reliability of facts and evidence • Motivation: values and beliefs of audience and writer

8. EVALUATING EVIDENCEIN AN ARGUMENT • Is the evidence: • SUFFICIENT • REPRESENTATIVE • RELEVANT • ACCURATE • FAIR AND BALANCED

9. Impediments to Logic, Good Reasoning, and Critical Thinking • LOYALTY – loyalty to our own community or group; see its beliefs as more favorable than others • PROVINCIALISM – narrowing our view to identify with ideas and interests of only our own group • THE HERD INSTINCT – keeping our beliefs and actions within society’s (or our community’s) boundaries • BACKGROUND BELIEFS • PREJUDICE AND STEREOTYPING • SCAPEGOATING – problems blamed on a person/group • PARTISAN MINDSET – “us” vs. “them” • SUPERSTITIOUS BELIEFS • WISHFUL THINKING AND SELF-DECEPTION • RATIONALIZATION – ignore evidence to justify actions • SUPPRESSION – avoiding the anxiety of stressful thoughts • DENIAL – change our view of the facts of the situation to be more positive in spite of evidence • LACK OF A SENSE OF BALANCE OR PRUDENCE

10. Inductive and Deductive Reasoning • Inductive Reasoning: • Reasons from specific to general • Notices many facts and comes to a general conclusion • No certainty possible • Deductive Reasoning: • Reasons from general to specific • Starts with a hypothesis and inserts a fact and comes to a conclusion based on hypothesis • Certainty can be possible if valid and true syllogism (say some people)

11. INDUCTIVE REASONING • Reasoning from sensory observation of specific facts/evidence to general conclusion • With inductive reasoning, there can NEVER be certainty, because only ONE example can modify or refute the conclusion. (This example can come from any future event, or events in remote places and times we are not able to observe.) • Based on an accumulation of many facts (one fact = “x”): • Observation of: x xxxxxxxxxxxxxxxxxxxxxxx Equals General Statement about X’s in future

12. Examples of inductive reasoning • If I jump off the building, I will fall to the ground. (More specifically: Every time something with weight and mass is released from any height, it falls to the ground. Therefore, all things fall to the ground (law of gravity). • Based on an evaluation and observation of multiple studies of adolescents who value peers more than parents, Judith Rich Harris concludes that peers matter more than parents in this age group. • Whenever it snows or rains, it will eventually stop snowing or raining. • George Bush, Sr. made promises during his 1988 campaign he didn’t keep. Bill Clinton made promises during his 1992 and 1996 campaigns that he didn’t keep. George Bush (Jr.) made promises in his 2000 and 2004 campaigns that he didn’t keep. Therefore, the next president in 2008 will make promises in his campaign that he very likely will not keep. • So far all U.S. presidents have been male. Therefore, the next U.S. president will be male.

13. Faulty Inductive Reasoning • Today I saw an 80 year old lady driving 40 miles an hour on 285, a 95 year old man going 50 mph on 400, and a 70 year old guy going 20 mph on Haynes Bridge Road. Conclusion: Old people drive slow. (This is a “stereotype,” or logical fallacy of inductive origin.) • Jesse Helms said in the Mexican Foreign Affairs Subcommittee (to prevent immigration from Mexico): “All Latins are volatile.” (This is a “stereotype,” or logical fallacy of inductive origin.)

14. Deductive Reasoning • Reasoning from general tenets and premises to specific conclusions. • With deductive reasoning, there CAN be certainty. • Syllogisms follow this format: • Major Premise (general truth about life/humans) • Minor Premise (specific fact that falls under the truth) • Conclusion (a conclusion that can be drawn about the specific fact based on the first generalization)

15. Syllogism Examples Correct Syllogism: • Major Premise: All mammals are warm-blooded animals. • Minor Premise: No lizards are warm-blooded animals. • Conclusion: Therefore, no lizards are mammals. Correct Syllogism: • Major Premise: All humans are mortal. • Minor Premise: All Greeks are human. • Conclusion: Therefore, all Greeks are mortal. Descartes’ Syllogism (correct) • Major Premise: Existence has be true if one is thinking. • Minor Premise: I am thinking. • Conclusion: I think, therefore, I am.

16. Syllogisms can be • Valid or Invalid (reasoning in incorrect order) AND • True or False (reasoning from a faulty major premise)

17. Examples of Faulty Syllogisms FALSE Syllogism (not TRUE -- false major premise) • Major Premise: Blondes have more fun • Minor Premise: Mary is blonde, Jane is brunette • Conclusion: Mary has more fun than Jane. INVALID Syllogism (not VALID – order of reasoning is incorrect): • Major Premise: All dogs eat meat • Minor Premise: Bob (a human) eats meat • Conclusion: Bob is a dog.

18. Corrections Syllogism One: The first faulty syllogism proceeds from a FALSE major premise and therefore can be thrown out entirely. Syllogism Two: • Major Premise: All dogs eat meat • Minor Premise: Rover is a dog. • Conclusion: Therefore, Rover eats meat.

19. Valid or invalid? True or False? Example One: • Major Premise: When it snows the streets get wet. • Minor Premise: The streets are getting wet. • Conclusion: Therefore, it is snowing. Example Two: • Major Premise: If you buy a Ferrari, you will instantly be popular. • Minor Premise: Ed just bought a Ferrari. • Conclusion: Ed will achieve instant popularity. Example Three: • Major Premise: When the batter is dead, the car will not start. • Minor Premise: The car will not start. • Conclusion: Therefore, the battery is dead.

20. Corrections: Valid and True Example One: • Major Premise: When it snows the streets get wet. • Minor Premise: It is snowing. • Conclusion: Therefore the streets are getting one. Example Two: • Example Two proceeds from the beginning from a FALSE major premise (Ferraris give instant popularity) and therefore can be thrown out entirely. Example Three: • Major Premise: When the batter is dead, the car will not start. • Minor Premise: The battery is dead. • Conclusion: Therefore, the car will not start.

21. Some types of syllogisms • Modus Ponens • Modus Tollens • Hypothetical Syllogism • Disjunctive Syllogism

22. Modus Ponens • If A then B • A • Therefore, B Examples: • If it’s spring, then the birds are chirping • It’s spring. • The birds are chirping. • If a world government doesn’t evolve soon, then wars will continue to occur • A world government isn’t going to evolve soon. • Wars will continue to occur

23. Modus Tollens • If A then B • Not B • Not A Example: • If it’s spring then the birds are chirping • The birds aren’t chirping • Therefore, it isn’t spring.

24. Hypothetical Syllogism • If A then B • If B then C • If A then C Example: • If we successfully develop nuclear fusion power, then power will become plentiful and cheap. • If power becomes cheap and plentiful, then the economy will flourish. • If we successfully develop nuclear fusion power, then the economy will flourish.

25. Disjunctive Syllogism • A or B • Not A • B Example: • Either McCain won in 2008 or Obama did. • McCain didn’t win. • Obama did win.

26. LOGICAL FALLACIES • Circular Reasoning/Begging the Question: Promising support for your claim but providing none • Bandwagon/: Inviting readers to accept a claim because everyone else does or because the prestigious group does • Argument from authority: Inviting readers to accept a claim because because the claim is put forth by someone in a position of authority – though the authority is invalid. • Slippery Slope: forecasting a series of events (usually disastrous) that will befall one if the first stated step is taken. • Straw Man: Inserting a false or unrelated premise into an argument, and then proving the false or unrelated premise wrong as a claim that the initial argument is wrong. • Appeal to Fear:scaring the reader to your point of view • Appeal to Pity: substituting emotions for reasoning. • Appeal to Force: abandoning reason and using or threatening strong arm methods by means of the political or physical power of the enforcer; “might makes right”

27. Red Herring: introducing an irrelevant issue intended to distract readers from the relevant issues – going off on a tangent. • Self Contradiction: using two premises that can’t be simultaneously true • False Cause or “Post Hoc” Fallacy:(from Latin: post hoc, ergo propter hoc, meaning “after this, therefore because of this”): assuming that because A preceded B, then A must have caused B. • False Analogy: Assuming that because two things are alike in similar ways, they must be alike in other ways • Either/Or Fallacy (False Dilemma):assuming that a complicated question has only two answers—one good, and one bad, both good, or both bad. • Hasty Generalization: making a claim on the basis of inadequate evidence. Generalizing about something on the basis of too little evidence. • Stereotypingis a type of Hasty Generalization applied to a group of people. • Sweeping Generalization: making an insupportable statement, often using absolute statements such as all, always, never, and no one. • Ad Hominem:(attacking the man) attacking the qualities of the people holding an opposing view rather than the substance of the view itself.

28. Guilt by Association: kind of “ad hominem” attack implying that an individual’s arguments, ideas, or opinions lack merit because of that person’s activities, interests or associates. • Non Sequitur: (Latin: It does not follow): linking two or more ideas that in fact have no logical connection; the statement does not follow logically from what has just been said • Card Stacking/Special Pleading: Ignores evidence on the other side of the question; only selecting those items that will build the best (or worst) possible case. • Oversimplification/Reductive Fallacy: Oversimplifying (reducing) the relation between causes and effects • Quibbling: Nitpicking at insignificant or possible errors in someone else’s basically valid and sensible argument • Language Fallacies: • Emotional, biased, or slanted language • Equivocation • Ambiguity or obfuscation • Euphemism or PC, Doublespeak • Pretentious language, bureaucratic language • Jargon

29. What is logically wrong with the following statements? • The Bible is true because it says so. • Boxing is dangerous because it is an unsafe sport.

30. Circular Reasoning/Begging the Question • A. Therefore, A. • promising support/evidence/reasoning for your claim but providing none • Promising: Claim Support • Delivering: Claim (Support)

31. ?? • Billy Joe is honest; therefore, he will get a good job

32. Non Sequitur • (Latin for “It does not follow”): linking two or more ideas that in fact have no logical connection • Missing is the unstated assumption that “honest people get good jobs” which is not always true.

33. ?? • Bill Clinton smoked pot when he was in college; therefore, he should not be president of the United States. • Bill Clinton is a womanizer; therefore, he should not be president of the United States.

34. Ad Hominem“Attacking the Man” • Attacking the personal qualities of the people holding an opposing view rather than the substance of the view itself • In this case, Clinton may well be an excellent president and policy maker even though we may prefer not to have him as our husband.

35. ?? • John Kerry protested at the same anti-war rally as Hanoi Jane; therefore, he should not be elected president.

36. Guilt by Association • A kind of “ad hominem” attack implying that an individual’s arguments, ideas, or opinions lack merit because of that person’s activities, interests or associates

37. ?? • Professor Perkins, if I don’t make an “A” in your class I won’t get my HOPE scholarship next semester. • A plaintiff’s attorney brings his injured client, who is seeking compensatory damages, into the courtroom and plays up the injury in front of the jury (“A Civil Action”) • Socrates at his death trial: My friend, I am a man and like other men, a creature of flesh and blood, and not of “wood and stone” as Homer says; and I have a family, yes, and sons, O Athenians, three in number, one almost a man, and two others who are still young; and yet I will not bring any of them here to petition you for acquittal.

38. Appeal to Pity • Substituting emotions for reasoning; an appeal to emotion, in which the altruism and mercy of the audience are appealed to

39. ?? • “George Bush is the candidate that can stop another terrorist attack on the United States; if you vote for John Kerry, be prepared for another 9/11.” • When Lyndon Johnson was running for president, his team ran a commercial of a little girl in a field holding a daisy, then an atomic bomb went off in the background.

40. Appeal to Fear • Tries to scare the reader to your point of view

41. ?? • When Reagan’s attorney general was under media attack, Howard Baker, then White House Chief of Staff, said to his staff: The President continues to have confidence in the Attorney General and I have confidence in the Attorney General and you ought to have confidence in the Attorney General, because we work for the President and because that’s the way things are. If anyone has a different view of that, or any different motive, ambition or intention, he can tell me about it because we’re going to have to discuss your status. (“White House Orders Silence on Meese,” Washington Post, 29 April 1988, qtd. in Copi and Cohen)

42. Appeal to Force • Abandoning reason to convince someone of your point of view and instead using or threatening “strong arm” methods by means of the political or physical power of the enforcer; “might makes right”

43. ?? • Mom, I should be able to go to Underground Atlanta to see the free Weezer concert that lasts til 1 AM – all my friends’ moms are letting them go. • Despite the cost, impending gas crisis, and the harm to the environment, it is desirable to own an SUV because successful people do. • More people in America drink Budweiser than any other beer.

44. Bandwagon • Inviting readers to accept a claim because everyone else does or because a prestigious group does

45. ?? • Television commercials that advertise their product using famous stars, for example, Ray Charles advertising Coke. • Matt Damon should write a novel about the CIA since he was in The Bourne movie trilogy.

46. False Authority • Citing the opinion of an expert who has no real claim to expertise on the topic

47. ?? • You should go on the “Lose Weight Overnight” diet plan because Mary Braddock and Tom Jones lost 100 pounds total in three months on it.

48. Card StackingSpecial Pleading • Ignores evidence on the other side of the question • Only selecting those items that will build the best (or worst) possible case.

49. ?? • The new mayor took office last January and crime in the streets has already increased 25 percent. • A new weather satellite was launched last week and it has been raining ever since. • After that black cat crossed my path this morning, I got into a car accident. That cat was bad luck.

50. Post Hoc FallacyFalse Cause • (from Latin: post hoc, ergo propter hoc, meaning “after this, therefore because of this”): assuming that because A preceded B, then A must have caused B.