LOGIC AND CRITICAL THINKING逻辑和批判性思维(-67)

1、LOGIC AND CRITICAL THINKINGby Karey PerkinsRHETORICAL APPEALS: USING LOGOS, ETHOS, PATHOS LOGOS = LOGIC and REASON= Soundness of facts, evidence, statistics, and reasoning; soundness of authoritys statements outside self; well-documented evidenceETHOS = Credibility and reliability of writer him/hers

2、elf; character and reputation of the authorPATHOS = EMOTION = Appeal to needs, values, and attitudes; uses the emotional power of languageLOGOS: Reason, Facts ACMEs new dihydro-cesium detonation process By combining cesium and dihydro-oxide in laboratory conditions, and capturing the released energy

3、, 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 c

4、urrently 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 ACMEs generators, we ca

5、n all relax and enjoy a much easier life.ETHOS: Credibility of Source Acme Gizmotronics, the company that youve 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 shipp

6、ed 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. PATHOS: Emotional AppealsCESIUM-BASED REACTOR KILLS! A baby turtle breaks free from the leathery shell of its egg, catching its first glimpse of its first

7、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

8、 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: ( )Inductive and Deductive ReasoningInductive Reasoning: Reasons

9、from specific to generalNotices many facts and comes to a general conclusionNo certainty possibleDeductive Reasoning: Reasons from general to specificStarts with a hypothesis and inserts a fact and comes to a conclusion based on hypothesisCertainty can be possible if valid and true syllogism (say so

10、me people)INDUCTIVE REASONING Reasoning from sensory observation of specific facts/evidence to general conclusionWith 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 pla

11、ces and times we are not able to observe.)Based on an accumulation of many facts (one fact = “x”):Observation of:x x x x x x x x x x x x x x x x x x x x x x x xEqualsGeneral Statement about Xs in futureExamples of inductive reasoningIf I jump off the building, I will fall to the ground. (More specif

12、ically: 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 t

13、hat peers matter more than parents in this age group.Whenever it snows or rains, it will eventually stop snowing or raining.So far all U.S. presidents have been male. Therefore, the next U.S. president will be male.Faulty Inductive ReasoningToday I saw an 80 year old lady driving 40 miles an hour on

14、 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)

15、: “All Latins are volatile.” (This is a “stereotype,” or logical fallacy of inductive origin.)Deductive ReasoningReasoning 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/h

16、umans)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)Syllogism ExamplesCorrect Syllogism:Major Premise: All mammals are warm-blooded animals.Minor Premise: No lizards are warm-blooded animal

17、s.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.Co

18、nclusion: I think, therefore, I am.Syllogisms can beValid or Invalid (reasoning in incorrect order) ANDTrue or False (reasoning from a faulty major premise) Examples of Faulty SyllogismsFALSE Syllogism (not TRUE - false major premise)Major Premise: Blondes have more funMinor Premise: Mary is blonde;

19、 Jane is brunetteConclusion: Mary has more fun than Jane.INVALID Syllogism (not VALID order of reasoning is incorrect):Major Premise: All dogs eat meatMinor Premise: Bob (a human) eats meatConclusion: Bob is a dog.CorrectionsSyllogism One: The first faulty syllogism proceeds from a FALSE major premi

20、se and therefore can be thrown out entirely.Syllogism Two:Major Premise: All dogs eat meatMinor Premise: Rover is a dog.Conclusion: Therefore, Rover eats meat.Valid or invalid? True or False?Example One:Major Premise: When it snows the streets get wet.Minor Premise: The streets are getting wet.Concl

21、usion: 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 battery is dead, the car will not start.Minor Premise: The car w

22、ill not start.Conclusion: Therefore, the battery is dead.Corrections: Valid and TrueExample 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 pre

23、mise (Ferraris give instant popularity) and therefore can be thrown out entirely.Example Three:Major Premise: When the battery is dead, the car will not start.Minor Premise: The battery is dead.Conclusion: Therefore, the car will not start.Some types of syllogismsModus PonensModus TollensHypothetica

24、l SyllogismDisjunctive SyllogismModus PonensIf A then BATherefore, BExamples:If its spring, then the birds are chirpingIts spring.The birds are chirping.If a world government doesnt evolve soon, then wars will continue to occurA world government isnt going to evolve soon.Wars will continue to occurM

25、odus TollensIf A then BNot BNot AExample:If its spring then the birds are chirpingThe birds arent chirpingTherefore, it isnt spring.Hypothetical SyllogismIf A then BIf B then C If A then CExample:If we successfully develop nuclear fusion power, then power will become plentiful and cheap.If power bec

26、omes cheap and plentiful, then the economy will flourish.If we successfully develop nuclear fusion power, then the economy will flourish.Disjunctive SyllogismA or BNot ABExample:Either Romney won in 2012 or Obama did.Romney didnt win.Obama did win.LOGICAL FALLACIES TO AVOIDCircular Reasoning/Begging

27、 the Question: Promising support for your claim but providing noneBandwagon/: Inviting readers to accept a claim because everyone else does or because the prestigious group doesArgument from authority: Inviting readers to accept a claim because because the claim is put forth by someone in a position

28、 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 clai

29、m that the initial argument is wrong.Appeal to Fear: scaring the reader to your point of viewAppeal 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 ri

30、ght”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 cant be simultaneously trueAd Hominem: (attacking the man) attacking the qualities of the people holding an opposing view rather t

31、han the substance of the view itself.Guilt by Association: kind of “ad hominem” attack implying that an individuals arguments, ideas, or opinions lack merit because of that persons activities, interests or associatesFalse Cause or “Post Hoc” Fallacy: (from Latin: post hoc, ergo propter hoc, meaning

32、“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 waysEither/Or Fallacy (False Dilemma): assuming that a complicated question has only two answ

33、ersone 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. Stereotyping is a type of Hasty Generalization applied to a group of people.Sweeping Generalization: making an

34、insupportable statement, often using absolute statements such as all, always, never, and no one.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 saidCard Stacking/Special Plea

35、ding: 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 effectsQuibbling: Nitpicking at insignificant or possible errors in

36、someone elses basically valid and sensible argumentLanguage Fallacies:Emotional, biased, or slanted languageEquivocationAmbiguity or obfuscationEuphemism or PCDoublespeakPretentious languageBureaucratic languageJargonWhat is logically wrong with the following statements?The Bible is true because it

37、says so.Boxing is dangerous because it is an unsafe sport.Circular Reasoning/Begging the QuestionA. Therefore, A.promising support/evidence/reasoning for your claim but providing none Promising: ClaimSupport Delivering: Claim (Support)?Billy Joe is honest; therefore, he will get a good jobNon Sequit

38、ur(Latin for “It does not follow”): linking two or more ideas that in fact have no logical connectionMissing is the unstated assumption that “honest people get good jobs” which is not always true. ?That candidate smoked pot when he was in college; therefore, he should not be president of the United

39、States.That candidate had an affair; therefore, he should not be president of the United States.Ad Hominem“Attacking the Man”attacking the personal qualities of the people holding an opposing view rather than the substance of the view itselfIn this case, the candidate may well be an excellent presid

40、ent and policy maker even though we may prefer not to have him as our husband.?Jane is friends with Bob who was caught embezzling from the company; therefore, she should be fired.Guilt by AssociationA kind of “ad hominem” attack implying that an individuals arguments, ideas, or opinions lack merit b

41、ecause of that persons activities, interests or associates?Professor Perkins, if I dont make an “A” in your class I wont get my HOPE scholarship next semester.A plaintiffs attorney brings his injured client, who is seeking compensatory damages, into the courtroom and plays up the injury in front of

42、the jury (“A Civil Action”)Appeal to Pitysubstituting emotions for reasoning; an appeal to emotion, in which the altruism and mercy of the audience are appealed to?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 bom

43、b went off in the background. The Bush campaign ran a 2004 commercial showing images from 9/11. (It was immediately withdrawn due to the families of victims complaining).Appeal to FearTries to scare the reader to your point of view?Mom, I should be able to go to Underground Atlanta to see the free W

44、eezer 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; therefore, it must be the best bee

45、r and you should buy it.BandwagonInviting readers to accept a claim because everyone else does or because a prestigious group does?Television commercials that advertise their product using famous stars, for example, Ray Charles advertising Coke.Matt Damon should write an expose about the CIA since k

46、nows all about it; he was in the Bourne trilogy.False AuthorityCiting the opinion of an expert who has no real claim to expertise on the topic?You should go on the “Lose Weight Overnight” diet plan because Mary Smith and Tom Jones lost 100 pounds total in three months on it.Card StackingSpecial Plea

47、dingIgnores evidence on the other side of the questionOnly selecting those items that will build the best (or worst) possible case.?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

48、ever since.After that black cat crossed my path this morning, I got into a car accident. That cat was bad luck.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.?Banning

49、pesticides to improve the environment is as impractical and unfeasible as banning the automobile.Education cannot prepare men and women for marriage. Trying to educate them for marriage is like trying to teach them to swim without allowing them to go into the water. It cant be done.False Analogyusin

50、g a comparison in which two things are alike in one way to justify that they will be alike in another way. However, the similarities are irrelevant to the claim the analogy is intended to support. 1. Ais likeB.2. Bhas propertyP.3. Therefore,Ahas propertyP.?America: love it or leave it.We have only t

51、wo choices: ban nuclear weapons or destroy the earth.Either we go to war against Iran, or the United States will suffer another terrorist attack.Either/Or Fallacy and False DilemmaStating that only two alternatives exist when in fact there are more than two? Teenagers are reckless drivers America is

52、 the best place to live (stated by one who has rarely visited other countries)“All Latins are volatile people” Jesse Helms to the Mexican Foreign Affairs Subcommittee (to prevent immigration from Mexico)Hasty GeneralizationGeneralizing or making a claim on the basis of inadequate evidence.?Why spend

53、 money on solving the problem of global warming when we ought to be doing something about the terrorists?Red Herringintroducing an irrelevant issue intended to distract readers from the relevant issues going off on a tangent: 1. Topic A is under discussion. 2. Topic B is introduced under the guise o

54、f being relevant to topic A (when topic B is actually not relevant to topic A). 3. Topic A is abandoned.?If we make handguns illegal, the state will gain too much power and eventually put us all in concentration camps for the slightest infraction. If we legalize marijuana, eventually everyone will s

55、tart smoking it regularly (at 4:20) and then theyll want to go on to more kinds of drugs soon heroin will become legal and most of America will become heroin addicts.Slippery Slopeforecasting a series of events (usually disastrous) that will befall one if the first stated step is taken?Only when nuc

56、lear weapons have finally destroyed us will we be convinced of the need to control them.Self Contradictionusing two premises that cant be simultaneously true?After Will said that we should put more money into health and education, Warren responded by saying that he was surprised that Will hates our

57、country so much that he wants to leave it defenseless by cutting military spending.Straw ManInserting 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:PersonA haspositionX.PersonB presentspositionY (whi

58、ch is a distorted or completed unrelated version of X).PersonB attackspositionY.Therefore X is false/incorrect/flawed.?“I am firm, you are stubborn, he is pigheaded.” Bertrand Russell “Friendly fire” military term for killing your own team by mistake“Collateral damage” military term for people who a

59、re inadvertently killed or property inadvertently destroyed in warfareLanguage FallaciesEmotional or biased languageEquivocationAmbiguity or obfuscationEuphemism or PC languageDoublespeakPretentious languageBureaucratic languageJargonImpediments to Logic, Good Reasoning, and Critical ThinkingLOYALTY

60、 loyalty to our own community or group; see its beliefs as more favorable than othersPROVINCIALISM narrowing our view to identify with ideas and interests ofonly our own groupTHE HERD INSTINCT keeping our beliefs and actions within societys (or our communitys) boundariesBACKGROUND BELIEFSPREJUDICE A