Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 errare humanum est (to err is human). FALLACIES.

Similar presentations

Presentation on theme: "1 errare humanum est (to err is human). FALLACIES."— Presentation transcript:

1 1 errare humanum est (to err is human)



4 4 INDUCTION (S  G) think “increase” (induction, increase) from specific/particular instance or instances to generalization quantity: (#) sufficient # of items or people asked, sufficient data (stats) quality: reliable source (authority), accurate & in-depth observation *PROBABILITY, not certainty*

5 5 INDUCTION BAD EXAMPLE: You compare the prices of 4 textbooks at store #1 with those at store #2 and notice that the prices are higher at the former than at the latter. You conclude that store #1 is more expensive.

6 6 INDUCTION GOOD EXAMPLE: A television documentary focuses on the issue of unwed teenage mothers in a particular city neighborhood. Four girls are interviewed and followed for several days. Then, a noted and respected sociologist who has studied thousands of unwed teenagers is interviewed, and she claims these four girls are representative of the many.

7 7 INDUCTION *INDUCTIVE FALLACIES: wrong use of data— –insufficient sample (not enough people interviewed) –ignore evidence (other possibilities)

8 8 DEDUCTION (G  S) think “decrease” (deduction, decrease) from inductive generalization to conclusion

9 9 DEDUCTION 3 Propositions of a Deductive Syllogism 1) MAJOR PREMISE: –inductive generalization –“All” –All humans are mortal. *(“syllogism”: Greek, to calculate using logic)*

10 10 DEDUCTION 3 Propositions of a Deductive Syllogism 2) MINOR PREMISE: –statement about a specific member of that group –“This” –My English professor is a human.

11 11 DEDUCTION 3 Propositions of a Deductive Syllogism 3) CONCLUSION: –Major Premise + Minor Premise = Conclusion = 3 S  G, G  S –“Therefore” –Therefore, my English professor is mortal.

12 12 DEDUCTION If the MAJOR premise = absent or faulty induction, if the MINOR premise = faulty observation concerning the individual at issue, then conclusion = faulty, invalid. HOWEVER, if the opposite is true, then the conclusion is a valid, strong one — stronger than induction. *CERTAINTY, validity, truth*

13 13 DEDUCTION *BAD EXAMPLE: A man is sitting opposite you on a train. He has what appears to be chalk dust on his fingers, and you conclude that he is a teacher.

14 14 DEDUCTION *BAD EXAMPLE: Major premise = “All men with chalk on their fingers are school teachers.” Minor premise = “This man has chalk on his fingers.” Conclusion = “Therefore, this man is a school teacher.”

15 15 DEDUCTION *BAD EXAMPLE: Faulty Conclusion: –other occupations: draftsmen, carpenters, tailors, artists –other powders: flour, confectioner’s sugar, talcum, heroin

16 16 DEDUCTION *DEDUCTION & your INTRODUCTORY PARAGRAPH “Funnel Effect,” “Inverted pyramid” G  S, syllogism, conclusion of syllogism = thesis statement Major premise = “Reducing awareness of social differences is a desirable goal for the school.” Minor premise = “A uniform dress code would help to achieve that goal.” Conclusion/thesis = “Therefore, students should be required to dress uniformly.”

17 17 DEDUCTION *DEDUCTIVE FALLACIES: failure to follow the logic of a series of statements an error in one premise or both premises other possibilities exist that were not taken into consideration reliance upon support other than facts


19 19 FACTS vs. OTHERS 1) FACTS: provable, verifiable * probable primary evidence: –senses –science secondary evidence: –testimony = secondary (beliefs, ideas not from senses) –historical evidence (documents, testimony, articles)

20 20 FACTS vs. OTHERS 2) IMPLICATIONS: unspoken message suggestion with indirect words * SUBTEXTS * Rhetorical Questions, Mincing Words

21 21 FACTS vs. OTHERS 3) ASSUMPTIONS: supposition idea taken for granted based on prior knowledge based on little knowledge

22 22 FACTS vs. OTHERS 4) INFERENCES: logical deduction based on evidence or observation educated guess

23 23 FACTS vs. OTHERS ASSUMPTION vs. INFERENCE: –assumption = based on belief –inference = based on sense data or premises IMPLICATION vs. INFERENCE: –implication = made by the speaker –inference = made by the listener

24 24 FACTS vs. OTHERS *Implications, Assumptions, Inferences: not = facts you fill in the gaps you make connections you supply missing data you draw conclusion without all of the information/facts

25 25 OCCAM’S RAZOR *RULE OF SIMPLICITY: (in textbook) When there are competing possibilities, choose the answer that requires the fewest assumptions. “Cut” through the obfuscation (BS) and choose the solution that would not appear on The X-files. *The simplest solution is often the best.



28 28 INSUFFICIENT EVIDENCE FAULTY INDUCTION: Inductive Fallacies –quantity: not enough evidence upon which to draw a reasonable conclusion –quality: unreliable data or sources bad Ethos implications, assumptions, inferences (not facts) FAULTY DEDUCTION: Deductive Fallacies –flawed Major Premise (generalization) –flawed Minor Premise (specific, observation)

29 29 INSUFFICIENT EVIDENCE 1) OVERGENERALIZATIONS: hasty, false, sweeping generalizations dicto simpliciter (spoken simply) implies ALL uses INDEFINITE PRONOUNS: –all, everyone, everybody –no one, nothing –everything, anything, always

30 30 INSUFFICIENT EVIDENCE 1) OVERGENERALIZATIONS: EASILY DISPROVED: too many exceptions and too many complications (life = too complex) QUALIFY WITH: –many, some, few –usually, often, in my experience DANGER with qualifying: too many maybe’s in your writing may make you look indecisive

31 31 INSUFFICIENT EVIDENCE *EXAMPLES of OVERGENERALIZATIONS: *stereotypes, prejudices, superstitions: –racism, ageism, sexism –“Teenagers today are fat and lazy.” –“Men don’t cry.” Hasty generalization: “Jim Bakker was an insincere Christian. Therefore, all Christians are insincere.” Sweeping generalization: “Christians generally dislike atheists. You are a Christian, so you must dislike atheists.” (senior citizens, Asians, guys, Americans = materialistic, war-mongers )

32 32 INSUFFICIENT EVIDENCE 2) STACKING the DECK (a.k.a. “card stacking”): poker metaphor: –d–dealing yourself a good hand; –s–stacking the card deck in your favor selecting only the data that supports your position ignoring contradictory data –(–(only 1 side of the issue) –(–(*needs other side/s of the issue) news bias, politicians, tobacco/oil industries fraudulent, misleading

33 33 INSUFFICIENT EVIDENCE *EXAMPLES of CARD STACKING: “Ninety-five percent of the people I interviewed agreed with the Democratic Opposition.” BUT I only interviewed people at the Democratic National Convention! “According to a Left-Wing Nut magazine poll, the Vice President has a low approval rating.” BUT only those people who read—i.e., agree with the ideology of—this publication were polled.

34 34 INSUFFICIENT EVIDENCE 3) AD IGNORANTIUM: since cannot disprove (or prove), then must be true assumes a lack of information (“ignorance”) is a source of information (*needs more info) yet, an absence of evidence is not evidence

35 35 INSUFFICIENT EVIDENCE CARD STACKING vs. AD IGNORANTIUM: –Don’t be fooled by the “ignoring” part – CS: purposefully ignores existing evidence  data that will disprove or weaken that side  the data does exist but is ignored AI: uses ignorance as evidence  uses the lack of existing evidence as evidence  the lack of evidence = the proof  the data does not exist

36 36 INSUFFICIENT EVIDENCE *EXAMPLES of AD IGNORANTIUM: “Since the library has no books on Eva Braun’s intimate relations with Adolf Hitler, then she must not have had any.” “Of course the Bible is true. Nobody can prove otherwise.” “Of course telepathy and other psychic phenomena do not exist. Nobody has shown any proof that they are real.” (aliens, ghosts)

37 37 INSUFFICIENT EVIDENCE 4) POST HOC ERGO PROPTER HOC: “after this, therefore b/c of this” assumes a causal relationship; –no other explanations –faulty Cause-Effect relationship assumes a later event was caused by an earlier one –simply because of chronology –*needs more info, more research B follows A; therefore, A causes B

38 38 INSUFFICIENT EVIDENCE DISPROVE with: (more information) –prove A and B are merely coincidences –show how A is merely 1 cause of many –show how A is not even a significant cause of the many *more than 1 cause of an effect, more than 1 effect of a cause indirect and direct causes complexity of life, of situations –OCCAM’S RAZOR: simpler, more credible answer or explanation is best


40 40 INSUFFICIENT EVIDENCE *EXAMPLES of P.H.E.P.H.: superstitions, astrology Consider additional causes for the following: “Because you left the milk out last night, it was spoiled this morning.” “The Soviet Union collapsed after instituting state atheism. Therefore, we must avoid atheism for the same reasons.” “A rooster crows every morning, and shortly after, the sun rises. Therefore, the rooster causes the sun to rise.”

41 41 INSUFFICIENT EVIDENCE *EXAMPLE of P.H.E.P.H.: “After the school principal suspends daily prayers in the classroom, acts of vandalism increase, and some parents are convinced that the failure to conduct prayer is responsible for the rise in vandalism.” But…decline in disciplinary actions, a relaxation of academic standards, a change in school administration, changes in family structure in the school community.

42 42 INSUFFICIENT EVIDENCE Post hoc ergo propter hoc: after this (subsequency), therefore because of this Cum hoc ergo propter hoc: with this (synchronicity), therefore because of this –mistakes a correlation for causation –overlooks coincidence, others causes –because of simultaneous occurrence –“Clinton had great economic policies because the economy was great during his two terms.”

43 43 INSUFFICIENT EVIDENCE 5) AD HOC: “for this (specific purpose)” – “impromptu, provisional” an after-the-fact explanation does not apply to other situations (for this special case alone) “God cured me of my cancer.” “But most patients with brain cancer die. Why did She save you? Are you special? Does She love you more than the rest of us?” “She moves in mysterious ways.” –because God treats all people equally, no special treatment –refuted by more evidence (radiation, medication, remission) –see also God & war, God & sports 1 time only!

44 44 INSUFFICIENT EVIDENCE 6) The Natural Law Fallacy -- Appeal to NATURE: draws a false analogy between the human and natural worlds assumes that humans are part of the natural world (animals) and should thus mimic “animalistic” behavior assumes that whatever is “natural” or consistent with “nature” is good AND that whatever is “unnatural” is bad –supplements, herbal remedies –“law of the jungle” arguments for genocide, capitalism –“Homosexuality is natural because monkeys have been observed engaging in homosexual behavior.” (or the opposite)

45 45 INSUFFICIENT EVIDENCE 6) The Natural Law Fallacy -- Appeal to NATURE: BUT –“natural” and “nature” = poorly defined –just because animals do it (or don’t) does not mean humans should (or shouldn’t) do so automatically, necessarily, unquestionably –naïve environmentalism –poison ivy, Ebola, climate, eat their young, eat bugs –bathrooms, plumbing, fire, literature, clothes, utensils


47 47 IRRELEVANT INFORMATION DIVERSIONARY TACTICS They introduce ideas that are off-topic. Their data is NOT germane to the present case. Diversions, Distractions from the argument at hand

48 48 IRRELEVANT INFORMATION 1) AD BACULUM: intimidation threat of harm: –physical or psychological * –economical, political, environmental extortion, blackmail –Rather than make a claim, point, or counter-argument, I make a threat, which isn’t discussing the issue at hand. –Because my evidence is rather weak, I try to win the argument with a “scare tactic.”

49 49 IRRELEVANT INFORMATION *EXAMPLES of AD BACULUM: “If citizens don’t start patronizing downtown stores, then businesses will be forced to close and then the city will be in ruin.” “If you don’t (believe in God, convert to our religion, illegalize that practice), then you’ll burn in Hell! “... In any case, I know your phone number and I know where you live. Have I mentioned I am licensed to carry concealed weapons?” “If we make abortions illegal, women will be getting butchered again in back alleys.” (ad misericordiam, slippery slope)

50 50 IRRELEVANT INFORMATION 2) AD HOMINEM: *name calling (think hombre, hommé) personal attack, insults attack the person, not the facts or issue a way to avoid dealing with the issue (*diversion)

51 51 IRRELEVANT INFORMATION *PLEASE NOTE* A bad person does not necessarily mean a bad argument (conclusion, point). –(even a broken clock…) Accusations against the person are NOT a fallacy IF the characteristics under attack are relevant to the argument. –For example, if a politician is irresponsible & dishonest in her/his personal life, then it is reasonable to think that s/he may be the same in public office.

52 52 IRRELEVANT INFORMATION *EXAMPLES of AD HOMINEM: “What does he know; look at the way he’s dressed.” “What can a priest tell us about marriage since he’s never been married himself.” (AA) “My doctor is overweight, so why should I listen to anything he has to say.” (Dr. Adkins) “I won’t see a Jayne Smith movie because she’s a drug addict.” (private life vs. professional record) “Since you don’t support gay marriages, you must be a homophobe.” (racist, sexist)

53 53 IRRELEVANT INFORMATION *EXAMPLES of AD HOMINEM: “You claim that atheists can be moral — yet I happen to know that you abandoned your wife and children.” “Hitler would be very proud of you” (in response to practically any conclusion or decision). “Therefore, it is perfectly acceptable to kill animals for food. I hope you won’t argue otherwise, given that you're quite happy to wear leather shoes.” “Of course you’d argue that positive discrimination is a bad thing. You’re white.”

54 54 IRRELEVANT INFORMATION 3) FALLACY of OPPOSITION: *name calling whatever comes from the opposition is automatically wrong AND detrimental assumes nothing good could come from those we oppose Us vs. Them EXAMPLE: “Of course you’d say that, you’re an atheist, hippie, teenager, Democrat ….” (a member of the opposing group)

55 55 IRRELEVANT INFORMATION 4) GENETIC FALLACY: *name calling assumes where the idea came from affects its validity (country, paper, school) akin to elitism, snobbery we come from our genes, –genes  genetic fallacy

56 56 IRRELEVANT INFORMATION 4) GENETIC FALLACY: *EXAMPLES: “The quality of those products is poor because they come from China (any country).” “Cars made in the USA (any country) are junks.” “Because that idea comes from a community college it must be flawed, erroneous, or just plain wrong.”

57 57 IRRELEVANT INFORMATION 5) GUILT by ASSOCIATION: birds of a feather stick together assumes a person’s behaviors must extend to their friends, to those around them *EXAMPLES: “Everyone who goes into a bar is an alcoholic.” “Sally’s promiscuous, so as her friend you must be, too.”

58 58 IRRELEVANT INFORMATION 6) AD MISERICORDIAM: an abuse of pity manipulation & obfuscation (*diversion) irrelevant –evoke pitiful image or situation, without basis, to distract from the issue relies wholly on pity (pathos)

59 59 IRRELEVANT INFORMATION *EXAMPLES of AD MISERICORDIAM: photos of kids: war, famine, AIDS, disaster “I couldn’t write my paper because my son, daughter, mother, girlfriend, neighbor down the street was sick.” “I did not murder my mother and father with an axe! Please don’t find me guilty; I’m suffering enough through being an orphan.”

60 60 IRRELEVANT INFORMATION 7) AD POPULUM: appeals to the “populace” biases & prejudices, appeals to tradition, halcyon days tells people what they want to hear, what they want to believe (“working the audience”) SLOGANS and SOUND BITES subvert the reasoning process because they do not define terms –which can mean whatever people want them to mean or –whatever people say they mean what exactly are “family values”?!

61 61 IRRELEVANT INFORMATION *EXAMPLES of AD POPULUM: sound bites, slogans, bumper stickers, tee shirts appeals to patriotism, change for change’s sake political cartoons, late-night-TV monologues or punch lines, Comedy Central shows if it appears on poster, tee shirt, bumper sticker “If guns are outlawed, then only outlaws will have guns.” “Zippo. It’s the grand old lighter that’s made right here in the good ol’ USA.…” (patriotism) “Freedom isn’t free.” “No blood for oil.” “Guns don’t kill people; people kill people.” “Just say no.”

62 62 IRRELEVANT INFORMATION 8) BANDWAGON: Argumentum ad numerum right/valid because popular jump on the bandwagon, join the parade do because others do: peer pressure, group/mob identity, conformity appeals or refers to NUMBERS BUT you can be correct even if no one else agrees with you (Copernicus, Columbus)

63 63 IRRELEVANT INFORMATION *EXAMPLES of BANDWAGON: “Sixty million people can’t be wrong.” “Over 5 million Americans have already switched to Grizzly Insurance.” “Last December, over 100 million people worldwide tuned in to see a television phenomenon: don’t be left out when Knucklehead TV returns in March.” “Everybody’s doing it anyway, so we might as well legalize it (lower the age).” #

64 64 IRRELEVANT INFORMATION *Similar to: Argumentum ad numerum AND to Argumentum ad populum. It consists of asserting that the more people who support or believe a proposition, the more likely it is that that proposition is correct. For example: –“The vast majority of people in this country believe that capital punishment has a noticeable deterrent effect. To suggest that it doesn’t in the face of so much evidence is ridiculous.” Or “All I'm saying is that thousands of people believe in pyramid power, so there must be something to it.” *Similar to: Appeal to Tradition: right/valid because it’s old; since it’s lasted this long, it should continue. ex: “Since the Fiesta Club has been an exclusive male-only society since its founding at the turn of the 20 th century, it should continue to exist in the same manner & form.”

65 65 IRRELEVANT INFORMATION 9) PLAIN FOLKS and SNOB APPEAL: right because popular –opposite of the Genetic Fallacy These are 2 different fallacies, but same “coin.” Plain Folks Appeal: do because the ordinary person does (& avoid the pretensions of snobs) Snob Appeal: do because rich/popular/beautiful do (*celebrity endorsements)

66 66 IRRELEVANT INFORMATION *EXAMPLES of PLAIN FOLKS & SNOB APPEAL: “Why pay fancy salon prices for a shampoo?” “Family values will return America to world prominence.” “Mark Twain said, ‘The clothes make the man. Naked people have little or no influence on society.’ So, if you want to be a winner, you’ve got to look like a winner, which means you need a Rolex watch, Italian shoes, and a Lexus to be successful.” “Use the deodorant that professional athletes like Illiterate Joe use.” (appeals to reader’s vanity) Think of 2 diametrically opposed musical genres. also known as: Argumentum ad lazarum: The fallacy of assuming that someone poor is sounder or more virtuous than someone who's wealthier. This fallacy is the opposite of the Argumentum ad Crumenam. For example: “Monks are more likely to possess insight into the meaning of life, as they have given up the distractions of wealth.”

67 67 IRRELEVANT INFORMATION 10) AD VERECUNDIAM: inappropriate use of authority assumes because a person is an expert in one field that s/he is an expert in another (*celebrity endorsements) OR the use of an obscure, hard to find source poor or irrelevant credentials, wrong field of expertise, no Other Side of the issue (Rogerian Method) *BAD ETHOS*

68 68 IRRELEVANT INFORMATION *EXAMPLES of AD VERECUNDIAM: Bad: “I play a doctor on TV, so take this new OTC pill.” “Isaac Newton was a genius and he believed in God, so you should, too.” “Dr. Housenick claims stem cell research for the development of cures for various diseases is (is not) a worthy venture.” “Because my parents were unavailable, I asked my English teacher for permission to stay out late.” Good: “Dr. Stephen Hawking has concluded that black holes give off radiation; therefore, there is a strong chance that they exist.”

69 69 IRRELEVANT INFORMATION 11) RED HERRING: *diversion skirt the issue; obfuscate the truth use an irrelevant point or a side issue to lead away from the issue at hand

70 70 IRRELEVANT INFORMATION *EXAMPLES of RED HERRING: “Sure, the Chargers had a bad year, but what about the Redskins.” “While it may be true that we withheld vital information from the public regarding the dangerous side effects of our products, while it may be true that we sought ways to enhance our products with addictive substances, and while it may be true that we profited immensely from all this, have you taken into consideration the fact that we have given bottled water to disaster victims and other acts of community involvement?”

71 71 IRRELEVANT INFORMATION 12) STRAWMAN ARGUMENT a.k.a. Weak Opponent, Scarecrow Argument *diversion, name calling this one has a few different (yet related) sides to it:

72 72 IRRELEVANT INFORMATION 1.Use or invent a convenient opponent that can be attacked (or applauded) without fear of retaliation –an easy target –to show how “strong” you are, you hold up a Scarecrow & slap it around (think WWE) –I can make fun of famous people because there’s little chance that they’ll come from Hollywood (e.g.) to rebut me. think of these easy targets: Britney Spears, KKK, Nazis

73 73 IRRELEVANT INFORMATION 2.Use or invent a generic/vague group or label –*no real person involved –no true subject of the argument is identified –label = unfair, inaccurate, manufactured solely for the argument –stereotypes, overgeneralizations (*based on personal biases/prejudices) –*could be positive group: the heroic war dead, brave immigrants (*no specific person indicated)

74 74 IRRELEVANT INFORMATION 3.*Attack your opponent’s weakest possible argument, one s/he is not even offering –put words into the opponent’s mouth ** –similar to #1, in that I set up an easy opponent (their weakest possible argument) just so I can easily knock it down (and look good in the process) –like: Tu Quoque, Ad Hoc, False Dilemma

75 75 IRRELEVANT INFORMATION *EXAMPLES of STRAWMAN: Richard Nixon’s 1952 Checkers speech (weakest possible argument) “kids/students today” (no real kid/student) “moral majority” (who are these people?) “welfare cheats” (do they really exist?) “liberal media” (is it really? all? proof?) “To be an atheist, you have to believe with absolute certainty that there is no God. In order to convince yourself with absolute certainty, you must examine all the Universe and all the places where God could possibly be. Since you obviously haven't, your position is indefensible.” (weakest argument)

76 76 IRRELEVANT INFORMATION 13) TU QUOQUE: (too kwo-kway) “you did it too” justify actions because accusers are supposedly guilty of same crime 2 wrongs make 1 right (see AD POPULUM)

77 77 IRRELEVANT INFORMATION *EXAMPLES of TU QUOQUE: “You did it too when you were my age.” quote: “It’s ok that I dis white people on my show because they’ve been doing it to us for years.” “How can you criticize my driving when you’ve had five accidents yourself?” “Why shouldn’t I cheat on my taxes? Everyone else does.”

78 78 IRRELEVANT INFORMATION 14) OVERSIMPLIFICATION: like: Post Hoc, Overgeneralization overlooks the complexity of an issue *no critical examination of the issue narrows complex issue down to single cause BUT an issue has more than 1 side (more than 2 sides) –legal, moral, religious, political, racial, philosophical... an effect always has more than one reason/cause

79 79 IRRELEVANT INFORMATION *EXAMPLES of OVERSIMPLIFICATION: “Kids are fat because they eat too much McDonald’s.” “The only reason we’re at war with Iraq is over oil.” –An ad populum statement may say, “No Blood for Oil!” “It’s as simple as that.” “Today’s college students can’t spell because of spellcheckers on computers.”


81 81 AMBIGUITY These fallacies have statements that are either purposefully or accidentally ambiguous, misleading, or confusing. Their problem often lies with LANGUAGE: –grammar –punctuation –diction –syntax

82 82 AMBIGUITY 1) AMPHIBOLY: a.k.a. “amphibole” Latin for “ambiguous” ambiguous, multiple meanings or interpretations caused by Bad Grammar –misplaced modifiers, poor pronoun reference misleading statistics –percentages: 89% sounds like much, but not if only 5 people were asked

83 83 AMBIGUITY *EXAMPLES of AMPHIBOLY: “Her parents watered the flowers, yet they died.” (confusing PN reference) “Sam gave Bob his baseball glove.” (confusing PN reference) “I shot a bear in my pajamas.” (misplaced modifier) “March moved to June.” “Girl’s slip seen by many.” “4 out of 5 dentists prefer Trident.” (80%, only 5 asked)

84 84 AMBIGUITY *EXAMPLES of AMPHIBOLY: Blind Bishop Appointed to See Patient at Death's Door — Doctors Pull Him Through Teacher Strikes Idle Kids Lawyers Give Poor Free Legal Advice Juvenile Court to Try Shooting Defendant Autos Killing 110 a Day — Let's Resolve to Do Better Collegians are Turning to Vegetables

85 85 AMBIGUITY 2) BEGGING the QUESTION: *circular reasoning circulus in demonstrando or petitio principii avoidance, non-responsiveness restating the premise without answering the question begs another question or other questions circular reasoning turns the question around without answering it uses what is trying to be proved as part of the proof: the proposition appears in the syllogism/proof

86 86 AMBIGUITY 2) BEGGING the QUESTION: (cont’d) “When is a fetus a person? When it is no longer a fetus. When the doctor says so. When it has the attributes of a person.” –Answers beg other questions: When is it no longer a fetus? When does a doctor say so? What are the attributes of a person? When does a fetus acquire such attributes? Syllogism: It is wrong to kill innocent human beings. Fetuses are innocent human beings. Thus, aborting fetuses is wrong. –“innocent” =? –fetus=human being?

87 87 AMBIGUITY *EXAMPLES of BEGGING the QUESTION: “My mother is a good person because she’s so moral.” “Homosexuals must not be allowed to hold government office. Hence any government official who is revealed to be a homosexual will lose his job. Therefore homosexuals will do anything to hide their secret, and will be open to blackmail. Therefore homosexuals cannot be allowed to hold government office.” Petitio principii: “The Bible is the word of God. The word of God cannot be doubted, and the Bible states that the Bible is true. Therefore the Bible must be true.”

88 88 AMBIGUITY 3) EQUIVOCATION: quibble on the meaning of word/s a deliberate tactic to delay, distort, clutter, or avoid issue trivial distinctions; euphemisms; misuse of definitions obfuscates, obscures the real issue: –“I didn’t steal your money; I merely borrowed it.” –The issue is not about if you “stole” or “borrowed,” but that you took the item without asking permission.

89 89 AMBIGUITY *EXAMPLES of EQUIVOCATION: Knock, knock! Who's there, in the other devil's name? Faith, here's an equivocator, that could swear in both the scales against either scale; who committed treason enough for God's sake, yet could not equivocate to heaven: O, come in, equivocator. (from Macbeth ) “That depends on what your definition of ‘is’ is.” “terrorists” or “freedom fighters,” “communist” or “Marxist,” “refugee” or “illegal immigrant”

90 90 AMBIGUITY 4) LOADED LANGUAGE: biased words leading questions/statements, the answer to which is misleading or damning readers should question users’ motives (ethos) –they don’t want to consider the issue; they’ve already made up their minds –their questions are often statements sarcasm & irony = ambiguity (so avoid using either)

91 91 AMBIGUITY *EXAMPLES of LOADED LANGUAGE: “Do I have to research any more junk on this stupid topic for this worthless class?” “Concerning the inexperienced President’s hasty, subvert, and ill-considered appointment of such an incompetent and unproven judge, is this the type of underhanded, thoughtless behavior we can expect from this administration?” “Have you stopped beating your wife?”

92 92 AMBIGUITY 5) FALSE ANALOGY: false relationship, false comparison, false impression more differences between the 2 than similarities –(despite few superficial similarities) dig more and find that not related –collapse when examined critically (difficult to use) exaggerations key words = “is like”

93 93 AMBIGUITY *DESCRIPTIVE vs. EXPLANATORY: DESCRIPTIVE = metaphorical, more colorful than precise, remain dissimilar, short cuts, not enough to support your claim “life is a bowl of cherries” Malcolm X, criticizing the participation of whites in the 1962 march on Washington, DC: “It’s like when you’ve got some coffee that’s too black, which means that it’s too strong. What do you do? You integrate it with cream, you make it weak. But if you pour too much cream in it, you won’t even know you ever had coffee.” –Claim = integration of whites & blacks in the march weakened the black movement for rights & jobs. –Support = putting white cream into black coffee weakens the coffee. –Warrant = weakening coffee with cream is analogous to weakening the black rights movement by allowing white people to participate. Vivid & descriptive, but not convincing. Too many dissimilarities. “Strong” and “weak” need to be defined. No facts, no proof, just racist opinion.

94 94 AMBIGUITY EXPLANATORY= more than imagery; offer facts, proof “In a world of nuclear overkill and redundance, the United States and the Soviet Union are like two rivals locked in a small room in a duel to the death where one has 1,400 pistols and the other 1,200. The one with 1,400 has no advantage when one or both of the parties are likely to be killed or maimed with the first pistol shot.” –Claim = In enlarging their nuclear arsenals, the US and the USSR are engaged in a duel that neither can win. –Support = A duelist in a locked room with 1,400 pistols could probably not win against a duelist with 1,200 pistols. –Warrant = A pistol duel is analogous to the nuclear arms rivalry between the US and the USSR. (still some dissimilarities)

95 95 AMBIGUITY *EXAMPLES of FALSE ANALOGY: “The Patriot Act turns our government into another Reich.” Bush and Hitler 9/11 and Pearl Harbor Vietnam and Iraq 2003


97 97 FAULTY REASONING The problem with these fallacies lies in the logic –the reasoning process rather than the data.

98 98 FAULTY REASONING 1) FALSE DILEMMA: “either/or” thinking HINT: the words “either/or” are often used LIKE: Oversimplification, Loaded Language assumes only 2 sides to an issue exist both sides may be unpleasant, but 2 nd usually is BUT: more than 2 options, causes, sides to an issue

99 99 FAULTY REASONING *EXAMPLES of FALSE DILEMMA: “You either support Feminism or you’re a sexist pig.” “Either man was created, as the Bible tells us, or he evolved from inanimate chemicals by pure random chance, as scientists tell us. The latter is incredibly unlikely, so...” “You are either for unilateral nuclear disarmament or for nuclear war.” “In a 1975 interview, the Shah of Iran was asked why he could not introduce into his authoritarian regime greater freedom for his subjects. He replied, ‘What’s wrong with authority? Is anarchy better?’ So, it’s either authoritarianism or anarchy.”

100 100 FAULTY REASONING 2) NON SEQUITUR: “it does not follow” Big Leap in logic, faulty conclusion, unconnected, doesn’t make sense irrelevant information (like ad populum) A + B does not necessarily = C Faulty INDUCTION –too big of a “leap” from the Specific to the General

101 101 FAULTY REASONING *EXAMPLES of NON SEQUITUR: “Since half a million copies were sold & it was a best-seller for two decades, it must be a great book.” “We don’t need books and libraries anymore because the Internet has so much information.” “Since Egyptians did so much excavation to construct the pyramids, they were well versed in paleontology.” “Since the President is away from the White House so often, the Vice President must run the country.” “Since is so popular, we might as well stop making envelopes, stamps, and paper.” “From the makers/producers/creators/director of the hit…” “From the team that brought you the hit…”

102 102 FAULTY REASONING 3) RATIONALIZATION: rationalize blame someone/thing else self-serving excuse flimsy justification it’s not my fault; it’s yours We talk ourselves into something -- Do we ever rationalize something good?

103 103 FAULTY REASONING *EXAMPLES of RATIONALIZATION: “I can’t hand in my paper today because the dumb computer wouldn’t print it.” (blame scapegoat, like Scarecrow) “You can’t make an omelette without breaking a few shells.” (blame virtue) “Yeah, I knocked over the garbage can, but you shouldn’t have put it in my way.” (blame another) “It’s OK if I have another piece of cake; I’ll just go for a run tomorrow.” (self-serving justification)

104 104 FAULTY REASONING *EXAMPLES of RATIONALIZATION: It’s only this one time. OK, but this is the last time. Just one more. It’s Spring Break. I’m away at college. I’m an adult now. No one will ever know. My parents will never know. Who’s ever going to see those pictures? I needed the money. It doesn’t hurt anybody. It’s in the privacy of my own home. I’m entitled: –age, class, race –I worked hard all week or semester. It’s my life! Everyone else is doing it. (like Tu Quoque) It’s on sale. I’ll just cram the night before. I’ll go out tonight and just study all day tomorrow. I’ll just…. CHEATING excuses: –Everyone’s doing it. –Look at the business world! –The technology was made to help us cheat. –If the teacher were smart enough to catch me cheating…. –The teacher grades on a curve, so I have to cheat. –I have to because of Affirmative Action. –I really need an A. –It’s not my major.

105 105 FAULTY REASONING *EXAMPLE from Blues Brothers: Jake: “Oh, please, don’t kill us. Please, please don’t kill us. You know I love you baby. I wouldn’t leave ya. It wasn’t my fault. Mystery Woman: You miserable slug! You think you can talk your way out of this? You betrayed me. Jake: No I didn’t. Honest... I ran out of gas. I, I had a flat tire. I didn’t have enough money for cab fare. My tux didn’t come back from the cleaners. An old friend came in from out of town. Someone stole my car. There was an earthquake. A terrible flood. Locusts. IT WASN’T MY FAULT, I SWEAR TO GOD!

106 106 FAULTY REASONING 4) REDUCTIO AD ABSURDUM: reduce to absurdity use opponents’ reasoning against them *extend their argument to its absurd conclusion often employed to ridicule opponent –sarcasm, ridicule similar, in this respect, to Straw Man also, based on the fallacious assumption that more is better or that less is better

107 107 FAULTY REASONING *EXAMPLES of REDUCTIO AD ABSURDUM: “If we allow a man to marry another man, then we might as well allow him to marry a dog or a sheep.” “If 2 are good, then 5 are better, but then all of them would be best.” “If 2 less is good, then 5 less would be better, but then getting rid of them all would be best.” “Since my physical therapist told me to do 3 sets of 10 with my dumbbells, I should be cleared to play sooner if I do 6 sets of 20; still, if I do 12 sets of 40, I’ll be reactivated much sooner.”

108 108 FAULTY REASONING 5) SLIPPERY SLOPE: next step=danger/forbidden always ends badly (highway to hell) one thing must lead to another –(1 drink/puff = addiction) dangerous proposals too simplistic, ignores the similarities, ignores the complexity of life and institutions, ignores checks and balances

109 109 FAULTY REASONING * SLIPPERY SLOPE vs. REDUCTIO AD ABSURDUM: SS: ends with something bad, but possible RAA: ends with something absurd, impossible Arguments against opening a casino: –If we pass this referendum and allow this casino to open, then we’ll be overrun by gambling addicts. (SS) one small steps, ends in something bad but possible –If we pass this referendum and allow this casino to open, then we’ll be overrun by zombies and demons. (RAA) ends with something absurd, impossible You want to open a casino in the area, so you’re pro-gambling. Because you’re in favor of gambling, you must also be in favor of child prostitution because that’s what gambling addicts force their children into in order to feed their addiction.

110 110 FAULTY REASONING *EXAMPLES of SLIPPERY SLOPE: “She kept her kid away from soda because one drink and he’d be addicted to it for life.” “If we legalize marijuana, then more people would start to take crack and heroin, and we’d have to legalize those too. Before long we'd have a nation full of drug-addicts on welfare. Therefore, we cannot legalize marijuana.” “Legalizing abortion will lead to murder of the elderly and the physically and mentally handicapped.” “If we ban handguns, what’s next?! Rifles and other hunting weapons?!” “If we allow gays to marry, then the human race will become extinct.”

111 extras

112 112 extras Argumentum ad antiquitatem: (appeal to antiquity or tradition) something (behavior, practice, policy) = right/acceptable because of tradition “It's always been done that way.” “Every great civilization has believed in a higher power.” Argumentum ad novitatem: opposite of the Argumentum ad Antiquitatem; something = better or more correct simply because it is new, or newer than something else. “Windows XP is better than Windows 2003 because WXP just came out."

113 113 extras Argumentum ad nauseam: made to the point of disgust by repetition repetition to substitute for actual, real arguments, w/o substantiation, w/o justification Leading or loaded or complex question: no right way to answer; assumes something to be true by its construction “Have you stopped beating your wife ?”

114 114 extras Appeals: to Authority to Belief to Common Practice to Consequences of a Beliefto Consequences of a Belief to Fear to Flattery to Pity to Ridicule to Spite to SEX!!! Biased Sample Burden of Proof Ad Hominem Tu Quoque Circumstantial Ad HominemCircumstantial Ad Hominem Composition Confusing Cause & EffectConfusing Cause & Effect Division Gambler's Fallacy Ignoring A Common CauseIgnoring A Common Cause Middle Ground Misleading Vividness Poisoning the Well Questionable Cause Relativist Fallacy Special Pleading Spotlight Two Wrongs Make A RightTwo Wrongs Make A Right

Download ppt "1 errare humanum est (to err is human). FALLACIES."

Similar presentations

Ads by Google