Logical FallaciesLogical FallaciesDr. Alan HaffaDr. Alan Haffa

Based on Gary Goshgarian and Kathleen Based on Gary Goshgarian and Kathleen Krueger in Krueger in An Argument Rhetoric and An Argument Rhetoric and

ReaderReader

What Are Logical Fallacies?What Are Logical Fallacies?

Fallere: to deceiveFallere: to deceive

Flaw in the logic of an argumentFlaw in the logic of an argument

Unintentional or intentionalUnintentional or intentional

Ad HominemAd Hominem

Attack against ‘the man’Attack against ‘the man’

Attacks the character or person of Attacks the character or person of the person making the opposing the person making the opposing argument rather than the argument argument rather than the argument itselfitself

Shows lack of objectivityShows lack of objectivity

Ad MisericordiamAd MisericordiamAppeal to PityAppeal to Pity

Attempts to persuade by making an Attempts to persuade by making an emotional argumentemotional argument

Example: Local Humane Society seeks Example: Local Humane Society seeks money for new shelter; shows a picture and money for new shelter; shows a picture and tells you that your donation could save this tells you that your donation could save this dog from being euthanized due to dog from being euthanized due to overcrowdingovercrowding

Appeal to a court to spare an eighty year Appeal to a court to spare an eighty year old man from the death penalty based upon old man from the death penalty based upon his age and frail healthhis age and frail health

Ad Populum ArgumentAd Populum ArgumentAn argument aimed at appealing to An argument aimed at appealing to the prejudices and emotions of the the prejudices and emotions of the massesmassesA parent who complains in an A parent who complains in an editorial about their child being editorial about their child being taught by a foreign teacher, appeals taught by a foreign teacher, appeals to the common prejudice against to the common prejudice against immigrants and foreignersimmigrants and foreignersJust because a majority believe Just because a majority believe something is true doesn’t make it something is true doesn’t make it logical or validlogical or valid

Bandwagon AppealBandwagon AppealIf you don’t want to be left out, you If you don’t want to be left out, you better get on the bandwagon and do and better get on the bandwagon and do and think the same thingsthink the same things

Similar to Ad Populum but emphasis is Similar to Ad Populum but emphasis is on the desire to persaude the undecided on the desire to persaude the undecided or non-conformist to ‘join the group’or non-conformist to ‘join the group’

““Smart Shoppers shop at Sears”Smart Shoppers shop at Sears”

““Everyone knows that Global Warming is Everyone knows that Global Warming is a Threat”; “Everyone knows that Global a Threat”; “Everyone knows that Global Warming is a liberal conspiracy”Warming is a liberal conspiracy”

Begging the QuestionBegging the Question

Similar to circular reasoning, begging Similar to circular reasoning, begging the question presents something as the question presents something as true which in fact needs to be true which in fact needs to be demonstrated.demonstrated.

““That foolish law should be repealed”That foolish law should be repealed”

““She is compassionate because she She is compassionate because she is a woman”is a woman”

Circular ReasoningCircular Reasoning

The conclusion of a deductive The conclusion of a deductive argument is hidden in the premiseargument is hidden in the premise

The argument goes in a circleThe argument goes in a circle

1) People who are happy with their 1) People who are happy with their work are cheerful because they enjoy work are cheerful because they enjoy what they’re doingwhat they’re doing

Smoking is bad for you because it Smoking is bad for you because it ruins your health.ruins your health.

Dicto SimpliciterDicto Simpliciter

From a general truth to a specific case, From a general truth to a specific case, regardless of the appropriatenessregardless of the appropriateness

““Simply spoken”Simply spoken”

Exploits an overly simplistic “rule of Exploits an overly simplistic “rule of thumb”thumb”

1) Men are stronger than women; 1) Men are stronger than women; Soldiers should be strong; Women Soldiers should be strong; Women should not serve in combat.should not serve in combat.

False AnalogyFalse Analogy

Analogy compares two thingsAnalogy compares two things

False analogy is when the two things False analogy is when the two things compared really are not similar in the compared really are not similar in the way being comparedway being compared

Sadaam Hussein is like HitlerSadaam Hussein is like Hitler

Therefore, the Gulf War is justified Therefore, the Gulf War is justified just as WW II was justifiedjust as WW II was justified

Faulty Use of AuthorityFaulty Use of Authority

When an expert in one area is used When an expert in one area is used as an authority outside of their area as an authority outside of their area of expertiseof expertise

Just because someone is a Ph.D. or Just because someone is a Ph.D. or M.D. doesn’t mean that they are an M.D. doesn’t mean that they are an expert on the particular topicexpert on the particular topic

Celebrity EndorsementsCelebrity Endorsements

Hasty GeneralizationsHasty Generalizations

Arriving at a conclusion based on too Arriving at a conclusion based on too little evidencelittle evidence

Students in America are learning less Students in America are learning less than in the past because their SAT than in the past because their SAT scores are lowerscores are lower

California students are less well California students are less well educated than other states because educated than other states because they are 46they are 46thth in per student funding in per student funding

Non SequiturNon Sequitur

““Does not follow”Does not follow”

A conclusion that doesn’t follow from A conclusion that doesn’t follow from the premisethe premise

““She’s so pretty; she must not be She’s so pretty; she must not be smart.”smart.”

““Candidate Jones will be a great Candidate Jones will be a great Senator because she’s been married Senator because she’s been married for twenty years.”for twenty years.”

Post Hoc, Ergo Propter HocPost Hoc, Ergo Propter Hoc““After this, therefore because of this”After this, therefore because of this”Establishes a questionable cause-and-effect Establishes a questionable cause-and-effect relationship between eventsrelationship between eventsBecause event Y follows event X, event X Because event Y follows event X, event X causes event Ycauses event YBlack folks do less well on standardized Black folks do less well on standardized tests; therefore the public school system tests; therefore the public school system must be racistmust be racistThere are more latch-key children since the There are more latch-key children since the Women’s Movement; Feminism and Women’s Movement; Feminism and Women’s Liberation is directly responsible Women’s Liberation is directly responsible for the rise of latch-key childrenfor the rise of latch-key children

Red HerringRed HerringEvidence that is used incorrectly and Evidence that is used incorrectly and intentionally to distract the audience from the intentionally to distract the audience from the true issuestrue issuesIn Detective Stories the Red Herring is the In Detective Stories the Red Herring is the “false suspect” “false suspect” A coach accused of using money improperly A coach accused of using money improperly defends himself by pointing out the teams defends himself by pointing out the teams winning recordwinning recordThe problem with education is a “lack of The problem with education is a “lack of accountability”accountability”‘‘There will be death panels who will decide if There will be death panels who will decide if Seniors can live or die’Seniors can live or die’

Slippery SlopeSlippery SlopeLike a muddy hill, if we go down this slope Like a muddy hill, if we go down this slope we will fall we will fall In other words, if we allow one thing a In other words, if we allow one thing a whole slew of other, negative events will whole slew of other, negative events will occur as a resultoccur as a resultIt is fallacious when there is not sufficient It is fallacious when there is not sufficient evidence offered to show that Event X will evidence offered to show that Event X will necessarily lead to Events Y and Znecessarily lead to Events Y and ZIf we pass this health care bill eventually If we pass this health care bill eventually the government will take over the decision-the government will take over the decision-making from patients and doctorsmaking from patients and doctorsGay marriage will lead to polygamy and Gay marriage will lead to polygamy and incestincest

Stacking the DeckStacking the DeckOnly offering evidence that supports the Only offering evidence that supports the premise, while disregarding contrary premise, while disregarding contrary evidenceevidence

““Data beautification”Data beautification”

A meat manufacturer advertises that its all-A meat manufacturer advertises that its all-beef hot dogs “now contain 10 percent less beef hot dogs “now contain 10 percent less fat,” but leaves out the fact that it still fat,” but leaves out the fact that it still contains 30 % fatcontains 30 % fat

If you leave out obvious evidence your If you leave out obvious evidence your reader knows about you lose credibilityreader knows about you lose credibility

Straw ManStraw ManA straw man is an easy targetA straw man is an easy targetIn rhetoric, it refers to a strategy of In rhetoric, it refers to a strategy of refutation that offers a distorted view of the refutation that offers a distorted view of the opponent’s position and then knocking it opponent’s position and then knocking it down.down.The speaker claims the opponent’s The speaker claims the opponent’s argument is false because of an error in a argument is false because of an error in a smaller, inessential part of the opponent’s smaller, inessential part of the opponent’s argumentargument““This bill is Socialist and would turn This bill is Socialist and would turn America’s Health Care system over to a America’s Health Care system over to a government bureaucracy.”government bureaucracy.”

Either/Or FallacyEither/Or FallacyWriter argues that we have two choices: Writer argues that we have two choices: we MUST do either THIS or THATwe MUST do either THIS or THAT

Typically one of the two options is clearly Typically one of the two options is clearly non-desirable or bad; hence, the non-desirable or bad; hence, the “conclusion” that we must do the “conclusion” that we must do the alternativealternative

The current bill is unacceptable; we must The current bill is unacceptable; we must start over from scratchstart over from scratch

Or, we have come too far not to pass this Or, we have come too far not to pass this bill; starting over would mean failurebill; starting over would mean failure

SummarySummary

If you can identify a fallacy in your If you can identify a fallacy in your opponent’s argument, point it out opponent’s argument, point it out and show how it is falseand show how it is false

Be sure to refute all of your Be sure to refute all of your opponent’s points and then you may opponent’s points and then you may offer up points of your own.offer up points of your own.