6 Reasoning Error

8/8/2019 6 Reasoning Error

1/39

Logical Fallacies

Introduction and Activities


2/39

Logical Fallacy

Logical = something that is reasonable,(it makes sense)

Fallacy = something that is faulty, (amistake)

SoLogical + Fallacy = A Mistake in

Reasoning


3/39

W hat is a logical fallacy?

A fallacy is an error of reasoning. Theseare flawed statements that often soundtrue

Logical fallacies are often used tostrengthen an argument, but if the reader

detects them the argument can backfire,and damage the writers credibility


4/39

O rigins

The word fallacy has derive from theLatin word fallere meaning, to deceive, to

trip, to lead into error or to trick. The wordmay also derive from the Greek phelos,meaning deceitful.

www.sun-design.com/talitha/fallacies.htm


5/39

Types of Logical Fallacies

Fallacies can be categorized as1. Reasons that seem logical but dont

necessarily support the conclusion2. Statements that distract listeners from the

real issue

For a comprehensive list see the following websites:http://sun-design.com/talitha/fallacies.htmlhttp://owl.english.purdue.edu/handouts/general/gl_fallacies.htmlwww.datanation.com/fallacies/index.htm


6/39

Inadequate Reasons asfallacies

Faulty analogiesFalse cause

Ad hominemTwo wrong make a rightSlippery slope

Straw manHasty conclusion


7/39

False Analogy

Analogy compares two thingsFalse analogy is when the two things

compared really are not similar in the waybeing comparedSadaam Hussein is like Hitler

Therefore, the Gulf W

ar is justified just asWW II was justified


8/39

P ost hoc (false cause)This fallacy gets its name from the Latin phrase " post hoc,

ergo propter hoc ," which translates as "after this,therefore because of this."

D efinition : Assuming that because B comes after A, Acaused B. O f course, sometimes one event really does cause another one

that comes later--for example, if I register for a class, and myname later appears on the roll, it's true that the first event causedthe one that came later. But sometimes two events that seemrelated in time aren't really related as cause and event. That is,correlation isn't the same thing as causation.

Examples : "President Jones raised taxes, and then therate of violent crime went up. Jones is responsible for therise in crime. The increase in taxes might or might not be one factor in the

rising crime rates, but the argument hasn't shown us that onecaused the other.


9/39

Ad Hominem

Attack against the man Attacks the character or person of the

person making the opposing argumentrather than the argument itself Shows lack of objectivity


10/39


11/39

Slippery SlopeD efinition : The arguer claims that a sort of chainreaction, usually ending in some dire consequence, willtake place, but there's really not enough evidence for that assumption.

The arguer asserts that if we take even one step onto the"slippery slope," we will end up sliding all the way to the bottom;he or she assumes we can't stop halfway down the hill.

Example : "Animal experimentation reduces our respectfor life. If we don't respect life, we are likely to be moreand more tolerant of violent acts like war and murder.Soon our society will become a battlefield in which

everyone constantly fears for their lives. It will be the endof civilization. To prevent this terrible consequence, weshould make animal experimentation illegal right now."

Since animal experimentation has been legal for some time andcivilization has not yet ended, it seems particularly clear that thischain of events won't necessarily take place.

Also known asthe Camels Nose


12/39

Straw ManD efinition : O ne way of making our ownarguments stronger is to anticipate and respondin advance to the arguments that an opponentmight make. The arguer sets up a wimpyversion of the opponents position and tries toscore point by knocking it down.

Example : "Feminists want to ban dowry andpunish everyone who indulge in it. But suchharsh measures are surely inappropriate, so thefeminists are wrong: " The feminist argument is made weak by being

overstated--in fact, most gifts are not dowry and donot propose an outright "ban or any punishment for

those who merely give it;


13/39

Evidence does not support the broadconclusion.Example: Adi tya, who i s from In di a, d ec id es to atten d gra du ate

school at Oh i o State Un iv ers i ty. He has ne v er been to the USbefore. The d ay after he arr iv es, he i s walk i ng back from anor i entat i on sess i on an d sees two wh i te (alb i no) sq ui rrels chas i ng each other aro u nd a tree. In h i s next letter home, he tells h i sfam i ly that A mer i can sq ui rrels are wh i te.

Example: Fre d the Au stral i an, stole my wallet. Th u s, all Au stral i ans are th i e v es.


14/39

Statements that distract listeners fromthe real issueThe Red Herring

Ad Populum: Jumping on the Bandwagon

Appeal to Tradition: wehv alaways doneit this wayAppeal to pity

The false DilemmaEquivocationBegging the question


15/39

Red HerringRed Herring ...named after a strong-smelling fish, the scent of which throws hounds

off the scent of a trail. The Red Herring occurs when one drawsThe Red Herring occurs when one drawsattention away from the main issue by focusing on a sideattention away from the main issue by focusing on a sideissue or on something irrelevant.issue or on something irrelevant.

Examples:Examples:"I work 60 hours a week to support my family, and I pay"I work 60 hours a week to support my family, and I pay

my taxes; you shouldn't arrest me just because I punched my taxes; you shouldn't arrest me just because I punched him in the face.him in the face.

Youre not being fair by denying me the opportunity Youre not being fair by denying me the opportunityto make up the quiz; after all, Im paying for my o w nto make up the quiz; after all, Im paying for my o w neducation, I w ork t w o jobs and have to raise my sixeducation, I w ork t w o jobs and have to raise my sixchildren on my o w n!children on my o w n!


16/39

Ad Populum: Jumping on the Bandwagon

An argument aimed at appealing to theprejudices and emotions of the masses

Just because a majority believesomething is true doesnt make it logicalor valid

If you dont want to be left out, you better get on the bandwagon and do and thinkthe same things


17/39

Appeal To Tradition: Appeal To Tradition:

... We should continue to do things as theydo things as theyhave been done in the past.have been done in the past. We shouldn'tchallenge time-honored customs or

traditions. (don't rock the boat)O f course you have to play Here Comes theBride" at your w edding, because that'sal w ays been the song that is played.W e always have liver on Thanksgiving evenW e always have liver on Thanksgiving eventhough we dislike it because its been athough we dislike it because its been afamily tradition for generations.family tradition for generations.


18/39

Appeal to PityD efinition : The appeal to pity takes place when

an arguer tries to get people to accept aconclusion by making them feel sorry for someone.Example : "I know the exam is graded based onperformance, but you should give me an A. MyDog has been sick, my car broke down, and I'vehad a cold, so it was really hard for me to study!" The conclusion here is "You should give me an A."

But the criteria for getting an A have to do withlearning and applying the material from the course;

the principle the arguer wants us to accept (peoplewho have a hard week deserve A's) is clearlyunacceptable.

Example : "It's wrong to tax corporations--thinkof all the money they give to charity, and of the

costs they already pay to run their businesses!"


19/39

FalseFalse DilemmaDilemma

...based on the f alse assumption that therethereare only two possibilitiesare only two possibilities . Sometimes calledthe Either/OrEither/Or fallacy. fallacy. Most situationsMost situationsprovide more than two possibleprovide more than two possibleoutcomes.outcomes.

Examples:Either you are with America's fightagainst terrorism or you are

America's enemy.I f you dont take this trip now, you will eitherI f you dont take this trip now, you will either live livewith lifelong regretwith lifelong regret or you willor you will take a better triptake a better triplaterlater in your life.in your life.


20/39

= EquivocationD efinition : Equivocation is sliding between twoor more different meanings of a single word or phrase that is important to the argument.Example : "Giving money to charity is the rightthing to do. So charities have a right to our money." The equivocation here is on the word "right": "right"

can mean both something that is correct or good (asin "I got the right answers on the test") and somethingto which someone has a claim (as in "everyone has a

right to life"). Sometimes an arguer will deliberately, sneakilyequivocate, often on words like "freedom," "justice,""rights," and so forth; other times, the equivocation isa mistake or misunderstanding. Either way, it'simportant that you use the main terms of your argument consistently.

=


21/39

Begging the QuestionD efinition : A complicated fallacy, an argument that begs the question asks

the reader to simply accept the conclusion without providing real evidence the argument either relies on a premise that says the same thing as theconclusion (which you might hear referred to as "being circular" or "circular reasoning"), or simply ignores an important (but questionable) assumption thatthe argument rests on.

Sometimes people use the phrase "beg the question" as a sort of generalcriticism of arguments, to mean that an arguer hasn't given very good reasonsfor a conclusion, but that's not the meaning we're going to discuss here.

Examples : "Active euthanasia is morally acceptable. It is a decent, ethicalthing to help another human being escape suffering through death." Let'slay this out in premise-conclusion form: Premise: It is a decent, ethical thing to help another human being escape

suffering through death. Conclusion: Active euthanasia is morally acceptable.

If we "translate" the premise, we'll see that the arguer has really just saidthe same thing twice: "decent, ethical" means pretty much the same thingas "morally acceptable," and "help another human being escape sufferingthrough death" means "active euthanasia." So the premise basically says,"active euthanasia is morally acceptable," just like the conclusion does! Thearguer hasn't yet given us any real reasons why euthanasia is acceptable;instead, she has left us asking "well, really, why do you think activeeuthanasia is acceptable?" Her argument "begs" (that is, evades) the realquestion (think of "beg off").


22/39

Can you name this Fallacy?

1) It is ridiculous to have spent thousands of dollars to rescue those two whales trappedin the Arctic ice. W hy look at all the peopletrapped in jobs they dont like.

RED HERRING


23/39


2) Plagiarism is deceitful because it isdishonest.

BEGGING THE QUESTI O N


24/39


25/39


4) I know three redheads who have terribletempers, and since Annabel has red hair,Ill bet she has a terrible temper too.

HASTY GENERALIZATIO N


26/39


5) Supreme Court Justice Byron W hite wasan All-American football player while incollege, so how can you say that athletesare dumb?



27/39


6) W hy should we put people on trial whenwe know they are guilty?

BEGGING THE QUESTI O N


28/39


7) You support capital punishment justbecause you want an eye for an eye, butI have several good reasons to believethat capital punishment is fundamentallywrong

STRAW MAN


29/39


8) The meteorologist predicted the wrongamount of rain for May. O bviously themeteorologist is unreliable.



30/39


9) You know Jane Fondas exercise videosmust be worth the money. Look at thegreat shape shes in.

P O ST H O C (false cause)


31/39


10) W e have to stop the tuition increase!The next thing you know, they'll becharging $40,000 a semester!

SLIPPERY SL O PE


32/39


11) The book Inv est i ng for D u mm i es reallyhelped me understand my finances better.The book Chess for D u mm i es was writtenby the same author, was published by thesame press, and costs about the sameamount, so it would probably help meunderstand my finances as well.

W EAK ANALO GY


33/39


12) Look, you are going to have to make upyour mind. Either you decide that you canafford this stereo, or you decide you aregoing to do without music for a while.

FALSE DICH O TO MY (Dilemma)


34/39


13) I'm positive that my work will meet your requirements. I really need the job sincemy grandmother is sick.

APPEAL T O PITY


35/39


14) Crimes of theft and robbery have beenincreasing at an alarming rate lately. Theconclusion is obvious, we must reinstatethe death penalty immediately.

MISSING THE P O INT


36/39

Classroom Activities

(Us i ng a pr i nto u t of the Owl fallacy l i st)

1) Logical fallacy roundup: in groups,search websites, newspapers,advertisements, etc. to find argumentsthat may contain logical fallacies.

Present these to the class.2) Find two logical fallacies to share withthe class


37/39

Activities, contd

3) Using your list of fallacies, createexamples of your own

4)W

rite a short op/ed article that is basedon one logical fallacy5) W rite an argument using as many logical

fallacies as you can6) Make a chart to tally logical fallacies that

you hear in everyday conversation


38/39

Even more activities

7) Bring in visual examples of logicalfallacies from advertisements, etc.

8) Identify logical fallacies from editorialcartoons


39/39

In conclusion, always be on the lookoutfor faulty reasoning!

If you read thisPowerPoint andcompleted some of the activities, you area genius!

Congratulations!

6 Reasoning Error

Documents

Transcript of 6 Reasoning Error