Fallacies
Why are fallacies effective?
• “Our brains are belief engines that employ
association learning to seek and find patterns.
Superstition and belief in magic are millions of
years old, whereas science, with its methods
of controlling for intervening variables to
circumvent false positives, is only a few
hundred years old. So it is that any medical
huckster promising that A will cure B has only
to advertise a handful of successful anecdotes
in the form of testimonials.” (Sci. Amer. 2008.)
Why learn the fallacies?
• Forewarned is forearmed!
• By recognizing these patterns of mistakes you
can avoid having them employed against you.
• You can also employ them.
– As an advertiser.
– As a salesperson.
– In law.
– In comedy.
What you should know…
• What makes the fallacy effective…
persuasively.
The Monroe Doctrine
will succeed if “we
• What makes the fallacy fail…
speak softly and carry
a big stick!”
Logically.
E-Text treatment of the Fallacies
• Covers a few fallacies in good detail:
– Begging the Question.
– Appeal to ignorance.
– Illegitimate authority.
– Ad Hominem.
– Strawman.
– Red Herring.
Phil’s Fallacies
• More!
• I.M. Copi grouped 19 informal fallacies into 3
groups.
– Fallacies where the primary deficiency is…
• Relevance R1-R7.
• Presumption P1-p7.
• Ambiguity A1-A5.
Any Grouping of Fallacies is somewhat
arbritrary.
Additional sources for Fallacies
• www.fallacyfiles.org
– Extensive collection of fallacies.
• http://www.nizkor.org/features/fallacies/
– Collection of fallacies relevant to the website:
rebutting holocaust deniers.
• http://onegoodmove.org/fallacy/
– This site indicates a “proof” condition for each fallacy
given.
More sites
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Links to sites helpful for fallacies.
http://web.cn.edu/kwheeler/fallacies_list.html
http://www.drury.edu/ess/Logic/Informal/Overview.html
http://www.csun.edu/~dgw61315/fallacies.html
Practise exercises for fallacies
http://web.cn.edu/kwheeler/Logic_Fallacies_Exercise.html
http://www.writing.eng.vt.edu/exercises/fallacies.html#2
Links will be posted on JUMP
To be a fallacy…
• To be a fallacy a series of statements must first
be an argument:
• You’re a jerk, therefore you’re wrong.
– Is a fallacy (ad hominem aka fallacy of abuse.)
• You’re a jerk,
– is not a fallacy, it is mere abuse.
Fallacies of Relevance: R1-R7
• Fallacy of…
– Ignorance
– Illegitimate authority
– Abuse
– Emotion
– Pity
– Force
– Irrelevant conclusion.
Appeal from ignorance (R1)
• Appeal from ignorance (R1)
– Argumentum ad ignorantiam.
Form:
There is no relevance
between the lack of evidence
for something, and its being
false.
There is no evidence for X,
Therefore X is false.
Note that “ignorance” here does not mean
Stupid, foolish or dumb, but rather a lack of
knowledge.
Examples: R1 (ignorance).
• There is no evidence that the “liberation
treatment” for MS will cure this condition,
therefore the liberation treatment is not an
effective treatment.
• There is no proof that climate change is
happening, therefore we can safely ignore it in
matters of public policy.
Persuasiveness
It is entirely reasonable to infer
That if you have no evidence for X
That you should not believe X.
There is a big difference between
not believing X
And having reason to think X is false.
Counterexample
• There is no evidence that an undiscovered
continent exists, therefore, I Chris Columbus
will encounter no difficulty sailing west from
Spain to China!
I’ve got good news
and bad news your
majesty!
Fallacy of ignorance often works both ways.
• There is no evidence that god exists:
therefore god does not exist.
• There is no evidence that god does not exist:
therefore god does exist.
If any argument is equally effective for opposing
conclusions, it is probably a fallacy.
This just in….
• there is a significant statistical link between
CCD, the iridescent virus and a fungal parasite
of the genus Nosema. We don’t know if (1)
these two pathogens cause CCD or …
• We believe that there is currently insufficient
evidence to conclude that bees are a natural
host for IIV-6, let alone that the virus is linked
to CCD.
Appeal to illegitimate Authority (R2)
• AKA Argumentum ad verecundiam.
• AKA false authority.
Form: an authority on X offers evidence for Y.
Therefore Y is true. (when X not= Y)
Description: the testimony of an inappropriate authority
is used as evidence.
• Key: deciding on the appropriateness of an authority.
Appropriate authority
• Appropriate: an expert provides evidence that
falls within the scope of their qualification(s).
– The surgeon general says smoking is harmful.
• Inappropriate: otherwise.
– The surgeon general says red bull rocks!
• The same person could be an appropriate
authority in one case, and inappropriate in
another.
Important minor detail!
• You can’t be your own false authority!
• Committing the F of FA is invoking someone
else’s authority inappropriately.
• You are not someone else!
Persuasiveness
• Authorities are important parts of knowledge
acquisition.
• We rely on authorities for many areas of
knowledge we haven’t mastered ourselves.
• For instance we all rely on Doctors for our
health and sometimes our lives.
• That doesn’t mean doctors should advise us
on our investments or our cottage repairs.
Examples of inappropriate authority
• Wayne Gretzky says
Ford is #1!
– Implied conclusion,
you should buy a ford.
• Sidney Crosby says that hydration is important to his
performance, so you should definitely buy your little
timbit player lots of G!
Counter example.
• Jenny McCarthy:
Has used her celebrity to publicize
Her belief that vaccines cause
autism. She is the spokesperson
For “Generation rescue”. When
asked for comment on recent
discovery that the main study used
as evidence for her claim was
fraudulent, She declined to comment.
Argument against the Person (R3)
• AKA: Argumentum ad hominem.
– Commonly known as “ad hominem”
• AKA: the Rush Limbaugh Fallacy.
Form: Abuse of Person X
Therefore What person X says/believes/stands for
is false.
Persuasiveness
• It is very common to form quick judgments
about people and how trustworthy and
reliable they are based on quick and
superficial impressions.
• People like successful poker players and
salesagents make their living this way.
• We are actually surprisingly good at this…
1st impressions aren’t always wrong.
“I’m not a Crook”
Unsaid: I’m
resigning before I
have to testify…
In the 1st live TV Debate, people who
listened on radio preferred Nixon,
people who watched chose Kennedy,
observing that Nixon seemed “shifty”
and “untrustworthy”.
13 yrs later, Nixon is forced to resign in
disgrace when it is revealed the watergate
break-ins were conducted by political
operatives under Nixon’s authority.
The superficial judgment of the TV audience turned out to be correct!
Subcategories: ad hominem
• Abuse.
– I offer abuse for X, therefore what X says is false.
• Circumstantial.
– Some abuse is deserved, but for irrelevant reasons.
• X is short, therefore what X says is false.
• Tu Quoque: (You too!)
– Person X’s actions/words are not consistent
• Hypocrites can still be right.
• If a doctor who smokes tells you to quit, you still should.
• Poisoning the well.
– Pre-emptive abuse.
• “You can’t believe anything a political hack would say”
Examples: Ad Hominem
• Stephen Harper is a control freak, therefore his economic
policies are deeply flawed.
– Abuse.
• Stephen Harper is from Calgary, so you can’t trust his
position on the oil sands in Alberta.
– Circumstantial
• Stephen Harper says we should all rely on private
enterprise to stimulate the economy: but his salary is
funded by government taxes!
– Tu quoque.
• You can’t believe anything Stephen Harper says, he’s just
desperate to hold on to power.
– Poisoning the well.
Beware! 2 common errors.
• Correct: Ad hominem:
– "You are an ignorant person, therefore your
arguments are wrong”.
• NOT an ad hominem:
– "Your arguments are wrong, therefore you are an
ignorant person.”
• The latter argument may be fallacious, but it's not an ad
hominem fallacy.
• “You’re an A___!”
• NOT a fallacy b/c its not an argument.
Appeal to Emotion (R4)
• AKA: Argumentum ad populum
• AKA: Mob appeal
• Form: Thinking X is true makes me feel good.
Therefore X is true.
Persuasiveness
• We all want to feel good.
• We all have an “ear” for the truth that is a
fairly reliable guide.
• It is probably true that we feel better when we
hear the truth then when we know we are
being lied to:
– It is a mistake to think that this works in reverse,
that feeling good means we are not being lied to.
Counterexample
• You should buy our new bodyshaper 2000.
This machine will really work. You’ll look great
on the red carpet or at that important
meeting in only a few weeks.
Mass Appeal
• Subcategory of Appeal to Emotion:
– This is when the appeal is to the emotions of
many people.
– Eg. George Bush using “attack” of 9/11 to justify
invasion of Iraq, etc.
Mass Appeal is often used by Despots and
Dictators to justify some pretty horrible
things.
• Hitler’s appeal to his populace was based
on making the Ethnic German majority feel
superiour to ethnic minorities within
Germany.
I believe today that I am acting in the
sense of the Almighty Creator. By
warding off the Jews I am fighting for
the Lord's work.
Benign Mass Appeal
• A true Canadian would support the team no
matter what…
• PM Harper frequently addresses speeches to
“my friends”; so far, no major harm…
• Advertisers often refer to the popularity of
their product as evidence that the product is
good.
Appeal to Pity (R5)
• AKA: Argumentum Ad Misericordium.
Form: I have a emotional response to X:
Therefore I should accept Y with respect to X.
EG: The earthquake in Haiti caused
unimaginable suffering: Therefore I should
accept corruption in the international
supervision of the recent Haitian election.
Persuasiveness
• There are important advantages to being
empathic and sensitive to the needs of others.
• The genes of people who have ignored their
children’s cry’s don’t reproduce very well.
• Some people might include this fallacy as a sub
category under “appeal to emotion” and argue
that the persuasiveness is due to the positive
emotion one gets for responding to the feeling of
pity.
Counter Example
• I feel sorry for people who cry in my office!
• Therefore I should not Fail students who cry in
my office.
Now I’ll never get
into Med School!
More Examples
“If you act now, you can save this child from a
lifetime of poverty and suffering.”
Worst Example
• Glenn Beck:
Cries on Camera in first
Mention of his 9/12 project.
This eventually morphs into
The Tea Party movement.
This probably commits
Both pity and the emotive
Fallacy.
Appeal to Force
• AKA: Argumentum ad Baculum
• Literally “from the stick”
Form: You should accept X, or else!
Varies from Blunt to subtle:
Agree or I’ll hit you with this stick! (blunt)
If you agree to my proposal, then I won’t have to refer your
expense claims for the previous year to our auditors.
(subtle)
Genghis Kahn: Master Fallacy user
• Genghis Kahn
would offer enemy
cities this choice:
surrender or die!
• Given his track
record, the choice
was obvious, many
cities surrendered
pro-actively.
Here’s an offer you
can’t refuse!
The areas which resisted remained depopulated for centuries!
Persuasiveness
• Fear is highly effective.
• I don’t want to die!
• Few of us want to lose whatever it is we care
about: Job, family, life…
• Tangent: Corruption of police forces.
– Police in weak states are often offered this choice:
Accept this bribe, or die.
Legitimate appeal to force?
• Are some appeals to force
Legitimate?
• Should threats made by
appropriate authorities be
considered fallacious.
• What do you think?
Irrelevant conclusion: (R7)
• AKA: Ignoratio elenchi
– Literally: ignorance of the disproof.
– Offering an argument that can be disproven.
• AKA: non sequitur
– Literally: Doesn’t follow.
Eg: Pres. Obama: “The ground zero Mosque should
be built, because it is legal to build it”.
Ignores that “should” and “legal” might not mean the same thing.
Counterexample
• The Chewbacca Defense!
“Why would a Wookiee, an eight-foot tall Wookiee,
want to live on Endor, with a bunch of two-foot tall
Ewoks? That does not make sense! But more important,
you have to ask yourself: What does this have to do
with this case? Nothing. Ladies and gentlemen, it has
nothing to do with this case! It does not make sense!
Look at me. I'm a lawyer defending a major record company, and I'm talkin' about
Chewbacca! Does that make sense? Ladies and gentlemen, I am not making any sense!
None of this makes sense! And so you have to remember, when you're in that jury room
deliberatin' and conjugatin' the Emancipation Proclamation, does it make sense? No!
Ladies and gentlemen of this supposed jury, it does not make sense! If Chewbacca lives
on Endor, you must acquit! The defense rests.”
Persuasiveness
• Our “ear” tends to judge the quality of an
argument by whether we agree with
statements within the argument.
• We are less good at judging how well the
argument “hangs” together: i.e. relevance.
• So if you agree that it doesn’t make sense for
Chewbacca to live on Endor, you are more
likely to accept the conclusion:
“you must acquit”.
More examples
I’m in favour of legalizing marijuana, after all, it
is not as dangerous as smoking tobacco.
All Cats are Felines
No relevance b/w premises here.
All Dogs are Canines
Therefore No Dogs are Cats.
Sub category: Red Herring
• Irrelevancy introduced as distraction in the
course of an extended argument.
• Common in relationship fights:
“Where were you were last night?”
“How come you never empty the dishwasher?”
Also common in Question Period answers, where
the question is usually ignored.
Further example: red herring
• “I think there is great merit in making the
requirements stricter for the graduate
students. I recommend that you support it,
too. After all, we are in a budget crisis and we
do not want our salaries affected.”
• Many US elections allow “ballot initiatives”
that significantly confuse voting decisions.
– You might vote differently if you were asked to
approve measures to increase taxes, decrease
services and euthanize elders on the same ballot.
Sub Category: Straw Man
• The straw man (strawperson) is an argument
deliberately misconstrued so as to be easier
to refute.
Eg: strawman
• People who think abortion should be banned
have no respect for the rights of women. They
treat them as nothing but baby-making
machines. That's wrong. Women must have
the right to choose.
– Its unlikely that pro-life advocates have such an
extreme view.
The principle of Charity
• To avoid committing strawman fallacies, we
should adopt a rule of thought called the
principle of charity.
• This principle requires us to
interpret the arguments of others in the most
cogent way possible.
• If you can refute your opponents best
argument, you deserve to win!
Principle of charity in action
• Flanagan said U.S. President Barack Obama
"should put out a contract and maybe use a
drone or something.” "I think Assange should
be assassinated, actually," Flanagan said with
a laugh, and when asked to expand upon his
answer, added that he "wouldn't be unhappy"
if Assange "disappeared.”
• How should we interpret Flanagan’s remarks?
Two possible interpretations
• Hyperbolic: Flanagan is indicating his
displeasure.
• "Not for a second did I think he was suggesting
seriously that someone's life be put at risk," said Reid.
"He's a great guy with strong opinions, not a mean guy
with lunatic opinions.”
• Literal: Flanagan was advocating murder.
Liberal MP Denis Coderre has filed an official complaint
with the CBC's ombudsman Vince Carlin regarding what
he called a "declaration to incite violence.”
Source:http://www.cbc.ca/politics/story/2010/12/01/flanagan-wikileaks-assange.html
END
• End of fallacies
of relevance.
Do exercises p. 63ff.