RomThirtythirtynine
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Aug 16, 2024
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About This Presentation
Informal policies
Size: 1.12 MB
Language: en
Added: Aug 16, 2024
Slides: 41 pages
Slide Content
Informal Fallacies
Defective reasoning that makes weak arguments
appear stronger.
Tools of advertisers, propagandists, charlatans,
and sincere yet self-deceived people who make
claims without the benefit of good evidence.
Aristotle was the first thinker to begin to classify
various types of defective inferences that
provide psychologically persuasive (but not
logically adequate) reasons to believe a claim.
Fallacious Assumptions
False Dilemma:
Presenting two
alternatives as the
only ones when others
are possible.
Either you accept every
verse of Scripture as
God’s word or reject it
all as false human
religious speculation.
If the glove does not fit, you
must acquit!
Sneaky Assumptions
Complex question:
Two questions asked as
one to trap the unwary.
How long have you had
the drinking problem?
When will Fox and CNN
get out of bed with the
Bush administration?
When will Obama stop
lying about his birth
certificate?
Innuendo: Saying one
thing but suggesting
something more
negative.
Yes, he’s telling the
truth, this time.
She’s competent in
many ways.
He’s pretty bright, for
a community college
instructor.
Circular Reasoning
Begging the question: when the arguer assumes as a
premise the conclusion he or she is arguing for.
Abortion is murder because it kills babies.
No affirmative action policy can be fair or just because
you can’t fix one injustice by committing another.
We have to have the death penalty to keep murderers
off our streets.
We must reject Obamacare. Government programs are
never as effective as private enterprise.
Ambiguity
Equivocation: Shifting
the meaning of an
ambiguous term.
Knowledge is power.
Power corrupts.
Therefore, knowledge
corrupts.
We have the right to
study logic. We have a
duty to do right….
Ambiguous Phrasing: Amphibole
Dog for sale. It eats
anything and is very
fond of children.
If you don’t go to other
people’s funerals, they
won’t come to yours.
He is trying to quit
smoking cold turkey.
Tired of cleaning
yourself, let us do it for
you.
False implication:
When an advertiser
says something true
but implies something
that isn’t true.
False Implication!
Fruity Pebbles
Captain Crunch Crunch Berries
Country Time Lemonade
The Navy, it’s not just a job,
its an adventure.
When you’re hungry, reach for a
Snickers.
You’ve come a long way, baby.
Tylenol, the official supplier of
pain relief products to the US
Olympic team.
Composition and Division
Composition:
Incorrectly inferring
that what is true of the
parts is true of the
whole.
We have the best
athletes in the league on
our team, so we have the
best team.
OxiClean is yours for just
four easy payments of
$19.95
Division: Incorrectly
inferring that what is
true of the whole is true
of the parts.
USC has a great school of
business. Therefore,
since Jane went to USC,
she must be a great
businesswoman.
TRW is a high paying
company so Lester will
make a lot now that he
works for them.
Vagueness
Abuse of vagueness: Using a vague expression for
it’s persuasive power as a substitute for evidence.
Homosexual behavior is perverse because it isn’t
natural.
Puffery: Intentional overstatement in advertising.
Great Western Bank, we’ll always be there.
Gillette, the best a man can get.
Hype: Exaggeration: Amazing bargains! Incredible
deals! Biggest sale of the season!
More Advertising Fallacies
Unspecified
Comparison:
When a product is
compared to an
unnamed competitor.
Taster’s Choice Coffee-
smoother taste.
Smoother than what?
Less filling, lower in
fat, etc.
Weasel Words:
Advertisers use weasel
words to make
vacuous claims look
substantive.
Make your floor look
like new.
Helps you look
younger!
Lasts up to eight hours.
Euphemism
Using a term that
sounds nicer than the
reality it refers to.
Passed on
Freedom fighters
Friendly fire
Terminate with
prejudice
We have to separate
you.
Loaded language-
when the terms
distort the issue.
Gun control fiasco
War on drugs
Abortion holocaust
Illegal alien invasion
Extreme Quantifiers and
Intensifiers shut off debate.
Everything she says is
a lie!
PETA activists are
completely misguided.
Obamacare is totally
flawed.
I know that my
redeemer liveth!
Your resume claims you
are absolutely the greatest
Economics instructor in the
World (?)
Rhetorical Questions
A question with only
one possible answer.
Do you want some
government
bureaucrat deciding
whether or not you’re
entitled to an
operation?
Should scientists
tinker in God’s work?
Phantom Distinctions:
Making a distinction
to suggest differences
that don’t really exist.
No, you aren’t being
fired but your position
has been eliminated
due to downsizing.
I’m not pro-abortion,
I’m pro-choice.
Red Herring
When the arguer changes the subject to a
different issue which is psychologically, but not
logically, connected to the original issue.
Some people say we need to do more about airline
safety. But more people are killed driving to the
airport than in plane crashes.
How can you whine about dead seals when people
are being killed in Africa?
Straw Person
Distorting another’s position (by making it appear
more radical, extreme, or simplistic than it really is)
and then attacking the distorted version of their view.
PETA members think a human life is no more valuable
than the life of a cow, a rat, or even a cockroach.
Liberal’s think poverty causes crime. What happened to
character and personal responsibility?
Professor Dylan favors legalizing marijuana.
Apparently he wants to live in a society where everyone
sits around stoned out of their minds all day long.
https://www.youtube.com/watch?v=dd1MMkdU
W6c
Two Wrongs
Shifts the blame by
introducing an
irrelevant
comparison:
Henry Hyde argued
that Clinton should be
impeached. But he had
an adulterous affair
that destroyed a
marriage.
Common practice:
Justifying some
morally suspect
behavior by claiming
that others do it too.
There’s nothing wrong
with exaggerating
your business expenses
for the IRS. Everyone
does it!
Ad Hominem
Ad hominem (against
the person) attacks the
arguer rather than the
substance of her
argument.
Abusive ad hominem:
Attempts to discredit
an argument by
assaulting the
character of the
arguer.
Reverend Bud Green
argues that hemp
should be legalized.
But he is a long-haired
weirdo from Venice
Beach, so what would
you expect?
Atheism starts in the
heart and spreads to
the head. Norman
Geisler
Circumstantial Ad Hominem
Attempting to discredit
an arguer’s position by
claiming that his view is
dictated by his
circumstances.
Cindy argued against the
single payer health care
proposal. But she works
for Blue Cross, so of
course she is against it!
Guilt By Association
Discrediting people,
views, or arguments
based on someone’s
relationships with
others.
We can ignore Rikki’s
anti-fur argument. She
belongs to PETA and
they are extremists.
Dear Tom,
No wonder your position stinks
because you are a stinking male!
Love, Mari
More Ad Hominems
Genetic Appeal:
Evaluating an argument
or policy strictly in
terms of its origin.
Christmas trees are of
the devil! They were first
used by Roman pagans.
Government health care
plans are bad because
they originated in
socialist countries.
Poisoning the Well:
Attempting to create
prejudice against a
position before it has
been heard.
Come on, Cardinal
Dolan! How can a
celibate male give an
argument on birth
control.
Provincialism and Tradition
Provincialism: Appealing to group loyalty rather
than evidence to support a position.
Support the B-2 Bomber! It means jobs for California.
The Teachers Union advises a no vote on measure S.
Appeal to Tradition: Claiming that a view is likely to
be true because it is affirmed by tradition.
Marriage has always been an institution involving a man
and a woman. So we should not permit same sex marriages.
Of course you will take my last name. Wives always do!
Novelty and Positioning
Novelty: It is good
because it is new or
different.
Vote Hayden, vote for
change!
Positioning:
Positioning a product
or person with a
better known rival.
7-Up, the uncola.
Damn, the novelty is already
wearing off.
Emotional Appeals
Appeal to Anger: Arouse feelings of anger as a
substitute for evidence.
If you want my gun you’ll have to pry it from my
cold, dead, hand!
Appeal to Fear (or force)
Listen, Galileo, drop this heliocentric nonsense or
Brother Vito will rotate your head around the sun!
Hurry in! These unbelievably low prices won’t
last!
FEAR!
Appeal to Pity
Please officer! If I lose
my license I’ll lose my
job. Who will pay for
Mama’s surgery?
Stop animal testing!
Save Fluffy!
Keep animal testing!
Save Granny!
Please, no truth tables on the exam.
I have an ulcer, I need less stress.
If not either p nor
q imply not both
r and s, then q is not
quite true, I think.
Appeals to Authority
Appealing to an authority who is either
unqualified, biased, mistaken, or lying; or when
there is no consensus of expert authority
Invincible authority: Using an authority to
override all other evidence.
The Bible says, “wives, obey your husbands.” So
start packing, we’re moving to Barstow.
Forget what your mama taught you, Susan.
Charlie says we have to kill the pigs!
False Authority
Unidentified Authority Irrelevant Authority
When expert opinion is
alluded to without explicit
identification of who the
expert is.
Studies show that gun
control doesn’t work.
Experts agree that
legalizing pot would be a
disaster.
The authority cited must
be qualified on the topic in
question.
Reverend John McArthur
claims that the theory of
evolution is not grounded in
good science. Apologist Hank
Hanegraaff, the Bible Answer
Man, concurs with this
opinion. Hence, we can
conclude that evolution is a
flawed theory.
More False Authority Fallacies
Testimonials: When a
celebrity or unknown
user of a product
endorses it’s value,
their testimony
provides weak support.
Tiger Woods says drive
a Buick, chicks dig it!
I lost 50 lbs in two days
with the lap band!
Division of Expert
Opinion: When the
experts have not
reached a consensus,
we cannot appeal to
one expert’s view to
resolve a dispute.
We know alien abductions
really occur. Even Harvard
psychiatrist John Mack
believes alien abduction
reports are authentic.
Conflict of Interest
Bbb
Trust me, I know!
When there is reason to
believe that the authority
cited has a vested
interest in the topic, his
or her testimony is
compromised by bias.
The CEO of Shell Oil says
offshore drilling is
completely safe, so we
can approve their request
to drill.
Statistical Inference Fallacies
Small Sample: Overestimating the statistical
significance of evidence derived from too few cases.
In a published article, three gay men testified that
their homosexuality was a choice, not a decision
forced on them by their genes or upbringing. Thus,
there is no biological basis for male homosexuality.
All three of my husbands had affairs so don’t deny
the fact that all men are cheaters.
My husband died of brain cancer and he was a pot
smoker so marijuana smoking causes brain cancer.
Unrepresentative Sample
Unrepresentative Sample
Overestimating the
statistical significance
of a sample drawn from
a particular sample
group where a bias
influences responses.
Of 50,000 residents of Salt Lake
City surveyed, 90% say they
oppose legal abortion. This
shows that Americans
overwhelmingly oppose
abortion.
Biased Methodology: A
study that uses loaded
or leading questions,
restricts range of
responses, etc.
Do you favor Obama’s
socialistic health care reform
that will bankrupt our country,
or do you prefer to continue to
allow private enterprise to
deliver the best health care in
the world?
Suppressed Evidence
Deliberately ignoring
evidence that tends to
undermine one’s
position.
I was the number one
salesman in the firm.
See how much dirt was left
behind by your vacuum
when we vacuum the same
area with the Oreck 3000!
We have less ships than we
had in 1916.
Bad Base Line:
Overestimating the
significance of some
trend (in crime rates,
welfare rates,
unemployment rates,
etc.)
Gambler’s fallacy: Thinking
past results of chance events
affect the probability of
future results.
I’m due to win, baby!
Faulty Analogy
An argument from analogy is weak when it
ignores relevant dissimilarities between the
items compared or uses similarities that are not
relevant to the conclusion.
Sure guns kill, but so do baseball bats and no one wants to ban
them!
Guns kill people like spoons made Rosie O’Donnell fat and pencils
misspell words and cars make people drive drunk.
"This bill [to ban the carcinogen chlordane] reminds me of
legislation that ought to be introduced to outlaw automobiles"
on the grounds that cars kill people, said Rep. Tom DeLay, R-
Texas,
Ad Ignorantiam
An argument from ignorance misplaces the burden
of proof by claiming either that because a certain
claim has not been proven false, it is probably true,
or that because a claim has not been proven true, it
is probably false.
No one can prove that angels don’t walk among us!
Invincible Ignorance: To refuse to accept the
burden of proof by denying all evidence that
contradicts a position.
You can keep your fossils and biology books, Genesis is God’s word
and it don’t say I come from no monkey!
Causal Fallacies
Confusing correlation
with causation.
83% of criminals drink
alcohol before committing
crimes. So Alcohol use
causes crime.
Post hoc ergo propter
hoc. Mistaking temporal
succession for causal
connection.
Prayer works! I said
four “Hail Mary’s” before
the game and the
Chargers won!
Common Cause:
Inferring a causal
connection when two
items are both produced
by an underlying cause.
75% of Prozac users have
contemplated suicide. That
stuff is dangerous!
Questionable Cause
Causal Oversimplification
Mistaking a
contributing cause as
the primary cause.
We can resolve the
budget crisis in
California if we crack
down on illegal
immigration and stop
giving benefits to people
who are here illegally!
False Inference to
Best Explanation:
Maintaining an
implausible hypothesis
simply because you
haven’t thought of a
better explanation.
I must have been a Egyptian
princess in a past life because I
uttered some Egyptian words
during hypnotherapy.
Questionable causal
assumptions
Disease and natural
disasters are divine
punishments for
human sin.
Comic books, or video
games, or certain types
of music produce
juvenile delinquency
A close brush with
death means God saved
you from harm.
Demons are
influencing events.
Personality is affected
by date of birth.
George Bush was
responsible for 9/11
Genetically modified
food is harmful.
God wants one person
to kill another.
Slippery Slope
An unwarranted
prediction of disastrous
results from adopting
some policy.
If we allow terminally ill
patients to take their own
lives, respect for the
sanctity of life will
diminish. Soon the elderly
and the disabled will be
killed against their will.