Fallacies
Fallacies in Making a Case
• Fallacies of Relevance
• Fallacies of Inadequate Evidence
• Fallacies of Illegitimate Assumption
Fallacies of Relevance
Irrelevant evidence is give to
support the argument
Fallacies of Relevance
Appeal to Ignorance
Example:
Of course I believe in ESP. No one has
ever demonstrated that it doesn’t exist.
Fallacies of Relevance
Appeal to Inappropriate Authority
Example:
Aldous Huxley, renowned author, wrote a
book advocating that nearsightedness
could be cured with eye exercises.
Fallacies of Relevance
Appeal to General Belief
Example:
We all know most people on welfare are
just too lazy to work. We should start a
program requiring those on welfare to
provide community service to earn their
money.
Fallacies of Relevance
Appeal to Popular Attitudes & Emotions
Example:
I’ll tell you why I believe we were right to
go into Iraq. It’s because I love my
country. If you love America, then you’d
agree.
Fallacies of Relevance
Gambler’s Fallacy
Example:
The last ten flips have been tails, so heads
should come up soon. We’d better bet all
we have on heads.
Monty Hall problem
Fallacies of Inadequate Evidence
Arguments with premises that present
relevant, but inadequate evidence to
support a conclusion
Fallacies of Inadequate Evidence
False Cause (Post Hoc)
Example:
I wore this pair of socks for the last game,
and we won, so the socks must have
given me good luck.
Fallacies of Inadequate Evidence
Hasty Generalization
Example:
An accountant opens her own business.
The first two clients lie about their income
and she finds out. She concludes that
most clients lie about their income.
Fallacies of Relevance
&
Inadequate Evidence
After death experiences are a reality.
Despite years of attempts at
debunking, no one has ever been
able to show that reports from beyond
the grave are all due to error,
deception, or simply wishful thinking.
I’ve been feeding this slot
machine for 20 minutes, and the
person before me pumped in
$200 with no payout. I’m due a
hit any minute.
Nobody wants to say so in public,
but we all know that immigrants
don’t have as strong a
commitment to this country as
those of us who were born here.
The Dallas group held a rain dance at
the Turtle Creek fountain Sunday
night, and the group leader, Debra
Denton, claimed it got results. “It
rained, didn’t it?” she asked.
Dr. R.J. Palmer, one of New York’s
leading oral surgeons, has pointed
out that evolution theory requires us
to say that a species of reptile
changed into a birdlike creature, so
the whole absurd theory is mistaken.
Dr. Palmer’s scientific assessment
shows why it is that no reasonable
person can be an evolutionist.
You don’t have to be of noble birth
to appreciate Cutty Sark Scotch
Whiskey. All that is required is
noble taste.
Americans reject gun control. A
2003 survey conducted at the
National Hunting Association
revealed that 71% of the 50
people interviewed are opposed
to legal regulation, including the
restriction of assault rifles.
Fallacies of Illegitimate Assumption
Arguments that rely on some sort of
illegitimate premise
Fallacies of Illegitimate Assumption
False Dilemma
Example:
Either you’re for us or against us. It is
obvious that you aren’t for us, so you must
be against us.
Fallacies of Illegitimate Assumption
Loaded Question
Example:
Are you still beating your wife?
Fallacies of Illegitimate Assumption
Begging the Question
Example:
James is a murderer because he wrongfully
killed someone.
Fallacies of Illegitimate Assumption
Slippery Slope
Example:
If we legalize marijuana, then next thing
people will be shooting up heroine in every
public bathroom.
Fallacies of Illegitimate Assumption
Are women still discouraged from
excelling in sports by a lack of
financial or emotional support?
Once we adopt a policy of failing
to enforce laws prohibiting
littering, loitering, and
panhandling, we might as well
give up on enforcing the laws on
assault, rape, and murder.
Adultery cannot be justified. The
reason it can’t is simply that it is
never acceptable for a married
person to have sex with someone
who is not his or her spouse.
When can I make up the exam I
missed?
We can achieve peace in the
Middle East either by negotiations
or by war. Negotiations have led
nowhere, so what is there left to
do but send in troops?
If we recognize Cuba
diplomatically, then we will have
to grant the same status to every
country run by an anti-American
dictator.
The reason you can’t trust Roth is
that he’s a liar, a fraud, and a
deliberate deceiver.
Senator Anson voted against the
proposed constitutional amendment
prohibiting burning the America flag
as a form of protest. A legislator must
either support the amendment or
support flag burners. Senator Anson
has made his choice, and next
November the voters will make theirs.
Why do the Democrats always
want to raise taxes?
Fallacies of Criticism
Misdirection away from the main point, so
the respondent doesn’t have to consider
the legitimacy of the claim
Fallacies of Criticism
Against the Person (Ad Hominem)
Example:
As a gay conservative, Andrew Sullivan
can’t possibly have anything constructive
to offer the right.
Fallacies of Criticism
You Too
Example:
• Brown: You are a cheat. You left half your
income off your tax return last year.
• Smith: Big deal. You lied about
deductions and had the nerve to claim
your dog as a dependent.
Fallacies of Criticism
Pooh-Pooh
Example:
Mr. Paulson would basically pooh-pooh
the subprime problems until major Wall
Street powers got in trouble and then—
presto—swing into action.
Fallacies of Criticism
Straw Man
Example:
The theory of evolution boils down to the
idea that human beings are descended
from apes.
Fallacies of Criticism
Loaded Words
Example:
Medical research on animals simply must
be stopped at once. This torture of
innocent creatures is morally indecency,
not science.
Fallacy of Response
Definitional Dodge
Example:
You’re not real fan of the Bengals because
you don’t finish watching the games when
they’re losing.
Yeah, well, only a real fan has season
tickets. And since I have season tickets
and you don’t, I’m the true fan.
Fallacies of Criticism
Jimmy Carter: The survival of the world
depends on ending the cycle of nuclear
arms development. That’s why it’s crucial
for us to join with other nuclear states and
sign the SALT II Treaty.
Ronald Reagan: Jimmy Carter says we
should sign the SALT II Treaty because
nobody will like us if we don’t.
If you can’t come up with
something besides the feminist
cliché that our ad demeans
women, I don’t see any reason to
answer you.
Gloria’s views on fighting terrorism
are wrong. Is she an intelligence
expert? No. Someone with police
experience? No. I tell you what she is,
she’s a commercial baker. That’s
right, a cookie maker!
So I don’t want to see gays in
public office, but you’ve got no
room to object. You don’t want to
see women get elected.
Senator Clemens says we should
spend less on giving tax rebates to
the rich and more on improving
education. But this is just the same
tired liberal cliché we’ve heard
before—nothing worth taking
seriously.
Bob is as morally bankrupt as
he is financially.
You’ve never had a taste of
beer because beer can’t be
tasted in a sip.