Fallacy Examples and explanations with pictures.ppt

This presentation helps students to understand the base argument fallacies out there today.

1. Fallacies in Reasoning
when good arguments go bad…

2. formal logic versus informal logic
Formal logic or deductive
reasoning should not be
confused with informal logic or
inductive reasoning.
In formal logic, if the premises
are true the conclusion
necessarily follows.
In informal logic, there is always
an “inferential leap” that is made.
Most everyday arguments rely on
inductive reasoning or informal
logic.

3. Formal versus Informal Logic
Deductive Reasoning
All cats have nine lives
Felix is a cat
Therefore, Felix has nine
lives
All Zorabs are Nimtotes
No Nimtotes are Wing
Lings
Therefore No Zorabs are
Wing Lings.
Inductive Reasoning
If it looks like a duck,
walks like a duck, and
quacks like a duck, it’s
probably a duck.
Loretta got teary-eyed
when she got her exam
back, so I guess she got
a bad grade.

4. fallaciousness versus invalidity
Fallaciousness is a matter of
degree.
An argument may be
“somewhat” fallacious,
“probably” fallacious,
“slightly” fallacious,
“highly” fallacious, and so
on.
Just because an
argument is fallacious to
some degree doesn’t
exclude the argument
from consideration.
In formal logic, the
conclusion of an argument is
either valid or invalid.
A deductive argument
cannot be “sort of” valid or
“mostly” valid.

5. post hoc or faulty cause
This ad implies that buying
Quaker Oats cereal bars will
transform kids from being
couch potatoes into active,
outdoorsy types.

6. post hoc fallacy
These employees are
confusing coincidence
with causation if they
think a particular office
chair is making them
pregnant
The women who worked
in the chair were
probably in their prime
child-bearing years.

7. post hoc or faulty cause
On June 15, 2006 Dick Cheney
claimed our success in Iraq is why
terrorists haven’t struck the U.S.
again.
the war in Iraq is ``in part
responsible for the fact that we
haven't been hit again in nearly five
years. That's no accident.” Dick
Cheney, June 2006
But Cheney has no actual proof that
any attacks have been thwarted.
Perhaps the terrorists are just biding
their time?

8. post hoc or faulty cause
The slogan “It’s gotta be the
dog chow” wrongly attributes
this dog’s super-canine
strength to a pet food.
This isn’t a serious fallacy,
because the ad is intended
to be humorous.

9. appeal to authority
Anna Nicole Smith was the
celebrity spokesperson for Trim
Spa.
But she was hardly an expert on
fitness or nutrition.
Did the fact that she was a paid
endorser affect her opinion of the
product?
Did she have any extra help such
as a personal trainer?
Could the other drugs she was
taking have produced her weight
loss?

10. appeal to authority
This “got milk?” ad is the worst
kind of appeal to authority
because
A) it targets little kids who are
uninformed consumers
B) it relies on fictitious cartoon
characters who can’t benefit
from drinking milk

11. ad hominem
Speaking at the Conservative Political
Action Conference, Anne Coulter
declared, “ I was going to have a few
comments on…presidential candidate
John Edwards, but it turns out you have
to go into rehab if you use certain
words.”
Anne Coulter called Senator Ted
Kennedy “an adulterous drunk.”
She joked that President Clinton had
“crack pipes on the White House
Christmas tree.”

12. ad hominem fallacy
This hate site is operated by
the Reverend Fred Waldron
Phelps, who is the pastor of
the “New Baptist Church.”
He and his followers believe
tolerance of homosexuality has
prompted god to kill U.S.
troops in Iraq.
Members of his church picket
public events, including military
funerals.
All mainstream religious
organizations, including the
Baptist church, have
condemned Phelps’ actions.

13. faulty analogy
Doctors Versus Guns?
Number of physicians in the U.S.
= 700,000
Accidental medical deaths each
year = 120,000
Accidental deaths per physician
per year = 0.171
Number of gun owners in the
U.S. = 80,000,000
Number of accidental gun deaths
each year (all age groups) =
1,500
Accidental gun deaths per gun
owner = .00001875
The ratio 0.171 to 0.00001875 =
9120
So doctors are about 9000 times
more dangerous than gun
owners!
there is no proof that physicians,
specifically, caused the accidental
medical deaths. Accidental deaths
in hospitals could be caused by
nurses, orderlies, therapists, or
other allied health personnel.
comparing accidental medical
deaths to accidental gun deaths
underestimates the number of
people killed by guns. Many gun
deaths are murders.
one involves a self-imposed risk, the
other does not. Before being
treated by a physician, patients give
their written consent.
To be fair, the comparison should
take into account how many lives
doctors save, not just how many
they kill
people killed by guns weren’t sick to
begin with. When people go see a
doctor they are usually ill. Some of
those patients are terminally ill.

14. faulty analogy
Stealing a car, a handbag, or
a DVD are property crimes
Downloading a movie is a
copyright infringement or a
violation of intellectual
property laws.

15. faulty analogy
Perhaps a Twix bar does
taste sinfully good.
However, god never
commanded anyone not to
eat a Twix bar.

16. hasty generalization
Testimonials are always
suspect because they involve
small, atypical samples.
Just because Slim Fast
worked for this woman
doesn’t mean it will work for
everyone.
A controlled clinical trial is
much better proof that a diet
product works.

17. hasty generalization
Perhaps Americans are
really dumb.
On the other hand this isn’t a
random, representative
sample of Americans
The video clip was likely
edited to include only the
dumbest responses.

18. false dilemma
Dilbert’s pointy-haired boss assumes there are
only two kinds of diets, and both are bad.

19. appeal to ignorance
The “thought screen helmet” was invented by
Michael Menkin in 1998
“The thought screen helmet blocks
telepathic communication between aliens
and humans. As of June, 2000, aliens
have not taken any abductees while they
were wearing thought screen helmets
using Velostat shielding.”
Just because this guy hasn’t been abducted,
doesn’t prove the “thought helmet screen”
works.
Moreover, the fact that someone claims aliens
are reading our thoughts doesn’t prove there
are aliens or that they are, in fact, scanning
our brains.
•"Since trying Michael
Menkin's Helmet, I
have not been
bothered by alien mind
control. Now my
thoughts are my own. I
have achieved
meaningful work and
am contributing to
society. My life is better
than ever before.
Thank you Michael for
the work you are doing
to save all humanity."
- Jon Locke, alleged
alien abductee

20. tautology
Tautology, or circular
reasoning, relies on
premises which lack
external proof or support.
Like a “house of cards” the
premises all depend upon
each other.
If there is no test capable of
disproving an argument, if
the argument is false, then
the argument is
tautological.

21. non-sequitur
This ad offers an irrelevant
reason for choosing Buckley’s
cough syrup.
The taste of a cough remedy
has nothing to do with how well
it works.

22. non-sequitur
“How can I be racist? I drive a
Prius!” says Julia Louise Dreyfuss’
character in the TV show The New
Adventures of Old Christine
Julia-Louis Dreyfus recommends
an African-American family be
admitted at her son’s school. As it
turns out, however, the family is
homophobic.

23. non-sequitur
“If you are against the war in
Iraq, then you are against
the troops.”

24. inconsistency
Shouldn’t an ad for educational
software be spelled correctly?
The ad should say “They won’t
even know they’re learning.”

25. inconsistency
Bush on global warming in 2006: "I
have said consistently that global
warming is a serious problem. There's a
debate over whether it's manmade or
naturally caused.” June 26, 2006
Bush on global warming in 2002: “We
need an energy bill that encourages
consumption” George W. Bush,
September 23, 2002
In 2001:, George W. Bush pulled the
USA out of the Kyoto accords as one of
the first acts of his presidency.

26. inconsistency
“It’s clear this election they’re
having is not going to count
for anything.”
Hillary Rodham Clinton,
October 2007
“If you are a voter from
Florida or Michigan, you
know that we should count
your vote.”
Hillary Rodham Clinton,
March 2008

27. inconsistency
Donald Rumsfeld caught in a
lie
He claims it is “folklore” that
he called Iraq an “immediate
threat,” until a journalist
confronts him with a
transcript of what he actually
said.
http://www.ifilm.com/ifilmdetail/2537851

28. inconsistency
It seems contradictory to
warn people about gambling
addiction on a Lotto ticket.

29. inconsistency
What is a motorist supposed
to do?

30. appeal to extremes
This fear appeal “appeals
to extremes” by implying
that if you smoke
marijuana you’ll hit and kill
a child.
But how many traffic
fatalities per year are
actually attributable to
marijuana use (as
opposed to alcohol)?

31. appeal to extremes
When Lindsay Lohan was
told by Delta airlines that
she would have to ride in
coach, because all the first
class seats were taken, she
through a tantrum and
claimed she would “die” if
she had to sit in coach.

32. equivocation
Dilbert’s pointy-haired
boss relies on
equivocation by
employing two different
meanings of the word
“exercise.”

33. equivocation
“I did not have sexual relations
with that woman, Miss
Lewinsky. I never told anybody
to lie, not a single time; never.
These allegations are false.”

34. begging the question
This letter to the editor
begs the question by
assuming everyone
believes in a god of some
sort.
What about atheists?

35. faulty sign
Advertisers of luxury goods want
you to think that owning their
products will is a mark of class or
sophistication. Not so.
Just because you wear the same
brand of watch that James Bond
wears, does not mean you are
cool, suave, and sophisticated.
(also an appeal to authority)

36. slippery slope
“once marriage is no longer
confined to a man and a woman, it
is impossible to exclude virtually
any relationship between two or
more partners of either sex--even
non-human ‘partners.’” Timothy J.
Daly, The Slippery Slope of Same
Sex Marriage, Family Research
Council
But society can take one step
(legalizing same sex marriage)
without taking any other steps
(legalizing polygamy, bestiality, or
incest)
As an example, setting the legal
age for marriage, without parental
consent, at age at 18 hasn’t
spawned a movement for legal
marriage at age 15.
As another example, being
allowed to marry a 1st cousin
didn’t produce a clamor to marry
brothers and sisters.

37. slippery slope
This NRA ad claims that
banning handguns would leave
to a ban on all guns
But other categories of
weapons, like machine guns
and automatic weapons, have
already been outlawed, and it
hasn’t led to a blanket ban on all
firearms.

38. red herring
Dick Cheney claimed Saddam
Hussein had ties to Al Qaeda as a
diversionary tactic to justify military
intervention in Iraq
Associated Press, June 15, 2004:
Vice President Dick Cheney said
Monday that Saddam Hussein had
“long-established ties” with al-Qaida,
an assertion that has been
repeatedly challenged by some
policy experts and lawmakers.