Formal Fallacies 1

Techniques for generating
emotional or psychological,
rather than rational,
responses from an audience.
Some people may believe that
Paul is dishonest, but I’ll
withhold my judgment and
allow Paul to prove he’s an
honest guy.
Loaded Question
Proof Surrogate
I can’t believe you’re so dumb
that you accept the arguments of
anti-gun rights fascists. Their
current proposal to control gun
sales at gun shows is just the kind
of law Hitler would have loved,
and I don’t know about you, but I
want nothing to do with any effort
to strip hard working Americans
of their constitutional right to
bear arms. No one will ever be
able to eliminate crimes
committed with guns, so if the
choice is between allowing
Americans to have full rights or to
make them live in a fascist state, I
choose the former.
An idea or line of reasoning is
offered in support of a claim that
does not bear on the truth-value
of the claim.
Ad Hominem
Argument by Force
Poisoning the Well
Argument from Pity
Guilt by Association
Apple Polishing
Genetic Fallacy
Straw Man
Two Wrongs Make
False Dilemma
Perfectionist Fallacy
Faulty Appeal to
Line-Drawing Fallacy
Misplacing the Burden of Faulty Appeal to
Appeal to Ignorance
Emotional Appeal
Faulty Appeal to
Argument from Outrage Common Practice
Faulty Appeal to
Wishful Thinking
Scare Tactics
Bandwagon Fallacy
Hasty Generalization
Fallacy of the Lonely Fact
Argument by Anecdote
Fallacy of Small Sample
Generalizing from Exceptional
Fallacy of the Biased Sample
Self-Selection Fallacy
Fallacy of Accident
False/Weak Analogy
Look, you can say Johnston is a
good teacher all you want, but I
read a dozen student comments
about him on, and it
seems like students last semester
thought he was aloof and
unavailable—and I don’t care that
he was dealing with health issues
that semester. My sister told me
of a time she spoke with him a
few semesters ago, and he sounds
Supporting general statements
with inadequate/weak reasoning like a jerk. I think you have to
take seriously the choice of
OR faultily applying general
instructor you sign up for, so you
statements to specific cases.
shouldn’t sign up with someone
who’s got negative feedback on
Failing to establish the basis for a
claim that one event is the
Post Hoc, Ergo Propter Hoc
Overlooking the Possibility of trigger for another event.
Overlooking a Possible
As I was driving in to school
Common Cause
today, I had to pull over because I
Overlooking the Possibility of had a massive allergy attack.
Random Variation
When I started going again, I
Overlooking the Possibility of came across a horrible accident
at the next intersection that had
Cum Hoc, Ergo Propter Hoc
just happened. That wouldn’t
Slippery Slope
been me! I guess God was really
Untestable Explanation
looking out for me by triggering
that allergy attack.
Affirming the Consequent
Denying the Antecedent
Undistributed Middle
Fallacy of Composition
Fallacy of Division
Confusing Explanations with
Contradictories & Contraries
Consistency & Inconsistency
Miscalculating Probabilities
Gambler's Fallacy
Overlooking Prior Probabilities
Overlooking False Positives
Putting together the terms of an
argument in a manner that violates
one or more rules of logic.
If it is legal for Sally to drink, then
she is 21 or older. It is not, though,
legal for Sally to drink, so she is not
21 or older.
If X, then Y.
Not X.
Therefore, not Y.
Denying the Antecedent creates an
invalid argument.
1. Professor Parker can tell
you if you are sick; after all
he is a doctor.
The laws imply lawgivers.
There are laws in nature.
Therefore there must be a
cosmic lawgiver.
A warm beer is better than a
cold beer. After all, nothing is
better than a cold beer, and a
warm beer is better than
When a key term of an
argument is used
ambiguously, with one
meaning being employed in
one part of the argument and
another meaning being
employed in another part of
the argument.
7. A dialogue:
JILL: Helen has her mother’s
BILL: Good lord! Can the
woman still see?
23. Child molesters are
inhuman. So I think it’s
perfectly acceptable to
punish them any way we
want because they are not
really human.
Sure philosophy helps you
argue better, but do we
really need to encourage
people to argue? There's
enough hostility in this
I don't see how you can say
you're an ethical person.
It's so hard to get you to do
anything; your work ethic is
so bad
2. If this man is the president, then he
believes in immigration reform. If this
man is vice president, then he believes in
immigration reform. Therefore, if this
man is president, then he is vice
All lions are animals.
All cats are animals.
Therefore, all lions are cats.
If X, then Y.
If Z, then Y.
Therefore, if X, then Z.
All X are Y.
All Z are Y.
Therefore, all X are Z.
X (subject term of the conclusion) is
the “minor term.”
Z (predicate term of the conclusion)
is the “major term.”
Y (doesn’t appear in conclusion) is
the “middle term.”
To be “distributed,” the middle term
must refer at least once to the class
as a whole.
If X, then Y.
If Y, then Z.
Therefore, if X, then Z.
All X are Y.
All Y are Z.
Therefore, all X are Z.
15. Anybody who is serious about
losing weight will go on a low-carb diet.
Since Jerry is now on such a diet, that
tells me he is serious about losing
All X are Y.
Z is Y.
Therefore, Z is X.
X=People serious about losing weight.
Y=People on low-carb diet.
Can you develop an
argument with these
terms that is valid?
All X are Y.
Z is X.
Therefore, Z is Y.
25. All the hotels in the
Southwest chain are
known for their
elaborate lobbies and
spectacular lobby bars.
The Arlington has a
fantastic lobby and a
great lobby bar, which
makes me believe it’s a
Southwest Hotel.
Translate with X, Y, & Z.
X=Hotels in the Southwest
Y=Hotels with elaborate
lobbies and elaborate lobby
All X are Y.
Z is Y.
Therefore, Z is X.
3. If global warming is for
real, then the mean global
temperature will have risen
over the past ten years.
And that is what has
happened. Therefore,
global warming is for real.
If X, then Y.
Therefore, X.
X=Global warming is for real.
Y=The mean global temp will
have risen over the past ten
If X, then Y.
Therefore, Y.
9. If Congress changes
marijuana from a Class 1 drug
to something lesser, next year
the penalties for possession
will be much less than they
are now. But Congress is not
going to declassify marijuana
anytime soon. So we’ll have to
live with the drastic penalties
for at least another year.
If X, then Y.
Not X.
Therefore, not Y.
If X, then Y.
Not X.
Therefore, not Y.
10. If you are rich, then your car is
something like a Mercedes or a Bentley.
Oh! Is that your Bentley, you rich old
thing, you?
16. You will have only a small probability
of Alzheimer’s disease if you study a
language, play a musical instrument, or
work puzzles. Unfortunately, you don’t
do any of these things, so you aren’t
going to lower you chances of
17. If bankers were honest, they’d turn
back the bonuses they got when their
companies were going broke. But
they’re not honest, so you know they
won’t turn back those bonuses.
18. If you filed before the first, then we
received your taxes on time, which we
did. See how nice it is to file before the
If X, then Y.
Not X.
Therefore, not Y.
If X, then Y.
Therefore, X.
If X, then Y.
If Z, then Y.
Therefore, if X, then Z.
All X are Y.
All Z are Y.
Therefore, all X are Z.
4. My chance of being born on
December 25 was the same as
yours. So the chances we were
both born on December 25
have to be twice as good.
--miscalculation of probabilities
11. Man! Three sons in a row?
Your next kid is bound to be a
--miscalculation of probabilities/gambler’s fallacy
19. I’ll bet the Baltimore
Ravens lose the coin toss
today. The last Super Bowl
they were in , they won it,
--miscalculation of probabilities
5. Sodium is deadly poisonous, and so is
chlorine. Salt consists of sodium and
chlorine, which must be why we’re told
not to eat too much of it.
-6. The Bible commands you to leave life
having made the world a better place.
And therefore it commands you to
make the world a better place each and
every day.
12. The design team for the new project
is made up of the best designer from
each division of the company. So you
know it is the best design team ever.
13. I like cranberry juice and I like beer.
So I’m going to buy a case of this new
thing, cranberry beer.
14. Voters overwhelmingly approved
the reelection of Obama. Therefore,
Sean Hannity overwhelmingly approved
the reelection of Obama.
20. Tyrannosaurs probably ate more
of the fellow creatures than any
other dinosaurs. After all, they were
the largest carnivores on the planet
during the Cretaceous period.
21. If anybody in the race, can raise
their speed by four miles per hour,
they will surely with the race. So, if
everybody in the race can raise
their speed by four miles per hour,
they can all win the race.
22. I know I gave more in taxes this
year! The federal gov. collected
about $2.4 trillion in taxes this year,
and that’s more than ever before in
What’s wrong with
socialism? I’ll tell you
what’s wrong with
socialism. Americans don’t
like it. That’s what wrong
with socialism.
“Everybody or most
people or many believe X
is right/true/good, so X
must be right/true/good.”
So you want to know why
you should try to do well on
these logic exercises in class
today? I’ll tell you: because
if you don’t, I’ll ask you to
leave and not return.
Scare tactics and Argument by Force.
Threatening rather than reasoning.
Motivating by fear rather than reason.
Some people have
the gift of psychic
power and can
read minds. Don’t
believe me? Name
one scientists or
identify one study
that proves no one
has psychic power.
There are very good reasons for the death
penalty. First, it serve as a deterrent to those
who would commit capital offenses. Second, it is
just and fair punishment for the crime committed.
Third, reliable polls show that over 70% of all
Americans favor it.
Why should I put a note on this guy’s car that I
just dented? Do you think he’d put a note on my
car if he put a dent in it?
Can I prove the Biblical flood really happened?
Hey, can you prove it didn’t?
There is no evidence against
the theory of evolution, so
until someone produces that
evidence, I’m going to accept the theory as a
credible one.
Can I prove the Biblical flood really happened?
Of course it happened! Why else would Noah
build an ark?
Stephen Colbert: “George W. Bush: great
president or greatest president?”
I believe that when we die, we are all given new,
young, perfect bodies, and we spend eternity with
those whom we love. I can’t imagine the point of life
if it all just ends when we die!
“Historically, marriage has been restricted to
heterosexual couples. Therefore, it’s right to restrict
marriage to heterosexual couples.”
“You’re giving me grief for downloading music on a
P2P network?? Please. Who doesn’t do that these
Hands off our freedom, atheists
Letter to the editor, Times Standard 08/29/2013
I agree with Dr. Lawrence's “My Word” (”Atheists' lawsuits disrespect our
nation,” Times-Standard, Aug. 20, Page A4). I am so sick and tired of atheists
attacking us Christians with idiotic lawsuits. We don't try to sue atheists
because they don't believe in God. If atheists want respect, they should be
respectful. They twist the Constitution claiming that separation of church
and state means no prayer, and no religion at all in any government office.
That is not what separation of church and state means! It was put in the
Constitution so the government couldn't tell us how to worship. The
pilgrims came to America to escape religious persecution. My problem with
atheists isn't because they don't believe like I do. My problem with them is
their constant complaining and whining and filing silly expensive lawsuits.
The only aim of such lawsuits has nothing at all to do with the Constitution
but it is to take away the freedom of Christians. We are told by atheists that
we can pray in church or at home but that we shouldn't pray in public. They
tell us where we can display nativity scenes. They want prayer out of the
schools. It wasn't very far back in history that schoolhouses were used as
churches on Sundays. If atheists don't want to be labeled as negative then
they need to keep their hands off our freedom! No, Dr. Lawrence, you need
not apologize. The atheists need to give us Christians an apology.
Becky Payton , Eureka

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