Logic Slides 3 Fallacies

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Logic Slides 3Fallacies

• PHIL 211
• Cosmos to Citizen
• Dr. Mike Miller
• Mount St. Marys College

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List of Fallacies
Any argument that makes a mistake in reasoning is
fallacious (that is, commits a fallacy). There
are many fallacies. We have already looked at a
number of fallacies, including the fallacies
of Ad hominium Confusing the worth of an
argument with the person making the
argument. Equivocation When two clear but
different meanings exist in the same
sentence. False Cause Either looking too hard for
a cause, overlooking a common cause, or reversing
cause and effect. Hasty Generalization Either too
small a sample, a non-representative sample, or a
biased survey. Loaded Language Including
euphemisms, dysphemisms, up-players, down-players
and weasel words. The following slides provide
just some of the more popular fallacies. Many
are covered in Weston, Chapter X. Others
presented here are not in Weston.
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An argument commits the Appeal to Ignorance (ad
ignorantiam) when it argues that a proposition
should be believed until it proven false. For
example, . . .
No one has ever proven that the Loch Ness Monster
does not exist. Therefore, we must conclude that
Nessie exists.
No, all that can be concluded from nothing is
nothing. Dont conclude more than you can.
Both of the following arguments are equally bad.
Do you understand why?
Believer God must exist because no one has ever
proven that he doesnt.
Atheist God cant exist because there is no
evidence to prove he does.
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Someone commits the Appeal to Emotion fallacy
when they use emotion alone to prove their
point, and not reason. Dont get me wrong
emotion has a place in our deliberations. But
the use of emotion without argumentation is wrong
because emotion alone is a lousy reason for
believing any claim.

• It is important to note that the use of emotion
  in an argument is wrong only if
• The appeal to emotion is the only claim
  supporting the conclusion
• The appeal to emotion isnt enough to justify
  the conclusion

Any emotion can be used in this fallacy. Here
are a couple of common variations of the appeal
to emotion fallacy . . .
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An argument is called an Appeal to Pity if it
says, roughly You should believe or do _____ if
you feel sorry for _____.
You should give me an A because I really need to
have a high GPA so I can get into a good law
school. If I dont, I think my mother will die.
An argument is called an Appeal to Fear if it
says, roughly You should believe or do _____ if
you are afraid of _____.
Vote for Anthony for class president. Oh, by the
way, did you know his older brother the 2 time
state boxing champ is very interested in the
outcome of the election? Think about it.
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An argument is called an Appeal to Spite if it
says, roughly You should believe or do ____ if
you are mad about what ____ has done or believes.
Co-worker You cant agree to take over Billys
responsibilities when he goes on vacation next
week! Dont forget, he told everyone that he
didnt like your haircut.
Appeals to emotion are fallacies. But dont
forget, not every argument that includes a
reference to an emotion is a bad argument. Can
you think of an example of an argument that
includes emotion, but is not an appeal to emotion?
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An argument is an Ad Populum fallacy when it
argues that since everyone else does something
(or believes something), then it is OK to do it
(or believe it). It is never a good idea to just
follow the crowd without a good reason. Be a
leader, or if you follow do so for a reason.
What do you think of the following?
Dont be an idiot! If everyone was jumping of
the Brooklyn Bridge . . .
Well, since everyone at school is sniffing glue,
Im going to do it too!
Since just about every great thinker in the past
thought that women were not as valuable as men,
men must be better.
Dont believe it. Everyone (even great thinkers)
can be wrong!
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Do you remember the deductive forms of modus
ponens and modus tollens? Both of these forms
are valid (that is, the premises really do
support the conclusion, assuming the premises are
true). However, some arguments that have a
similar form (that is, rely on a sentence with
the form if P, then Q or if antecedent, then
consequent) are invalid. One such fallacious
argument is called Affirming the Consequent. It
looks like this If P (antecedent), then Q
(consequent) If it is raining, the street gets
wet. Q (affirming the consequent) The street is
wet. Therefore, P Therefore, it is
raining. This argument form is always invalid
(the premises dont support the conclusion, even
if they are true). Why? Well look at the
example above. It doesnt mean that it is
raining just because the street is wet. A fire
hydrant may have been left on. Some kids may
have had a massive water balloon fight. Or, the
dam could have sprung a leak. Any number of
things other than a rain storm could account for
why the street is wet so the conclusion doesnt
have to be true.
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A similar fallacy is called Denying the
Antecedent. Here is the form and an example If
P, then Q If George hits a home run, then we will
win the game. Not-P George didnt hit a home
run. Therefore, not Q Therefore, we didnt win
the game. Fine. Lets imagine the two premises
are true. The conclusion, however, does not
necessarily follow because it is possible that we
can win the game in other ways than George
hitting a home run. Maybe he strikes out, but
another hitter scores the game winning run.
Since the premises of this argument could be
true, but the conclusion false we know that the
argument is invalid as is every argument that
commits the fallacy of Denying the Antecedent.
Can you identify the fallacies committed in the
following arguments?
If I am not happy, then it is Monday. It is
Monday. Therefore, I am not happy.
If I am not hungry, then it is late. I am
hungry. Therefore, it is not late.
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Begging the Question (or circular reasoning)
occurs when someone implicitly uses their
conclusion as a premise. In doing so the
conclusion has no support. Just as it is
impossible to pull yourself up by your
bootstraps, so too you cant successfully prove a
conclusion by assuming the conclusion is true.
This fallacy is called begging the question
because the answer to the question being asked is
given before any reasoning is offered. For
example . . .
Frankie is telling the truth because he never
lies.
Sleeping pills makes you sleepy because they put
you to sleep.
I believe in God. Why? Because the Bible says
God exists.
Do you understand why each of these arguments is
begging the question?
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A Complex Question is a question that conceals a
dubious claim that should be argued for rather
than assumed. Complex questions try to trap the
respondent into admitting something they might
not want to admit, or to agree with a conclusion
that is not supported by any evidence. For
example, . . .
When did you stop beating your wife? When are you
going to do something worthwhile with your
life? Where did you hide the cookies you stole?
The best way to escape a loaded question is to
directly address the concealed claim, rather than
answer the question as it is asked. How would you
escape the complex questions above?
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A False Dilemma is an argument that uses an or
claim that appears to be true but isnt, because
another possibility exists that is purposely left
hidden. Similar to a complex question, the
person who uses a false dilemma is trying to trap
someone else. But this time, he or she is trying
to trap you into a particular action or belief.
Husband to wife Either you will buy me Hummer or
you hate my guts. Since you dont hate me, you
must buy me a Hummer.
False dilemmas try to force you into a corner.
To get out of a false dilemma, simply point out
that other possibilities exist.
Dad You are either going to go to college or be
a bum for the rest of your life. Son I will not
go to college. Dad Then you will be a bum for
the rest of your life. What is the way out?
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You cant prove anything without giving an
argument, even if you claim that you have done
so. If you attempt to do so, you have committed
a Proof Substitute. A proof substitute is a word
or a phrase that suggests there is proof, but no
proof is actually offered.
That is, you dont prove anything when you try to
browbeat others into accepting your argument by
using phrases such as it is obvious that . . .,
clearly . . . or surely, anyone of
intelligence will agree that . . .. You win
arguments by giving reasons, not by making it
appear as if you have reasons. For example, . .
.
Wheres the proof?
It is certain that dogs are better pets than
cats. Without a doubt Michael Jordan is the best
basketball player ever.
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A person commits the Red Herring fallacy when
they try to divert the attention away from the
topic being discussed to a different and often
controversial topic. It is hoped that the new
topic will be so interesting that the first topic
will never be taken up again. For instance, in
the following argument notice how Senator Smith
tries to steer the conversation away from the
issue the reporter wants to discuss. . .
Reporter Senator, why did you accept a 20,000
dollar donation to your campaign from John Jones,
a convicted felon? Senator Smith Well, John
Jones is a citizen of Arizona, who is deeply
troubled by those in his state that want to make
Spanish an official state language. I love all
Americans, including those hard-working people
who came to America from Mexico. But I believe
all immigrants must become true Americans. That
means they must learn to speak English. We must
provide education for all people, so that
everyone rich or poor have the ability to
speak and read English, so as to become
productive members of society.
The Senator is hoping that the reporter (and
others who are listening) will forget the
scandalous issue and focus instead on his
controversial comments about immigration. If
they do, hes pulled off a red herring.
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Ridicule is bad because it doesnt give a reason
why an argument is wrong. It instead tries to
belittle the creator of the argument. Although
it may end the argument, it makes a lot of
enemies.
What? You think that it follows that men should
wear dresses from what you said. The only thing
that follows from what you said is that you are
an idiot! Ha! Ha!
Note Since Ridicule (which is illegitimate) and
reducing to the absurd (which is legitimate) are
somewhat similar, if one does not make it clear
that they are reducing an argument to the absurd
it is best to consider the refutation to be
ridicule.
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Although hypothetical syllogisms are a valid
deductive form, when one of the conditionals is
false (or even dubious) the hypothetical
syllogism may end up committing the Slippery
Slope fallacy. For instance . . .
If you drop philosophy you wont have enough
credits to graduate. If you dont graduate, you
will never get a good job. And without a good
job your life will be miserable. Therefore, you
will end up living on the street, drunk and
lonely.
Whats wrong with this example? Its valid,
right? It is a fallacious argument because at
least one of its conditionals is dubious. That
is, what about summer school? Is it really true
that if you dont graduate from college you will
never get a good job? Or that without a good job
your life will be miserable? Or that misery
leads to being a drunk?
The danger with a slippery slope argument is that
if you fail to reject the dubious or false
premise, you might end up sliding all the way
to a faulty conclusion.
Can you make an argument that commits the
slippery slope fallacy?
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When one person makes a claim and a second person
does not address that claim directly but attacks
a misrepresentation of what the first person said
(or even what the first person did not say at
all), and suggests that they have defeated the
claim made by the first person, they have given a
Straw Man fallacy. Consider this following
exchange in a debate . . .
Candidate Jones I think we should use any
surplus tax revenue to pay down the national
debt. Candidate Smith Obviously my opponent
doesnt care about protecting Social Security and
all of our nations senior citizens. These
people deserve our protection. To abandon them
to poverty as she suggests is wrong. Obviously,
any surplus tax revenue should not be used to pay
down the national debt.
Did you notice how Smith twisted Jones
statement into something else, defeated the new
statement, and then claimed victory over Jones
initial statement? This fallacy is very
successful if the listening audience is not
paying attention . . .. So stay awake!
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Although red herring and straw man fallacies are
somewhat similar (both use misdirection) they
should not be confused. Those committing a red
herring fallacy want to pull their listening
audience to a new topic and never return to it!
They hope you dont notice the switch, so they
dont have to discuss the initial point. However,
those committing the straw man fallacy do return
to the initial topic, but only after they have
defeated a different (and often weaker) version
of what someone said. They hope you dont notice
the switch and will think that they did indeed
defeat the first claim. By the way, why do you
think these two fallacies have the names that
they do?
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Please contact me with any questions about the
information in these slides or the related
assigned reading

• Weston, Chapter X
• Logic Handout, p. 6-14.