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Fallacies
in Logic
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Begging
the Question
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The
arguer provides no support; (s)he "begs the question" and
restates the claim over and over by rewording it.
For example “Capital punishment deters crime because it
keeps criminals from committing murder,” says the same thing
twice, just in different words.
Most of all, it fails to answer the question "Is capital
punishment a deterrent to crime?"
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Red
Herring
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A
red herring is irrelevant and misleading support that detracts
audience attention away from the real argument. For example,
"I won't hire John Smith because he drives an expensive red
sports car" is a red herring; the model and color of John
Smith's car have nothing to do with his qualifications for the
job. Detective
fiction writes use red herrings as a plot device to throw the reader
off the track of the real killer.
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Non
Sequitur
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Non
sequitur is Latin for “it does not follow”
and is used when the conclusion drawn does not make sense based on
the evidence presented. Here are some examples: lazy
students sit in the back of the classroom; professors who wear jeans
are easy graders; and young men with red cars are unsafe
drivers. The claims are that a student's location in the
classroom indicates a willingness to work hard or not, a professor's
clothes indicate his/her grading standards, and the color of one's
care reveals how one drives. You can probably see the problems
with these claims -- they are so unbelievable that they fail to make
convincing arguments.
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Straw
Man
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The
straw man occurs frequently in politics. It involves claiming
that an opponent made an argument that (s)he never made and then
refuting it in a way that appears as though the argument has been
won. For example, Candidate A makes the claim that Candidate B
said his unhealthy eating habits could interfere with his ability to
do the job, when in reality Candidate B never brought up the issue
of eating habits. Candidate A goes on to refute the eating
habits issue by citing the advantages of eating healthy, which he
does, and gives the appearance that he has won the argument even
though this has never been an issue. Unfortunately, by using
the straw man tactic, Candidate A may convince people that he could
refute Candidate B's other arguments equally easily.
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Stacked
Evidence
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Presenting
only one side of an argument that clearly has two sides creates a
distorted view of the issue. This is stacking the
evidence. For example, to prove that the internet is
dangerous for children, the only evidence given is that pedophiles
lurk in internet chat rooms, pornographic material is easy to find
on the internet, and information on building bombs is available to
everyone. The access to educational resources that the
internet offers is never mentioned.
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Either-Or
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When
no alternative or compromise positions in an argument are
acknowledged, an either-or fallacy occurs. Here are some
examples of an either-or argument: The U.S. can either have a
strong military or a strong welfare program; A woman can either work
or be a mother; Graduates can either continue their education or get
a full-time job. Because these arguments fail to acknowledge
that a middle-ground solution is possible in each scenario, they
fail the test of logic.
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Post
Hoc
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This
is an abbreviated form of post hoc, ergo propter hoc, a Latin
phrase that means “after this, therefore because of this.”
In simple terms, post hoc is
a fallacy of faulty cause. Advertisers frequently use post hoc
fallacies to sell a
product. Think, for example, of the American cultural icon of
the Marlboro man. He is handsome, strong, and virile.
How did he get that way? By smoking Marlboro cigarettes!
Alcohol ads make similar claims -- drink Brand X beer and get the
beautiful girl, wear Brand X clothes and you'll be popular,
etc. Because there is no causal relationship between the claim
and the support, a post hoc fallacy has occurred.
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Hasty
Generalization
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Jumping
to a conclusion without sufficient supporting examples results in a
hasty generalization and often contributes to
stereotyping.
Concluding that large dogs
are dangerous because one bit a child or that because some students
in inner-city schools belong to gangs, most students in those
schools are gang members constitutes a hasty generalization.
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Fallacies
that Affect Ethos
Ad
Hominem
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Ad
hominem means “to the man” in Latin, and an ad hominem
argument places attention on the man rather than the ideas
prejudicing the public against the individual and ignoring his/her
position on the issues. Election campaigns are increasingly
focused on "the character issue" -- the idea that a
candidate's character is as important, if not more important, than
his/her ideas. This focus shifts the public's attention to
negative information about a candidate's personal life and away from
the issues that (s)he believes are important. Discrediting the
individual in the public's eyes is the primary purpose of an ad
hominem attack.
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Guilt
by Association
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An
argument based on the belief that a person's character is determined
by the people with whom (s)he associates falls under the category of
"guilty by association." If a young man associates
with gang members, he is assumed to be a criminal. He is
guilty by association, not by deed.
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Using
Authority Instead of Evidence
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When
a used car salesman tells you to buy a car from him because he is
trustworthy, he is using authority instead of evidence.
Name-dropping instead of facts and figures in support of an argument
causes this fallacy.
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Emotional
Fallacies
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Bandwagon
Appeal
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Teenagers
often use bandwagon appeal to win an argument with their parents.
They need an $85 pair of shoes because "everyone else
has them" or they need to go to the party because
"everyone else is going. "The argument is that everyone is
doing something, so you should too.
This type of argument is also
used in public promotions and ad campaigns that suggest because most
people think a certain way or buy a certain product, you should
too.
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Slippery
Slope
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"If
you give them an inch, they'll take a mile" is a slippery slope
argument because it implies that if we allow one thing to happen, we
will immediately begin a downward spiral to disaster. If
we don't stop wasting so much paper, we will soon lose all the
forests. If the law requires women to wait twenty-four hours
before having an abortion now, tomorrow it will be forty-eight hours
and then women won't be able to have an abortion at all. If we
allow children to read Harry Potter books, they will want to
practice witchcraft. All of these arguments point in one
direction -- it's best not to start because the end result may be
disaster.
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Creating
False Needs
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Emotional
proof appeals to what people value and think they need.
Advertisers often create a false sense of need in order to sell a
product. Parents who want to raise emotionally healthy
children should buy Jane Doe's book. Housewives who want shiny
countertops should buy only Product X.
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