Logical Fallacies

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Logical Fallacies
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What is a logical fallacy?
A logical fallacy is an error in logic that can
make a plausible, but misleading
argument. Inductive fallacies Inductive
fallacies are the result of the incorrect use of
evidence. Ex This chalk is white therefore,
all chalk is white. With inductive fallacies,
an arguer leaps to a conclusion based on
insufficient evidence Deductive fallacies
Deductive fallacies are the result of a failure
to follow the logic of a series of
statements. Ex The rooster crows at 500 AM,
and the sun rises at 500 AM therefore the
rooster makes the sun rise. With deductive
fallacies, an arguer makes an incorrect or
unsupported link between cause and effect
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Logical Fallacies (cont.)
While there are two main categories of logical
fallacies, it is important to note that there is
often overlap. Some fallacies may fit into both
categories.

• However, it is important to note that logical
  fallacies occur when
• An arguer incorrectly links cause and effect.
• An arguer leaps to a conclusion based on
  insufficient evidence.

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1.) HASTY GENERALIZATION
Prematurely jumping to a presumptuous
conclusion. Prejudices and superstitions are the
result of making a hasty generalization. Ex
There was a news story about a guy in a
fraternity who was a rapist, so now I carry mace
if I know Ill be going anywhere near a frat
house. How is this an example of the Hasty
Generalization logical fallacy? Its a prejudiced
point of view. The arguer assumes that because
one person in a fraternity is a rapist, all
people in fraternities are rapist. The arguer is
jumping to a presumptuous conclusion about people
in fraternities.
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2.) FALSE AUTHORITY
Falsely recognizing someone as an authority on
something. Accepting someones credentials
without careful evaluation. EX http//www.youtube
.com/watch?vbZIzRqDOSZo How is this commerical
an example of the Faulty Use of Authority logical
fallacy? Each commercial assumes a connection
between the specific celebritys popularity and
their authority on the product or service they
are promoting.
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3.) POST HOC/FALSE CAUSE
Post Hoc, Ergo Propter Hoc after this,
therefore because of this. Assuming that because
one event follows another, the first event is the
cause of the second. Ex The rooster crows at
500 AM, and the sun rises at 500 AM therefore
the rooster makes the sun rise. How is this an
example of the Post Hoc logical fallacy? The
arguer assumes that simply because these two
events occur sequentially, there is a cause and
effect relationship between them. Ex A tornado
hit my town after a group of Satan worshippers
moved in, so god sent the tornado to punish us
for allowing them to move here. How is this an
example of the Post Hoc logical fallacy? The
arguer assumes a connection between the Satan
worshippers and the tornado.
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Post Hoc- Correlation vs Causation

• Just because two things are related (correlated)
  doesnt mean that one caused the other.
• For example the murder rate has decreased, while
  the average temperature has increased steadily
  since 1975. Therefore, global warming prevents
  murder.

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Post Hoc- Correlation vs. Causation
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Post Hoc- Magical Thinking

• Last time I walked past a black cat, I tripped
  and hurt my arm, so now it must have been the
  cat.
• Mr. Governor issues a proclamation for the people
  of his state to pray for rain.  Several months
  later, it rains.  Praise the gods!
• I knew I should have helped that old lady across
  the road.  Because I didnt, I have been having
  bad Karma all day.

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4.) FALSE ANALOGY
Drawing an analogy or comparison between two
situations that are totally dissimilar. Ex We
know that overweight people have a higher
mortality rate than thin people. We also know
that black people have a higher mortality rate
than white people. Do we subject black people to
torturous treatments to bleach their skin? Of
course not. We have enough sense to know that
skin-bleaching will not eliminate sickle-cell
anemia. So why do we have blind faith that
weight loss will cure the diseases associated
with obesity? -Susan Wooley, Director of
eating disorders clinic at The University of
Cincinnati. How is this an example of the False
Analogy logical fallacy? The arguer assumes that
skin color and weight are analogous. She assumes
that diseases that are specific to people of a
certain skin color can be treated just like
diseases that are specific to people of a certain
weight.
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5.) AD HOMINEM
Attacking a persons character rather than their
statements. Latin for against the man. Ex
Ernest Hemingway was an alcoholic and a terrible
father, so I wont read his books. How is this
an example of the Ad Hominem logical fallacy? The
arguer is attacking Ernest Hemingways character
rather than his intellectual output. Ex "She
asserts that we need more military spending, but
that is false, since she is only saying it
because she is a Republican." A person's
interests and circumstances have no bearing on
the truth or falsity of the claim being made.
While a person's interests will provide them with
motives to support certain claims, the claims
stand or fall on their own.
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6.) FALSE DILEMMA
Poses an either/or situation by suggesting that
only two options are possible. Sometimes called
the black/white fallacy Ex If you dont
watch football, youre not a real man. How is
this an example of the False Dilemma logical
fallacy? This statement poses an either/or
scenario in which a person either watches
football (therefore making them a real man) or
that person does not watch football (in which
case they are not a real man).
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6.) FALSE DILEMMA (Cont.)
Ex Trust fund babies and corporate weasels are
not allowed to read this bookif you are in one
of these categories, heres my first piece of
advice you must learn to be a problem solver not
a problem creator. -Bill OReilly, Whos
Looking Out For You? How is this an example of
the False Dilemma logical fallacy? Bill
OReilly poses a situation in which one is either
a problem solver or a problem creator without
evaluating any middle ground in between the two.

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7.) SLIPPERY SLOPE
Claiming that one event will trigger a series of
similar, undesirable events. If an arguer fails
to provide evidence to support his or her claim
that one event will lead to a similar,
undesirable event, then they are guilty of the
slippery slope fallacy. Ex Cloning animals
should be illegal because that would lead to
cloning humans, and then we would have a race of
clones. How is this an example of the slippery
slope logical fallacy? The arguer assumes that
if cloning of animals is allowed, then cloning of
humans will be too. Then, the arguer assumes that
this hypothetical cloning of humans will grow out
of control.
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7.) SLIPPERY SLOPE (Cont)
Ex If they legalize gay marriage, then they
will legalize bestiality and pedophilia. How
is this an example of the Slippery Slope logical
fallacy? The arguer jumps to the conclusion
that if gay marriage is legalized, then other
undesirable things will also be legalized.
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8.) BEGGING THE QUESTION/CIRCULAR LOGIC

• A circular argument. When an arguer makes a
  statement that assumes that the very question
  being argued is already answered. The premises
  assume that the conclusion is true.
• Ex Women should not be permitted into the mens
  club because the club is only for men.
• How is this an example of the Begging the
  Question logical fallacy?
• The arguer does not adequately answer the
  original question (why shouldnt women be
  permitted into mens clubs?). Instead, the
  arguer treats the question as if it has already
  been answered.
• Ex Paranormal activity is real because I have
  experienced what can only be described as
  paranormal activity.
• EX If such actions were not illegal, then they
  would not be prohibited by the law.

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9.) STRAW MAN
Setting up an extreme example of an opposing view
to argue against. Ex Listen, you trust-fund
babies and children of privilege, if youre going
to drink a quart of bourbon every day and smoke
crack, this book is not for you. -Bill
OReilly, Whos Looking Out For You? How is this
an example of the Straw Man logical fallacy?
Bill OReilly sets up an extreme example of
trust-fund babies and corporate weasels. His
example is so extreme that it becomes very easy
to argue against. Ex "Senator Jones says that
we should not fund the attack submarine program.
I disagree entirely. I can't understand why he
wants to leave us defenseless like that."
Attacking a distorted version of a position
simply does not constitute an attack on the
position itself.
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10.) Tu Quoque

• A rebuttal to an argument which does not refute
  the allegations, but simply counterattacks.
• Ex
• My step dad says Im irresponsible, but Im not.
  Besides, hes a jerk.
• How is this an example of the Tu Quoque fallacy?
• The arguer does not refute the allegations
  that they are irresponsible instead, they simply
  counterattack.
• Ex
• Helga You should not be eating that... it has
  been scientifically proven that eating fat
  burgers are no good for your health.
• Hugh You eat fat burgers all the time so that
  cant be true.
• It doesnt matter (to the truth claim of the
  argument at least) if Helga follows her own
  advice or not. 

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11.) NON-SEQUITUR

• A totally illogical connection between cause and
  effect.
• Ex. People generally like to walk on the beach. 
  Beaches have sand.  Therefore, having sand floors
  in homes would be a great idea!
• As cool as the idea of sand floors might sound,
  the conclusion does not follow from the
  premises.  The fact that people generally like to
  walk on sand does not mean that they want sand in
  their homes, just like because people generally
  like to swim, they shouldnt flood their houses.
• Ex. Buddy Burger has the greatest food in town. 
  Buddy Burger was voted 1 by the local paper. 
  Therefore, Phil, the owner of Buddy Burger,
  should run for President of the United States.
• I bet Phil makes one heck of a burger, but it
  does not follow that he should be President.

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12.) AD POPULUM/BANDWAGON
When an arguer assumes that he or she can neglect
properly supporting his or her argument by
appealing to a thread of commonly held
beliefs Ex If leprechauns arent real, then why
do so many people believe in them? No amount of
believing in them will make leprechauns
real. Ex Ten million (and counting) Americans
can't be wrong, can they? Ten million Americans
can be wrong, though.
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13) Equivocation

• When a key term or phrase in an argument is used
  in an ambiguous way, with one meaning in one
  portion of the argument and then another meaning
  in another portion of the argument.
• EX 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 nothing.
• We used two meanings of the word nothing
  interchangeably.

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Equivocation (continued)

• EX I have the right to watch "The Real World." 
  Therefore it's right for me to watch the show. 
  So, I think I'll watch this "Real World" marathon
  tonight instead of studying for my exam.
• EX Noisy children are a real headache. Two
  aspirin will make a headache go away. Therefore,
  two aspirin will make noisy children go away.

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14) Middle Ground

• Assumes that the middle position between two
  extremes must be correct simply because it is the
  middle position. This sort of "reasoning" has the
  following form
• Position A and B are two extreme positions.
• C is a position that rests in the middle between
  A and B.
• Therefore C is the correct position.

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Middle Ground (continued)

• Example Congressman Jones has proposed cutting
  welfare payments by 50 while Congresswoman
  Shender has proposed increasing welfare payments
  by 10 to keep up with inflation and cost of
  living increases. I think that the best proposal
  is the one made by Congressman Bumple. He says
  that a 30 decrease in welfare payments is a good
  middle ground, so I think that is what we should
  support.

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15) Moving the Goalposts

• Demanding from an opponent that he or she address
  more and more points after the initial
  counter-argument has been satisfied refusing to
  conceded or accept the opponents argument.
• Example
• The moon landing were a hoax because we have no
  photos of the sites.
• Okay, we now have photos of the sites, but those
  are clearly photoshopped.

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16) No True Scotsman

• When a universal (all, every, etc.) claim is
  refuted, rather than conceding the point or
  meaningfully revising the claim, the claim is
  altered by going from universal to specific, and
  failing to give any objective criteria for the
  specificity.
• Logical Form
• All X are Y.
• (it is clearly refuted that all X are not Y)
• Then all true X are Y.

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No True Scotsman (continued)

• Example
• John Members of the UbaTuba White Men's Club are
  upstanding citizens of the community.
• Marvin Then why are there so many of these
  members in jail?
• John They were never true UbaTuba White Men's
  Club members.
• Marvin Whats a true UbaTuba White Men's Club
  member?
• John Those who don't go to jail.

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No True Scotsman (continued)

• "Real men eat meat
• "Real Americans don't question the existence of
  God"
• "Real artists don't use a computer
• Angus declares that Scotsmen do not put sugar on
  their porridge, to which Lachlan points out that
  he is a Scotsman and puts sugar on his porridge.
  Furious, like a true Scot, Angus yells that no
  true Scotsman sugars his porridge.

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17) Appeal to Tradition

• Assumes that something is better or correct
  simply because it is older, traditional, or
  "always has been done." This sort of "reasoning"
  has the following form
• X is old or traditional
• Therefore X is correct or better.
• EX Of course this mode of government is the
  best. We have had this government for over 200
  years and no one has talked about changing it in
  all that time. So, it has got to be good.

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18) Biased Sample

• When a person draws a conclusion about a
  population based on a sample that is biased or
  prejudiced in some manner.
• EX Large scale polls were taken in Florida,
  California, and Maine and it was found that an
  average of 55 of those polled spent at least
  fourteen days a year near the ocean. So, it can
  be safely concluded that 55 of all Americans
  spend at least fourteen days near the ocean each
  year.

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19) Cherry Picking

• When only select evidence is presented in order
  to persuade the audience to accept a position,
  and evidence that would go against the position
  is withheld.
• EX My political candidate gives 10 of his
  income to the needy, goes to church every Sunday,
  and volunteers one day a week at a homeless
  shelter.  Therefore, he is honest and morally
  straight.

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20) Appeal to Ignorance

• The burden of proof is placed on the wrong side,
  or a lack of evidence for side A is taken to be
  evidence for side B in cases in which the burden
  of proof actually rests on side B.
• EX
• Bill "I think that some people have psychic
  powers." Jill "What is your proof?" Bill "No
  one has been able to prove that people do not
  have psychic powers."
• The absence of evidence does not constitute
  evidence.

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Appeal to Ignorance (continued)

• John Unicorns exist.
• Jane Can you prove that unicorns exist?
• John Can you prove that they dont?
• The burden of proof is not on Jane to prove that
  unicorns dont exist. John has made a claim and
  it is his job to back up his claim.
• Note The burden of proof is the obligation to
  prove ones assertion. The burden of proof
  belongs to the side making a claim.

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21) Loaded Language

• Substituting facts and evidence with words that
  stir up emotion, with the attempt to manipulate
  others into accepting the truth of the argument.
• The phrase family values immediately invokes
  the feelings of warmth, security, honesty and
  support that a family brings, even though the
  term really means a few pet social issues -
  hatred of gays, being anti-abortion, and
  restricting roles for women.

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Loaded Language (continued)

• Insurgent, freedom fighter, and terrorist
  can all be applied to the same group depending on
  the speaker's perspective.
• The "USA PATRIOT Act" is a (brutally forced)
  acronym for Uniting and Strengthening America by
  Providing Appropriate Tools Required to Intercept
  and Obstruct Terrorism Act, but due to the title,
  it implies that those opposed to the Act are
  inherently unpatriotic.

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22) Erroneous Appeal to Emotion

• This is the general category of many fallacies
  that use emotion in place of reason in order to
  attempt to win the argument.  It is a type of
  manipulation used in place of valid logic.
• Emotions manipulated can include pity, fear,
  flattery, and others.
• Appealing to emotion is a necessary rhetorical
  strategy (think pathos), but is not a substitute
  for logical thinking.

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Erroneous Appeal to Emotion (continued)

• Ex. Power lines cause cancer.  I met a little boy
  with cancer who lived just 20 miles from a power
  line who looked into my eyes and said, in his
  weak voice, Please do whatever you can so that
  other kids wont have to go through what I am
  going through.  I urge you to vote for this bill
  to tear down all power lines and replace them
  with monkeys on treadmills.

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23 Red Herring

• Shifting the Issue