Transcript Document

GXEX1406
Thinking and Communication Skills
Logical Fallacies
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Premise & Conclusion
Premise:
All girls have long eyelashes.
Cows has long eyelashes
Conclusion:
Therefore, all girls are cows
Is this statement logically right?
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Is this reasoning logical?
Premise:
“A cloud is 90% water.
A watermelon is 90% water.
A plane can fly through a cloud.
Conclusion:
Therefore, a plane can fly through
a watermelon”
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There is logic in the premise
of the statements –
BUT the conclusion makes no
logical sense.
The reasoning is flawed
The conclusion is illogical
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This type of arguments are called
Logical fallacies
Fallacy is a mistake in reasoning
A statement or argument based on false
inference that causes incorrectness in
reasoning
Used to cloud our logical thinking, appeal to our
emotions rather than intellect
Often masquerade as logical statements
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Objective of the course
You will be able to identify
fallacies
Able to indicate instances
or type of fallacy
Situations
Found in newspapers,
magazines, reports,
advertisements
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Why Study
Fallacies ?
Able to spot poor
reasoning & know why it is
wrong
Able to correct other’s
mistakes, or refute them
convincingly
Supplements your
knowledge on logic
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Why Study
Fallacies ?
Know when your reasoning
in an essay is flawed or
questionable
Prevent you from making
generalized statements
without backing it up with
sound evidence
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3 categories of fallacies
(1) Fallacies that appeal to emotions
(total 4)
- Claims are made that appeal to emotions
rather than reason
(2) Fallacies that distract (total 3)
-
Claims made to divert attention
from the main issue
 (3) Other common types (total 5)
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(1)
TYPE 1- appeal to emotions
(a) Appeal to fear/force/scare tactics -ad
baculum
The claim makes use of threats.
The threats are irrelevant to the argument.
Therefore the claim is fallacious
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Example: appeal to fear/force/scare tactics
If you don’t finish your vegetables,
you will get cancer
If you do not forward this mail to
10 friends, you will face bad luck (chain mail)
Listerine: kills the germ that
causes bad breath
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WHY FALLACIOUS?
- No proof that not eating veges can
cause cancer + Not all cancers are
caused by not eating veges
-
No proof that the chain mail causes bad
luck
- Other factors may also cause bad
breath.
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(1)
TYPE 1
(b) Appeal to vanity/flattery
Use flattery to make the reader or listener feel
special.
Use persuasive language.
Often used in advertisements. To entice
consumers to buy products or services
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Example: Appeal to vanity/flattery
I don’t moisturize, I don’t tone, I
just use Dove!
BMW 3.0Si: for those who deny
themselves nothing
SBB blue-chip MasterCard, a
radically new way of life
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WHY FALLACIOUS?
- Where is the proof that Dove is 3 in
1? That it moisturizes & tones other
than it just cleans ?
- Can a car really last for life?
- having the new master card may not
necessary change your life in a
radical way
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(1)
TYPE 1
(b) Appeal to numbers/ bandwagon
/peer pressure
Use to solicit group identity
Put pressure on individuals to follow the
crowd.
Often used in adverts - to buy software or
hardware or other products & services
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Example: Appeal to numbers/bandwagon/peer pressure
Millions of people smoke. Therefore
smoking must not be bad for people.
All the really smart people watch
University Challenge. You should watch
too.
 Classical music is really neat - but like
my friends I prefer Linkin’ Park. We are
not nerds.
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WHY FALLACIOUS?
-
Just because millions of people do
something is a poor basis to say that the
action is right.
-
Not smart people also watch that TV
show!
-
You don’t have to follow your friends in
your choice of music to listen to. Where
is the proof that classical music lovers
are nerds?
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(1)
TYPE 1
(b) Appeal to pity (ad misericodium)
Use pity to establish the truth of a
conclusion
Use language to evoke compassion to
induce the listener to accept the claim
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Example: Appeal to pity
You should hire him as a coach of
our football team because he broke
his leg and cannot play big time
football anymore.
We should re-elect Encik Fauzi as
our MP because his wife just died
and his crippled mother lives with
him.
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Why Fallacious?
Pity does not serve as evidence for a
claim.
Therefore the claim is fallacious
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TYPE 2 - Fallacies that distract (total 3
- Claim that diverts attention from the
main issue)
(a) Ad Hominem / against the person
Sometimes called - fallacy of opposition
Attacks the person’s personality,
beliefs, affiliation, ethnicity to reject a
claim
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Example: Ad-Hominem
Encik Latif just divorce his wife. How
can his proposal be any good?
 How can you vote for Salmah as
prefect when she is related to the
Headmistress?
You agree that the
government should
increase on military spending because
your father works in a munitions factory.
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Why Fallacious?
The character or circumstance of the person
has no claim on the truth of the claim.
Encik Latif divorcing his wife has got nothing
to do with his working ability
Salmah may have the makings of a good
prefect even though she is related to the
head mistress.
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TYPE 2
(b) Red Herring
An issue brought into the picture to divert the
listener’s or reader’s attention from the real
issue
This happens a lot in meetings and group
discussions.
Be aware of this!
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Example: Red herring
Why worry about the Pandas becoming
extinct when we have a large number of
homeless in our own country?
 Why should we donate to the Iraq war
when we still have people living in
poverty?
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Why Fallacious?
One issue is not related to the other.
Therefore the first claim cannot justify the
second claim.
The extinction of pandas and the homeless
are two separate issues
The contribution to Iraq war and the plight of
the poor are two separate issues.
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TYPE 2
(c) Straw Man
Oversimplify an evidence to support a
claim.
The simplification, therefore cannot
support the claim
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Example: Straw Man & why fallacious
Those who favor gun control also favor
disarming the police
This is oversimplifying the issue. The
first claim is not strong enough to
support the second claim.
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Example: Straw Man & why fallacious
What women in her right mind would
support total equality with men. No
women wants the right to go to war or
the right to pay alimony
Oversimplify the issue. Equality does not
mean for every situations!
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TYPE 3 - Other common fallacies
(a) Begging the question
(circular
argument)
The claims in the premise is again drawn in
the conclusion.
Redundant
Repeating an issue (going in circles)
The argument does not go anywhere!
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Example: begging the question & why
fallacious?
My argument must be correct because I
am the smartest student in the class.
The conclusion merely restate the
premise. Being smart does not mean
that you are correct.
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Example: begging the question & why
fallacious?
Murderers should be executed because
they are killers!
The conclusion merely restate the
premise. Murderers are killers by
definition. So, what is the justification
why killers must be executed?
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Example: begging the question & why
fallacious?
The bible is the word of God because it
says it is.
Whether or not the bible is the word of God is a
matter of personal faith. The statement should
be written as:
The Bible says that it is the word of God. The
word of God cannot be false. Therefore, the
Bible is the word of God.
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TYPE 3 - Other common fallacies
(b) Slippery slop (snowball argument/
domino theory)
Suggests to the listener that if one action is
taken, it will lead to similar actions & the end
result is negative or undesirable
Assumes a chain reaction of cause-effect of
events
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Example: slippery slope & why fallacious?
Let one student disrupt my lecture, then
other students would want to ask & I
therefore cannot complete my lecture in
time.
Student’s interruptions may disrupt a
lecture BUT not all lectures are delayed
because of students disruptions.
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Example & why fallacious?
President Richard Nixon - We have to
win in Vietnam or the entire SEA will
become communist
Winning the Vietnam war might have
saved Vietnam from Communism BUT
not all communist state are dependent
of the success of the Vietnam War.
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TYPE 3 - Other common fallacies
(c) False dilemma or black / white
argument/ either -or
A limited number of opinion is given
when in reality there are more options
An illegitimate use or the word “or”
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Example of False Dilemma (black/white) &
why fallacious?
FSKTM Love it or leave it.
Should have been written as:
One of the ways to excel in FSKTM is to love
the life here. Hating it would affect your
studies and may result with you having to
leave.
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Example of False Dilemma (black/white) &
why fallacious?
Stop smoking or die young.
Fallacious because death can be
caused by other factors not just by
smoking. Should have been written as:
One of the ways to avoid dying young is
to stop smoking as smoking might affect
one’s health.
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Example of False Dilemma (black/white) &
why fallacious?
Either go to college or forget about
getting a good job.
Fallacious because good jobs are not
dependent on going to college alone.
Should have been written as:
Going to college and getting a degree is
one means of getting a good job.
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TYPE 3 - Other common fallacies
(d) Hasty generalization
This is the chief error made by many.
Leaping to a conclusion without a
strong or large enough justification.
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Example of Hasty generalization
Feminists hate men. Ramlah is a
feminist. Ramlah hates men.
I notice that my fat friend is jolly.
Therefore all fat people are jolly.
 All pop stars are rude. I asked Elton
John for his autograph at a restaurant
and he told me to get lost.
All the arguments are based on insufficient evidence
& there fore are not valid.
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TYPE 3 - Other common fallacies
(b) Burden of Proof (Appeal to ignorance)
Premise: If something has not been proven
as false, the claim must be true.
Shifts the burden the other party to prove in
order to make a claim.
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Example of burden of proof & why
fallacious?
Since you cannot proof that ghosts does
not exist, then they do exist.
Since scientists cannot proof that global
warming will take place, it probably wont.
The new experimental drug must be
working because not a single patient has
returned to complain.
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SUMMARY OF FALLACIES
(1) Fallacies that appeal to emotions (total 4)
- Claims are made appeal to emotions rather
than reason
Appeal to Fear/Force/ Scare tactics or ad baculum
Appeal to Vanity/Flattery
Appeal to Numbers/ Belief/
Bandwagon/Peer pressure
Appeal to Pity (Ad misericordium)
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3 categories of fallacies
(2) Fallacies that distract (total 3)
- Claims made divert attention from the
main issue
 Ad hominem (attack/against the
person)
 Red herring
 Straw Man
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3 categories of fallacies
 (3) Other common types (total 5)
Begging the question (circular
arguments)
Slippery slope (domino theory)
 False dilemma (either- or)
 Hasty generalization
 Burden of proof
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THE END
THE END
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WARMING UP
Identify & explain the logical
fallacy in the following
statements.
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1. Could I receive an A for this class. If I
don't get an 'A' I won't get the
scholarship that I apply for
1. Appeal to fear/scare tactics
2. Appeal to numbers /bandwagon/ peer
pressure
3. Redherring/smokescreen
4. Appeal to pity
5. Slippery slope / domino theory
6. Begging the question / circular argument
7. Hasty generalization
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1. Could I receive an A for this class. If I
don't get an 'A' I won't get the
scholarship that I apply for
Appeal to pity
This line of "reasoning" is fallacious
because pity does not serve as
evidence for a claim
Just to get a scholarship does not
justify a person to be given an A –
There are other criteria to be considered
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2. The women in my family love
babies. All women love babies
1. Appeal to numbers /bandwagon/peer
pressure
2. Redherring/smokescreen
3. Appeal to pity
4. Appeal to fear /scare tactics /ad
bacculum
5. Ad hominem
6. Begging the question/circular argument
7. Hasty generalization
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2. All women in my family love
babies. All women love babies
Hasty generalization
Faulty logic – unqualified
A generalization. This fallacy is
committed when a person draws
a conclusion about a population
based on a sample that is not
large enough
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3. You shouldn’t accept national
health care because it is a socialist idea
1. Appeal to numbers /bandwagon/peer
pressure
2. Redherring/smokescreen
3. Appeal to pity
4. Appeal to fear /scare tactics /ad
bacculum
5. Ad hominem
6. Begging the question/circular argument
7. Hasty generalization
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3. You shouldn’t accept national
health care because it is a socialist idea
Red herring
Switching to another issue to distract
from the main argument. This sort of
"reasoning" is fallacious because
merely changing the topic of
discussion hardly counts as an
argument against a claim.
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4. In a democracy the people are free
because democracies are free countries.
1. Appeal to numbers /bandwagon/peer
pressure
2. Redherring/smokescreen
3. Appeal to pity
4. Appeal to fear /scare tactics /ad
bacculum
5. Ad hominem
6. Begging the question/circular argument
7. Hasty generalization
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4. In a democracy the people are free
because democracies are free countries.
Begging the question
Circular argument
This sort of "reasoning" is fallacious because
simply assuming that the premise is true does
not constitute evidence for that conclusion.
Democracy = free country = free people.
Circular argument with no end.
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5. The gang members caught by the police last
night comprises immigrants from country X.
Most immigrants who work in this country
have trouble with the law and come from
country X where thievery are rampant.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Hasty generalization
7. Burden of proof/Appeal to ignorance
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5. The gang members caught by the police last
night comprises immigrants from country X.
Most immigrants who work in this country
have trouble with the law and come from
country X where thievery are rampant.
Hasty generalization
Faulty logic – unqualified
Generalization. Making a
judgment based on a small
Sample.
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6. Ralph Nader was the best candidate
for president, because he was totally
better than any of the others.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Hasty generalisation
7. Burden of proof/Appeal to ignorance
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6. Ralph Nader was the best candidate
for president, because he was totally
better than any of the others.
Begging the question/
Circular argument
Assumption -- Nader is better than the other
candidates, conclusion -- Nader is the best. This
sort of "reasoning" is fallacious because simply
assuming that the conclusion is true (directly or
indirectly) in the premises does not constitute
evidence for that conclusion.
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7. If you don't finish your homework you
won't get a good grade. Then you won't be
able to get into the college you want. You
will end up cleaning toilets for a living.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Hasty generalization
7. Burden of proof/Appeal to ignorance
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7. If you don't finish your homework you
won't get a good grade. Then you won't be
able to get into the college you want. You
will end up cleaning toilets for a living.
Appeal to fear /scare tactics
It is an appeal to force or threat
instead of trying to convince
someone with facts or a logical
argument
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8. How could anyone vote for Hilary Clinton
for senator?The fact that she is married to
Clinton proves that she has no self respect.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Hasty generalization
7. Burden of proof/Appeal to ignorance
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8. How could anyone vote for Hilary Clinton
for senator?The fact that she is married to
Clinton proves that she has no self respect.
Ad hominem
Attacking the person rather than the issue. Ad Hominem"
means "against the man" or "against the person.
Ad Hominem is a fallacy because the character,
circumstances, or actions of a person do not (in most
cases) have a bearing on the truth of the claim being made
(or the quality of the argument being made).
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9. UFO must exist because no reputable studies
have proven conclusively that they do not.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Hasty generalization
7. Burden of proof/Appeal to ignorance
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9. UFO must exist because no reputable studies
have proven conclusively that they do not.
Burden of proof
Shifts
the
burden
of
proof
to
the
other
Causal fallacy
party in order to make a claim.
However, no evidence is given to
proof that UFO do exist.
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10. If you are beautiful, you could live like
this, so buy Buty-EZ and become beautiful.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Appeal to vanity/flattery
7. Burden of proof/Appeal to ignorance
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10. If you are beautiful, you could live like
this, so buy Buty-EZ and become beautiful.
Appeal to vanity/flattery
Here the appeal is to beautiful people.
This line of "reasoning" is fallacious
because the fact that flattery does not,
in general, serve as evidence that the
claim is true.
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11. State the fallacy implied
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My friends uses Linux because it makes their
PC more powerful & stable. My friend uses
Linux so must I.
Appeal to number /Bandwagon /
peer pressure
Implies something is right because
everybody believes so. This line of
"reasoning" is fallacious because
peer pressure and threat of
rejection do not constitute evidence for
rejecting a claim
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12. We can’t allow students any voice in
decision making, if we do, it wont be long
before they are in total control
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. Scare tactics /ad bacculum
4. Ad hominem
5. Begging the question/circular argument
6. Appeal to vanity/flattery
7. Burden of proof/Appeal to ignorance
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12. We can’t allow students any voice in
decision making, if we do, it wont be long
before they are in total control
Slippery slope /domino theory
No middle road is given. Assumes that
when the first action is taken, it would
subsequently follow through to the
last. Is this true?
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13. Women need to be either brilliant or
beautiful to survive in this world.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. False dilemma (black or white/either-or)
4. Ad hominem
5. Begging the question/circular argument
6. Appeal to vanity/flattery
7. Burden of proof/Appeal to ignorance
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13. Women need to be either brilliant or
beautiful to survive in this world.
False dilemma (black or white/
either – or)
Include either…or… . Just gives two
opposite extremes instead of allowing
for other possibilities. Not all women
who survive in this world are brilliant
or beautiful.
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14. Those who favor gun-control legislation
just want to take all guns away from
responsible citizens and put them into the
hands of the criminals.
1. Redherring/smokescreen
2. Slippery slope/ domino theory
3. False dilemma (black or white/either-or)
4. Ad hominem
5. Begging the question/circular argument
6. Strawman (oversimplification)
7. Burden of proof/Appeal to ignorance
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14. Those who favor gun-control legislation
just want to take all guns away from
responsible citizens and put them into the
hands of the criminals.
Strawman (oversimplification)
misrepresent an opponent's position to
make it easier to attack, usually by
distorting his or her views to ridiculous
extremes
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