PSC 202

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Discourse Fallacies

• PSC 202
• Political Argument and Reasoning

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Categories of Fallacious Reasoning
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Categories of Fallacious Reasoning
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Fallacy of Subjectivism

• I believe (or want) x to be true, therefore x is
  true.
• Well, I was just brought up to believe that x.
• That may be true for you but it isnt true for
  me.

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Appeal to Majority

• A majority of people believe x, therefore x is
  true.
• I use correlation analysis as my statistical
  technique because it is one of the most popular
  methods among social scientists.
• Socialized medicine is good social policy
  because it is the wave of the future.

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Appeal to Emotion

• Long political history of rabble-rousing.
• Not all emotional arguments are appeals to
  emotion.

• A coherent argu-ment can have profound emotive
  force.
• The trouble comes when the pathos replaces the
  logos.

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Appeal to Force(argumentum ad baculum)

• Appeals to force can take the form of actual
  physical threats.
• Usually they do not.
• The appeal to force is committed whenever any
  kind of threat is used to secure agreement with a
  conclusion.

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Appeal to Force(argumentum ad baculum)
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Appeal to Force(argumentum ad baculum)

• Persuasion by threatening the loss of
  affection.
• Holding dissenters up to ridicule.

Examples

• Parents threaten to withdraw support of a child
  who wont adopt their religious beliefs.
• Teachers threaten dissenting students with lower
  grades.

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Appeal to Force(argumentum ad baculum)

• Persuasion by threatening the loss of
  affection.
• Holding dissenters up to ridicule.

Examples

• Parents threaten to withdraw support of a child
  who wont adopt their religious beliefs.
• Teachers threaten dissenting students with lower
  grades.

The appeal to force occurs whenever intimidation
supplants logic.
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Identify the Fallacy
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
The Golden Rule is a sound moral principle, for
it is basic to every system of ethics in every
culture.
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
The Golden Rule is a sound moral principle, for
it is basic to every system of ethics in every
culture.
appeal to majority
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
Foreign imports are wrecking our economy and
savaging our workers, the backbone of our
country. Buy American! Before you put your
money on that Honda, think of the guy in Detroit
whose kids may not eat tomorrow. Before you buy
those Italian pumps, ask yourself whether a
little glamour is worth the job of the shoemaker
in Boston whos worked all his life to make an
honest living.
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
Foreign imports are wrecking our economy and
savaging our workers, the backbone of our
country. Buy American! Before you put your
money on that Honda, think of the guy in Detroit
whose kids may not eat tomorrow. Before you buy
those Italian pumps, ask yourself whether a
little glamour is worth the job of the shoemaker
in Boston whos worked all his life to make an
honest living.
appeal to emotion
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
You can argue all you want to that democracy
gives us only the illusion of control over the
government, but I dont buy it. I was brought up
to believe in the democratic system.
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
You can argue all you want to that democracy
gives us only the illusion of control over the
government, but I dont buy it. I was brought up
to believe in the democratic system.
subjectivism
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
The most effective way to increase government
revenues would be to raise the corporate income
tax, since opinion polls show widespread support
for such an approach.
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
The most effective way to increase government
revenues would be to raise the corporate income
tax, since opinion polls show widespread support
for such an approach.
appeal to majority
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
Warning! Before answering the next question,
please remember who assigns the grades in this
course.
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
Warning! Before answering the next question,
please remember who assigns the grades in this
course.
appeal to force
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
Fine. Go ahead and marry him. Why should you
care about breaking your mothers heart? I guess
you love him more than me -- but why should I
care? Who am I to complain? Im only your
mother. I only spent twenty years trying to make
a good match for you, a nice boy, and now you run
off . . . .
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Identify the Fallacy
Is it subjectivism, appeal to majority, appeal
to emotion, or appeal to force?
Fine. Go ahead and marry him. Why should you
care about breaking your mothers heart? I guess
you love him more than me -- but why should I
care? Who am I to complain? Im only your
mother. I only spent twenty years trying to make
a good match for you, a nice boy, and now you run
off . . . .
appeal to emotion
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Categories of Fallacious Reasoning
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Appeal to Authority(Argumentum ad Verecundiam)

• Rely on experts only if the conditions of
  credibility are satisfied.
• The putative expert must be competent.
• The putative expert must be objective.
• The subject matter must be too technical for the
  audience.

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Ad Hominem

• Attacking the speaker and not her argument.
• x says that p and x is bad therefore p is false.
• Traits of the speaker relevant only when
  assessing the competence of an expert.
• Crudest form insult.

• More sophisticated is the tu quoque variant.
• Accusing the accuser of the accusation.
• Poisoning the well is another variant.
• Attacking a position by claiming an inconsistency
  with other positions.

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Identify the Fallacy
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
I think America should be more careful about the
international organizations we join and
the treaties we sign. After all, wasnt it
George Washington himself who warned against
foreign entanglements?
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
I think America should be more careful about the
international organizations we join and
the treaties we sign. After all, wasnt it
George Washington himself who warned against
foreign entanglements?
appeal to authority
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
Why should Congress consult the Joint Chiefs of
Staff about military funding? They are military
men, so obviously they will want as much money as
they can get.
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
Why should Congress consult the Joint Chiefs of
Staff about military funding? They are military
men, so obviously they will want as much money as
they can get.
Ad hominem -- poisoning the well
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
A The poor nations of the world will have to
learn to produce their own food if they are to
solve the problem of hunger in the long run. B
Thats a heartless position. You would
never have said that if you had ever really been
hungry.
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
A The poor nations of the world will have to
learn to produce their own food if they are to
solve the problem of hunger in the long run. B
Thats a heartless position. You would
never have said that if you had ever really been
hungry.
ad hominem
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
This must be an important event. The New York
Times gave it four columns on the front page.
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
This must be an important event. The New York
Times gave it four columns on the front page.
appeal to authority
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
TV commentators are always attacking big business
for making obscene profits, but the companies
they work for have higher profits than almost any
other industry.
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Identify the Fallacy
Is it appeal to authority, or ad
hominem (including tu quoque and poisoning the
well)?
TV commentators are always attacking big business
for making obscene profits, but the companies
they work for have higher profits than almost any
other industry.
ad hominem -- tu quoque
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Categories of Fallacious Reasoning
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Begging the Question(Circular Reasoning)
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Example Society has an obligation to support
the needy because people who cannot provide for
themselves have a right to the resources of the
community.
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Example
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Example a. Why do you believe God exists?
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Example a. Why do you believe God exists? b.
Because the Bible says so.
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Example a. Why do you believe God exists? b.
Because the Bible says so. a. Why do you take the
Bibles word for it?
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Example a. Why do you believe God exists? b.
Because the Bible says so. a. Why do you take the
Bibles word for it? b. Because God wrote it.
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Complex Question Have you stopped beating your
spouseperson?
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Begging the Question(Circular Reasoning)
Using an arguments conclusion as one of its
premises.
Complex Question Have you stopped beating your
spouseperson? There are two questions here.
The first is implicit have you been beating
your spouseperson? An affirmative answer to
this is presupposed in the explicit question.
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
A took place before B, therefore A caused B..
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
A took place before B, therefore A caused B..
Example Marijuana use should remain illegal
because most heroin addicts started off as
marijuana users.
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
A took place before B, therefore A caused B..
Example Marijuana use should remain illegal
because most heroin addicts started off as
marijuana users.
Then lets make milk drinking illegal too!
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
Two variables correlate positively to the extent
that their values rise and fall together. They
correlate negatively to the extent that one rises
whenever the other falls, and vice versa.
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
Two variables correlate positively to the extent
that their values rise and fall together. They
correlate negatively to the extent that one rises
whenever the other falls, and vice versa.
Importantly,
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
Two variables correlate positively to the extent
that their values rise and fall together. They
correlate negatively to the extent that one rises
whenever the other falls, and vice versa.
Importantly, correlation is not causation!
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
Social Unrest
Ice Cream Sales
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
Social Unrest
Ice Cream Sales
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Post Hoc, Ergo Propter Hoc(after this, thus
because of this)
Spurious correlation
Hot Weather
Social Unrest
Ice Cream Sales
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False Alternative

• Failure to consider all the possibilities.
• Joe is a liberal because hes not a
  conservative.
• Often found in a complex question
• Do you favor reducing the deficit by increasing
  taxes or by reducing social spending?
• Sometimes seen in public opinion research.
• Absolutely nothing can be shown from data
  produced by such questions.

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Appeal to Ignorance(Argumentum ad Ignorantiam)

• p hasnt been proven false, so p is true.
• The positive proposition generally starts the
  argument and bears the evidenciary burden of
  proof.

• Legal principles apply rules to avoid appeals to
  ignorance.
• The presumption of innocence in criminal law.
• The presumption of non-liability in civil law.

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Non Sequitur(It Does Not Follow)

• Here, the premises are irrelevant to the
  conclusion.
• Example Internet pornography is harmful.
  Therefore there ought to be a law against it.
• Whats missing?
• Support for the implicit contention that
  government intervention is appropriate in this
  case.
• Why might it not be?
• First amendment.
• Global scope of internet.

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Non Sequitur(It Does Not Follow)

• Another form
• Because an action had certain conse-quences, they
  were intended.
• Another form is di-version or red herring.
• Changing issues in middle of argument.

• The straw man argument.
• Distorting opponents position.
• Oversimplifying or caricaturing oppo-nents
  argument.
• Arguing against a position no one has taken.

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Identify the Fallacy
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
The federal government should save New York City
from default, for New York deserves such aid.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
The federal government should save New York City
from default, for New York deserves such aid.
begging the question
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
The layoffs at Acme Corporation were obviously
racist over 60 percent of the people laid off
were Puerto Rican.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
The layoffs at Acme Corporation were obviously
racist over 60 percent of the people laid off
were Puerto Rican.
non sequitur
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Hard-core pornography is disgusting and offensive
to any civilized person, so it cannot be included
in the right to free speech.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Hard-core pornography is disgusting and offensive
to any civilized person, so it cannot be included
in the right to free speech.
non sequitur
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Six months after President Hoover took office in
1929, the stock market crashed and the Great
Depression began. He is therefore responsible for
this tragic episode in our national history.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Six months after President Hoover took office in
1929, the stock market crashed and the Great
Depression began. He is therefore responsible for
this tragic episode in our national history.
post hoc ergo propter hoc
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Why are you so skeptical about ESP? Can you
prove that it doesnt exist?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Why are you so skeptical about ESP? Can you
prove that it doesnt exist?
appeal to ignorance
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Congressman Jones denies that hes a liberal, so
he must be a conservative.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Congressman Jones denies that hes a liberal, so
he must be a conservative.
false alternative
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
As a determinist, I believe that none of our
actions results from free choice, and that all of
them are determined by the strongest motive
acting upon us. To be sure, it sometimes does
seem that we choose to act on the weaker of two
motives. But if we do that, it only shows that
the motive which seemed weaker was really the
stronger of the two, since it determined our
action.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
As a determinist, I believe that none of our
actions results from free choice, and that all of
them are determined by the strongest motive
acting upon us. To be sure, it sometimes does
seem that we choose to act on the weaker of two
motives. But if we do that, it only shows that
the motive which seemed weaker was really the
stronger of the two, since it determined our
action.
begging the question
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
101
Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Twenty-five years after graduation, Harvard
alumni have average incomes much higher than the
average college graduate. A Harvard education
must be the road to riches.
102
Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Twenty-five years after graduation, Harvard
alumni have average incomes much higher than the
average college graduate. A Harvard education
must be the road to riches.
post hoc ergo propter hoc
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
104
Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Opinion poll question Do you favor more money
for welfare programs, or do you feel we should
let people starve in the streets?
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Opinion poll question Do you favor more money
for welfare programs, or do you feel we should
let people starve in the streets?
false alternative
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
107
Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Mary says she loves me. I dont know whether to
believe her or not, but I guess I do, because I
dont think she would lie to someone she loves
about something that important.
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Identify the Fallacy
Which fallacy or fallacies of logical
structure are committed?
Mary says she loves me. I dont know whether to
believe her or not, but I guess I do, because I
dont think she would lie to someone she loves
about something that important.
begging the question
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The Naturalistic Fallacy

• Deriving an evaluative conclusion from
  descriptive premises.
• Inferring ought from is.
• Should be at least one evaluative premise if
  conclusion is evaluative.
• Example We should teach multiplication by rote
  because we have always done so.
• Searles naturalistic fallacy fallacy.
• Duffys naturalistic fallacy fallacy fallacy.

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Fin
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