3.4 Fallacies of Presumption, Ambiguity, and Grammatical Analogy

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• 3.4 Fallacies of Presumption, Ambiguity, and
  Grammatical Analogy

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Other Fallacies

• Fallacies of Presumption
• 15. Begging the Question (or circular reasoning
  presumes that the premises support the conclusion
  when they do not)
• Premises in which the truth of the conclusion is
  claimed or the truth of the conclusion is assumed
  (either directly or indirectly).

3

• Only an untrustworthy person would run for
  office. The fact that politicians are
  untrustworthy is proof of this.
• Bill "God must exist."
• Jill "How do you know."
• Bill "Because the Bible says so."
• Jill "Why should I believe the Bible?"
• Bill "Because the Bible was written by God."

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Other Fallacies

• 16. Complex Question (or loaded question presumes
  that a question can be answered with a simple
  yes or no)
• X and Y are unrelated questions. They are
  combined into question Z, which requires a single
  answer.

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• (Pre-employment psychological testing)
• Do you agree or disagree?
• I wish I were not bothered by thoughts about
  sex.
• I believe that my sins are pardonable.

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Other Fallacies

• 17. False Dichotomy ( presumes that an
  eitheror statement presents jointly exhaustive
  alternatives)
• Either claim X is true or claim Y is true (when X
  and Y could both be false). Claim Y is false.
  Therefore claim X is true.

7

• Are you with us, or with the forces of racism and
  oppression?
• Either I keep smoking, or I'll get fat. I don't
  want to get fat, so I better keep smoking.
• Either you use Speed Stick deodorant, or you will
  stink to high heaven. You don't want to stink, so
  you better by Speed Stick.

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Other Fallacies

• 18. Suppressed Evidence (presumes no important
  evidence has been overlooked)
• The fallacy of suppressed evidence occurs when an
  arguer intentionally omits relevant data.

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• Milk causes weight loss.
• Milk and cheese are more likely to pack on
  pounds than help people slim down," said Dan
  Kinburn, PCRM's general counsel. "This case calls
  into question other advertising claims made by
  the industry, especially the notion that milk
  builds strong bones. Evidence shows it does
  nothing of the kind." (PCRM)
• Player heals.
• What the Sicher study didn't reveal was that the
  original study had not been designed to do any of
  these measurements they report as significant.
  (skepdic.com)

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Other Fallacies

• 19. Equivocation ( uses the same word in
  different meanings in an argument, implying that
  the word means the same each time around

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• There are no convincing arguments in books. In
  order to be convincing, an argument has to be
  sound, but arguments written in books clearly do
  not make any noise.

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Other Fallacies

• 20. Amphiboly (ambiguity due to grammar)

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• March Planned for Next August
• Blind Bishop Appointed to See
• Patient at Death's Door--Doctors Pull Him Through
• Teacher Strikes Idle Kids
• Lawyers Give Poor Free Legal Advice
• Juvenile Court to Try Shooting Defendant
• Killer Sentenced to Die for Second Time in Ten
  Years
• Autos Killing 110 a Day--Let's Resolve to Do
  Better
• Collegians are Turning to Vegetables

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Other Fallacies

• 21. Composition ( assuming that because all the
  parts have some characteristic that anything
  composed of those parts has that characteristic
  too)
• If A is X and B is X then the group to which A
  and B belong are all X.

15

• All people in this town are idiots.
• (Presumably because one or two are idiots. But
  this is a generalization fallacy not a
  composition fallacy. Cf..)
• The town is an idiot.

16

• Every human has a mother therefore, humanity has
  a mother.
• You like pizza, gumballs and cheetos therefore,
  you will like the gumball and cheetos pizza I
  made for you.

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Other Fallacies

• 22. Division ( Assuming that because the whole
  has some characteristic that each of its parts
  has the same characteristic)
• The whole, X, has properties A, B, C, etc.
  Therefore the parts of X have properties A, B, C,
  etc.

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• The ball is blue therefore, the atoms that make
  it up are also blue.
• Chloride is a safe chemical. After all, table
  salt (sodium chloride) is safe.

19

1. Appeal to force
2. Appeal to pity
3. Appeal to the people
4. Argument against the person (abusive,
   circumstantial, tu quoque)
5. Accident (applies rule to exception)
6. Straw Man (distorts/weakens opponents argument)
7. Missing the point (premises support a different
   conclusion)
8. Red herring (listener led off track)
9. Unqualified authority
10. Ignorance (reports lack of argument, asserts
    conclusion)
11. Hasty generalization (conclusion drawn from
    atypical sample)
12. False cause (conclusion based on weak/nonexistent
    causal relation)
13. Slippery slope (unlikely chain reaction)
14. Weak analogy
15. Begging the question (key premises missing,
    conclusion used as premise)
16. Complex question (multiple questions conflated)
17. False dichotomy (Eitheror ignores other
    options)
18. Suppressed evidence (ignores evidence that would
    support a different conclusion)
19. Equivocation (meaning shift)

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The First Exam Tue 9/27

• 1-5 MC (1.1-1.2) Argument or Nonargument?
  Identify conclusion
• 6-15 MC (1.3) Inductive or Deductive? Type of
  argument
• 16-20 MC (1.4) Inductive or deductive? Sound,
  valid, cogent, strong, weak
• 21-30 T/F (1.4) Sound, valid, cogent, strong,
  weak
• 31-35 MC (1.1-1.4) Arguments, Statements
• 36-50 MC (3.1-3.4) Fallacies
• Activity Logs will be collected!

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Review

• Thu, 9/20, 430-630 PM, Optional Review, Dr.
  Smith and Taryn, EHFA 242
• Tue, 9/20, 1000-1115 AM, Optional Review, Dr.
  Smith, EHFA 256
• Tue, 9/25, 430-600 PM, Optional Review, Taryn,
  Prince 201