Chapter 28: Fallacies of Ambiguity

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Chapter 28Fallacies of Ambiguity
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Introduction to Informal Fallacies (pp. 319-320)

• A fallacy is an unacceptable argument. If there
  is no argument, there is no fallacy.
• A formal fallacy is an invalid argument.
• An informal fallacy is a common argumentative
  error. Often it is a valid argument with a false
  premise.
• The fallacies of ambiguity can be seen as formal
  fallacies there is always a shift in the
  meaning of a word or phrase in the argument.

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Equivocation (pp. 320-321)

• To equivocate means, literally, to speak in more
  than one voice.
• Equivocations outside of arguments
• There are equivocations outside of arguments, but
  theyre not fallacies since there is no argument.
  Consider the following exchange from Through the
  Looking-Glass (Chapter 7)
• Speaking of his messengers, the Red King says
  Just look along the road, and tell me if you can
  see either of them.
• I see nobody on the road, said Alice.

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Equivocation (pp. 320-321)

• I only with I had such eyes, the King remarked
  in a fretful tone. To be able to see Nobody!
  And at that distance too! Why, its as much as I
  can do to see real people, by this light!
• Since Alice uses nobody as a pronoun and the
  King uses Nobody as a proper name, there is an
  equivocation. Since there is no argument, there
  is no fallacy.
• The fallacy of equivocation
• If there is a shift in meaning in the context of
  an argument, there is a fallacy of equivocation.

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Equivocation (pp. 320-321)

• We have already noticed this when discussing
  categorical syllogisms if there is an
  equivocation in what appears to be a categorical
  syllogism there are four (or more terms), so its
  not a categorical syllogism.
• Consider the following passage from Through the
  Looking-Glass (Chapter 7), in which the King
  talks with a messenger who had just arrived
• Who did you pass on the road? the King went
  on, holding out his hand to the Messenger for
  some more hay.

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Equivocation (pp. 320-321)

• Nobody, said the Messenger.
• Quite right, said the King, this young lady
  saw him too. So of course Nobody walks slower
  than you.
• I do my best, the Messenger said in a sullen
  tone. Im sure nobody walks much faster than I
  do!
• He cant to that, said the King, or else
  hed have been here first.
• Here there is an argument, so there is a fallacy.
  

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Amphiboly (p. 322)

• The fallacy of amphiboly occurs when there is a
  shift in meaning in the course of an argument due
  to loose sentence construction, and accepting the
  conclusion requires that the shift in meaning is
  unacknowledged.
• Poor sentence construction can result in
  ambiguous claims, as in For those of you who
  have children and dont know it, we have a
  nursery downstairs. But in this case, there is
  no argument, so theres no fallacy.

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Amphiboly (p. 322)

• The following is an instance of the fallacy of
  amphiboly
• If you want to avoid cancer, youll want to
  avoid the Biology Building, since there is a
  lecture tonight on the causes of cancer in the
  Biology Building.
• Presumably, the lecture is on the causes of
  cancer, and the lecture will be given in the
  Biology Building, but thats not clear from the
  sentence construction. The conclusion requires
  that the causes of cancer although, perhaps,
  not the lecture are in the Biology Building.

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Accent (pp. 322-324)

• There are two versions of this fallacy.
• A. Arguments based on unusual stress
• If words in a common claim are given an unusual
  stress, the meaning can shift. If I argue, The
  commandment says Thou shalt not steal, so its
  okay for me to pilfer I have committed the
  fallacy of accent.

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Accent (pp. 322-324)

• B. Arguments based on incomplete quotations or
  quotations out of context
• This is the more common form of the fallacy. It
  occurs when a quotation is taken out of context
  or is incomplete, and this shift changes the
  meaning of the claim. If I argue, The
  commandment says Thou shalt steal, so its
  okay for me to pilfer, indeed its divinely
  commanded, I have committed the fallacy of
  accent.

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Division (pp. 324-325)

• A. Fallacy of division
• The fallacy of division occurs when a property
  that is true of a whole thing or a whole class is
  improperly attributed to either a part of the
  whole or a member of the class.
• If I argue, My car is red. So, the tires on my
  car are red I have committed the fallacy of
  division.

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Division (pp. 324-325)

• B. Nonfallacious cases of division
• Its not always fallacious to attribute a
  property of a whole to a part. If I argue, My
  car weights fewer than 3,000 pounds. So, the
  engine of my car weighs fewer than 3,000 pounds
  there is no fallacy.

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Composition (pp. 235-326)

• A. Fallacy of composition
• The fallacy of composition occurs when a property
  that is true of a part of a whole or a member of
  a class is attributed to the whole thing or
  class.
• If I argue, The tires on my car are black. So,
  my car is black I have committed the fallacy of
  composition there is no connection between the
  color of the tires and the color of the car as a
  whole.

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Composition (pp. 235-326)

• B. Nonfallacious cases of composition
• There are cases in which the inference from a
  part to a whole is nonfallacious. If I argue,
  The engine of my car weighs over 100 pounds, so
  my car weighs over 100 pounds there is no
  fallacy.

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Composition (pp. 235-326)

• If I argue, Wagner Hall was built after the
  college was founded, and Wagner Hall is over 100
  years old. So the college is over 100 years old
  there is no fallacy. But if you had less
  information, you wouldnt know. If I argued,
  Wagner Hall is over 100 years old. So the
  college is over 100 years old you cannot know
  whether or not the inference is warranted. If
  Wagner Hall was built after the college was
  founded, the inference is a warranted. If the
  college was built on the site of a former
  plantation and Wagner Hall was formerly Mr.
  Wagners palatial home, the inference would not
  be warranted.

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Fallacies of Ambiguity (pp. 320-326)

• Warning In subsequent chapters we shall
  examine fallacies called Accident (Chapter 29)
  and Hasty Generalization (Chapter 31). Both of
  these concern principles or general statements.
  Many students confuse them with division and
  composition. In the case of division and
  composition, you are concerned with the
  relationship between parts and wholes (members of
  a class are parts of a class). In the case of
  Accident and Hasty Generalization, you are
  concerned with general statements. Do not
  confuse the two issues.