Logical Fallacies

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Logical Fallacies
Identifying and Understanding Cogent Arguments in
Business Settings

• Wayne Smith, Ph.D.
• Department of Management
• CSU Northridge

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Informal Fallacies

• Individuals make arguments, and not all arguments
  are valid.
• This invalidity is due to false premises.
• Individuals also commit fallacies, and such
  fallacies are the result of incorrect or weak
  reasoning.
• We will focus on the latter, and refer to the
  former as needed.
• The text that follows uses the terms arguer and
  reader. However, the terms speaker and
  listener, respectively, can be substituted as
  appropriate.

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Fallacies of Reference
Fallacies of Reference have arguments that
contain premises from which the conclusion does
not flow logically.
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Appeal to Force

• This fallacy occurs when an arguer poses a
  conclusion to a reader, and the reader is
  compelled to accept the conclusion only under a
  physical or psychological threat made by the
  arguer.

5
Appeal to Pity

• This fallacy occurs when an arguer attempts to
  support a conclusion by merely evoking pity from
  the reader.

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Appeal to the People

• This fallacy occurs when an arguer uses desires
  (e.g., love, esteem, admiration, value,
  recognition, etc.) to get the reader to accept a
  conclusion.
• Direct Approach
• Directed to an entire group
• Indirect Approach
• Directed to an individual that represents the
  groups values
• Variations
• Bandwagon Argument
• Appeal to Vanity
• Appeal to Snobbery

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Argument Against the Person

• This fallacy always involves two arguers. It
  occurs when an arguer advances a certain
  argument, and the other then responds by
  directing his or her attention not to the first
  persons argument, but rather to the first person
  himself/herself.
• Variations
• Abusive
• Circumstantial
• tu quoque (you too)

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Accident

• The fallacy of accident is committed when a
  general rule is applied to a specific case it was
  not intended to cover.
• Typically, the general rule is cited in the
  premises and then wrongly applied to the specific
  case.

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Straw Man

• This fallacy occurs is committed when an arguer
  distorts an opponents argument for the purpose
  of more easily attacking it, demolishes the
  distorted argument, and then concludes that the
  opponents real argument has been demolished.

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Missing the Point

• Missing the point is a special form of
  irrelevance.
• This fallacy occurs when the premises of an
  argument support one particular conclusion, but
  then a different conclusion, often vaguely
  related to the correct conclusion, is drawn.

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Red Herring

• This fallacy occurs when an arguer diverts the
  attention of the reader by changing the subject
  to a different but sometimes subtly related one.
  By doing so, the arguer purports to have won the
  argument.

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Fallacies of Weak Induction
Fallacies of Weak Induction occur because the
connection between premises and conclusion is not
strong enough to support the conclusion.
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Appeal to Unqualified Authority

• This fallacy occurs when an arguer uses a
  citation that lacks credibility.

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Appeal to Ignorance

• This fallacy occurs when the premises of an
  argument state that nothing has been proved one
  way or the other about something, and the
  conclusion then makes a definite assertion about
  that thing.

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Hasty Generalization (Converse Accident)

• This fallacy occurs when there is a reasonable
  likelihood that a sample is not representative of
  the group. Such a likelihood may arise if the
  sample is either too small or not randomly
  selected.

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False Cause

• The fallacy of false cause occurs whenever the
  link between premises and conclusion depends on
  some imagined causal connection that probably
  does not exist.

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Slippery Slope

• This fallacy is a variation of the false cause
  fallacy. It occurs when the conclusion of an
  argument rests upon an alleged chain reaction and
  there is not sufficient reason to think that the
  chain reaction will actually take place.

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Weak Analogy

• The fallacy of weak analogy is committed when the
  analogy is not strong enough to support the
  conclusion that is drawn.

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Fallacies of Presumption, Ambiguity, and
Grammatical Analogy
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Begging the Question

• The fallacy of begging the question occurs
  whenever the arguer creates the illusion that
  inadequate premises provide adequate support for
  the conclusion by leaving out a possibly false
  (or shaky) key premise.

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Complex Question

• This fallacy is committed when two or more
  questions are asked in the guise of a single
  question and a single answer is then given to
  both of them.

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Suppressed Evidence

• This fallacy occurs when an argument ignores some
  important piece of evidence that outweighs the
  presented evidence and entails a very different
  conclusion.

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Equivocation

• This fallacy occurs when the conclusion of an
  argument depends on the fact that a word or
  phrase is uses, either explicitly or implicitly,
  in two different senses in the argument.
• Such arguments are either invalid or have a false
  premise, and in either case they are unsound.

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Amphiboly

• The fallacy of amphiboly occurs when the arguer
  misinterprets an ambiguous statement and then
  draws a conclusion based on this faulty
  interpretation.
• Often, this fallacy arises from a mistake in
  grammar or punctuation.

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Composition

• The fallacy of composition is committed when the
  conclusion of an argument depends on the
  erroneous transference of an attribute from the
  parts of something onto the whole.

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Division

• The fallacy is committed when the conclusion of
  an argument depends on the erroneous transference
  of an attribute from a whole (or a class) onto
  its parts (or members).
• This fallacy occurs is exact reverse of
  composition.

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Sources

• Hurley, P. (2006), A Concise Introduction to
  Logic, 9th ed., AustraliaThompson.