Fallacy of accident

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General logic
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Not to be confused with overgeneralization or fallacy of accent.
No rule is so general, which admits not some exception.
—Robert Burton, The Anatomy of Melancholy

Fallacy of accident is a logical fallacy that occurs when a general rule (a rule of thumb or a "soft" generalization) is taken to be universal (an unconditionally true statement).

The fallacy is an imprecision fallacy and an informal fallacy.

Alternate names[edit]

  • a dicto simpliciter ad dictum secundum quid
  • sweeping generalization
  • misuse of a principle
  • ignoring qualifications

Form[edit]

P1: Bs are normally Cs.
P2: A (an abnormal example) is a B.
C1: A is C.

Examples[edit]

Water boils at a temperature of 212° Fahrenheit; therefore boiling water will be hot enough to cook an egg hard in five minutes: but if we argue thus at an altitude of 5,000 feet, we shall be disappointed; for the height, through the difference in the pressure of the air, qualifies the truth of our general principle.
—H. W. B. Joseph
  • "Birds can [normally] fly" is a general rule, and doesn't imply that all birds (such as emus or penguins) can fly. To take this general rule and apply it to all birds would be committing a sweeping generalization.

Subfallacies[edit]

External links[edit]