Hasty generalization

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Hasty generalization is an informal fallacy of faulty generalization by reaching an inductive generalization based on insufficient evidence—essentially making a hasty conclusion without considering all of the variables. In statistics, it may involve basing broad conclusions regarding the statistics of a survey from a small sample group that fails to sufficiently represent an entire population.[1] Its opposite fallacy is called slothful induction, or denying a reasonable conclusion of an inductive argument (e.g. "it was just a coincidence").


Hasty generalization usually shows this pattern

  1. X is true for A (as in Anton).
  2. X is true for B (as in Bravo).
  3. Therefore, X is true for C, D,E (as in Charly, Delta, Echo) etc.

For example, if a person travels through a town for the first time and sees 10 people, all of them children, they may erroneously conclude that there are no adult residents in the town.

Or: A person is looking at a number line. The number 1 is a square number; 3 is a prime number, 5 is a prime number, and 7 is a prime number; 9 is a square number; 11 is a prime number, and 13 is a prime number. Therefore, the person says, all odd numbers are either prime or square. In reality, 15 is a counterexample.

Alternative names[edit]

The fallacy is also known as:

  • Illicit generalization
  • Fallacy of insufficient sample
  • Generalization from the particular
  • Leaping to a conclusion
  • Hasty induction
  • Law of small numbers
  • Unrepresentative sample
  • Secundum quid

When referring to a generalization made from a single example it has been called the fallacy of the lonely fact[2] or the proof by example fallacy.[3]

When evidence is intentionally excluded to bias the result, it is sometimes termed the fallacy of exclusion and is a form of selection bias.[4]

See also[edit]


  1. ^ "Fallacy: Hasty Generalization (Nizkor Project)". Retrieved 2008-10-01. 
  2. ^ Fischer, David Hackett (1970). Historians' Fallacies: Toward a Logic of Historical Thought. HarperCollins. pp. 109–110. ISBN 978-0-06-131545-9. 
  3. ^ Marchant, Jamie. "Logical Fallacies". Retrieved 2011-04-26. 
  4. ^ "Unrepresentative Sample". Retrieved 2008-09-01. 

External links[edit]