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Logical Fallacies (common types of errors in reasoning):
Fallacies are broken down into two categories: formal and informal. Formal fallacies are based strictly on the logical formation of an argument (deductive). Informal fallacies, which are the most commonly recognized and easiest to learn, take into account the non-logical content of an argument (inductive); they are false for epistemological, dialectical or pragmatic reasons, and typically fall under three categories: relevance, presumption, and ambiguity. The first formation of logical fallacies comes to us from Sir Thomas Aquinas and “The Scholastics”.


  1. Ad Hominem
  2. Ad Hominem Tu Quoque
  3. Appeal to Authority
  4. Appeal to Belief
  5. Appeal to Common Practice
  6. Appeal to Consequences of a Belief
  7. Appeal to Emotion
  8. Appeal to Fear
  9. Appeal to Flattery
  10. Appeal to Novelty
  11. Appeal to Pity
  12. Appeal to Popularity
  13. Appeal to Ridicule
  14. Appeal to Spite
  15. Appeal to Tradition
  16. Bandwagon
  17. Begging the Question
  18. Biased Sample
  19. Burden of Proof
  20. Circumstantial Ad Hominem
  21. Composition
  22. Confusing Cause and Effect
  23. Division
  24. False Dilemma
  25. Gambler’s Fallacy
  26. Genetic Fallacy
  27. Guilt By Association
  28. Hasty Generalization
  29. Ignoring A Common Cause
  30. Middle Ground
  31. Misleading Vividness
  32. Personal Attack
  33. Poisoning the Well
  34. Post Hoc
  35. Questionable Cause
  36. Red Herring
  37. Relativist Fallacy
  38. Slippery Slope
  39. Special Pleading
  40. Spotlight
  41. Straw Man
  42. Two Wrongs Make A Right
Though liberal / leftist in its leaning, this list gives an excellent understanding of the core fallacies. Just look out for that “libertine fallacy”.

Copyright 1995 Michael C. Labossiere. If you have questions or comments about this work, please direct them both to Dr. Labossiere (

42 Fallacies, by Dr. Michael Labossiere, 2010. Free ebook download, or free PDF download.

Other sites that list and explain fallacies include:

Description of Fallacies

In order to understand what a fallacy is, one must understand what an
argument is. Very briefly, an argument consists of one or more premises
and one conclusion. A premise is a statement (a sentence that is either
true or false) that is offered in support of the claim being made, which
is the conclusion (which is also a sentence that is either true or

There are two main types of arguments: deductive and inductive. A
deductive argument is an argument such that the premises provide (or
appear to provide) complete support for the conclusion. An inductive
argument is an argument such that the premises provide (or appear to
provide) some degree of support (but less than complete support) for the
conclusion. If the premises actually provide the required degree of
support for the conclusion, then the argument is a good one. A good
deductive argument is known as a valid argument and is such that if all
its premises are true, then its conclusion must be true. If all the
argument is valid and actually has all true premises, then it is known
as a sound argument. If it is invalid or has one or more false premises,
it will be unsound. A good inductive argument is known as a strong (or
“cogent”) inductive argument. It is such that if the premises
are true, the conclusion is likely to be true.

A fallacy is, very generally, an error in reasoning. This differs
from a factual error, which is simply being wrong about the facts. To be
more specific, a fallacy is an “argument” in which the
premises given for the conclusion do not provide the needed degree of
support. A deductive fallacy is a deductive argument that is invalid (it
is such that it could have all true premises and still have a false
conclusion). An inductive fallacy is less formal than a deductive
fallacy. They are simply “arguments” which appear to be
inductive arguments, but the premises do not provided enough support for
the conclusion. In such cases, even if the premises were true, the
conclusion would not be more likely to be true.

Examples of Fallacies

  1. Inductive ArgumentPremise 1: Most American cats are domestic house cats.Premise 2: Bill is an American cat.

    Conclusion: Bill is domestic house cat.

  2. Factual ErrorColumbus is the capital of the United States.
  3. Deductive FallacyPremise 1: If Portland is the capital of Maine, then it is in Maine.Premise 2: Portland is in Maine.

    Conclusion: Portland is the capital of Maine.

    (Portland is in Maine, but Augusta is the capital. Portland is the largest city in Maine, though.)

  4. Inductive FallacyPremise 1: Having just arrived in Ohio, I saw a white squirrel.Conclusion: All Ohio Squirrels are white.

    (While there are many, many squirrels in Ohio, the white ones are very rare).

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