Online Writing Lab

Common Logical Fallacies

As the name suggests, logical fallacies are flaws in reasoning that detract from the overall value of an argument.  Politicians are often guilty of using logical fallacies in an attempt to gain public support.  Writers, however, cannot resort to such tactics, especially since writing is usually closely evaluated.  Good writers avoid using logical fallacies since they detract from the value of an argument rather than add to it. 

The following is a list of common logical fallacies that all writers should avoid using:

  1. Hasty Generalization (also called overgeneralization):  The writer bases the argument on insufficient evidence.  The writer draws a larger conclusion than the evidence supports.
  2. Non Sequitor (“It doesn’t follow”): The writer’s conclusion is not necessarily a logical result of the facts.
  3. Begging the Question: The writer presents as truth what is not yet proven by the argument.  (Before an argument on a topic can be made, or a solution offered, the reader must be convinced that there is a problem.)
  4. Red Herring: The writer introduces an irrelevant point to divert the reader’s attention from the main issue.
  5. Argument Ad Hominem (“to the man”): The writer attacks the opponent’s character rather than the opponent’s argument.
  6. Faulty use of authority (ad verecundiam): The writer relies on "authorities" who are not convincing sources.
  7. Argument Ad Populum (“to the people”): The writer evades the issues by appealing to the reader’s emotional reactions to certain subjects.
  8. Either/or: The writer tries to convince the readers that there are only two sides to an issue.  Most reasonable people understand that there is often a middle ground, especially when dealing with complex issues.
  9. Hypostatization: The writer uses an abstract concept as if it were a concrete reality (i.e. science has proven, research shows, history has taught, etc.).
  10. Bandwagon Appeal: The writer tries to validate a point by suggesting that "everyone else believes in this."
  11. Straw Man: The writer selects the opposition’s weakest or most insignificant point to argue against.
  12. Faulty Analogy: The writer uses an extended comparison as proof of a point.
  13. Card Stacking:  The writer selects only data that supports his own viewpoint and ignores contradictory data. 
  14. Oversimplification:  the tendency to overlook complexity in an argument (relying on a simple explanation because it comes easily).
  15. Slippery Slope: The assumption that one thing leads to another (the next step).