Logical fallacy

From A+ Club Lesson Planner & Study Guide

Logical fallacies, or logical errors, are erroneous, illogical, or misleading arguments or claims; also called " informal logic fallacies"

This article includes "rhetorical tricks" (redirects to here)

  • erroneous = contains an error of fact or
  • illogical = draws a conclusion not supported by premises
  • misleading = deliberately constructed to deceive or mislead

See Social Studies skills: Logical and observational fallacies & paradoxes for list of logical and observational fallacies regarding the Social Sciences.


  • as an independent study, logic is not taught in secondary schools
    • nevertheless, it is used in all disciplines
    • math equations are logic-based
    • social students arguments are logic-based
    • literary comprehension and analysis employs logic
  • it is less important for students to learn the names of the fallacies (which is useful) than to recognize when a logical fallacy is used.
  • therefore,
    • the first chapter below categorizes logical and rhetorical fallacies, then identifies the name
    • the subsequent chapters is alphabetical list of logical and rhetorical fallacies and their definitions

Logical and Rhetorical strategies & the logical fallacy it represents[edit | edit source]

  • "Rhetorical strategy" = a technique for presenting an argument, not the argument itself
    • i.e., the word choice and structure, presentation technique, etc.
  • "Logical strategy" = the actual argument and how it is structured
  • "Logical fallacy it represents" = the term and definition of the rhetorical or logical strategy employed
Rhetorical strategy Logical strategy Logical Fallacy it represents Definition
Accuse opponent of bad character or moral shortcoming

Insults such as inhumane, Communist, Nazi, bigoted, sociopathic, etc., or even milder flaws such as insensitivity, selfishness, etc.

ad hominem
Only allows for two sides to an argument, or giving only two options, such as yes or no and no in between
Ask a question that assumes an answer rhetorical question
Offer only two alternatives (either this or that)

Logical fallacies[edit | edit source]

  • also called "rhetorical fallacies"

ad hominem[edit | edit source]

  • a form of "character attack"
    • ad hominem appeals to prejudice and emotions of the audience rather than addressing the opponent's argument itself
    • similar to a "false equivalency" that may include making an argument that "impugns" (insults, denigrates) the opponent's integrity through an association with someone or something else that is otherwise unrelated to the opponent's argument
      • ex.: "My opponent believes in private schools, just like all racists do"
  • can be a valid argument: see: Character Attacks: How to Properly Apply the Ad Hominem - Scientific American
  • fallacy: makes an illogical comparison

ad populum / bandwagon appeal[edit | edit source]

  • argument by exception
    • a fallacy of the particular, in which an argument is attacked based upon a single or rare instance of exception
    • ex.: "We're in a drought"
      • exception: "But it rained the other day"
  • fallacy: just because it rained once doesn't mean the drought is over

association fallacy[edit | edit source]

  • equates having similar ideas or circumstances to a group as being the same as that group
    • ex. "You think smoking is bad. Hitler thought smoking was bad."
  • fallacy: a type of ad hominem argument

broken leg fallacy[edit | edit source]

  • presents a solution for a problem caused by that or a related solution
  • i.e, break the leg, then offer to fix it

circular argument[edit | edit source]

  • argument whose premise is its own conclusion
  • i.e., restates the argument rather than proving it
  • ex. "She's a great skater because she skates well"

confusing credentials for evidence[edit | edit source]

  • i.e., "98% of dentists recommend flossing"
    • does not provide evidence for the benefits of flossing, just that supposed experts say so

either-or fallacy[edit | edit source]

  • incorrectly argues only two options or possibilities
  • fallacy: illogically confines or limits the argument

fallacy of relevance[edit | edit source]

false dilemma[edit | edit source]

  • similar to "either/or" fallacy
  • limits the argument to certain premises
    • thereby denying other possible premises or explanations for an argument
  • = a type of "disjunctive claim"

false equivalence[edit | edit source]

  • illogical comparison of dissimilar subjects
  • i.e., comparing "apples to oranges"

genetic fallacy[edit | edit source]

  • fallacy that of the origins of something determine its value
    • ex., the VW was designed by Hitler, and Hitler is evil, therefore the VW is evil

hasty generalization[edit | edit source]

moral equivalence fallacy[edit | edit source]

  • illogically compares things of distinct moral or ethical dimensions
    • ex., "Any politician that disagrees with me is a Nazi!"

non sequitur[edit | edit source]

  • " Humpty Dumptying" or "Humpty Dumptyisms":
  • = an "arbitrary redefinition" like that used by Humpty Dumpty in "Alice in Wonderland"
  • who tells Alice, "“When I use a word it means just what I choose it to mean—neither more nor less.”

red herring[edit | edit source]

strawman fallacy[edit | edit source]

  • = the target of an argument (the "strawman") has nothing to do with the actual argument
  • weak analogy
  • see

Rhetorical tricks[edit | edit source]

  • In addition to use of logical fallacies
    • students should be able to recognize use of "rhetorical tricks"
  • many logical fallacies are also "rhetorical tricks," but here we will focus on those that are not-logic based fallacies
  • they are more about a method of presentation (rhetorical device) than logic/illogic

begging the question[edit | edit source]

dodging the issue[edit | edit source]

  • speaker or debater briefly mentions the topic, then discusses something else
  • goal is to change the topic

Gish gallop[edit | edit source]

  • rapid use of multiple arguments in order to overwhelm a debate or argument
    • avoids scrutiny of individual arguments
    • named for Duane Gish who spoke rapidly and without allowing the opponent to intervene or analyze each individual arguments
      • "gallop" indicates rapidly running horse
  • defense against a Gish gallop is achieved by focusing on only one or a few of the core arguments that would thereby undermined the logical basis of all the others presented in the Gish gallop

ignoratio elenchi[edit | edit source]

  • an argument that misses the point
  • may be used as a deliberate "dodge"

weasel words[edit | edit source]

  • words and phrases that create the impression that something meaningful has been said, but actually only makes a vague or ambiguous claim

See also[edit | edit source]