Logical fallacy

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.

Logical fallacies

• also called "rhetorical fallacies"

ad hominem

• 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

• 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

• 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

• 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

• 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

• 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

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

false dilemma

• 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

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

genetic fallacy

• 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

moral equivalence fallacy

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

non sequitur

• " 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.”

strawman fallacy

• = the target of an argument (the "strawman") has nothing to do with the actual argument
• weak analogy
• see
  • https://en.wikipedia.org/wiki/List_of_fallacies
  • Fallacies – The Writing Center • University of North Carolina at Chapel Hill (unc.edu)

Rhetorical tricks

• 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

dodging the issue

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

Gish gallop

• 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

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

weasel words

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

See also

• Rhetorical analysis