Monday, October 16, 2006

Stephen's Guide to the Logical Fallacies

Stephen's Guide to the Logical Fallacies
by Stephen Downes

Table of Contents

Welcome
  • False Dilemma: two choices are given when in fact there are three options
  • From Ignorance: because something is not known to be true, it is assumed to be false
  • Slippery Slope: a series of increasingly unacceptable consequences is drawn
  • Complex Question: two unrelated points are conjoined as a single proposition
Appeals to Motives in Place of Support
Changing the Subject
  • Attacking the Person:
    1. the person's character is attacked
    2. the person's circumstances are noted
    3. the person does not practise what is preached
  • Appeal to Authority:
    1. the authority is not an expert in the field
    2. experts in the field disagree
    3. the authority was joking, drunk, or in some other way not being serious
  • Anonymous Authority: the authority in question is not named
  • Style Over Substance: the manner in which an argument (or arguer) is presented is felt to affect the truth of the conclusion
Inductive Fallacies
  • Hasty Generalization: the sample is too small to support an inductive generalization about a population
  • Unrepresentative Sample: the sample is unrepresentative of the sample as a whole
  • False Analogy: the two objects or events being compared are relevantly dissimilar
  • Slothful Induction: the conclusion of a strong inductive argument is denied despite the evidence to the contrary
  • Fallacy of Exclusion: evidence which would change the outcome of an inductive argument is excluded from consideration
Fallacies Involving Statistical Syllogisms
  • Accident: a generalization is applied when circumstances suggest that there should be an exception
  • Converse Accident : an exception is applied in circumstances where a generalization should apply
Causal Fallacies
  • Post Hoc: because one thing follows another, it is held to cause the other
  • Joint effect: one thing is held to cause another when in fact they are both the joint effects of an underlying cause
  • Insignificant: one thing is held to cause another, and it does, but it is insignificant compared to other causes of the effect
  • Wrong Direction: the direction between cause and effect is reversed
  • Complex Cause: the cause identified is only a part of the entire cause of the effect
Missing the Point
  • Begging the Question: the truth of the conclusion is assumed by the premises
  • Irrelevant Conclusion: an argument in defense of one conclusion instead proves a different conclusion
  • Straw Man: the author attacks an argument different from (and weaker than) the opposition's best argument
Fallacies of Ambiguity
  • Equivocation: the same term is used with two different meanings
  • Amphiboly: the structure of a sentence allows two different interpretations
  • Accent: the emphasis on a word or phrase suggests a meaning contrary to what the sentence actually says
Category Errors
  • Composition: because the attributes of the parts of a whole have a certain property, it is argued that the whole has that property
  • Division: because the whole has a certain property, it is argued that the parts have that property
Non Sequitur
Syllogistic Errors
Fallacies of Explanation
  • Subverted Support (The phenomenon being explained doesn't exist)
  • Non-support (Evidence for the phenomenon being explained is biased)
  • Untestability (The theory which explains cannot be tested)
  • Limited Scope (The theory which explains can only explain one thing)
  • Limited Depth (The theory which explains does not appeal to underlying causes)
Fallacies of Definition
  • Too Broad (The definition includes items which should not be included)
  • Too Narrow (The definition does not include all the items which shouls be included)
  • Failure to Elucidate (The definition is more difficult to understand than the word or concept being defined)
  • Circular Definition (The definition includes the term being defined as a part of the definition)
  • Conflicting Conditions (The definition is self-contradictory)
Author

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