Distraction 

Bifurcation/False Dilemma: two choices are given when in fact there are three or more
Invincible Ignorance: because something is not known to be true, it is assumed to be false 
Slippery Slope: assumed that increasingly unacceptable consequences will follow 
Complex Question: two unrelated points are conjoined as a single proposition 
Genetic Fallacy: nothing good could come from such a source 

Blinding With Science: using technical jargon or inappropriately claiming scientific support

Appeals 

Appeal to Force: the reader is persuaded to agree by force 
Appeal to Pity: the reader is persuaded to agree by sympathy 
Appeal to Consequences: the reader is warned of unacceptable and dire consequences 
Loaded Language: value or moral goodness is attached to believing the author 
Appeal to Popularity: a proposition is argued to be true because it is widely held to be true 
Appeal to Antiquity: "that's the way we've always done it"

People Power 

Ad Hominem--Attack the Person: 
1.the person's character is attacked 
2.the person's circumstances are highlighted 
3.the person's hypocrisy is presented as a disqualifier 

Appeal to Authority: 
1.the person is an authority in the field 
2.experts in the field disagree 
3.the authority was joking

 
Anonymous Authority: the authority in question is not named 
Style Over Substance: the manner an argument is presented is more important than the conclusion

Induction Problems 

Hasty Generalization: the sample is too small to support an inductive generalization
Biased Sample: the sample is unrepresentative of the population 
False Analogy: the two objects or events being compared are dissimilar 
Slothful Induction: the conclusion of a strong inductive argument is denied despite the evidence
Evidence of Exclusion: evidence which changes the outcome of an inductive argument is excluded

Generalizations 

Accident: a generalization is applied when circumstances suggest otherwise 
Converse Accident : an exception is applied in circumstances where a generalization should apply 

Cause and Effect 

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 effects of a 3rd cause 
Insignificant: one thing is rightly held to cause another but is insignificant compared to other causes 
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 another conclusion
Straw Man: the author attacks a weaker argument than the opposition's best argument 

Ambiguity 

Equivocation: the same term is used with two different meanings 
Amphiboly: the structure of a sentence allows two different interpretations 
Accent: the verbal emphasis suggests a meaning contrary to what the sentence actually says 

Category Errors 

Composition: because the parts of a whole have a certain property, the whole has that property 
Division: because the whole has a certain property, it is argued that the parts have that property 

Non Sequitur 

Affirming the Consequent: any argument of the form: If A then B, B, therefore A 
Denying the Antecedent: any argument of the form: If A then B, Not A, thus Not B 
Inconsistency: asserting that contrary or contradictory statements are both true 

Syllogistic Errors 

Fallacy of Four Terms: a syllogism has four terms 
Undistributed Middle: two separate categories said to be linked because they share a property 
Illicit Major: the predicate of the conclusion talks about ALL of something, but the premises only mention SOME cases of the term in the predicate 
Illicit Minor: the subject of the conclusion talks about ALL of something, but the premises only mention SOME cases of the term in the subject 
Exclusive Premises: a syllogism has two negative premises 
Drawing a Positive Conclusion From a Negative Premise: as the name implies 
Existential Fallacy: a particular conclusion is drawn from universal premises 

Support 

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) 

Scope

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 should be included) 
Failure to Elucidate (The definition is more difficult to understand than the thing being defined) 
Circular Definition (The definition includes the term being defined as a part of the definition) 
Conflicting Conditions (The definition is self-contradictory) 


Source in part: Stephen Downes' Homepage 


For Educators
Stephen Downes Guide to the Logical Fallacies
Copyright © Stephen Downes, 1995-2000 
stephen.downes@ualberta.ca 

Copyright Notice

Reference

The Guide should be referenced as follows: 

Stephen Downes. Stephen's Guide to the Logical Fallacies.
Brandon, Manitoba, Canada, 1995-2000.
http://www.datanation.com/fallacies

 

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