Consider all. Test All. Hold on to the good.

Stephen Downes

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Many kudos are owed to Stephen Downes, the logician who originally authored this list of fallacies and made it freely available on the Web. His basic structure remains. A mirror of Downes' original site can be found here.

Accent

Type:
illogic
Date:
In:
Uncategorized
Emphasis is used to suggest a meaning different from the actual content of the proposition. ... » Go

Division

Type:
illogic
Date:
In:
Civility and Rhetoric
Because the whole has a certain property, it is argued that the parts have that property. ... » Go

Conjunction (and)

Type:
illogic
Date:
In:
Uncategorized
The proposition P and Q is true if and only if both P and Q are true. It is false otherwise. ... » Go

Conditional (if-then)

Type:
illogic
Date:
In:
Uncategorized
The proposition If P then Q is true if and only if either P is false or Q is true. It is false only when ... » Go

Disjunction (or)

Type:
illogic
Date:
In:
Uncategorized
The proposition P and Q is true if and only if either P or Q are true. It is false only if both P and ... » Go

Insignificance

Type:
illogic
Date:
In:
Uncategorized
One thing is held to cause another, and it does, but it is insignificant compared to other causes of the effect. ... » Go

Composition

Type:
illogic
Date:
In:
Civility and Rhetoric
Because the parts of a whole have a certain property, it is argued that the whole has that property. ... » Go

Joint Effect

Type:
illogic
Date:
In:
Uncategorized
One thing is held to cause another when in fact both are the effect of a single underlying cause. ... » Go

Non-Support

Type:
illogic
Date:
In:
Uncategorized
The explained phenomenon does not in fact occur, or there is no evidence that it does occur. ... » Go

Truths

Type:
illogic
Date:
In:
Uncategorized
A proposition is true if and only if what it says about the world is in fact the way it is. ... » Go

Negation (not)

Type:
illogic
Date:
In:
Metaethics
The proposition Not P is true if and only if P is false. It is false only if P is true. ... » Go

Propositions

Type:
illogic
Date:
In:
Uncategorized
A logical operator joins two propositions to form a new, complex, proposition. ... » Go

Irrelevant Conclusion

Type:
illogic
Date:
In:
Uncategorized
An argument which purports to prove one thing instead proves a different conclusion. ... » Go

Amphiboly

Type:
illogic
Date:
In:
Uncategorized
An amphiboly occurs when the construction of a sentence allows it to have two different meanings. ... » Go

Four Terms

Type:
illogic
Date:
In:
Evolution
The fallacy is committed when a standard form categorical syllogism contains four terms. ... » Go

Undistributed Middle

Type:
illogic
Date:
In:
Evolution
The middle term in the premises of a standard form categorical syllogism never refers to all of the members of the category it describes. ... » Go

Illicit Major

Type:
illogic
Date:
In:
Evolution
The predicate term of the conclusion refers to all members of that category, but the same term in the premises refers only to some members ... » Go