Affirming the Consequent

From EvoWiki

This page is part of the EvoWiki encyclopedia of fallacies. Browse: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Contents 1 Synonyms 2 Explanation 3 Examples 4 Category 5 Twin Fallacy 6 External Links 7 Examples in creationist arguments

Synonyms

• Affirmation of the Consequent
• Asserting the Consequent
• Fallacious Modus Ponens
• Proving a premise from a conclusion fallacy

Explanation

"If A is true, then B is true; B is true, therefore A is true"

This argument is fallacious because the fact of 'B' being true is not enough reason to suggest 'A' is true. Usually 'B' can be true for other reasons, not just 'A'. The argument should then turn to deciding which cause for the truth of 'B' is the most parsimonious explanation.

This argument would only be valid if it is true that "if and only if A is true, B is true", which is normally not the case.

Examples

"If Bill Gates owns Fort Knox, then he is rich.

Bill Gates is rich.

Therefore, Bill Gates owns Fort Knox."

"If the Bible is true, then Jerusalem is a real city.

Jerusalem is a real city, therefore the Bible is true."

Category

• Improper Transposition

Twin Fallacy

• Denying the Antecedent

External Links

• Fallacy Files [1]
• Internet Encyclopedia of Philosophy [2]
• Wikipedia [3]

Examples in creationist arguments

• James Bryce found a 4-foot timber high on Ararat