# Propositional Fallacies

A propositional fallacy is one where an error in logic takes place due to compound propositions--a proposition is a 'statement'. In order for a compound proposition to have a true value, each component proposition must also be true.

Logic formulas:

- Affirming a disjunct:
*A or B; A; therefore not B*
- Affirming the consent:
*A, then B; B, therefore A*
- Denying the antecedent:
*If A, then B; not A, therefore not B*

### Example of Propositional Fallacies

William Shatner is Captain Kirk or he is in Miss Congeniality. William Shatner is in Miss Congeniality. Therefore he is not Captain Kirk.

**Note**

Alternative Name: Denying the Antecedent