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Illicit major
From Wikipedia, the free encyclopedia
Illicit major is a logical fallacy committed in a categorical syllogism that is invalid because its major term is undistributed in the major premise but distributed in the conclusion.
Example:
- All dogs are mammals.
- No cats are dogs.
- Therefore, no cats are mammals.
In this argument, the major term is "mammals". This is distributed in the conclusion (the last statement) because we are making a claim about a property of all mammals: that they are not cats. However, it is not distributed in the major premise (the first statement) where we are only talking about a property of some mammals: Only some mammals are dogs.
The error is in assuming that the converse of the first statement (that all mammals are dogs) is also true.
- This article was originally based on material from the Free On-line Dictionary of Philosophy, which is licensed under the GFDL.
| Argument from fallacy | Fallacy of modal logic | Masked man fallacy | Appeal to probability
|
|
|---|---|
| Fallacy of propositional logic: | |
| Affirming a disjunct | Affirming the consequent | Commutation of Conditionals Denying a conjunct | Denying the antecedent | Improper Transition |
|
| Fallacy of quantificational logic: | |
| Existential fallacy | Illicit Conversion | Quantifier shift | Unwarranted contrast | |
| Syllogistic fallacy: | |
| Affirmative conclusion from a negative premise | Negative conclusion from an affirmative premise Exclusive premisses | Necessity | Four-term Fallacy | Illicit major | Illicit minor | Undistributed middle |
|
| Other types of fallacy | |
