Fallacy of exclusive premises
Encyclopedia
The fallacy of exclusive premises is a syllogistic fallacy
committed in a categorical syllogism that is invalid
because both of its premise
s are negative.
Example of an EOO-4 invalid proposition:
Syllogistic fallacy
Syllogistic fallacies are logical fallacies that occur in syllogisms. They include:Any syllogism type :*fallacy of four termsOccurring in categorical syllogisms:*related to affirmative or negative premises:...
committed in a categorical syllogism that is invalid
Validity
In logic, argument is valid if and only if its conclusion is entailed by its premises, a formula is valid if and only if it is true under every interpretation, and an argument form is valid if and only if every argument of that logical form is valid....
because both of its premise
Premise
Premise can refer to:* Premise, a claim that is a reason for, or an objection against, some other claim as part of an argument...
s are negative.
Example of an EOO-4 invalid proposition:
- E Proposition: No mammals are fishesMiddle termThe middle term must distributed in at least one premises but not in the conclusion of a categorical syllogism. The major term and the minor terms, also called the end terms, do appear in the conclusion.Example:...
. - O Proposition: Some fishesMiddle termThe middle term must distributed in at least one premises but not in the conclusion of a categorical syllogism. The major term and the minor terms, also called the end terms, do appear in the conclusion.Example:...
are not whales. - O Proposition: Therefore, some whalesMinor termThe minor term is the subject term of the conclusion of a categorical syllogism. It also appears in the minor premise together with the middle term. Along with the major term it is one of the two end terms.Example:...
are not mammalsMajor termThe major term is the predicate term of the conclusion of a categorical syllogism. It appears in the major premise along with the middle term and not the minor term. It is an end term .Example:...
.
See also
- affirmative conclusion from a negative premiseAffirmative conclusion from a negative premiseAffirmative conclusion from a negative premise is a logical fallacy that is committed when a categorical syllogism has a positive conclusion, but one or two negative premises.For example:...
, in which a syllogism is invalid because the conclusion is affirmative yet one of the premises is negative - negative conclusion from affirmative premisesNegative conclusion from affirmative premisesNegative conclusion from affirmative premises is a syllogistic fallacy committed when a categorical syllogism has a negative conclusion yet both premises are affirmative...
, in which a syllogism is invalid because the conclusion is negative yet the premises are affirmative