Affirmative_conclusion_from_a_negative

Affirmative conclusion from a negative premise

Affirmative 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:

No fish are dogs, and no dogs can fly, therefore all fish can fly.

This could be illustrated mathematically as

If A ⊄ B and B ⊄ C then A ⊂ C.

It is a fallacy because any valid forms of categorical syllogism that assert a negative premise must have a negative conclusion.

v • d • e Formal fallacies

Argument from fallacy • Fallacy of modal logic • Masked man fallacy • Appeal to probability • Bare assertion fallacy

Fallacy of propositional logic:	Affirming a disjunct • Affirming the consequent • False dilemma • Denying the antecedent

Fallacy of quantificational logic:	Existential fallacy • Illicit Conversion • Proof by example • Quantifier shift

Syllogistic fallacy:	Affirmative conclusion from a negative premise • Exclusive premises • Necessity • Four-term Fallacy • Illicit major • Illicit minor • Undistributed middle

Other types of fallacy

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