# Fallacy of exclusive premises

- Fallacy of exclusive premises
The **fallacy of exclusive premises** is a formal fallacy committed in a categorical syllogism that is invalid because both of its premises are negative.

"Example:"

:"No mammals are fish.":"Some fish are not whales.":"Therefore, some whales are not mammals."

It is not a syllogistic fallacy because at least one premise of a given syllogism has to be affirmative.

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