Negative Conclusion from Affirmative PremissesAlias:
This diagram shows that both the Example and Counter-Example are invalid, since it does not show that there is anything in the area with the question mark.
Syllogistic Rule Violated:
Any validating form of categorical syllogism with both premisses affirmative has an affirmative conclusion.
Robert Audi (General Editor), The Cambridge Dictionary of Philosophy (Second Edition), 1995, p. 272.