Alias: Two Negative Premisses
Type: Syllogistic Fallacy
Form: Any form of categorical syllogism with two negative premisses.
|No moslems are christians.
No jews are moslems.
Therefore, no jews are christians.
|No reptiles are mammals.
No dogs are reptiles.
Therefore, no dogs are mammals.
This diagram represents both the Example and Counter-Example, which it shows to be invalid, since the area with the question mark is not shown to be empty.
Syllogistic Rule Violated:
At least one premiss of a valid categorical syllogism is affirmative.
Robert Audi (General Editor), The Cambridge Dictionary of Philosophy, 1995, p. 272.