!! '''[[http://www.fallacyfiles.org/exclprem.html Two Negative Premises]]''':
:: If A is not B, and B is not C, then A is C. This is always invalid logic (although it may happen to be true), as it is not possible to make a valid conclusion from two negative premises; logic is not arithmetic. This is a fallacy because simply identifying what something ''isn't'' doesn't identify what it ''is''.

-->No Jews are Muslims.
-->No Muslims are Christians.
-->Therefore Jews are Christians.

--> No dogs are reptiles.
--> No reptiles are magenta.
--> Dogs are magenta.

--> No dogs are reptiles.
--> No reptiles shoot lasers out of their eyes.
--> Dogs shoot lasers out of their eyes.