Per fas et nefas

"Per fas et nefas" (Latin for "through right and wrong") refers to unfair eristic treatment. It occurs when Interlocutor A postulates a theory, and cites several reasons that justify it. Interlocutor B then refutes one of the arguments, and triumphantly declares that A's argument has no basis, even though he never said a word about the other arguments that A put forth.

See also

• Eristic
• Dialectic
• Logic