A Critical Assessment of the Negation Argument for Intellectual Moral Good and Bad

What we call the "negation argument" is the second of the three arguments that Nasir al-Din al-Tusi advanced in his influential work, Tajrīd al-iʿtiqād, in defense of intellectual moral good and bad(husn wa qubh 'aqli). According to this argument, the negation of revealed moral good and bad (husn wa qubh shar'i) entails the negation of intellectual moral good and bad (husn wa qubh 'aqli). The presence of various semantic, ontological, and epistemological factors make al-Tusi‘s intended conclusion and the premises of his argument open to multiple interpretations. The logical form of the most reasonable reading of this argument, which we call the “skeptical reading”, demonstrates that the end result is the denial of the epistemological revealed moral good and bad. Certain shortcomings of this reading have also made it incapable of denying the epistemological revealed moral good and bad; ambiguity in the concept of possibility employed by the argument, the use of counterintuitive and unwarranted premises, and a confusion between the occurrence of a lie and the possibility of it in deeming the other unreliable in declaring oneself. The purpose of this article is not to defend revealed moral good and bad, neither is it to deny the intellectual moral good and bad; rather, it’s merely a demonstration of the incompleteness of the negation argument with respect to the latter.