The problem of evil, along with its three subdivisions (ethical, physical and metaphysical) is among the most challenging philosophical and theological problems. One of the most important answers which have been given to this problem from various philosophical and theological traditions from ancient times until today is to judge that evil is related to non-existence. It seems that on the basis of Allamah Tabatabaei’s innovative theory regarding conventional perceptions (idrakat-i itibari) one can derive a new formulation of the classic theories, which is in significant ways different from them, on the basis that evil is to be considered ‘conventional’ as the term is understood by Allamah Tabatabaei. As Allamah Tabatabaei understands it, all practical propositions relating to report-based or real perceptions involve the creation of human conventions for the sake of satisfying certain practical and existential needs and the inclinations arising from these. On the basis of the consideration of evil as conventional, it seems that this problem can find a satisfactory solution and it can be shown that the existence of evil does not contradict the existence of a universe based on a wise divine plan. Furthermore the experience of evil is also recognized in this theory as a human fact and is not completely denied as is the case with similar theories.