The probability of effectiveness is considered one of the most important conditions for enjoining good and forbidding evil. However, its validity has long been a matter of disagreement among scholars of Islamic theology and jurisprudence. Some scholars regard the obligation of this duty as conditional upon the probability of effectiveness, while others maintain that it is obligatory absolutely, regardless of such probability. Although the hadiths cited as evidence for this condition are all subject to debate concerning both their chains of transmission and their semantic implications, most discussions have continued to revolve around these narrations. Meanwhile, independent and precise examination of the Qur’anic evidence has generally been brief and scattered.
Accordingly, by examining the Qur’anic proofs presented by both groups, this study seeks to overcome the problem of superficial treatment of Qur’anic evidence. Using a library-based research method and an analytical approach, the present study investigates whether the Qur’anic evidence supports or rejects the condition of the probability of effectiveness. The findings indicate that the Qur’anic arguments advanced by those who deny the condition not only fail to negate the requirement of probability of effectiveness, but in some cases even reinforce it. Moreover, the view affirming the condition is substantiated through the principle of purposiveness in divine actions. Consequently, the Qur’anic evidence cited by the proponents of unconditional obligation faces significant objections, while the condition of probability of effectiveness is established on the basis of the principle of purposiveness in divine actions.