Some erudite claims have been put forward by Cahm b. Safwan, Hisham b. Hakam and Ibn Sina with regard to God’s knowledge. Although God affirms in the Qur’an that He knows both the known and unknown, it has been witnessed that God’s knowledge of non-existence (ma’dûm) except for the universals (kullî) is not probable. Nowadays we have some scholars defending the same position. in view of that we will discuss this hot debate bringing arguments in this regard