Aristotle's God is pure self-thinking thought — the Unmoved Mover contemplates only itself, the highest object. Avicenna's version allows that God knows the world but only through universal principles: God knows that fire burns, not that this fire burned this cotton at this moment. To know particulars would require God to be receptive to change in the temporal world, compromising divine immutability.
For Al-Ghazali, this doctrine of limited divine knowledge is not merely philosophically questionable but religiously catastrophic. A God who does not know particular events cannot hear prayers, cannot respond to individual supplications, cannot exercise providential care over individual lives. The God of the philosophers is too remote for Islamic worship and for the Quranic picture of a God who is closer to man than his own jugular vein.
Al-Ghazali does not simply assert that God knows particulars — he engages the philosophers' objection about how a timeless God can know temporal facts. His answer is that God's knowledge of particulars does not require God to be temporal or to change; the temporality belongs to the known facts, not to the knowing. Divine knowledge encompasses all temporal facts in a single eternal act of knowing.
Divine knowledge of particulars is the subject of the 13th discussion in The Incoherence of the Philosophers. It is one of the three positions Al-Ghazali explicitly labels heretical.
