Brian Leftow

Medieval philosophers distinguished God from all else by calling Him supremely one. Realists about properties affirmed God's special unity by arguing either that God cannot be conceived to be without His properties or that God wholly lacks the real complexity having properties involves. ;This thesis examines the latter, more radical doctrine of divine simplicity. On this doctrine, for all F, what makes God F differs in no way from what makes Him God. ;If all truths about God have the same truth-condition, they all are materially equivalent. Their predicates' senses seemingly must shift in divinis to allow this unusual equivalence. Many medievals concluded from this that God is simple, it is impossible to say anything comprehensible about Him and in particular to ascribe to Him personal attributes. ;By distinguishing sense- from application-fixing properties associated with predicates, I so analyze talk of a simple being as to give it comprehensible sense. I argue that we can ascribe a simple God the sort of knowing involved in understanding a proposition and that this renders such a God "personal enough" for religion. ;If coherent, the radical doctrine of divine simplicity follows from God's being the most perfect logically possible being on the assumptions that something is a better F the less likely it is to cease being F and that being "one with one's Fness" involves more "unity" with one's Fness than does being necessarily F. Divine simplicity entails God's timelessness, immutability, uniqueness and aseity. It also entails two conditionals, that if God wills, He is omnipotent and that if God knows, He is omniscient. By tracing out these connections I show that divine simplicity brings to a concept of God both systematic neatness and plausible explanations for God's having many of His traditional attributes