Divine Belief Simplicity is the thesis that all of God's acts of belief are the same act of belief, the same belief token. While my belief that 2+2=4 seems distinct from my belief that the sky is blue, God's believings are all one. This is a special case of divine simplicity.
Here is an argument for Divine Belief Simplicity. The primary alternative to Divine Belief Simplicity is:
- Divine Belief Diversity: God's act of believing p is distinct from God's act of believing q whenever p and q are different.
- For any plurality, the Fs, there is a distinct proposition that the Fs exist or don't exist.
- Separation: Given any plurality, the Fs, and a predicate, P, that is satisfied by at least one of the Fs, there is a plurality of all and only the Fs satisfying P.
- Plurality of Believings: If Divine Belief Diversity holds, then there is a plurality of all divine acts of believing.
Say that a divine believing b is settish provided that there is a plurality, the Fs, such that b is a believing that the Fs exist or don't exist. For any settish divine belief b, there is the plurality of things that b affirms the existence or nonexistence of. Say that a divine believing b is nonselfmembered provided that b is settish and is not in the plurality of things that b affirms the existence or nonexistence of. By (1), Separation and Plurality of Believings, let p be the proposition that affirms existence-or-nonexistence of the nonselfmembered believings. Now p is true. So there is a divine believing b in p. This is settish. Moreover, this b either is among the nonselfmembered believings or not. If it is, then it's not. If it's not, then it is. So we have a contradiction.
Moreover, this argument does not need to take propositions ontologically seriously. It only needs divine believings to be taken ontologically seriously.
Denying Divine Belief Diversity, however, denies that there is such a thing as the plurality of things that b affirms the existence or nonexistence of.