A Defeater for the Incredulous Stare against Extrinsic Divine Knowledge

Proponents of the Thomistic doctrine of Divine simplicity often rely upon partially extrinsic grounds for Divine knowledge in order to explain how propositions of form "God knows that p," where p is some tensed proposition, can change truth value without any intrinsic change in God. Such reliance is often met with an incredulous stare from non-classical theists, who insist that Divine knowledge of this kind isn't worthy of the name "knowledge," possibly resting on a intuition that knowledge is a mental state, and that surely mental states of all things are purely intrinsic.

But this incredulous stare faces a devastating undercutting defeater: the partial extrinsicality of creaturely knowledge, except for knowledge of truths without truthmakers and self-knowledge. For all knowledge is factive, and commonly, the fact in question is extrinsic to the knower and constitutes the truthmaker for the proposition known. So, for example, when I know that the cat is on the mat, my knowledge is grounded partially in the truth of the proposition that the cat is on the mat, and the truth of this proposition is itself grounded in the fact (or state of affairs, or whatever one's favorite kind of truthmaker is) of the cat's being on the mat. Thus, by the transitivity of partial grounding, my knowledge is partially grounded in the wholly extrinsic fact of the cat's being on the mat, and therefore is partially extrinsic to me. Thus, whenever any person, God or creature, knows a proposition with a truthmaker that is extrinsic to the knower, that knowledge is partially grounded in something extrinsic to the knower. So extrinsic knowledge is, contrary to the incredulous stare, quite common and includes paradigmatic cases of knowledge, such as knowing that the cat is on the mat or that the Sun is larger than the Earth.

From the Incommunicability of Creative Power to Divine Simplicity

The Divine creative power, the power to create ex nihilo, is often thought to be incommunicable: not even God can confer this power on His creatures. Here's one reason to accept such a thesis: if God's creative power were communicable, whatever a creature created in virtue of that power would rightly worship that creature as its Creator. But only God should be worshiped in this way. So the Divine creative power is incommunicable.

But what metaphysically explains the power's incommunicability? Proponents of Divine simplicity can say: it is incommunicable because the power is God, and no creature can possess God as a power. I doubt there's an equally good explanation of this fact on the denial of DDS.

Divine Simplicity Contributes Nothing to a Modal Collapse

The doctrine of Divine simplicity is widely accused of leading to a modal collapse, but it really contributes nothing to the alleged problem. To see this, consider the case where God has accidents (such as those of knowing, desiring, intending, etc. which are supposed to avoid a modal collapse for creationists). Now we can ask: are those accidents caused or uncaused? If we say they are uncaused, then they are necessary, for nothing can be contingent but uncaused. And if they are necessary, they do nothing to avoid a modal collapse. Suppose then that they are caused. By what are they caused? By the Divine Essence, for that is all that is ontologically prior to them. But the Divine Essence is intrinsically invariable across possible worlds (on pain of God not being a necessary being), and so we would have a modal collapse with respect to the Divine accidents, and therefore with respect to everything. So it is simply a mistake to think that Divine simplicity makes any difference to whether the doctrine of creation ex nihilo leads to a modal collapse.

A Trinitarian Trilemma for Deniers of Divine Simplicity

The doctrine of Divine simplicity is closely tied to the doctrine of Divine aseity, and proponents of DDS regularly claim that the doctrine of Divine aseity entails the DDS, for if God had parts, these parts would ground Him, and He would not be a se. Deniers of DDS often reply that God grounds His parts and not vice versa, and so the denial of DDS poses no problem for Divine aseity. But they face the following argument:

1. If God has parts, then the Divine Persons have parts.
2. If the Divine Persons have parts, then they share at least some of those parts with each of the other Divine Persons.
3. If the Divine Persons share at least some of their parts with each of the other Divine Persons, then either (i) those parts are fully grounded by more than one thing or (ii) at least one of the Divine Persons is at least partially grounded by some of that Person's parts.
4. Therefore, if God has parts, then either (i) those parts are fully grounded by more than one thing or (ii) at least one of the Divine Persons is at least partially grounded by some of that Person's parts.

(1) is true because the Divine Persons cannot be simpler than God. The whole force of arguments against DDS is that it is incoherent for anything to be absolutely metaphysically simple. So the denier of DDS can't admit that the Divine Persons are simple while insisting that God is not. (2) is true because if the Persons do have parts, at least some of those parts will be properties that all three of the Persons share in common, such as Their power, or Their knowledge, or Their will. This is confirmed by professions of faith concerning the Trinity in which it is emphasized that although there are three Persons who are omnipotent, there are not three omnipotents (Denzinger §39). And (3) exhausts the possibilities of what could ground what between the Persons and their common parts: for any common part (let's call it O, for concreteness), either more than one Person fully grounds O, or O partially grounds at least one Person. This assumes that grounding is irreflexive and transitive, as commonly believed. One might object here that the each of the Persons might partially ground O, but this certainly can't be the story with some Divine attributes, such as power or knowledge. What would such partial grounding look like? The Divine Persons obviously don't contribute some part of the Divine power or knowledge to God.

(4) can be restated as a trilemma. One of the following must be true:

1. The common parts of the Divine Persons are fully grounded by more than one thing (i.e. there is grounding overdetermination).
2. At least one of the Divine Persons is at least partially grounded by some of that Person's parts.
3. God is simple.

Grounding overdetermination (other than in logical grounding, such as the grounding of a true disjunction in both of its true disjuncts) is bad, and allowing that some of the Divine Persons are grounded by Their parts returns the denier of DDS to the same problem he was trying to escape by claiming that God grounds His parts. So we should accept (iii) and affirm DDS.