Drange’s third argument (see here) claims that divine immutability, the idea that God is incapable of change in any sense, is incompatible with divine omniscience, the idea that God knows all and only truths. He argues as follows:
The Immutability-vs.-Omniscience Argument
- If God exists, then he is immutable.
- If God exists, then he omniscient.
- An immutable being cannot know different things at different times.
- To be omniscient, a being would need to know propositions about the past and future.
- But what is past and what is future keep changing.
- Thus, in order to know propositions about the past and future, a being would need to know different things at different times (from 5).
- It follows that, to be omniscient, a being would need to know different things at different times (from 4 and 6).
- Hence, it is impossible for an immutable being to be omniscient (from 3 and 7).
- Therefore, it is impossible for God to exist (from 1, 2, and 8).
As with the previous argument, I’m quite unmoved by this because I think premise 1 is false. I don’t think that God is immutable in the strong sense of being incapable of any sort of change. At most, this argument is a refutation of this idea of divine immutability, not a refutation of theism per se.
But suppose we accept for the moment the idea that theism entails divine immutability. Can the argument still be resisted?
Premise 2 is very hard for a theist to deny. Given that God is supposed to be the greatest possible being, unless it can be shown that there are truths that simply cannot be known, by anyone, it seems that the greatest possible being would have to know them. Are there any such truths? It’s hard to see what they could be. And even if there are any, the incompatibility argument will still go through unless the class of unknowable truths permanently includes certain truths about the past and the future, which is highly implausible. Let’s concede premise 2 and move on.
Premise 3 is beyond question because it simply draws out what’s implied by the notion of immutability.
Premise 4, however, is strictly false. An omniscient being would only need to know propositions about the past and the future if there are any such propositions that are true. But suppose that an immutable God has eternally decided never to create. In that case, there never will be any temporal reality to make any temporal propositions true. That said, the argument can be reformulated to avoid this criticism by adding the premise that there are true propositions about the past and the future. But then we can’t get an internal contradiction within theism from this argument. The most we can get is a contradiction between theism and the claim that truths about the past and the future exist.
This brings us to premise 5. For my part I accept this premise, but one concerned to affirm divine immutabilty and omniscience could reject it simply by opting for what’s known as the ‘B’ theory of time. According to the ‘B’ theory, temporal becoming is not real, but merely apparent. If that’s so, then truth is timeless, and thus does not change over time. For example, on this view, that JFK is assassinated in 1963 is eternally the case even though from earlier temporal points of view this is not apparent.
In the absence of an a priori refutation of the ‘B’ theory of time, therefore, this argument fails to refute the conjunction of divine immutability and omniscience. Given the popularity of the ‘B’ theory of time today among philosophers, that’s probably easier said than done.
Drange mentions at this point another argument that he thinks might refute theism:
It should be noted that a somewhat different incompatible-properties argument could also be constructed using the divine attribute of transcendence instead of immutability. The argument would focus on the point that a transcendent being must be timeless and a timeless being cannot know propositions about the past and future. However, an omniscient being, as shown above, must know propositions about the past and future. Therefore, it is impossible for a transcendent being to be omniscient.
The weak point of this argument is the claim that “a transcendent being must be timeless”. Why? Contrary to what Drange seems to think, the doctrine of divine transcendence is not the idea that God is “outside” space and time. Rather, it is at bottom the idea that God is “outside” creation; that God is in no sense “part” of creation or in any way dependent on creation for his existence. These two understandings of divine transcendence are often conflated on the basis of the following argument:
- God exists “outside” creation.
- Creation includes space, time, and all that exists “in” space and time.
- Therefore God exists “outside” space and time. (from 1 and 2)
But the problem here is that premise 2 is open to question. Theists like myself who reject divine immutability would not say that time is a created thing or that it is part of creation. There are some who hold that time is a necessary concomitant of activity internal to God himself, such that God could not exist atemporally. I don’t hold that view. What I hold is that time is a necessary concomitant of the act of creating. In other words, simply by virtue of creating, God brings about a before-after relation between two different states of affairs: (a) God and God alone existing, (b) God and creation existing.
In conclusion, neither the Immutability-vs.-Omniscience argument, nor the Transcendence-vs.-Omniscience argument poses much of a challenge to theism.