In an article by Daniel J. Pedersen and Christopher Lilley, "Divine Simplicity, God's Freedom, and the Supposed Problem of Modal Collapse," (Journal of Reformed Theology 16, 2022, 127-147), the authors quote Boethius:
. . . if you know that someone is walking, he must necessarily be walking. (Consolation, v. 6)
Pedersen and Lilley then paraphrase and endorse the point as follows:
That is, supposing a man is walking, so long as he is walking, he must necessarily be walking.
Both the Boethian claim and the authors’ paraphrase strike me as interestingly false. Suppose Tom is walking at time t. Surely he might not have been walking at t. So it is not necessarily, but contingently, the case that Tom is walking at t. For although he is actually walking at t, it is possible that he not be walking at t. Of course, a man cannot walk and not walk at the very same time. For that would violate the law of non-contradiction (LNC). But that is not the question. The question is whether the following could be true: Tom is walking at t & it is possible that Tom is not walking at t. And of course the conjunctive proposition could be true. Had Tom died at t* (t* < t) , he would not have been around to do any walking at t. To understand the point, you must not confuse possibly (p & ~p) — which is necessarily false — with p & possibly ~p. The latter has true substitution-instances.
Boethius, lately quoted, mentioned knowledge. Is my knowing that Tom is walking at t relevant to the question whether, if he is walking, he is necessarily walking? Right after the sentence quoted, Boethius writes, "For what a man really knows cannot be otherwise than it is known to be." Suppose I know that Tom is walking at t. Would it follow that Tom is necessarily walking at t? No. Boethius appears to have committed a modal fallacy. While it it true that
1) Necessarily (if S knows that p, then p)
it does not follow that
2) If S knows that p, then necessarily p.
To think otherwise is to commit the modal fallacy of confusing the necessity of the consequence (necessitas consequentiae) with the necessity of the consequent (necessitas consequentis). (1) is true; (2) is false; hence the inferential move from (1) to (2) is invalid. Most of the propositions we know are contingent. For example, I know that I was born in California, but this is a contingent fact about me. I might have been born elsewhere. I might not have been born at all. One cannot know what is false, and so it follows that whatever one knows is true; it does not follow, however, that what one knows is necessarily true. For again, most of what we know is contingently true. In the patois of 'possible worlds,' most of what we know is true in some but not all possible worlds.
So we can set aside knowledge that a man is walking as a good reason for believing that a man walking is necessarily walking. Tom cannot walk and not walk at the same time. But if he is walking at a given time, it is possible that he not be walking at that time, which is to say: Tom's walking at t is contingent, not necessary. Again, don't confuse possibly (p & ~p) with p & possibly ~p. Mind not only your ps and qs, but also the scope of the modal operator. In the first expression it has wide scope; in the second it has narrow scope.
The authors do not agree. They follow Boethius, Thomas Aquinas (Summa Contra Gentiles I, 67), and other scholastics. While they grant that it is not absolutely or unconditionally necessary that a man walk, on the ground that there is nothing in the concept human being or the essence human being to require that an instance of this concept/essence walk, it is nevertheless hypothetically or conditionally necessary that a particular man walk if he is in fact walking. I will argue against this distinction in a moment. I will argue that the distinction between unconditional or absolute necessity and conditional or hypothetical necessity is bogus. But first: why does it matter?
Modal collapse and DDS
Why is the topic above metaphysically important and not a mere logical bagatelle? One reason is because it is relevant to the problem of modal collapse that bedevils classical theism. (As I use ‘classical theism,’ classical theists are by definition committed to the doctrine of divine simplicity (DDS).) Here is (one aspect of) the problem in brief compass.
God exists of absolute metaphysical necessity. The ground or source of this necessary existence is the divine simplicity. God is necessarily existent because he is ontologically simple. Since God alone is ontologically simple, no other necessary being, the number 9, for example, is such that it has the same ground of its necessary existence. The ground in the case of the number 9 and its colleagues is God.
Divine ontological simplicity implies that there are no (real) distinctions in God, hence no distinction between God and his attributes — He is what he has, as Augustine says — and no distinction between God and his actions: he is what he does. Hence there is no distinction in God between God and his creating of our (presumably) contingent universe U. That is a distinction that we make, and must make given our discursive/dianoetic intellects. If we didn’t make that distinction, then I could not have written the meaningful sentence I wrote two sentences supra and you would not have understood it. But I wrote it, and you understood it.
Note further that since God is omnipotent, his creating of our universe U ex nihilo is efficacious: he cannot fail to 'pull off' what he intends. His creating is also deterministic: divine efficient agent-causation of U is not probabilistic or 'chancy.' Note also that God, being simple and thus devoid of internal complexity, is pure act (actus purus), which is to say, purely actual. As such, he harbors no unrealized potencies, or powers, or potentialities. So if God creates, his creating is necessary. He could not have created anything other than what he in fact did create. And since his creating is necessary, if he creates, that which he creates is also necessary.
It follows that God, his free creating of U, and U itself are all three absolutely (as opposed to conditionally) necessary. Now everything is either God or created by God, including so-called abstract objects. It follows that everything is absolutely necessary and thus that nothing is contingent. The distinction between necessity and contingency collapses. The senses of the modal terms, no doubt, remain intact and distinct on the intensional plane, the plane of sense; the collapse occurs on the extensional plane, the plane of reference. DDS thus entails modal collapse. Well, what’s wrong with that?
Modal collapse is unacceptable if you believe, as most classical theists do, that creation is contingent, both the action of creating and its logically inevitable effect, the ensemble of creatures. (Note the process-product ambiguity of 'creation.') A separate problem in the immediate vicinity, one that I will not discuss here, concerns whether the contingency of creation requires a libertarian model of divine free agency.
A response via the distinction between absolute and hypothetical necessity
One among several responses to the threatened collapse of the contingent into the necessary is to say that there is no modal collapse, no reduction of everything to absolute necessity, because, while God is absolutely necessary, his creatures are not absolutely but only hypothetically or conditionally necessary. This distinction is supposed to avert the collapse. I do not believe that this distinction, despite its distinguished pedigree, does avert the collapse. Let me explain.
I will start with abstract objects and argue that their modality is exactly the same as God’s modality, namely, absolute metaphysical necessity, but that they differ from God in that they, being creatures, are dependent on God for their existence, whereas God is not dependent on anything for his existence. Thus I distinguish between the modal status of an entity and its dependency status. Dependency status has to do with how an entity exists, whether originally (underivatively) or derivatively. God exists originally, creatures derivatively. Abstract entities are absolutely necessary, but dependent on God, whereas God is absolutely necessary but not dependent on anything. The modality is the same, absolute necessity, but the way of existing is different. God exists in a non-derivative way whereas creatures, whether abstract or concrete, exist derivatively. In terms of aseity (from-itself-ness), we may say that God’s dependency status is a se, or independent, whereas the dependency status of abstract objects, being creatures, are ab alio, or dependent, from another, namely, God. Despite this difference, both abstracta and God are absolutely or unconditionally necessary.
If a thing exists necessarily, one may reasonably ask about the ground or source of its necessary existence. In the case of God, if there is such a ground, it would have to be God himself in his ontological simplicity: God is necessary because he is simple, and not vice versa. God is necessary in se, in himself, and not ab alio, from another. This is because God does not and indeed cannot derive his existence from another. In the case of so-called abstract objects such as the number 9 or the set {7, 9}, however, the ground of their necessary existence is in God. For abstracta are creatures: they derive their existence from God. Or at least this is a reasonable thing to say. It is in fact the view of Aquinas, no slouch of a philosopher. Accordingly, abstracta are necessary ab alio, necessary from another. Given that they too are creatures, they cannot exist in themselves, but are dependent on God for their existence. If, per impossibile, God were not to exist, then abstract entities would not exist either, and this regardless of the fact that they 'exist in all possible worlds' just as God does.
There is no harm in speaking of abstracta as hypothetically necessary if all this means is that abstracta are absolutely necessary beings that are dependent on God for their existence. There is no harm as long as it is realized that God and the number 9, for example, are necessary in the very same sense with the difference being that God exists unconditionally whereas the number 9 exists conditionally or dependently ('hypothetically'). But then there are not two kinds of necessity, absolute and hypothetical, as the authors seem to think, but one kind only, with however two different sources or grounds of the existence of those items that enjoy this one kind of necessity (absolute metaphysical necessity).
By my lights, one must distinguish between the question whether a thing exists dependently or independently from the question whether the thing exists necessarily or contingently. The two distinctions 'cut perpendicular' to each other. Accordingly, God exists independently and necessarily; abstracta exist dependently and necessarily; poor Socrates exists dependently and contingently. What holds for Socrates holds for every ‘sublunary’ creature, every concrete item in space and time that is created by God. Every such creature is existentially dependent and modally contingent. The same goes for the universe that includes Socrates and his fellow creatures. It too is existentially dependent and modally contingent. (No, I have not just committed the fallacy of composition, but to explain why I have not committed it it would take us too far afield for a mere Substack entry.)
To say of an item that it is modally contingent is to say that it is “possible to be and possible not to be” as per Aquinas. I, for example, am modally contingent: I actually exist and so it is possible for me to be. It is also possible for me not to be because I might never have existed, and at any time at which I do exist I might not have existed at that time. But my modal contingency leaves wide open the question whether I depend for my actual existence on God. This is why one cannot validly argue straightaway from the modal contingency of the universe to the existence of a ground or support or cause of its existence. To do so is to confuse two different senses of ‘contingency’ the modal sense and the existential sense.
I conclude that there is no evading the modal collapse objection to DDS by distinguishing between absolute and hypothetical necessity, and this for the reason that there is no such modality as hypothetical necessity. The phrase 'hypothetical necessity' can only mean that certain entities that are modally necessary, the inmates of what Plantinga has called the "Platonic menagerie," are nevertheless dependent on God for their existence.
If I am told that Tom and the rest of the denizens of the world of space and time and matter are not modally contingent, but hypothetically necessary, I will repeat my point that there is no such modality as hypothetical necessity. The notion is an illicit amalgam that elides the distinction between existence and modality. Everything that exists is either necessary or contingent. And everything that exists either exists dependently or independently. Hypothetical necessity is a misbegotten notion.