Back in 2011, I wrote a paper called “The Fivefold Openness of the Future” in which I argued that if the future is causally open (i.e., not wholly causally determined) then there are strong reasons to think that it is ontically, alethically, epistemically, and providentially open as well.
In my 2024 book Open Theism I strengthened this claim by arguing that the causal openness of the future entails that the future is open not only in those other four respects but in every possible respect. In short, causal openness entails open futurism (period), where open futurism is the thesis that there is no such thing as a “unique actual future” (UAF), that is, a complete extension of the actual past and present that is, or that definitely is going to be, the actual future.
Open futurism means that any way in which one might try objectively to define or pick out a UAF is wrong. There just is no such thing. Thus, one can’t objectively pick out a UAF
- causally, because the totality of causal facts leaves the future in part an open question;
- ontically, because the totality of what exists leaves the future in part an open question;
- alethically, because the totality of what’s true leaves the future in part an open question;
- epistemically, because the totality of what’s known leaves the future in part an open question;
- providentially, because the totality of what God has ordained leaves the future in part an open question.
Indeed, if open futurism is true, then not even the totality of all facts combined suffices to pick out a UAF.
To the above list we can add that one can’t objectively pick out a UAF
- modally, because the totality of modal facts (i.e., facts about what’s actual, necessary, contingent, possible and impossible, probable and improbable) leaves the future in part an open question.
I actually blogged about the modal openness of the future back in 2009, well before my “Fivefold Openness” paper ever came out. I think I excluded it from that paper because I wasn’t sure at the time whether modal openness amounted to anything distinct from alethic openness. The two seem to entail each other because actuality and truth naturally go hand-in-hand. If the totality of what’s true leaves the future open, then the totality of what’s actual etc. should also leave the future open, and vice-versa.
But I now think there are good reasons to distinguish alethic and modal openness. First, there are different modal logics (see diagram above) and different types of modality (logical, metaphysical, causal, etc.). So, if we are to address the modal implications of open futurism directly, then we should address them under the rubric of modal openness rather than alethic openness. Second, just as truth and ontology operate at different explanatory levels, so do truth and modality. This is the case whether one is a modal actualist or a modal possibilist. The modal actualist thinks that ontology coincides with what’s actual—there are (in an ontologically committing sense of “there are”) no non-actual entities. Hence, what’s true must correspond to and be grounded in what is actual. The modal possibilist, in contrast, thinks that ontology includes things that are merely possible and thus not actual. Hence, some truths correspond to and are grounded in mere possibilities. Now, I think modal possibilism is absurd (for reasons noted in the next section), but regardless, the mere fact that modality operates at a deeper explanatory level than truth (e.g., some things are true because certain things are actual, possible, necessary, etc.) is a reason to keep alethic and modal openness distinct.
In the remainder of this blog post I want to do three things. First, I want to explain what modality is. Second, I want to explain how one can construct a modal argument for fatalism and how the modal openness of the future defangs that argument. And, third, I want to explore some important implications of the modal openness of the future.
1. The nature of modality
Many philosophical discussions of modality fail to consider the topic foundationally and start instead with high-level concepts like “possible worlds.” This is a mistake because it leads many people to take on a lot of unnecessary conceptual baggage when discussing modality. Modality at its core is quite down-to-earth. The core idea behind all modality is that of possibility. When we describe something as “possible” we conceptualize it as one from among potentially many outcomes accessible from a defined starting position. For example, suppose I have in my hand a standard coin. One side is marked “heads” and the other “tails.” I now ask, “What outcomes are possible if I should toss the coin onto a hard, flat surface?” Idealizing to exclude cases where the coin lands on its edge, morphs into a different shape, falls upward or hovers in the air, etc., there are two and only two possibilities: Either the coin lands with the “heads” side up, or it lands with the “tails” side up. The pre-toss starting position defines a possibility space, in this case {heads, tails}. Relative to that space, outcomes that lie inside it are possible; outcomes that lie outside it are impossible; outcomes that describe the entire space (e.g., the coin lands either-heads-or-tails) are necessary; outcomes that describe part of the space but not the whole of it are contingent; and an outcome’s probability is defined as the proportion of the space that it occupies. Finally, actuality enters into modality in two different ways. Antecedently, actuality defines the starting position, that is, it tells us what’s actually possible by telling us how the possibility space itself is defined. Consequently, actuality describes the ending position, that is, it tells us which possibility actually results when the experiment is performed (e.g., the coin is actually tossed and lands heads side up).
Side note: The preceding comments about actuality demonstrate that modal possibilism is nonsense. There is no such thing as possibility apart from a possibility space defined by antecedently posited actualities. Nothing is possible unless it is actually possible, that is, unless it conforms to whatever constraints actually define the possibility space in question. Contra possibilism, there are no non-actual possibilities. As for consequent actuality, this is not, as possibilism supposes, an indexical status, i.e., a perspectival status that each possibility can claim for itself. It is, rather, an objective status. If the experiment is never actually performed (e.g., the coin is never actually tossed) then there is no actual result and, unless there is only one possible outcome, it remains an open question which possibility should result were the experiment to be performed.
In sum, all modal concepts depend on the idea of a possibility space. That space is defined by whatever antecedent constraints apply to it. The minimal constraint is internal consistency. This is because if we allow internal inconsistency then all bets are off, the boundary between the possible and impossible disappears, and we no longer have a possibility space. At best we have a chaotic, pre-modal space.
Different types of possibility arise from differently constrained possibility spaces. For example,
- formal/narrowly logical possibility is defined by the law of non-contradiction and nothing else—whatever is not demonstrably inconsistent is “possible”;
- informal/broadly logical possibility (aka abstract metaphysical possibility) adds as a further constraint complete information about the natures or essences of things (e.g., there’s no contradiction in saying that the prime minister is a prime number, but if you understand what those things are, you’ll see that’s impossible);
- concrete metaphysical possibility (aka causal possibility) adds as a further constraint the way reality actually is, that is, not just the essences of things but also their contingent properties, accidents, or modes;
- epistemic possibility is defined by a specified person’s or community’s state of knowledge—whatever is compatible with what that person or community thinks they know is “possible.”
And so forth.
With the foregoing in mind it’s unfortunate that influential metaphysicians like Alvin Plantinga and David Lewis focus their modal musings on the super high-level concept of a possible world. This takes the focus off concrete, human-level uses of modality, which we can easily grasp, and shifts it to something that only an infinite mind like God’s can fully grasp. Moreover, they both assume, for different reasons, that possible worlds must include a complete, determinate timeline—a determinate past, present, and future. Thus, Plantinga focuses on what he calls “broadly logical”/”metaphysical” possibility (he supposes these to be the same) and takes modal metaphysics to concern total ways things could have been (i.e., possible worlds) from the pre-volitional perspective of an omnipotent God surveying His creative options. A possible world, from this perspective, is a world God hypothetically could have created or, in Plantinga’s jargon, “actualized.” But even from that perspective it’s not clear why possible worlds have to include a complete, determinate timeline. What if God decides to create a dynamically open-ended world, one with a defined starting-point but no defined ending-point? Plantinga assumes that’s not a possibility because he conceives of possible worlds as abstract and static “states of affairs” that can be actualized or not actualized all at once. Lewis, for his part, thinks of possible worlds as concrete and physical but also as static space-time blocks. On any dynamic metaphysics of time, however, both of these views are false. Dynamically conceived, what’s actual changes from moment-to-moment and there is no single timeline which is such that it, as a whole, is actual.
Side note: Plantinga is a presentist and therefore affirms a dynamic metaphysics of time. Throughout his metaphysics, however, he routinely privileges the abstract and static over the concrete and dynamic. For him, the “actual world” is first and foremost something abstract, like a big conjunctive proposition. It’s not anything you and I experience as the concretely actual world. It’s not, we might say, the actual actual world.
With these modal preliminaries aside, I now want to make clear how the modal openness of the future is a response to modal arguments for fatalism.
2. Fatalism and the modal openness of the future
By fatalism I mean the thesis that there is only one causally possible future, only one complete extension of the concretely actual past and present that has any positive objective chance of coming to pass.
There are many different ways in which one might argue for fatalism, but all such arguments—if they are logically valid—have the following two features in common. First, they posit a set of information-laden facts that, so it is claimed, are now-fixed or now-unpreventable. A fact is now-fixed just in case nothing or no one now has any causal “say” about whether that fact obtains. Whatever causal “say” anything or anyone might once have had about these facts has already been “said.” Moving forward, these facts can’t be changed or prevented; hence, all causally possible futures must conform to these facts. These facts are the antecedent actualities that define the future’s possibility space. Highly plausible examples of now-fixed facts include mathematical truths, the basic principles of morality, logical and metaphysical necessities, and the actual past and present. Second, they posit that these fixed facts single out a complete extension of the actual past and present—a specific possible future—as the unique actual future (UAF). If a fatalistic argument satisfies both of these conditions, then fatalism logically follows.
To see this, let’s call Q the collection of now-fixed facts. Because Q is now-fixed, every causally possible future must conform to Q. This gives us
- In all causally possible futures, Q.
Let’s also assume that Q singles out or specifies a UAF and call F the specific causally possible future that Q entails. This gives us
- Necessarily, if Q then F,
where the conditional (if Q then F) is a material conditional (the simplest kind of conditional) and the type of necessity in question is broadly logical necessity. Since this conditional is part of what defines the future’s possibility space, it follows that it cannot fail to obtain in any causally possible future. Hence, it follows from (2) that
- In all causally possible futures, if Q then F.
Finally, it logically follows from (1) and (3) that
- In all causally possible futures, F.
This follows for the same reason that (☐p ∧ ☐(p ⊃ q)) → ☐q is an axiom in all normal systems of modal logic, including all the systems referenced in the above diagram. The necessity operator ☐() is a universal quantifier over an entire possibility space. It doesn’t matter what types of possibilities the space contains. All that matters is that the necessity applies to all possibilities in the space. Thus, if all causally possible futures are Q-futures and if all causally possible futures are such that Q ⊃ F (⊃ is a symbol for a material conditional), then all causally possible futures are F-futures. The inference from (1) and (3) to (4) is therefore demonstrably valid. If there is a collection of now-fixed facts (Q) sufficient to single out a unique causally possible future (F), then it follows straightaway that F is the only causally possible future. That, of course, is fatalism.
Different arguments for fatalism can be generated by plugging in different types of now-fixed facts for Q. For example, if now-fixed causal facts suffice to pick out a UAF, then we get a causal argument for fatalism. If now-fixed alethic facts suffice to pick out a UAF, then we get an alethic argument for fatalism. And so on for ontic, epistemic, providential, and modal facts.
Thus, let M be a collection of now-fixed modal facts. For example, let us suppose with Plantinga that there is a unique “actual world” containing a complete timeline. And let’s suppose that which possible world is “actual” is now-fixed. Under these suppositions, we can swap out Q for M to generate a valid modal argument for fatalism. As now-fixed, M defines the future’s possibility space and as including a complete timeline it constrains that space to only one causally possible future.
Once we recognize the validity of the fatalist’s reasoning there remain only two ways to avoid fatalism:
- Preventable futurism: admit a collection of UAF-entailing facts but deny that those facts are now-fixed.
- Open futurism: deny that there is any collection of UAF-entailing facts, now-fixed or otherwise.
With respect to modal arguments for fatalism, preventable futurism denies that the modal facts in question are now-fixed. They are not among the antecedent actualities that define the future’s possibility space. Rather, akin to a heads result obtained by flipping a coin, they are among the consequent actualities that result from divine and/or creaturely actualizations. It is in precisely this vein that Ben Arbour proposes “possible worlds Ockhamism” (PWO). While agreeing with Plantinga that possible worlds necessarily contain a complete timeline, Arbour denies that God is the unilateral actualizer of any of those worlds. In his view, which world emerges as “actual” depends in part on us, specifically on which free decisions we creatures actually make.
In contrast, the open futurist response to modal fatalism, and indeed to all arguments for fatalism, is simply to deny that the facts, whether now-fixed or otherwise, suffice to pick out a UAF.
Both of these responses deny premise (3) of the above fatalistic argument schema, but for very different reasons. For both the preventable futurist and the open futurist there is no collection of now-fixed (antecedent) facts Q that entails a unique causally possible future F. Where they differ is on whether there is any collection of non-fixed (consequent) facts that entails a unique causally possible future. For the preventable futurist, there is a unique actual future (UAF) but which future that is is the result of an actualization process that has already (in some sense) been completed. The future, for the preventable futurist, has already (in some sense) been actualized. As my friend Greg Boyd once put it to me, the preventable futurist has “a past view of the future.” The open futurist, in contrast, has a future view of the future. There is no unique actual future yet because the actualization of the future is still in process. The future, for the open futurist, is still being actualized.
Side note: Preventable futurism is incoherent. It posits that consequent, post-actualization information is eternally available despite being explanatorily posterior to the actual occurrences of future events. This is like saying that the complete, true story of reality both eternally exists—it’s already “published,” so to speak—and is still being written and thus is not yet “published.” This of course is impossible. If information is explanatorily posterior to an event then it doesn’t exist until (in the order of explanation) that event actually occurs. Hence, there is an explanatory moment at which the information in question does not exist and a subsequent explanatory moment in which it does exist. Because these two moments are mutually incompatible, the transition between them must be temporal. It cannot be “merely logical,” whatever that means. There is, thus, a temporal moment at which the information does not exist. But then the information is not eternally available. Because the information temporally comes into being as the events in question come to pass, there cannot be a UAF until (in the temporal order) all relevant event have come to pass.
3. Some implications of the modal openness of the future
If the future is modally open, then the facts, now-fixed or otherwise, do not suffice to pick out a UAF. This means that the future’s possibility space contains multiple causally possible futures and that none of those futures is (as yet) actual. The future is thus objectively open-ended.
As time elapses, however, which possible futures remain is always changing and thus the modal landscape is always changing. Contrary to Plantinga and Lewis, the modal landscape is not static but dynamic.
For example, suppose we’re considering the possible results of tossing a single coin 10 times. Initially, the possibilities take the form of 10-length sequences of heads and tails. After the first toss, however—let’s suppose it lands heads—that result is now-fixed and the possibilities now take the form of 9-length sequences of heads and tails. And so on. Every time a toss occurs it creates a new now-fixed fact and the modal landscape describing the possibility space for the remaining tosses updates accordingly.
If the modal landscape of the future is dynamic, then we must make a decision how we’re going to think about possible worlds or complete ways things could be / could have been. On the one hand, if we wish to insist with Plantinga and Lewis that possible worlds must contain a complete timeline, then we should conclude that no possible world is (as yet) actual because no complete timeline is (as yet) actual. On the other hand, if we reject that Plantingian/Lewisian assumption, then we should conclude that which possible world is actual is always changing. In consequence of this, we should think of possible worlds not as abstract states of affairs nor as giant conjunctive propositions, but as concrete and tensed. It’s the world, objective reality as a whole, that is changing and, as it changes, things that were not previously possible may become possible and things that were previously contingent may become necessary. For example, it’s now-possible for me to die, but that’s only possible because I’m actually alive and embodied. Had the possibility of my embodied existence never become actual, then my dying would never have become concretely possible. Likewise, before making a free choice between, say, chocolate and vanilla ice cream, which option I choose is contingent—both are possible and neither is necessary. But after my choice, one of the options (chocolate, say) has become actual and now-fixed and the other is no longer possible because I can’t undo that choice once I have actually made it.
Finally, regarding modal logic, if the modal landscape is dynamic, then the modal logic for concrete metaphysical possibility—that is, for what is really possible given how reality actually is—must be asymmetric. That something was possible in the world as it actually was yesterday does not mean that it is still possible in the world as it actually is now or as it might be tomorrow. Likewise, that something could happen in the world as it might actually be tomorrow does not mean that it is possible in the world as it actually is now or in the world as it actually was yesterday. In short, what’s possible need not remain static over time and so we cannot symmetrically conclude that what’s possible under one set of concrete conditions is also possible in every other set of concrete conditions. Given the failure of modal symmetry, this means that all modal logics that presuppose symmetry (most notably S5) are wrong, at least when concrete metaphysical possibility in in view.