Abstract
Open futurism is the indeterministic position according to which the future is ‘open’, i.e., there is now no fact of the matter as to what future contingent events will actually obtain. Many open futurists hold a branching conception of time, in which a variety of possible futures exist. This paper introduces two challenges to branching-time open futurism, which are similar in spirit to a challenge posed by Fine to (standard) tense realism. The paper argues that, to address the new challenges, (branching-time) open futurists must (1) adopt an objective, non-perspectival notion of actuality and (2) subscribe to an A-theoretic, dynamic conception of reality. Moreover, given a natural understanding of “actual future”, (3) it is perfectly sensible for open futurists to hold that a unique, objectively actual future exists, contrary to a common assumption in the current debate. The paper also contends that recognising the existence of a unique actual future helps open futurists to avoid potential misconceptions.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Notes
Let us note that such views as presentism and the growing block view do not count as forms of open futurism in our sense. Albeit we are not willing to press this point here, we think that there is an obvious rationale for our terminological choice. Growing blockers and presentists deny the (Quinean) existence of the future, and it is reasonable to regard existence as a minimal necessary condition for openness. More generally, in our mind, saying that there is nothing like the future is very different from saying that the future is open.
Future contingents are statements that predict future events (states, processes, ...) that are neither inevitable nor historically impossible at their moment of use (see, e.g., Øhrstrøm and Hasle 2011). Statement (1) is the standard, Aristotelian example of a future contingent; we assume that it is uttered today and that it is a future contingent (if anything is).
Let us note that, in our framework, the entities that are in the domain of a moment m are not just the objects that are located at m, but also all the things that, at m, can be said to exist (in the sense relevant to ontology). Thus, for instance, if a standard, tenseless ontology is assumed, then all historically possible things or events, including all moments within the tree, are in the ‘local’ domain (see, e.g., Belnap et al. 2001, p. 141). The reason for this choice is that we are interested in the ontological commitments of open futurism and not on empirical facts concerning the temporal location of objects.
As hinted above, we are conscious that McCall’s version of open futurism can be construed as different from the TRL view also from an ontological viewpoint. For reasons that will be clear on due course, however, such ontological difference is virtually irrelevant to our purposes.
Throughout the paper, we make reference to facts, a widespread practice in contemporary metaphysics. We assume, however, that ‘facts’ talk is ultimately dispensable, for instance, by appeal to Fine’s (2001) “In reality” operator.
As a matter of fact, two philosophers who are usually classified as open futurists, Belnap and MacFarlane, are sometimes ambiguous as to their underlying metaphysical commitments. More precisely, they seem to flirt with a ‘static’ form of determinism—and consequently, with a position very different from what we call open futurism (see below, note 11). We shall broadly ignore these flirts.
The basic idea underlying primitive tenses is adumbrated in Prior (1967, Appendix B, 1968a, p. 4). In (1968b), Prior shows that a B-theoretical temporal logic can be reduced to an A-theoretical tense logic, whose tense operators are taken as primitive and are not dealt with in terms of B-theoretical relations between times. In the literature, when reference is made to primitive tenses, these are understood in (more or less close) analogy to Prior’s primitive tense operators.
As a matter of fact, there is another possible reply to the MacTaggart-esque perplexity expressed in the text, namely, appealing to a second temporal dimension or ‘meta-time;’ see again (Pooley 2013). See also (Leininger 2015, pp. 4–7), for a critical assessment of this possibility. Our main point can be restated, mutatis mutandis, even if this alternative, much less popular reply is adopted.
In passing, we note that the very same expression “will” is used in a different sense by Prior (1967, p. 131 ff). to indicate the Peircean future tense.
Recall that we are assuming that all histories extend indefinitely toward the future (see above, p. 3), so this view is to be understood not as the claim that some future moment will be the last one, but, rather, as the claim that some future instant, and all the subsequent ones, will contain distinct possible moments but no actual ones. In this respect, the frozen actuality view is analogous to Fine’s frozen present view, which entails the negation of (\(2^{\prime \prime \prime }\)), but not the view that the objectively present moment is the last moment in the timeline.
Consider, for instance, the following quotations:
In what follows I will try to avoid indexical language. In particular, I will not draw a distinction (inevitably indexical when not relational) between the actual and the possible except in motivating or giving examples. ‘Possible point events’ are thus just ‘point events’. These point events are to be taken not as mere spatiotemporal positions open for alternate concrete fillings, but as themselves concrete particulars. (Belnap 1992, p. 388)
There is nothing in the branching model that corresponds to a car moving along the branching road, and nothing that corresponds to the decision the car will have to make to go down one branch or the other. If worlds branch, then we branch too. (MacFarlane 2014, p. 212; see also p. 202)
The distinction between subjective and objective actuality closely corresponds to Stalnaker’s (1976, pp. 67–69) distinction between an indexical analysis of actuality and an absolute property of actuality. See also (Lewis 1973, p. 86). Note that such an objective property need not be called actuality. For instance, the statement that a moment m is (or will be) objectively actual translates, within McCall’s (1994) framework, into the claim that m will never drop out of existence.
For reasons introduced above (note 7), we ignore the other dialectical possibility at the open futurist’s disposal, that is, resorting to a ‘meta-time.’
To prove this, suppose that \( Will (n)\exists x{\mathcal {A} }x\) is satisfied by g at m/h, and let \(m'\) be the moment located n-time units in the future of m on h. Then, by the Ockhamist clauses (iv), (v) (see above, p. 5), some \(g'\) is such that \({\mathcal {A} }x\) is satisfied by \(g'\) at \(m'/h\), and \(g'(x)\in Domain(m')\). Since \(m\le m'\), anti-monotonicity entails that \(g'(x)\) is also in Domain(m). Accordingly, some \(g''\) is such that \(g''\) satisfies \({\mathcal {A} }x\) at \(m'/h\) and \(g''(x)\in Domain(m)\). Therefore, again by (v) and (vi), also \(\exists x Will (n){\mathcal {A} }x\) is satisfied by g at m/h.
Here is a quick proof. Suppose that the antecedent of (7) is satisfied by g at m/h, and let \(m'\) be the moment located n-time units in the future of m on h. Then, by the Ockhamist clauses (ii) and (v) (see above, p. 5), g does not satisfy \(\exists xy(x\ne y\wedge {\mathcal {A} }x\wedge {\mathcal {A} }y)\) at \(m'/h\). Now assume, by contradiction, that \(\exists xy(x\ne y\wedge Will (n)({\mathcal {A} }x\wedge {\mathcal {A} }y))\) is satisfied by g at m/h. By the clauses (iv) and (v), and by standard assumptions concerning identity, it follows that, for some \(g'\), \(g'\) satisfies \({\mathcal {A} }x\wedge {\mathcal {A} }y\) at \(m'/h\) and \(g'(x)\ne g'(y)\). Since \({\mathcal {A} }x\) is existence-entailing, we can conclude that \(g'(x)\) and \(g'(y)\) are both in \(Domain(m')\). Therefore, by (iv), g satisfies \(\exists xy(x\ne y\wedge {\mathcal {A} }x\wedge {\mathcal {A} }y)\) at \(m'/h\), against our hypothesis.
For instance, in both Łukasiewicz’s original semantics and in its refinement proposed by Briggs and Forbes (2012), even an instance of the excluded middle \( Will (n){\mathcal {A}} \vee \lnot Will (n){\mathcal {A} }\) is untrue when \( Will (n){\mathcal {A} }\) is a future contingent. As another example, in Bourne’s (2004) semantics, \( Will (n)\lnot {\mathcal {A} }\) is not always equivalent to \(\lnot Will (n) {\mathcal {A} }\), against strong intuitions (see, e.g., MacFarlane 2014, p. 216).
As a matter of fact, there is another way to make the ambiguity of (UF) explicit. As we have seen (p. 15), open futurists should endorse a tensed conception of reality. But if so, they do not need to regard actuality as a special, tensed property—no more than they need to regard quickness or humility as special properties. The role of the distinction between present and future actuality can be played by another distinction, namely, the one between facts that are (now) part of reality and facts that are not. Accordingly, we can distinguish between a strong understanding of (UF), which only TRL theorists can accept:
- \((\hbox {UF}^{\prime })\):
A unique future is such that it is part of reality that it is objectively actual.
and a weak, open futuristically acceptable reading:
- \((\hbox {UF}^{\prime \prime })\):
It is part of reality that there exists a unique, objectively actual future.
Recall that open futurists admit only inevitable facts as part of reality. Therefore, they regard \((\hbox {UF}^{\prime })\) as equivalent to the indeterministically unacceptable claim that a unique possible future is such that, inevitably, all of its moments will obtain. In contrast, they regard \((\hbox {UF}^{\prime \prime })\) as equivalent to the indeterministically acceptable view that, inevitably, a unique future is such that all of its moments will obtain.
References
Bacciagaluppi, G. (2002). Remarks on space-time and locality in Everett’s interpretation. In T. Placek & J. Butterfield (Eds.), Non-locality and modality (Vol. 64, pp. 105–122). Dordrech: Springer.
Barnes, E., & Cameron, R. (2009). The open future: bivalence, determinism and ontology. Philosophical Studies, 146(2), 291–309.
Barnes, E., & Cameron, R. (2011). Back to the open future. Philosophical Perspectives, 25(1), 1–26.
Belnap, N. (1992). Branching space-time. Synthese, 92, 385–434.
Belnap, N., & Green, M. (1994). Indeterminism and the thin red line. Philosophical Perspectives, 8, 365–388.
Belnap, N., Perloff, M., & Xu, M. (2001). Facing the future: Agents and choices in our indeterminist world. Oxford: Oxford University Press.
Borghini, A., & Torrengo, G. (2013). The metaphysics of the thin red line. In F. Correia & A. Iacona (Eds.), Around the tree (pp. 105–125). Dordrecht: Springer.
Bourne, C. (2004). Future contingents, non-contradiction, and the law of excluded middle muddle. Analysis, 64(282), 122–128.
Briggs, R., & Forbes, G. (2012). The real truth about the unreal future. In K. Bennet & D. W. Zimmermann (Eds.), Oxford studies in metaphysics 7 (pp. 257–304). Oxford: Oxford University Press.
Cameron, R. (2015). The moving spotlight. Oxford: Oxford University Press.
Deasy, D. (2015). The moving spotlight theory. Philosophical Studies, 172(8), 2073–2089.
DeWitt, B. S., & Graham, N. (2015). The many worlds interpretation of quantum mechanics. Princeton: Princeton University Press.
Di Maio, M. C., & Zanardo, A. (1994). Synchronized histories in Prior-Thomason representation of branching time. In D. Gabbay & H. Ohlbach (Eds.), Proceedings of the first international conference on temporal logic (pp. 265–282). Dordrecht: Springer.
Earman, J. (1986). A primer on determinism (Vol. 37). Dordrecht: Springer.
Fine, K. (2001). The question of realism. Philosophers’ Imprint, 1(2), 1–30.
Fine, K. (2005). Modality and tense. Oxford: Oxford University Press.
Fitting, M., & Mendelsohn, R. L. (1998). First-order modal logic. Dordrecht: Springer.
Greaves, H. (2004). Understanding Deutsch’s probability in a deterministic multiverse. Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, 35(3), 423–456.
Hoefer, C. (2015). Causal determinism. In E. N. Zalta (Ed.), The stanford encyclopedia of philosophy (Fall 2015 ed.). http://plato.stanford.edu/archives/fall2015/entries/determinism-causal/. Accessed 8 May 2018.
Kaplan, D. (1989). Demonstratives. In J. Almog, J. Perry, & H. Wettstein (Eds.), Themes from Kaplan (pp. 481–563). Oxford: Oxford University Press.
Koymans, R. (1990). Specifying real-time properties with metric temporal logic. Real-Time Systems, 2(4), 255–299.
Leininger, L. (2015). Presentism and the myth of passage. Australasian Journal of Philosophy, 93(4), 724–739.
Lewis, D. (1973). Counterfactuals. Cambridge, MA: Harvard University Press.
Łukasiewicz, J. (1968a). On three-valued logic. The Polish Review, 13(2), 43–44.
Łukasiewicz, J. (1968b). On determinism. The Polish Review, 13(2), 47–61.
MacFarlane, J. (2003). Future contingents and relative truth. Philosophical Quarterly, 53(212), 321–336.
MacFarlane, J. (2008). Truth in the garden of forking paths. In M. Garcìa-Carpintero & M. Kölbel (Eds.), Relative truth (pp. 81–102). Oxford: Oxford University Press.
MacFarlane, J. (2014). Assessment sensitivity. Oxford: Oxford University Press.
Malpass, A., & Wawer, J. (2012). A future for the thin red line. Synthese, 188(1), 117–142.
McCall, S. (1976). Objective time flow. Philosophy of Science, 43(3), 337–362.
McCall, S. (1994). A Model of the Universe. Oxford: Clarendon Press.
McCall, S. (2009). Objective quantum probabilities. In D. Greenberger, K. Hentschel, & F. Weinert (Eds.), Compendium of quantum physics (pp. 420–425). Dordrecht: Springer.
Merricks, T. (2006). Goodbye growing block. In K. Bennett & D. Zimmerman (Eds.), Oxford studies in metaphysics (Vol. 2, pp. 103–110). Oxford: Oxford University Press.
Øhrstrøm, P. (2009). In defence of the thin red line: A case for Ockhamism. Humana.mente, 8, 17–32.
Øhrstrøm, P. (2014). What William of Ockham and Luis de Molina would have said to Nuel Belnap: A discussion of some arguments against “The Thin Red Line”. In T. Müller (Ed.), Nuel Belnap on indeterminism and free action (pp. 175–190). Dordrecht: Springer.
Øhrstrøm, P., & Hasle, P. (2011). Future contingents. In E. N. Zalta (Ed.), The stanford encyclopedia of philosophy (Summer 2011 ed.). http://plato.stanford.edu/archives/sum2011/entries/future-contingents/. Accessed 8 May 2018.
Papineau, D. (2010). A fair deal for Everettians. In S. Saunders, J. Barrett, A. Kent, & D. Wallace (Eds.), Many worlds? Everett, quantum theory, and reality (pp. 206–226). Oxford: Oxford University Press.
Pooley, O. (2013). Relativity, the open future, and the passage of time. Proceedings of the Aristotelian Society, Supplementary Volumes, 113(3), 321–363.
Prior, A. (1967). Past, present, and future. Oxford: Oxford University Press.
Prior, A. (1968a). Papers on time and tense. Oxford: Clarendon Press. Second revised edition: P. Hasle, P. Øhrstrøm, T. Braüner, & J. Copeland (Eds.) (2003). Oxford: Oxford University Press.
Prior, A. (1968b). Tense logic and the logic of earlier and later. In Prior 1968a (pp. 117–138).
Rosenkranz, S. (2013). Determinism, the open future and branching time. In F. Correia & A. Iacona (Eds.), Around the tree (pp. 47–72). Dordrecht: Springer.
Rumberg, A. (2015). Transition semantics for branching time. Journal of Logic, Language and Information, 25(1), 77–108.
Saunders, S., & Wallace, D. (2008). Branching and uncertainty. The British Journal for the Philosophy of Science, 59(3), 293–305.
Skow, B. (2009). Relativity and the moving spotlight. The Journal of Philosophy, 106(12), 666–678.
Stalnaker, R. (1976). Possible worlds. Noûs, 10(1), 65–75.
Thomason, R. H. (1970). Indeterminist time and truth-value gaps. Theoria, 36(3), 264–281.
Thomason, R. H. (1984). Combinations of tense and modality. In D. Gabbay & F. Guenthner (Eds.), The Handbook of Philosophical Logic (Vol. 2, pp. 135–165). Dordrecht: Reidel.
Todd, P. (2016). Future contingents are all false! On behalf of a Russellian open future. Mind, 125(499), 775–798.
Torre, S. (2011). The open future. Philosophy Compass, 6(5), 360–373.
Van Benthem, J. (1984). Correspondence theory. In D. Gabbay & F. Guenthner (Eds.), The Handbook of Philosophical Logic (Vol. 2, pp. 167–247). Dordrecht: Reidel.
Wallace, D. (2005). Language use in a branching universe. Available online from http://philsci-archive.pitt.edu. Accessed 8 May 2018.
Wawer, J. (2014). The truth about the future. Erkenntnis, 79(3), 365–401.
Wilson, A. (2012). Everettian quantum mechanics without branching time. Synthese, 188(1), 67–84.
Acknowledgements
We would like to thank Andrea Iacona, the LOGOS research group (Universitat de Barcelona), Giuliano Torrengo, Alberto Zanardo and two anonymous referees for Erkenntnis for their helpful comments on previous versions of this paper.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Spolaore, G., Gallina, F. The Actual Future is Open. Erkenn 85, 99–119 (2020). https://doi.org/10.1007/s10670-018-0020-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10670-018-0020-x