Abstract
In this paper, I argue that perdurantism is incompatible with priority monism: the view that the universal mereological fusion, U, is fundamental. For the monist’s fundamental object can neither persist by being a trans-temporal object (i.e., a space-time ‘worm’) nor by being an instantaneous stage. If U persisted via being a worm, it would be grounded in its temporal parts, meaning that it would not be fundamental as it would not be ungrounded. If U were a stage, on the other hand, it would face a problem from the possibility of ‘temporal gunk’. But if U persisted by neither being a worm nor a stage, then U could not persist via having temporal parts, and thus perdurantism would be false. Given that a similar combination of perdurantism and priority pluralism also faces a problem from temporal gunk, I conclude that perdurantism does not sit well with mereological based accounts of fundamentality.
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Notes
I take this definition of a temporal part from Sider (2001, 60), but formulate it to be neutral about whether said temporal part is instantaneous or not. As we’ll see, if temporal gunk is possible, it will not be metaphysically necessary that any object with duration has instantaneous temporal parts.
The former view is worm-theoretic perdurantism, while the latter is stage-theoretic perdurantism (i.e. exdurantism).
For instance, Sider (2001, xiii) describes perdurantism as “an ontology of the material world according to which objects have temporal as well spatial parts.”
Wasserman (2016) has also argued that perdurantism should be understood as a thesis which explains facts about persistence in-virtue-of facts about temporal parts of objects.
As noted by an anonymous referee, Composition as identity (CAI) theorists have claimed that we can secure this mereological intimacy between parts and wholes by holding that they are identical. CAI, though, is an extremely controversial mereological thesis and given its commitment to mereological essentialism (i.e., Merricks 1999), we should prefer an account of mereological intimacy which avoids such a commitment (i.e., Cameron 2014). While I do not think that grounding and CAI are incompatible (see Loss (2016) and my (2022) paper), I think grounding makes CAI redundant, as through it we can have the benefits of CAI at a cheaper metaphysical cost.
Another example would be that of Hofweber & Velleman (2011), who think that ordinary continuants have temporal parts, yet are endurantists about persistence because they claim that an object’s identity is fully determined at each moment it exists; whereas to be a perdurantist would to be hold its identity would only be partially determined at each such moment. Again, this shows there is more to being a perdurantist than accepting the existence of temporal parts.
As the referee suggests, this could be comparable to how a person’s feet explain why they are located on the ground. That they have feet explain why they are located on the ground, but that does not mean we have to accept their feet explain why they exist.
Which is a claim I am deeply sceptical of. For if U’s temporal parts fully non-causally determine its intrinsic nature throughout its history, then U would seem dependent on them for their existence. Without those parts having those properties, U would not have its intrinsic properties, and U cannot exist unless it has some intrinsic properties. For reasons of space, however, I will not argue for this claim in depth in this paper.
Concerning the analogy given in footnote eight, then, I agree with the referee that a monist would likely want to avoid holding that a person’s feet explaining why they are located on the ground is a metaphysical explanation. Rather, it would be a ‘pragmatic’ explanation for one’s location, and the actual metaphysical explanation of one being located on the ground would be that I pervade a spatial region exactly occupied by my feet, and that spatial location is on the ground. Saying that my feet explain why I am located on the ground would just be a paraphrase or loose talk for the actual metaphysical explanation for my location. If one is a pluralist on the other hand, one will undoubtedly hold that my feet do partially ground my existence and what properties I have.
Furthermore, as a referee at this journal has pointed out, Schaffer would not have a problem if he claimed that he was a four-dimensionalist about persistence, as objects are four-dimensionally extended across time and are not ‘wholly present’ at each instant of time they exist. Like Parsons (2000), Schaffer can insist that TDPs account for the persistence of four-dimensional objects and that U is a four-dimensional object as it is exactly located at the spatiotemporal region which is a fusion of all the spatiotemporal regions occupied by its parts. But as it would be the TDP and not U’s temporal parts which account for how U persists through time, this would not be a version of perdurantism.
What I have shown, then, is that not only is there good reason to accept the explanatory conception of perdurantism, what perdurantists – such as Lewis - have historically been interested in is the explanatory conception of the thesis. So, even if somebody were to stubbornly insist, they are a perdurantist and a monist because an ontological conception of perdurantism and monism do not conflict, then fine. But what can’t be denied is the importance of showing there is a tension between the explanatory conception and monism, considering what I have shown above.
This objection was raised by an anonymous referee at another journal.
Grounding is internal just in case if some ψ ground x, then in any world in which the ψ and x exist, the ψ ground x.
An immediate ground is a ground which need not be mediated, where for x to mediately ground z is for there to be some y which grounds z and is grounded in x. I say an immediate ground ‘need not be mediated’ as opposed to ‘not mediated’, as there are cases of a ground being both an immediate and mediate ground (Fine, 2012, 50–51).
I have argued (2022) they can, but only if the monist accepts composition as identity (CAI) as a mereological thesis. CAI, as we have seen, is a deeply controversial mereological view, which – at least in in its strong variant – is rejected by most metaphysicians.
It’s possible that the perdurantist monist might claim that ordinary continuants perdure – while U does not – in order to avoid the puzzles of coincidence. We need temporal parts, for instance, to explain why it is not problematic that Tibbles and Tib coincide after Tibbles loses his tail. However, as there are no puzzles of coincidence involving U, U does not perdure. But this is wrong; we can generate puzzles of coincidence which involve U. Suppose there is a world, w, which at a time, t, consists of just two particles. U will be the fusion of those particles at t. At a later time, t’, however, one of the particles is annihilated, and thus U and the remaining particle will coincide. Now if the monist claims they can resolve the puzzle involving U and the particle without appealing to temporal parts to explain their temporary coincidence, then it seems we also do not require temporal parts to explain the temporary coincidence between Tibs and Tibbles. An acceptable solution for one should be an acceptable solution for the other.
This would be false if one is a modal counterpart theorist, but even if so, it still doesn’t seem plausible that Winston would be identity dependent upon his actual temporal parts. For he would still have person counterparts which lacked temporal parts that he had in the actual world (or to be more precise, lacked temporal parts which were counterparts to actual Winston’s temporal parts). By contrast, a pile of stones in the actual world would not have any counterparts which were compiled out of different stones.
Baron & Tallant (2016), for instance, argue that if island universes are metaphysically possible, monism would be false as there would be multiple distinct, fundamental, spacetimes. Such spacetimes might be more monistic than entities usually posited as fundamental by the pluralist, but Baron and Tallant still think this would count as being a version of priority pluralism.
Even if one is a stage theorist about persistence, then one will likely need to admit fusions of temporal stages into one’s ontology. Sider (2001, 197) points out that sentences involving timeless counting (such as, ‘fewer than two trillion persons have set foot in North America’) will need to be about such fusions if they are to be true.
An anonymous referee at another journal, however, has suggested that perhaps in embracing presentism the monist would avoid the worries of there being an infinite amount of fundamental objects, as no more than one temporal instant – and thus one world stage – would ever exist atemporally. This would also forestall my upcoming objection from temporal gunk, as if only what exists is the present instant then an instant of time must exist. However, I cannot see how presentism is compatible with perdurantism. Note that earlier on in the paper I said that perdurantists believe that ordinary continuants persist by either possessing temporal proper parts or standing in temporal counterpart relations to other temporal parts. But as Benovsky (2009) points out, if presentism is true then objects can neither have temporal proper parts or be counterpart related to other temporal parts, as nothing ever exists other than one stage at a time. Alternatively – as suggested by another referee - one might perhaps accept Sam Baron’s (2015) Priority Presentism – in which past and future entities exist but are less fundamental than present ones. In which case, the monist could say that only the present world stage is fundamental and the world stages of past/future times are derivative objects. Now this could work, though it does seem incredibly counterintuitive to think things in the past depend – either ontologically or causally – on how things are in the ‘present’ (Tallant, 2015, 217).
For time to be continuous is not synonymous to it being gunky. Any gunky interval of time is continuous, but it is not necessary that a continuous interval be gunky. For continuous time could still ultimately be constituted by intervals which have no temporal extent (i.e., continuous atomistic time). Both continuous atomistic time and gunky time are dense temporal series’, but an extended temporal series being infinitely divisible and ‘gap-free’ does not suffice for it being temporally gunky; just as a spatial region being infinitely divisible does not entail it does not ultimately decompose into points.
See Dainton (2010, 294–299) for discussions of both objections to discrete space-time.
Stuchlik (2003) makes the same point and utilises it to argue against stage-theoretic perdurantism. Giberman (2019) considers the idea that stage theory doesn’t necessarily need instantaneous stages (i.e., the ‘shortish stage’ strategy (2019, 230)), but in the end concludes that stage theory and temporal gunk are incompatible. However, even if the shortish stage strategy could save stage-theory, it would not save stage-theoretic monism, as it would, in accepting temporal mereological gunk, involve embracing an infinite regress of grounding. So, stage-theoretic monism seems in an even worse position than an ordinary stage-theorist is in respect to temporal gunk (I’d like to thank an anonymous referee at another journal for getting me to clarify on how stage-theoretic monism fares with temporal gunk in comparison to ordinary stage-theory).
For ease of explanation, I have formulated my objection here in terms of worm-theoretic perdurantism. If one is a stage theorist, though, one can simply amend the explanation of change/possible change to be in terms of temporally counterpart related stages. For instance, I could have had red hair for five seconds because the stage I am is temporally counterpart related to some past stages which collectively have a duration of five seconds, and each of which could have had red hair.
I have previously argued (2020) that priority pluralism, perdurantism, and temporal gunk are incompatible.
And indeed, Schaffer himself has argued this (2010a, 63).
A referee at another journal, however, has questioned whether perhaps a certain view on what is fundamental might be able to cope with temporal gunk, but in non-temporally gunky worlds monism or pluralism could be true because the alternative view has some vice which means we should prefer either monism or monism in non-temporally gunky worlds. Without a full investigation of what alternatives there are to monism or pluralism – which I lack space for in this paper - it is difficult to think of what such a vice might be, however, and that prima facie it is plausible to assume that it is explanatorily preferable to favour a view which is compossible with all metaphysical possibilities than one which cannot.
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Taylor, J. The Incompatibility of Perdurantism and Priority Monism. Philosophia 51, 961–976 (2023). https://doi.org/10.1007/s11406-022-00571-3
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DOI: https://doi.org/10.1007/s11406-022-00571-3