Growing Blockism, The Epistemic Objection and The Zombie Past Markel Kortabarria Areitio APhil Master, Debates in Contemporary Theoretical Philosophy markelkor96@gmail.com Abstract: The Growing Block Theory of time arose within the field of time metaphysics partly as an alternative position to the doctrines of Presentism and Eternalism. According to the growing blockists, while both the past and the present are real, the future is not. As time goes on the universal block of reality increases, adding new slices of present events to the current past ones. Consequently, the layers of reality grow and so does our ontology. The purpose of this paper will be to examine the growing block theory from the perspective of the epistemic objection. According to Bourne (2002) and Braddon-Mitchell (2004), if reality is taken to be a growing block and all there is is past and present, there is no way in which we could know whether the current now is the objective now. Firstly I will disect both the growing block theory and the epistemic objection. Then, we will consider one possible response that came from Forrest (2004), who invoked the notion of consciousness in arguing that it is simply wrong to ascribe any phenomenology to the past. This is what came to be known as the Dead Past Reply. Ultimately I will argue that although the dead past reply is able to dodge the criticism it does so at the cost of weird metaphysics and a zombie ontology. Key Words: Growing Block Theory, Epistemic Objection, Now-Now Objecrion, Dead Past Reply, Zombie Ontology. 1. Introduction For many years two theories were championed through the time debate in philosophy, Presentism and Eternalism. Broadly speaking, while the former one holds that only the present (and the presently existing things) exist, the latter one argues that both the past and the future exist in the same way the present does1. Presentists tend to argue that the property of being present is a genuine feature of the world and that this feature changes as time goes by. In opposition, eternalists deny this thesis and consider that all past, present and future exist in the very same way, as well as the objects that inhabit those time-locations. The debate between presentists and eternalists has been quite extensive, many different perspectives have taken 1 There has been considerable debate over the correct characterization of both presentism and eternalism. However, since it is not our topic I won't go into details. The present definition would suffice for our purposes. For a good characterization of both theories I recommend to see Miller (2013) and Golosz (2013). place and, although interesting, it is not my intention to cover that debate here. My intention is rather to examine the presence of a third contender in this arena, the Growing Block Theory2. Growing-blockism, or no-futurism as some philosophers have called it, has been characterized as a halfway theory. Just like eternalists the growing block theory denies that only the present is existent. They contend that both the past and the present are part of our universal ontology. However, growing-blockists deny that future moments and events exist. According to them, reality grows in the sense that every event that is present constitutes the last slice located at the end of the universal block of existence. Being so, events that were once at the verge of existence fade into the past ceasing to presently exist. Different criticism have arisen since the appearance of the growing block theory in Broad's (1923) Scientific Thought. One of the most famous criticisms was the famous epistemic objection, also known as the now-now problem. The objection was originally raised by Bourne (2002) and also developed by Braddon-Mitchell (2004). Both argued that if the growing block theory is correct, and our ontology, as well as the metaphysics of time are to be understood in terms of a gradually increasing reality, there is no way in which an agent could know whether our current now is the objective now. In other words, it would be impossible to determine whether we are in the objective present or past. It will be my task in this paper to dissect and thresh this criticism. The first part of the paper will be dedicated to briefly sketch out the core notions of the growing block theory. Then, in section two I will analyze the problem that Bourne and Braddon-Mitchell famously posited becoming one of the main obstacles of growing-blockists. Part three of the article will be devoted to present Forrest's Dead Past reply. Finally, in the last section, I will argue that even though Forrest's response is able to effectively avoid the objection it only does so at the cost of postulating a phenomenological asymmetry that results in a zombie ontology and the appearance of new and old worries such as the persistence problem or the cartesian solipsism. 2. The Growing Block Theory of Time: The Future is Yet to Come So, as I said, the growing block theory was originally presented in 1923 by C. D. Broad in his famous Scientific Thought. In this book Broad presented a new dynamic account of the metaphysics of time, according to which what there is and exists increases as time goes by. Reality is understood as a growing block, things are constantly added to the set of our ontology in the verge of existence, often also called the edge of becoming. Otherwise speaking, things begin to exist at the very verge of existence, meaning that events always happen on the last layer of reality and there is nothing else beyond. As the block continues to grow the moments that were once on the last layer of reality are pushed back in to the objective past. When new moments come into existence they become part of the objective present. Being so, becoming is nothing more than coming into existence. In chaper two of his book Broad stresses this in the following way: 2 There is in fact a fourth contender in the ring, namely The Moving Spotlight Theory. Nevertheless, I take this theory to fall under the umbrella of eternalism. This might be arguable, but that's a topic for another essay. When we say that a thing changes in quality, or that an event changes in pastness, we are talking of entities that exist both before and after the moment at which the change takes place. But, when an event becomes, it comes into existence, and it was not anything at all until it had become. You cannot say that a future event is one that suceeds the present, for a present event is defined as one that is suceeded by nothig. [...] since future events are non entities, they cannot stand in any relations to anything, and therefore cannot stand in the relation of succession to present events. [...] if future events succeeded present events, they would have the contradictory property of succeding something that has no successor, and therefore they cannot be real.3,4 Here, Broad stands both against presentism and eternalism. Presentists are committed to the doctrine that change always happens in the present. As long as they deny the existence of past and future, change over time is taken to be understood in terms of temporal passage. Broad attacks this notion of change arguing that when events happen at the verge of existence they do not suffer any change, they simply come into existence. Now, in regard to eternalism Broad denies that future events could be considered existent in any sense. To the extent that the objective present is defined as the last layer of reality, nothing can succeed it. Following Miller (2013) the growing-blockists are committed to two main theses: T1. Growing Block Ontological Thesis (GBOT): Past and present moments and events exist, but future moments and events do not exist. T2. Dynamical Thesis (DT): The present moves, which moment is the present moment changes.5 Both theses have the virtue of going hand in hand with our intuitive understanding of what the metaphysical nature of time is. On the one hand, (GBOT) is based on the intuition that while the past remains fixed, the future is open. As long as the future has not still happened it does not exist, whereas the past has already happened and the present is just happening. On the other hand, (DT) grasps our ordinary understanding of how the present is an everchanging state. Events that were once present fade constantly into the past and those that are yet to be present come in to existence at the verge of existence. Growing-blockism offers us an explanation of our intuition that while reality is dynamic the present is evanescent. As time keeps passing, reality keeps becoming. 3 Broad (1927) pg. 68. 4 Italics by Broad. 5 Miller (2013), pg. 348. 3. The Epistemic Objection: Is It Already Now? On the light of what we have said above it seems hard to deny that the growing block theory has some advantageous features. However, not everybody was persuaded by the growing block proposal. The most prominent complaint to the growing blockists came in the form of the nownow objection, more commonly known as the epistemic objection. This problem was first formulated by Bourne in When am I? A tense time for some tense theorists? And further developed by Braddon-Mitchell in How do we know it is now now? To make a long story short, both Bourne and Braddon-Mitchell argued that if reality is taken to be a growing block, there is no possible way in which an agent could know whether she is located at the objective present or past. The reason for this is that on the growing block view the notion of now is referentially ambiguous between the indexical and objective use. While we can know that it is now on the indexical sense, we cannot know that it is now in the objective sense, since past and present are claimed to exist in the same way and phenomenology of time passage remains unchanged across time slices. A Bourne & Braddon-Mitchell type of example will illuminate the problem: Let's suppose that reality is in fact a growing block. Temporal flow and our phenomenical perception of time passage is explained in terms of the progressive growth of reality. New slices of present events are constantly added to the block in the ceaseless verge of becoming thereby pushing back moments that were once present into the objective past. In such scenario, Neil Armstrong was once at the moment in which he stepped down the Apolo 11 becoming the first person to walk on the moon. There was an objective time in which the event of Armstrong giving his first step on the moon was located in the verge of existence, namely, the objective present. Afterwards, that event was pushed back in the block thereby becoming part of the objective past. Now, let us suppose that for a moment, when stepping down the spaceship, Armstrong believed to be doing so in the present. No one could deny that such a belief was correct. However, as Armstrong's stepping on the moon became part of the objective past that same belief did so, thus becoming immediately wrong. The reason is that the past Armstrong would no longer be stepping the moon in the objective present. The problem is that since the growing-blockist seems to be unable to account for the subjective phenomenology of agents across objective times, it would appear to be impossible to determine which objective time we are experiencing. In other words, while Armstrong stepping on the moon is clearly past for us, it was once indexically present for him. But, how could he know that was objectively so? Moreover, there is a further concern with the locational problem besides skepticism. If reality is a growing block and there are an infinite (or huge) amount of events located in the past slices, given that there is only one single moment located in the objective present, it is much more likely to think that we are in the objective past. Simply put, odds are against us. Miller (2018) does an excellent job unpacking the argument: 1. If w is a growing block world, then for any arbitrary slice, S, in w, and individual, J, located at S, there are very many more times at which S is not objectively present than times at which S is objectively present. 2. J's S-predicaments are subjectively indistinguishable. 3. If J's S-predicaments are subjectively indistinguishable then J ought to assign equal credence to being in each of the S-predicaments. 4. So J ought to assign equal credence to being in each of the S predicaments. 5. Since there are many more S-predicaments at which S is objectively non-present, than at which S is objectively present, J ought to assign very low credence to being in a predicament at which S is objectively persent, and very high credence to being in some predicament or other at which S is objectively non present. 6. If J ought to assign very high credence to being in some predicament or other at which S is objectively non present, then J is not justified in believing that she is located in the objective present. 7. If J is not justified in believing that she is located in the objective present, then J does not know that she is located in the objective present. 8. Therefore, if w is a growing block world, J does not know that she is located in the objective present.6 4. A Response: Zombifying the Past So far we have presented the growing block theory and one double counting objection. On the one hand there is the epistemic worry that none of us could know whether we are located in the objective present or not. On the other hand, there is the objection that given the ontological and metaphysical structure of the growing block framework it seems that we have much more reasons to think that we are located in the past than in the objective present. Furthermore, on assumption that our phenomenology remains untouched as present slides fade in to the past we would require of an explanation to our temporal phenomenology that is not grounded on our perception of the objective present . The core of the epistemic objection lays in that there really are no compelling reasons to believe that we are on the last layer of the block. Now, one interesting response that some defenders of the growing block theory invoke came from Forrest's (2004). Forrest criticized premise (2) in arguing that the epistemic objection presupposes past phenomenology. According to Forrest both Bourne and Braddon-Mitchell assume that individuals located at past slices of the block enjoy the same kind of existence as the individuals that are located at the verge of reality. However, consciousness could never take place at past slices of the block for it only happens at the boundary of existence. The Armstrong that is now located at the past slice in which he stepped down the Apolo 11 lacks any phenomenology because he is simply dead. Being so, the growing block theory implies that it is necessary for the existence of any phenomenology at a given time that that time is in fact the objective present. Thus, as long as an agent J has any phenomenology at all she knows that she is in the objective present. This has come to be known as the Dead Past reply. Having said this, we can see how the dead past view addresses the Bourne and BraddonMitchell objection about the comparative status of past and present events by introducing phenomenological (and ontological) asymmetry. The dead past response argues that it is simply 6 Miller (2017), pg. 4. wrong to ascribe any kind of phenomenology to the past. It is in this sense that Forrest argues that there is no life located in the past slices of the block. Given that there could not be consciousness in the dead past, nor could there be any thought and, thus the epistemic objection is blocked. As Forrest himself puts it ''life and sentience are activities not states. Activities only occur on the boundary of reality, while states can be in the past.''7,8 Accordingly, only those that inhabit the last layer of reality are considered living, conscious and perceiving beings. Adopting this metaphysical view allows the growing-blockist to block the skeptic argument by deriving knowledge of objective presentness from the a priori knowledge of consciousness. 5. Consequences: Zombie Ontology, Persistence and The Return of The Cartesian Doubt It appears that the dead past solution does solve the epistemic objection. However, it only does so at the cost of positing some odd metaphysical consequences. I will begin with my major concern. The dead past view's answer to the epistemic objection raises the worry of committing to two distinct types of existence. The phenomenological asymmetry that Forrest introduces distinguishes past and present in saying that the entities located at past slices of the block lack any kind of life or activity, whereas the objective present is the only possible time in which one could postulate such ontological features. If so, it begins to look as if the growing-blockist would be allowing for distinct types of existence. Namely, the lively ones at the verge of existence and the zombie existent entities in the dead past. I think that Occam would have something to say about Forrest's ontological consequences. Having said this, there is an additional worry that arises from this notion of a zombie ontology. The problem of persistence through time. It is intuitive enough to say that past objects persist through time just like the ones that are alive and active in the growing end of the block. Although dead and past, earlier slices of myself persist through time in the very same way that I do when inhabiting the last layer of reality. However, the dead past view commits to an odd type of persistence for as soon as new temporal slices of a given entity come in to existence the old ones are pushed back into the dead past, changing from being presently alive and active to exist pastly and dead. Hence, it is not that things that are alive and existing at the end of the block continue to persist as they currently are, rather it would seem that they persist by having part of them die and fade off into the past. This would imply that the Armstrong that landed in the earth on the 24th of July 1969 after having stepped in the moon would have lost something in the ceaseless voyage that is time passage. Perhaps Forrest is saying that the old Armstrong died and a new one came in to existence? A very strange way of understaing identity and persistence if you ask me. Finally, It would be unfair not to mention Braddon-Mitchell's concern about Forrest's cartesianism. In his paper Braddon-Mitchell acknowledges that the dead past view does in fact solve the epistemic problem, but at the cost of falling prey of solipsism. Assuming that there is 7 Forrest (2004), pg. 359. 8 Italics by me. in fact an objective now located at the verge of existence, and that we can epistemically access this a priori knowledge, it seems difficult to explain the simultaneous existence of other entities that apparently inhabit the objective present. Forrest requires going one step further if he wishes to explain the presentness of those entities who seem to share our temporal location. In words of Braddon-Mitchell ''if objective presentness is required for consciousness, then unless we know which the preferred frame of reference is, we do not even know whether our apparent colleagues are Zombies; for perhaps the preferred frame is one in which none of these colleagues are simultaneous with me.''9 Forrest explicitly bites this bullet in saying that enough is good enough, it is simply out of our possibilities to know and be sure that our co-temporal colleges are alive and conscious with respect to our frame of reference. All that we are left with is hope and reasonable belief. 6. Conclusion and Corollary Having reached the end of this article it is now time for a brief recap. On the first section we presented the core notions of Broad's growing block theory of time. We saw how growingblockists are committed to the ontological and dynamical thesis and how the theory matches our folk metaphysics and ontology of time. On part two we brought up the famous epistemic objection as originally presented by both Bourne and Braddon-Mitchell. We unpacked the argument and saw how skepticism about the objective present poses a problem for the growing block theory. On section four we analyzed Forrest's dead past reply in order to see how effectively he dodges the epistemical criticism. Finally, in the last section above we claimed that even though Forrest's response does in fact avoid the now-now objection it gives raise to new ontological and metaphysical problems concerning existence, persistence and a potential solipsism. To close up I would like to now clear the air. The aim of this paper was not to challenge or attack the growing block theory in any way. In fact, I sympathize with Broad's account of time, and I do think that the growing block theory is the theory that best matches our intuitive perception of time. However, intuition does not suffice and further explanations are needed. The epistemic objection poses a legitimate worry about epistemic accessibility to time location, a challenge that the growing-blockist needs to answer. Forrest's dead past view attempts to answers this challenge, but it does so at great and irredeemable cost. 9 Forrest (2004), pg. 360. Bibliography Bourne, C. (2002). "When am I? A tense time for some tense theorists?" In Australasian Journal of Philosophy Vol. 80, No. 3, 359-371. Forrest, P. (2004). "The Real but Dead Past: A Reply to Braddon-Mitchell" In Analysis Vol. 64, No4, 358-362. Braddon-Mitchell, D. (2004). "How do we know it is now now?" In Analysis Vol. 64, No4, 199-203. Miller, K. (2013). "Presentism, Eternalism, and The Growing Block" In A Companion to The Philosophy of Time, Chpt 21, (Eds) Heather Dyke & Adrian Bardon (2013). Oxford: Blackwell. Miller, Kristie, 2018. "The New Growing Block Theory VS Presentism" In Inquiry Vol. 61, No3 (2018) 223-251. Broad, C. D. (1927). "Scientific Thought" London: Routledge.