The conclusion that a significant aspect of temporal passage may well be a real and physical feature of our world will be a welcome one to those who find the case for the Block conception compelling—perhaps because the dynamic alternatives look to them to be metaphysically dubious, perhaps because they can see no other way of accommodating Einstein’s relativity theories—but who also find it difficult to accept that passage is wholly illusory. But this welcome (to some) conclusion is not yet secure. A Block universe will only be capable of containing E-passage in the way envisaged if E-passage is essentially independent of any mode of M-passage. If it could be demonstrated, for example, that experiences with the immanent flowing qualities characteristic of E-passage can only exist in universes of the Growing Block or Presentist varieties, then clearly there would be no possibility of E-passage existing in a Block universe. Moreover, at first view at least, it seems by no means absurd to suppose that there could be significant connections between the two modes of passage: might it not be that the dynamic features of (say) a Growing Block universe—the incremental expansion of time, as new presents are continually created—contribute to the dynamic qualities of experience? Or perhaps the combination of creation and annihilation which is characteristic of Presentist universes makes an essential contribution to the continual renewal of phenomenal content in our experience from moment to moment.
The relationship between E-passage and M-massage is likely to prove a complex issue, not least because of very different models of M-passage which need to be taken in to account, and I can do no more than touch on it here.9 However, only a cursory examination is needed to establish that, first appearances not withstanding, it is by no means obvious how the various modes of M-passage could make an essential or significant contribution to E-passage. Indeed, as we shall see, the boot may well be on the other foot: E-passage, in one of its guises, places a significant constraint on accounts of M-passage.
Before we are in a position to proceed any further with this line of inquiry we will need to take a closer look at the experiential side of the equation. That the change, succession and persistence we encounter in our immediate experience are apprehended through the brief temporal aperture of the “specious present”, or so most of those who believe we do directly apprehend temporally extended phenomena maintain, even if terminological preferences vary (e.g., some use the expression “phenomenal present”, others favour “living present”). However, when it comes to detailed theoretical accounts of the specious present—its character, composition and relationship to ordinary objective time—we find some radical disagreements: the two leading approaches, the Extensional and the Retentional (as we can call them) have very different tales to tell, as can be seen from Figure 2.10
Figure 2 Two Conceptions of the Specious present
Subjectively, as one might expect, Extensional and Retentional specious presents are very much alike: both present (or vividly represent) events or processes which seemingly extend over a brief interval of time, perhaps as much as a second, perhaps somewhat less. But there the similarities end. The Extensionalist’s specious present is a brief “chunk” of unified experience (or more accurately, a short segment of a stream of consciousness) which extends through ordinary objective time in much the way it seems to: in a typical case, the apparent duration of an Extensional specious present corresponds closely with its real duration. The contents of these phases are unified both synchronically and diachronically: although the successive phases are experienced as successive, they are also experienced together, as parts of a single temporally extended experience. The Retentionalist’s specious present has a similar apparent duration, but objectively speaking it is momentary—so although its contents seem to unfold over a brief interval of time, in reality they don’t. In the familiar terminology of Husserl, these contents comprise a momentary “primal impression” and a complement of “retentions”—or distinctively vivid representations of the recent past (the backwards-pointing nature of these retentions is conveyed by the downward-pointing arrows in Figure 2).
A further significant difference between the two approaches lies in the way individual specious presents combine to form continuous streams of consciousness. For Retentionalists, a stream of consciousness consists of a (dense) succession of momentary specious presents, each of which is a self-contained episode of experiencing whose (retentional) contents represent the contents contained in immediately preceding stream-phases. In sharp contrast Extensionalist’s usually hold that neighbouring specious presents overlap by part-sharing—in a manner approximated by Figure 3.
Figure 3 Extensional Specious Presents combining to form a stream of consciousness. The figure on the left has to be interpreted the same way: neighbouring specious presents share parts or phases (in the way a semi-detached house shares a wall), they are not superimposed on one another (in the manner of fanned playing cards, say). In this respect the figure on the right is less misleading.
There is a good deal more to be said about these competing accounts, see Dainton (2010a §5 and §6) for a more detailed overview. But we need not trouble ourselves here with these refinements here: they are largely irrelevant to our present purpose of gauging whether it is plausible to suppose that the existence of E-passage depends on the reality of some form of M-passage.
We can start by considering the situation from the Retentional theorists’ perspective. So as to bring the essentials into clear focus, let us consider a very simple specious present, SP1, whose content is of a brief snippet of P-movement: the seeing of a ball moving a short distance along a floor. Let us further suppose that SP1 exists in a temporally dynamic Growing Block universe U1 (as we can label it), a universe where the sum total reality is continually expanding, thanks to continuous creation of fresh momentary (universe-wide) phases. Now, as well as being highly dynamic, the content of SP1 also has a prominent directional character: taken as a whole, the experience seems to flow or unfold in a particular (earlier-to-later) temporal direction. Could either of these characteristics be dependent on, or a consequence of, the metaphysically dynamic nature of the universe where SP1 finds itself? It is difficult to see how, and for three reasons.
(1) Although events could be said to undergo “becoming” in U1, what this amounts to is simply coming into existence. As a momentary episode of experience, the Retentional specious present SP1 comes into existence all at once, as a whole—its contents seem to occur successively, but objectively speaking they occur simultaneously. As a consequence of this, there is no obvious or transparent connection between the dynamic properties of U1 and those of SP1. For what comes into successive existence in U1 are entire specious presents, each possessing contents that are already dynamic in character.
(2) As they are normally conceived, the only difference between a Block universe and a Growing Block universe is the manner in which the latter comes into existence in a phase-by-phase fashion. Crucially for present purposes, there are no differences in the kind of intrinsic properties which can be instantiated in either sort of universe. Consequently, if we suppose that SP1 in U1 has just been created and so lies in U1’s present, there is a possible universe U1* which is (what we can call) the non-growing counterpart of U1, i.e., U1* is a universe of the Block variety which is indistinguishable from U1 (when SP1 is present) in all respects apart from its lack of metaphysical dynamism—as a Block universe, U1* does not come into existence in a phase-by-phase manner. Since these two universes are intrinsically indistinguishable, U1* will contain a specious present SP1* which is qualitatively indistinguishable from SP1 in U1. If these two specious presents are qualitatively indistinguishable, then SP1* will have exactly the same P-dynamic properties as SP1. And since this result holds more generally, there is every reason to suppose that all the phenomenal features which contribute to E-passage can exist in growing and non-growing universes. In which case, there is no reason to no reason to suppose that E-passage essentially depends on this form of M-passage.
(3) A Growing Block theorist could hold that there is a metaphysically necessary law-like connection between the mechanism of “absolute becoming” which brings new phases of reality into existence and the existence of the dynamic phenomenal features associated with E-passage. Thanks to the existence of this distinctive psycho-(meta)physical law, non-growing intrinsic duplicate universes, of the sort just envisaged, cannot exist. However, in the light of the considerations set out under (1) above, this stipulation looks to be entirely arbitrary: we have been given no positive reason for supposing that any such thing exists.
Closely analogous considerations apply to the combinations of options: “Retentionalism + Moving Spotlight” and “Retentionalism + Presentism”. Since in both Moving Spotlight and Presentist universes a Retentional specious present (such as SP1) will come into existence as a whole, the considerations outlined in (1) are very much relevant: the experienced change and succession within the confines of a single specious present bear no obvious relationship—and hence a fortiori are not obviously dependent upon—the relevant forms of metaphysical passage: specifically, the movements of the privileged plane of existence in Spotlight universes, and the continual creation and annihilation characteristic of Presentist universes. The considerations noted in (2) are also applicable. Although Presentists and Spotlighters both narrow the (normal, fully real) universe down to momentary slices, the intrinsic properties of these privileged slices are undistinguished: exactly similar slices could exist as parts of a Block universe, and so there is no reason to suppose E-passage essentially depends on the relevant forms of M-passage. And as noted in (3), although this result can be avoided by the postulation of a previously unsuspected mechanism connecting metaphysical passage (whether of the Presentist or Spotlight varieties) to the existence of dynamic phenomenal features, in the absence of anything resembling a positive reason for thinking such a mechanism exists, there is no reason to take this proposal seriously.
What of the Extensional case? We can again start off by considering our single specious present SP1 in Growing Block universe U1. Since the Extensionalist’s specious presents extend through an interval of time, SP1’s contents do not come into existence simultaneously, they come into existence successively, as the U1 expands, momentary phase by momentary phase. Given this, it clear that objection (1) does not apply in this context. But we are not yet out of the woods: standing in the way of the notion that the metaphysically dynamic character of U1is in any way responsible for the phenomenally dynamic character of SP1’s contents are the considerations set out in (2). There is a logically possible Block universe U1* which is intrinsically just like U1 in all respects save that it does not come into existence phase-by-phase, and since U1* contains SP1*, the non-dynamic but otherwise qualitatively indistinguishable counterpart of SP1, we have no reason whatsoever to suppose that SP1’s phenomenally dynamic features owe their existence to the fact that it comes into existence in a Growing Block universe. In reply it might be claimed, once again, that universes such as U1* are not logically possible, by virtue of some mechanism which connects the very existence of dynamic phenomenal contents to the process of “absolute becoming”. But while such a mechanism would certainly render worlds such as U1* impossible, we have not been given any reason for supposing that the required mechanism does in fact exist.
By way of a dramatic illustration of the lack of any obvious connection between the process of absolute becoming and E-passage it is useful to consider the reverse of this process: a universe which in other respects is exactly similar to our own, but which is continuously shrinking in size, as momentary layers of it are successively annihilated. See Figure 4 for a depiction of these competing dynamic models. The focus here is on the brief period of time in which SP1 comes into existence (in universe U) or suffers progressive annihilated (in universe U-); to keep things manageable only three snapshots of this complex process are shown—in reality there would be many intermediate phases.
Figure 4 Growing Block v. Shrinking Block
It may seem very natural to suppose that the experience of the subject of SP1 in the shrinking universe U- would be very different in character from the experience enjoyed by the subject in the growing universe, U. On reflection, however, it is by no means clear that his would be the case. The main reason for is simple to see. If we focus our attention just on the contents of the matching phases of these two universes (i.e., phases which contain precisely the same sub-phases, in the manner—see Figure 4—of U2 in U and U2 in U), while ignoring the order in which these contents come into being (or depart from it), we will find that they are intrinsically indistinguishable.
More concretely, if we confine our attention to SP1 then in both universes there are occasions when the location of the moving NOW is such that (i) P1, P2 and P3 are all experienced together in a complete specious present, (ii) P1 and P2 are experienced together, without P3, (iii) only P1 is experienced, without P2 and P3. Given that the subject’s memories are precisely the same in both universes—which, don’t forget, are intrinsically alike in all respects save their mode of metaphysical dynamism—how could the order in which these sum totals come into (or go out of) existence impact upon the subjective character of the relevant subject’s lives? Although the idea that temporal passage could consist in the successive annihilation of universe-phases may well seem bizarre, what is even stranger is the realization that life in a Shrinking Block universe could easily be much the same, experientially, as life in a Growing Block universe.
Let us move on. Anyone who tries to combine the Extensionalist account of the specious present with either the Presentist or the Moving Spotlight models of M-passage is confronted with an immediate difficulty. Presentists and Moving Spotlight theorists standardly assume that the (metaphysical) present is momentary, and that the domain of the real—or fully real, in the case of the Moving Spotlight model—is similarly constrained. Since Extensional specious presents are temporally extended, it looks as though specious presents of this kind cannot be housed in universe of this kind: they lack the requisite temporal breadth. This difficulty may well not be an insuperable one; after all, the Extensional specious present doesn’t have very much by way of temporal extension, perhaps a second, perhaps less, and it may be possible to develop modified versions of Presentism and the Moving Spotlight theories which feature metaphysical presents that are similarly extended—presents that are “thick” rather than “thin”. However, even if this proves to be the case, the prospects for establishing that E-passage essentially depends on either of these modes of M-passage do not look promising. Why? Because if we confine our attention to purely experiential structures and relationships that would be generated by these forms of M-passage, what we find are structures and relationships which are intrinsically indistinguishable from those to be found in Block-type universes. By way of an illustration, Figure 5 depicts an isolated fragment of a Moving Spotlight universe, where P1-P6 are successive phases in an uninterrupted stream of consciousness. The duration of the specious present can encompass no more than two of these phases, and the duration of the metaphysical present is of the same duration; the figure shows five snapshots of motion of the NOW, at five neighbouring locations labeled L1 to L5, indicated by bold. Only the stream-phases in bold are properly real, the remainder possessing the shadowy lesser form of reality common to everything that is non-present in a Moving Spotlight universe. The same figure can be used to depict how the Presentist views things: it suffices to regard all the non-bold phases as entirely lacking in existence.
L1P1 P2 P3 P4 P5 P6
L2 P1P2 P3 P4 P5 P6
L3 P1 P2P3 P4 P5 P6
L4 P1 P2 P3P4 P5 P6
L5 P1 P2 P3 P4P5 P6
If we disregard everything but the sequence of stream-phases in bold we are left with the following: [P1-P2], [P2-P3], [P3-P4], [P4-P5], [P5-P6], i.e., a succession of partially overlapping specious presents, all of which are fully real. There is nothing to prevent a succession of partially overlapping specious presents of this sort from existing in a Block universe, and if they did so, there is every reason to think their subjective character would be exactly the same as in the envisaged Moving Spotlight and Presentist universes: so far as their intrinsic nature is concerned, the succession of specious presents in all three types of universe will be exactly the same. Of course, there are other differences. In the Moving Spotlight and Presentist universes, as of the time (say) when [P3-P4] is real, all the other (earlier and later) experiences in this stream of consciousness are not real. But how could the non-existence of these earlier and later experiences impinge on the character of [P3-P4]? In short, if we suppose, as seems highly plausible, that the phenomenal character of an experience—i.e., what it’s like to undergo the experience—depends solely on its intrinsic features, there is no reason to suppose that the distinctive metaphysical dynamism to be found in Presentist and Moving Spotlight universes impacts in any way on the phenomenal character of any experiences they contain.
Pulling these various points together, we see that there are powerful considerations which weigh against the initially appealing notion that E-passage might essentially depend on any form of M-passage. I would not pretend that these considerations are decisive. The relationship between these modes of passage has not yet been thoroughly explored, and no doubt there is much about E-passage we have yet to understand—indeed, there may well be other ways of conceiving of M-passage, ways which connect it more directly with the dynamic aspects of conscious experience. But as things currently stand, I think the burden of proof lies firmly in the camp of those who claim the alleged dependency does exist.
At the start of this section I suggested that “the boot may well be on the other foot” because E-passage, in one of its guises, might place a constraint on accounts of M-passage. We have already encountered the constraint I had in mind: the Extensionalist account of temporal experience is incompatible with both the Presentist and the Moving Spotlight models of dynamic time, at least as these are doctrines are normally construed. In worlds where change is directly experienced via the medium of Extensional specious presents, reality cannot be confined to strictly momentary “nows”. The difference between a durationless instant and half a second (or even a second) might seem almost negligible by the lights of our ordinary human time-scales, but from a metaphysical standpoint the difference is a unquestionably a significant one.11
It might be thought that this revisionary constraint does not apply to those orthodox Presentists who combine the doctrine that “only what lies in the momentary present is real” with a way of interpreting statements about the past or future which allows these to be true or false, despite their lack of a (real) subject matter. If there can be true statements about the past then it can be true to say, for example, that my present experience is a part of a diachronically unified stretch of experience that has lasted for about half a second. What more does the Extensional theorist need? The answer, as far as I can see, is a good deal more—or at least, something rather different. Presentists secure truth for propositions about the past (or future) by appealing to truthmakers which are very unlike any everyday object or process. One currently popular approach runs like this: statement such as “It rained yesterday” are made true not by a quantity of water falling yesterday (the sum total of reality contains no such day, and hence no such water), but by a certain non-actual possible world which happens to contain a rainy day, and which is a member of a set of possible worlds which jointly constitute our past history (and perhaps our future); the same goes, mutatis mutandis, for any other statement about actual occurrences in the past—for further detail see Markosian (2004), Bourne (2006) and Crisp (2007). I think it is clear that this will not provide Extensionalists with what they need. An Extensional specious present is a single unified experience, an experience whose parts are all experienced together as well as in succession. It is absurd to suppose a single unified experiential state could be composed of a combination of ingredients, some of which are actual and some of which non-actual. Just imagine how different your visual experience would be if the lower-half of your visual field were composed of merely possible (but quite unreal) visual experiences: wouldn’t your visual field be only half of its actual size? The claim that the vast bulk of a specious present is composed of wholly unreal experiences is quite implausible. But Presentists who attempt to accommodate Extensional specious presents in the way envisaged are committed to precisely this position.12