3 Feb 2014

Notes from Barry Dainton’s Time and Space for comparison with his “Sensing Change”

by Corry Shores
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Notes from Barry Dainton’s

Time and Space

for comparison with his “Sensing Change”

In Barry Dainton’s article “Sensing Change,” he describes his overlap model of the specious present of our phenomenal awareness.

Of course, anyone who believes that concrete reality is itself confined to what the present instant contains will find the Extensional approach problematic. If the past simply does not exist, contents located in the past cannot be co-conscious with contents located in the present. (This thought may well underlie the Retentionalist doctrine that only items that are momentary and simultaneous can be phenomenally unified.) But while this view of time—Presentism—may have some appeal at the level of commonsense, it does not sit easily with the four-dimensional space-time ontology that (many believe) Einstein’s theories of relativity require. By allowing phenomenal unity to connect contents that are separated by time as well as space, it is the Extensional approach that is more in tune with the findings of contemporary physics. (Dainton “Sensing Change” 380)

Dainton writes more about the four-dimensional space-time view of temporality in his book Time and Space. What might be implied in this is that Dainton’s overlap model is also more in tune with contemporary physics because it is extensionalist. So we will see if his writings in Time and Space might determine this.

In the first chapter of Time and Space Dainton introduces McTaggart’s distinction between A- and B-series. The temporal character of events in the A-series are understood in terms of their relation to the now-moment from which we see them. This means that events are understood as being located either in the present now, or in the future that comes after the present now or the past that happened before the present. Events understood in terms of the B-series however are not seen as though there is a origin point which can make these distinctions. An event can come before or after, or be simultaneous with another, like how we think of historical events, but the temporal character of the B-series is not one that allows for present, future, and past. (TS 11)

Dainton then makes the following distinctions.

• The Block view: all times and events timelessly coexist, and all are equally real; temporal passage is unreal.

• The dynamic view: temporal passage is real, and time is not an ensemble of coexisting times and events. In short, the block-universe view is false.

• The tensed theory: A- concepts such as past, present and future have an essential and ineliminable role to play in any metaphysically adequate account of the nature of time.

• The tenseless theory: B- concepts such as earlier than, later than and simultaneous with are all we need for a metaphysically adequate account of time. (TS 11-12)

Because the overlap model is one in which the present ceaseless passes, it would seem to observe the dynamic view and not the block view. The question is then, does the contemporary physics that Dainton refers to here also take the dynamic view? In the overlap model, it is the present which is extended and passing. Do physicist think in the four-dimensional view that there is a one second long present that passes through time?

In the third chapter Dainton looks more closely at the four-dimensional ‘block’ view of time, which might be the view he says is popular in contemporary physics and required by Einstein’s relativity theories.

Beginning the first section, titled “Time without Passage,” he writes:

Many contemporary philosophers are convinced that McTaggart was essentially correct: our world is a block-like four-dimensional ensemble, lacking a moving present, wherein all times and events are equally real. (TS 27)

A bit later he writes:

Of all the models of time that we will be considering, the B-theory is currently the most popular among philosophers and physicists, but in many respects it is also the strangest and most counterintuitive. (TS 27)

In the fourth chapter he further claims that for B-theorists time does not really have a moving now that flows with time’s passage:

But if the B-theory is true, time is not going anywhere: there is no moving “now”, no slippage into the past, no crystallization from mere possibility into present actuality. (TS 44)

In chapter 5 he formulates a particular claim that in chapter 6 he critically examines:

The world is a four-dimensional ensemble, and all times and events are equally real and coexist. (TS 63)

In the 6th chapter he examines presentism, which he mentions in the paragraph we cited from “Sensing Change”. Presentism thinks that only the present is real. Here in Time and Space he says something similar:

Once one becomes aware of the Block view, and the scientific considerations (especially Einstein’s special theory of relativity) that can be mustered in its favour, denying reality to everything but the present can easily come to seem absurd. (TS 81)

In the 7th chapter Dainton examines the phenomenology of time. He begins first with phenomenological data of the phenomena of change and persistence.

Let us start by gathering some basic phenomenological data. Our typical experience is a combination of persistence and change. You are, let us suppose, lying in a deckchair gazing at the sky, where you can see a few white clouds moving very slowly against the unvarying blue backdrop. You see the occasional bird overhead. Sometimes they circle around for a while, and often they fly right on by. When you do see a bird in flight you are directly aware of its motion: the flapping of wings; the sometimes fast, sometimes slow changes of position. You are as fully and immediately aware of these movements and changes as you are of the unchanging blue of the sky. The same holds quite generally for other modes of consciousness. We see change, but we also hear it (a rapid sequence of notes played on a piano), feel it (slowly move your finger across the palm of your hand) and imagine it (recreate in your imagination the final shot in a tennis tournament – a ball goes out, a player leaps with joy, the crowd roars). In addition, there can be changes in what we smell and taste, and in our emotional state (a surge of anger). And then there is the inner soliloquy, the conversation we have with ourselves in thought, conducted sometimes in words, sometimes in images, sometimes in neither, which rarely ceases during our waking hours.

All this is obvious: consciousness is alive with change and variation. More elusive is the subtle but distinctive sort of dynamism that is characteristic of unchanging sensations. Return to the deckchair scenario. For some moments now you have been staring at an empty region of blue sky and nothing has changed. Your inner monologue has (if only briefly) ground to a halt, you have seen no movement, your visual field is filled with an unvarying expanse of blue. But is your consciousness entirely still or frozen? Have you come to a complete stop? No. Throughout this period you remain conscious, and conscious of the blue presence continuing on; you have a (dim, background, passive) awareness of the blue constantly being renewed from moment to moment. This passive awareness of continuation and renewal is perhaps more vivid in the case of auditory experience. Imagine hearing a sustained but unwavering note played on a cello: you hear a continuous and continuing flow of sound. This feature – call it “immanent phenomenal flow” – is possessed by all forms of experience (think of the burning sensation on the tongue caused by biting on a chilli pepper), and is a dynamic feature of experience that is independent of changes of the ordinary qualitative sort (the chilli- induced burning is felt as continuing on even when its intensity and qualitative character remains constant). Phenomenal flow is especially important in the case of easily overlooked but ever- present bodily experiences: the feeling of one’s limbs being disposed one way rather than another, the feeling of being vertical rather than horizontal or upside down, the feelings of pressure on one’s skin caused by clothes, seats, shoes and so on. When we are not moving about, our bodily experience is largely unvarying in quality, and so goes largely unnoticed, but it remains a constant – and constantly flowing – presence within our consciousness. (TS 104)

Thus we may distinguish two temporal phenomenal traits, passage (change) and flow (persistence):

• our experience of change is as direct and immediate as our experience of colour or shape;

• our experiences possess the feature of phenomenal flow. (TS 104)

Phenomenal flow, by the way, involves an awareness of the newness even of persistent things in our awareness:

As well as providing an explanation of how we can have an immediate experience of change, the model provides an account of phenomenal flow, the impression we have that a qualitatively unvarying sensation is continuously refreshed and renewed. (TS 110)

We also note that again Dainton in this book, like in other writings including “Sensing Change” claims that contents in his awareness do not linger.

If the two- dimensional model were true, we could expect that:

experiences would never end abruptly, they would always linger on for a short while as they are represented in successive awarenesses as possessing diminishing presentedness;

• at each moment we would be aware of our current experience together with a constantly shifting complex of representations of recent experiences, and so our consciousness would be choked with the residues of recent experiences.

But this is wrong on both counts. As far as I can tell, my consciousness is not clogged up with fading residues of prior experiences, and experiences do not always linger; they sometimes do end abruptly. It could be objected, “Ah, but the residues are very brief. That’s why you don’t notice them. Likewise, for the shifting constellations of representations.” This reply is unconvincing. If we cannot discern the posited representations, there is no reason to suppose that they have any phenomenological reality, and hence no reason to suppose that they contribute to our actual experience of change and persistence. (TS 111)

[[Dainton also at times refers to the blur behind a fast moving object. In cases when he mentions these he does not explain why these are not instances of lingering contents, and in cases when he says we never have lingering contents, he does not mention cases of blurred moving objects in order to clarify how they are not instances of lingering.]]

We also note here that in “Sensing Change” Dainton says that what is in the extensive specious present of his overlap model is present because it has the full force and vivacity of present things.

What quality, added to a pain sensation, would make that sensation seem to be in the past rather than in the present? If I am now experiencing some sensation, won’t the experience seem to be occurring now irrespective of any peculiar qualities it might possess? Someone might say, “Presentedness is not an additional property that experiences have. It is akin to Hume’s ‘force and vivacity’. It is simply a measure of the intensity of an experience; as experiences lose presentedness they become progressively fainter, until they fade away altogether.” But this won’t work. Do some parts of the image in Figure 7.5 appear “more past” than others? [This figure shows a star-shaped image of light where the center is bright and diminishes toward the edges](112)

[[But when discussing non-extensional models, he examine a similar concept called presentedness, which is a quality that retentional contents have to diminishing degrees as they move further away from the present toward the past. He says that presentedness cannot be understood as Hume’s full force and vibrancy, because presently given weak phenomena like faint sounds or light do not now sound as if in the past. Those advocating for a diminishing presentedness might say that what makes the content seem more past is not merely its faintness as much as how much fainter it is from when it first presented itself. The faint sound now gets even fainter and as it does, and only as it does, it appears less and less present. It is also unclear how it is that Dainton’s criticism of presentedness does not apply to his concept of presence which is defined in exactly the same terms as presentedness. If a sound is currently very faint, does it seem less present than other concurrent sounds which are prominent? If not, how exactly do we make a clear distinction between presentness and presence with respect to currently faint phenomena?]]

When describing his overlap model, he explains how contents separated by others are not transitively co-conscious, and he also says that the specious present is less than a second.

Since the specious present is of limited duration (probably less than a second), the relationship of co- consciousness over time (diachronic co- consciousness) cannot be transitive. (114)

Later there is a paragraph which might help us better understand how the features of the overlap model might be in tune or not in tune with the contemporary physics understanding of time. It is not here clear if he is saying that moments outside the present are real in the same way as those inside the specious present. He only says that they are real in the present, but he puts in it a way that might suggest we cannot say something about the reality of those outside it.

However, in assessing the plausibility of what is being offered here, we must not lose sight of the model of time with which we are dealing. The overlap theory tells us that for me to experience C flowing into D, or D flowing into E, my experiencing of C must be co-conscious with my experiencing of D, and my experiencing of D must similarly be co-conscious with my experiencing of E. When two experiences are (diachronically) co-conscious, they are experienced together, in a unified temporally extended episode of experiencing. It is difficult to see how C could be related to D in this way if C is unreal when D occurs – and similarly for D and E. In order for C and D to be part of one unified experience, C and D must surely coexist. But according to the Dynamic Presentist, since C and D occur in succession, they do not coexist. (118)

[[A presentist might also say that to perceive C flowing into D is to perceive the passage between and thus to have both simultaneously in consciousness in that instant of their passage.]]

[[More generally speaking, it is not clear if the overlap model assumes time makes up a B-series, because the present has an extensive structure where successive moments co-exist, or if because the present is always in motion that it makes it not a B-series. If it is not a B-series on account of the movement of the present, then it is unclear how it is compatible with contemporary theories of physics which seem to construe time as B-series.]

Then he specifically addresses the question of whether the overlap model is compatible with other metaphysically intelligible views of time, and he says that it is “neutral” with respect to them. First he looks at the block view, which is like the B-series conception. All moments have their place, none are present, and there is no flowing now. But the way he describes it here suggests that within the four-dimensional block a stream of consciousness is like a small part that is only aware of tiny moving portion of it. It does not explain the relationship between the movement of the stream of consciousness and the non-movement of the block. So he explains why it is that the specious present is only a small part of the whole block, but he does not explain why in the block a small part of it is moving.

What of the other models of time that we have considered and found metaphysically intelligible? For better or worse, the overlap theory seems entirely neutral with respect to these.

Consider the Block view. The overlap theory tells us that co-consciousness extends over short periods to create temporally extended “phenomenal presents”, that successive phenomenal presents overlap, and that the contents of these phenomenal presents have an inherent dynamic character. That our experience is structured in this way guarantees that we will have the impression that our consciousness is confined to a forward-moving present even if, in reality, past and future experiences are just as real as present ones. From the four-dimensional perspective, a stream of consciousness is akin to a glowing filament embedded in a long glass block; the filament is aglow throughout its entire length, but this is not discernible to the subject of these experience, who is only ever aware of those tiny stretches of experience joined by co-consciousness. (119)

Dainton contrasts his overlap theory to ones which conceive of the present as durationless. He claims that such models cannot account for the phenomenon of passage. But one argument against Dainton’s position, which he does not address, is that physics understands an instant of motion as being like the smallest part of passage. In one sense it is durationless in that it is not an extent of time, but it is not the same as a lack of temporality. It in a way is greater than a zero amount of time and less than any givable finite amount of time. At any such instant of motion, we can calculate the instantaneous velocity of the motion. In a sense, the object is both in motion and at rest. It is at rest because it does not travel any extent of space or occupy any extent of time, however it is in motion because it is still in passage between locations, and thus it can have a certain rate of making that passage even though no extend of time or space transpires. Dainton in fact discusses and describe this operation in physics, and he even notes that modern scientific and technological calculations depend on it. This suggests that the instantaneous view of parts of motion are compatible with contemporary views of time in physics. What is interesting is that he does not consider this view of the instant when examining possible models of time consciousness where the present is instantaneous. Could not the present in our phenomenal consciousness be an instant which is aware off the smallest part of change? He explains instantaneous velocity when discussing the at-at account of motion, which can solve Zeno’s paradox of the arrow. An arrow in flight occupies a series of points in space coordinated to instants in time where it is found at those locations. But it is not at motion in any of the points, so it is never at any point or moment in flight. Dainton explains how those who think time and space are continuous can reply that since the arrow was at a different location prior to any in its motion, then it is changing location across time and thus is in movement. It is at certain points at certain times, and at intermediate points between them. He then looks at the calculus way of looking at this to show how even in the instant the arrow would have an instantaneous velocity, which suggests that no matter how small of a part of its motion we look at, it is at motion in that instant.

17.1 The “Arrow”

Imagine an arrow in flight. At every instant during its flight, the arrow is at some specific location, occupying a volume of space that corresponds exactly to the arrow’s own size. Since instants are durationless, and motion takes time, the arrow is not in motion at (or during) these instants. Yet the arrow’s entire flight is composed of these instants, and nothing but these instants. If the arrow is not in motion at any of the instants that jointly make up its flight, it is not in motion at all.

This is Zeno’s “Arrow” paradox. The reasoning obviously generalizes – what holds for the arrow holds for any object in motion – and so if the argument is sound, motion does not and cannot occur. The argument is sometimes taken as being directed – along with “Stadium”, which we will be looking at shortly – against the doctrine that space and time are discrete, rather than continuous. While this may well be true for the Stadium, it is not obviously true in the case of the Arrow. In any event, the Arrow reasoning certainly poses a significant problem for those who believe space and time are continuous rather than discrete, the conception of the continuum with which we are currently concerned. If space and time are composed of dimensionless points, and the arrow’s flight involves its occupying a continuous succession of different locations, we are undeniably confronted with the problem of explaining how it is possible for the arrow to have moved, given that it is not (seemingly) moving during any of the momentary stages which constitute its flight.

The at-at theory

Those who subscribe to the orthodox conception of the continuum have a response to the Arrow challenge that is widely, although by no means universally, accepted as adequate. The proposal runs as follows. Whether or not an object is in motion at a given time t does not depend on the object’s condition or state at time t. Rather, it depends on how the object behaves at those temporal instants neighbouring t. If at these neighbouring times the object is at precisely the same location as it is at t, then we say that it is not moving at t; but if it is at different locations, then we say that it is moving at t. Since everyone can agree that an object is moving if it is changing its location over time, this simple account seems to give us all we might want. Or as Russell puts it, “Motion consists merely in the fact that bodies are sometimes in one place and sometimes in another, and that they are | at intermediate places at intermediate times” (1917: 84) [Russell, B. 1917. “Mathematics and Metaphysicians”. In his Mysticism and Logic. London: George Allen & Unwin]; hence the “at-at” label for this view.

It will be useful to take a closer look at what proponents of the at-at account are proposing. Suppose we start with an interval I1, running from half a second before t to half a second after t (see Figure 17.1). We calculate the arrow’s average velocity over I1 by dividing the distance travelled over the course of this interval by the time taken, which in this case is one second. This gives us an initial, reasonably accurate, approximation of the object’s velocity at t. To get more accurate approximation we repeat the procedure for a shorter interval I2, which is also centred on t, but running (we can suppose) from a quarter of a second before it to a quarter of a second after it. By working out the average velocities over shorter and shorter t-centred intervals we will generate increasingly accurate estimates of our object’s velocity at t itself. In standard fashion we now introduce the limit-value of the series at t: it is the average velocity to which the series of ever-decreasing intervals converges as the end-points of the intervals approach arbitrarily close to t itself. We can now stipulate that our object’s instantaneous velocity at t is simply this limit-value.

This procedure can be applied quite generally to deliver the instantaneous velocities of any moving object at any time. Indeed, the procedure just outlined is essentially that used in the calculus, where velocity is the “first derivative” of change of position with respect to time (acceleration, the rate of change of velocity, is the “second derivative”). Since the day of Newton and Leibniz, calculus has been at the heart of physics and applied mathematics, and it is undeniable that much of the success of the former is due to the latter; without the methods of the calculus we would not be able to calculate the rates of change of interdependent quantities in the precise and accurate ways our science and technology require. (TS 289-290)

Dainton. Time and Space fig17.1

Figure 17.1 from page 290 of Barry Dainton's Time and Space (2010 2d ed)

As we can see, time is understood here as an extension, and this is specifically Dainton’s claim, that contemporary theories in physics regard time as extensive in their four-dimensional models. Our question is whether or not the overlap model’s other features are compatible with this four-dimensional view. We might for example wonder, do these contemporary conceptions of time think that within the extent of time there is a one second long moving present? One way Dainton might locate something like this in Einstein’s special relativity theory is in how there is no absolute simultaneity. Events that in one frame seem simultaneous might in another seem successive.

In the context of STR, simultaneity is not absolute but frame-relative. Spatially separated events that are simultaneous from the perspective of one inertial frame are not simultaneous from the perspective of other inertial frames, and since the perspectives of all inertial frames are equally valid, there is no sense in the idea that the events in question are “really” simultaneous or not. (TS 322)

So the present cannot be seen as an instant that all frames share. So we consider all possible observations. In one such comparison, there will be events that in one frame seem simultaneous and in another seem successive, and we are looking at the pairing where magnitude of the extent of time in the succession of events is greatest for any other comparison of frames. This difference in magnitude would be the extensive present, because it is the extent of time during which all other observations fit the same events. So while in the frame where the events seem maximally successive, in another they are simultaneous. The presence in the simultaneous case is extensively stretched in the successive case, and this is the extent of the present. This brings us closer to seeing how the extensive overlap model might be closer to contemporary physics and Einstein’s relativity in particular, but there is still a lot that is not clear about this account. Does that mean that because our specious present is one second long, this extent of time is the greatest possible temporal difference between all frames in the universe? And are we suggesting that when we view the specious present we are somehow perceptive of the temporally difference between reference frames of which we are not otherwise perceptively aware of? Perhaps, but Dainton does not clarity if and how this might be so.

When discussing general relativity, Dainton more specifically addresses when it is compatible with B-series conceptions of time and dynamic conceptions of time. He writes that “Nothing in GTR is obviously incompatible with the Block conception;” (381) and “A certain class of GTR models are surprisingly friendly to those versions of dynamism that posit a universe-wide tide of becoming” (TS 381). However, in this section Dainton does not clarify whether or not in any version of relativity theory that there is a moving extensive present of a second or so in duration.

Thus at least in his book Time and Space, Dainton does not give us reason to think that all the important features of the overlap model of the specious present [the present is an extent of time of about one second long where all phases or contents of that present are equally present with those outside its scope being past and future] correspond with the features of time as conceived in contemporary physics and in particular in Einstein’s relativity theories. The main point of difference would be that while both see time as extensive, it is unclear if physical theories think there is a moving present of a length of about one second long. We recall how Dainton writes in “Sensing Change:”

But while this view of time—Presentism—may have some appeal at the level of commonsense, it does not sit easily with the four-dimensional space-time ontology that (many believe) Einstein’s theories of relativity require. By allowing phenomenal unity to connect contents that are separated by time as well as space, it is the Extensional approach that is more in tune with the findings of contemporary physics. (Dainton “Sensing Change” 380)

It seems that while extensional approaches in general are compatible with the way that contemporary theories of physics portray time as being part of a four-dimensional space-time manifold, the overlap model of the specious present as a specific extensional model of time does not correspond with the way that contemporary physics understands the ‘present’ within the extent of space-time. Thus unless Dainton can maker further clarification, it does not seem safe to claim that his overlap model is compatible with contemporary theories of time in physics.

Works cited:

Barry Dainton. (2010, 2nd edition [1st edition 2001]) Time and Space. Durham: Acumen.

Barry Dainton (2008) “Sensing Change.” Philosophical Issues, 18: 362–384.


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