William James quotes Mozart, describing how he perceives music he is composing:
. . . and I spread it out broader and clearer, and at last it gets almost finished in my head, even when it is a long piece, so that I can see the whole of it at a single glance in my mind, as if it were a beautiful painting of a handsome human being; in which way I do not hear it in my imagination at all as a succession - the way it must come later - but all at once, as it were.
We all do this, although usually for much shorter riffs than entire symphonies. I have argued that the all-at-onceness of our thoughts and perceptions is at least as inexplicable as what it is like to see red; I think the aural/temporal all-at-onceness makes the point at least as vividly as the visual/spatial all-at-onceness of the curl of smoke in an art nouveau poster.
The temporal aspects of consciousness can be illustrated visually too, of course. Imagine seeing dust motes swirl around in the air in the bright sunlight coming through a window, or someone riding a bicycle past you on a street. When you see these things, you see them in motion. That is, your consciousness is of objects in motion, just as directly and absolutely as your consciousness of a red tomato really is of redness. There may be all sorts of neurobiological and cognitive tricks going on behind the scenes, so to speak, but my actual subjectively experienced moment of consciousness is not instantaneous - it has temporality built in. It is, as Horgan and Tienson (2002) say, temporally thick. The motion of something we see moving is not something we infer or conclude or extrapolate, but something we see, right there in the perception, just as much as shape and color. Our conception of time is not, like the weird laws of quantum mechanics, some counter-intuitive scientific theory that our mathematics drove us to accept, but that we will never quite feel in our guts. We do feel time in our guts. A given moment of consciousness does not exist as a snapshot taken at a particular instant, or even a series of such snapshots from which we intellectually infer continuous change. As William James (1952) said,
. . . between the mind's own changes being successive, and knowing their own succession, lies as broad a chasm as between the object and subject of any case of cognition in the world. A succession of feelings, in and of itself, is not a feeling of succession. And since, to our successive feelings, a feeling of their own succession is added, that must be treated as an additional fact requiring its own special elucidation . . .(emphasis original)
It would seem that for perception of motion to exist at all, it must be what it is, in its entirety, over a non-zero period of time. Whatever a moment of consciousness is, if you cut a piece off temporally, it just won't be the same moment of consciousness. You can not be conscious of a piece of music, even a short advertising jingle, without having it temporally in your mind's ear as one undivided thing. As Dainton (2000, p. 127) asks, is a strictly durationless auditory experience even possible? Even of something like a single click? For a sound of any kind to be what it is to you, there always has to be an attack and decay of some duration.
There is a spooky way in which consciousness spans time, and is not what it is at a given instant, the way a dumptruck is, but can only be what it is smeared out over time. That is, one can imagine a dumptruck winking into existence for an infinitesimal period of time, then winking out again, and for that instant, it would have been a complete dumptruck. But my percept of Marilyn Monroe breathily singing "Happy birthday, Mister President" simply takes time. It is a single percept, but it would not be what it is if it were just an instantaneous slice of that experience.
James commented on this also and used (but did not coin) the term "the specious present" to describe the illusion that the present instant is an instantaneous point. As he said (James, 1952):
In short, the practically cognized present is no knife-edge, but a saddle-back, with a certain breadth of its own on which we sit perched, and from which we look in two directions into time. The unit of composition of our perception of time is a duration, with a bow and a stern, as it were - a rearward - and a forward-looking end. It is only as parts of this duration-block that the relation of succession of one end to the other is perceived. We do not first feel one end and then feel the other after it, and from the perception of the succession infer an interval of time as a whole, with its two ends embedded in it. The experience is from the outset a synthetic datum, not a simple one; and to sensible perception its elements are inseparable, although attention looking back may easily decompose the experience, and distinguish its beginning from its end. (emphasis original)
Given this immediate, undeniable temporality built into our perceptions, the big question is to what extent does this have metaphysical implications? Put another way, can we account for the subjective experience, the phenomenology of the situation, without making extravagant claims about the nature of the universe?
On one hand, it could be the case that the infinitesimal point that we usually think of as being "now" is an abstraction foisted on us as a by-product of calculus, and is not real. There may well actually be no precise point of "present" that divides "past" from "future", and William James's saddleback present is not just a phenomenological or psychological fact, but a literal objective truth of the real world. In this case, our consciousness simply directly perceives a temporally smeared-out reality. Let's call this position the temporal realist position: time really is just smeared out just the way it seems to us, and we simply perceive it directly that way. The part of this position that pertains to experience only is sometimes called the extentionalist position, since it posits that experience itself is extended through time.
Many philosophers of time and consciousness would not agree, but I believe that extentionalism is metaphysically strange. I have been using the term all-at-once a great deal to describe a certain holism in our thoughts and percepts, but in the context of the present discussion this is exactly not what I want to convey. All-at-once suggests a simultaneity, an instantaneousness, that is exactly what extentionalism throws out the window. At the same time (har!) I want to preserve the sense of holism at the core of what I meant all along by all-at-once. I perceive things, the length and breadth of them, the beginnings and the ends, and I perceive them as one, at once, if not at one instant. I perceive, then I may, as a further effort, have a subsequent percept of the original percept as being made of parts, but my percepts are not therefore made of parts. A macro percept is not just an aggregate or composite of micro experiences.
If this temporal holism is true, it is weird. For this wholeness of perception to take place throughout a non-zero length of time, it would seem to be the case that I can see forward in time, or perhaps backwards in time, or both. My mind is at once in immediate touch with the bow and the stern of a percept, and not just some memory trace of them, but actually reaching through time to them.
It has been asked why it should seem any stranger that experiences have duration than that an electron persists through time. An electron, however, is like the dumptruck above: the only connection between the electron past and the electron present and the electron future is a causal connection, if one chooses to see it that way. The electron in the future is caused by the electron in the present, but each may be thought of as its own, self-contained, self-defined thing. Experiences are not like that. My experience of a car horn honking would not be what it is at any point in its timeline if any part of it were missing or different. If extentionalism is true, then I actually touch the past and/or future directly with my mind. As I said, weird.
Must there be such a tight correspondence between time as we experience it and "real" time? Are we so sure that we need time to represent time, or is this just a failure of imagination on our part? Rather, could it be the case that we present time to ourselves using something other than time itself?
It may well be the case that there really is an objective, infinitesimal point of "now", and our minds somehow buffer information from successive moments. As each moment of consciousness happens, it could include this buffered residue from recently past moments smeared out in the appropriate way. Husserl used the term "retention" to describe this. Moments just past are preserved not in long-term memory, but in a retention that is given whole to consciousness all at once. Let us call this position retention theory.
Retention theory helps somewhat to overcome the sticky metaphysical problems with extentionalism and addresses the concerns nicely summarized in this quote by Thomas Reid, and which I swiped from Ian Phillips:
[I]f we speak strictly and philosophically ... no kind of succession can be an object either of the senses, or of consciousness; because the operations of both are confined to the present point of time, and there can be no succession in a point of time; and on that account the motion of a body, which is a successive change of place, could not be observed by the sense alone without the aid of memory.
It is simply weird to think in terms of actually smeared-out experiences that are nevertheless perceived as one thing, given whole to consciousness. If perception happens at a point in time, then as Reid says, we must employ some kind of retention to perceive succession.
Computers can do a remarkably good job analyzing data (like sound waves) over time without suggestion of metaphysical strangeness going on. They employ a sort of retention. They map the waveform to data structures, then perform their analysis on the data structures. I'd rather not go back into the computer consciousness debate right now, but my argument against a computer having time consciousness would be similar to my arguments against it having any consciousness.
Briefly, we have no reason to believe that a computer perceives duration the way we do; rather, it computes itself into a particular state (in the technical sense, in which the computer is seen to implement a Finite State Machine). This state is manifested by a particular (possibly quite long) number. By virtue of being in this state, the computer has a predilection to produce certain outputs that we might interpret as meaning that the computer has "perceived" the waveform, but at any instant during its analysis, the computer was just in a particular state, looking at a tiny crumb of data, and moving to another state as a result.
Some have argued against various construals of retention theory on the basis that it predicts results that we simply do not observe (Thompson 1990, Kelly 2003). In particular, if my seeing the long arc of a pop fly were due to my retention of each successive position of the ball, and superimposing these retentions on my current moment of consciousness, I would see not a ball in motion, but a static arch, perhaps with the longer-ago ball images growing fainter, so that the overall impression would be that of a comet with a parabolic tail. Likewise, if I heard a song according to retention theory, I would hear a cacophony - a simultaneous clash of notes, or at best a chord.
I think that these objections are imaginatively constricted and do not give retention theory a fair hearing. Why should we insist on projecting our presumed time-sense onto our instantaneous space of (visual and aural) perceptions in this way? For the time being, speaking metaphorically, let us think of moments of consciousness as points or shapes in a many-dimensional hyperspace, qualia-space. We already know that, for example, each "pixel" of our visual field has a color that can be mapped onto a three-dimensional color space (hue, saturation, and brightness being the axes). In addition to axes for all of the aspects of all of the other sense modalities, there are many other (possibly infinite) axes. There are many qualia that are not reducible to the five senses: what is it like to think about your father, to get a raise, to want ice cream?
My intention here is not to get into the no-man's land between qualitative consciousness and cognition but to argue that qualia-space is big and has lots of dimensions. Why couldn't there be one more axis, a time axis, in qualia-space? When we see the pop fly, we see it smeared out, but not in such a way that the smearing-out takes place within the instantaneous visual field, but along the axis of an entirely different quale, the time quale. Similarly, the notes of a song are arranged along this axis, imbued with this quale as well, and not all jumbled into an instantaneous aural experience as a chord.
What is it like to experience duration? It just is what it is, and a given conscious experience can have a temporal aspect along with, say visual, aural, and emotional aspects without any of these aspects clashing or having to be mapped to another (as in the hypothesized case of the temporal aspect of the pop fly having to be mapped to the visual field, creating the comet-with-tail effect).
This construal of retention theory does not necessitate anything like a late-night comedy five second delay: each individual moment of consciousness would be experienced as quickly as it could along with a continuum of just-past moments of consciousness, and would then itself also be retained along this temporal axis in qualia-space, to be similarly subsumed by subsequent moments of consciousness. After some time, the longer-ago moments fade out completely.
According to this construal of retention theory, what we perceive as the immediate undeniable passage of time, directly perceived, that is, the time we experience whenever we see anything moving or hear just about anything at all, is, in a sense, an illusion created within the mind. Just as redness is only how we happen to paint our experiences of certain wavelengths of light, and is only arbitrarily associated with that range of wavelengths, this time-quale merely represents actual time, and is only arbitrarily associated with it. The real nature of actual time is then as imponderable as the "real" color of the photons we see as red. Let's call this position the time-quale position.
On the face of it, it seems that the retentionalist/time-quale position is much easier to swallow than the extentionalist/temporal realist position. Why make a (somewhat outlandish) metaphysical claim when you can make a merely psychological one instead? Certainly adding just one more axis to qualia-space doesn't seem much flakier than the claims I have already made about qualia and their implications for Nature, but positing objectively smeared-out presents, and direct perception of them is an entirely different matter.
Ultimately, however, while the extentionalist position implies some metaphysics that are hard to swallow, the retentionalist position is impossible. I once again appeal to direct subjective experience. The retention theory/time-quale position entails a distinction between time as perceived (the time-quale) and something else, which I will call scientific, or actual time. For a retentionalist, Time actually passes in the real world, in scientific time, and throughout time, different sensory impressions are made upon the mind and buffered there as they are experienced. These impressions are tagged with a timestamp in some way and ordered appropriately. When the buffered information is presented consciously as part of the just-past of a subsequent moment of consciousness, it is strung together and presented as one thing, imbued with the time-quale, or smeared out along the time axis in qualia-space. Each of the seemingly smeared-out moments we have ever experienced, then, has actually been perceived in an instantaneous flash, and the smeared-outness through time that we think we are perceiving is really another quale, like a new color.
This seems plausible enough at first, but it is a very fine line to hold. That which is mysterious about time, that which seems unlikely to be captured in an instantaneous percept, is not just some collection of facts about scientific time distilled from some formulas, but right there in our immediate temporal percepts. By positing a distinction between scientific time and perceived time, we were trying to let the mind have its temporally smeared-out percepts, but in a way that is metaphysically "safe"; the aspects of time that make it metaphysically inconvenient to give directly to consciousness are to be cordoned off in the realm of scientific time, while the mind plays with its instantaneous time quale, and getting its timestamped retentions in order.
But now we have to ask ourselves if we can get away with this maneuver. Can we separate our sense of duration from scientific, actual time in this way? How much of what we know about time is already built in, inextricably, to our intuitive sense of duration? When we speak of our sense of a non-zero duration being contained in a zero-length instant of "actual" time, to what extent is this the same as (nonsensically) speaking of a non-zero amount of time being contained in a zero-length amount of time? As David L. Thompson said (1990),
. . . if all our ideas are based on experience, then of course the notion of objective time, as we understand it, (and what else can we speak about?) must be based on experience. The objective notions of scientific time, and any philosophical concepts based on these, must be constituted out of our original experience of internal time.(emphasis original)
To what extent does retention/time quale theory let the fox into the henhouse? Even if there is a radical mismatch between external time and our experience of time, this may not help if the problems about time consciousness are inherent parts of the time experience. Some people say that while my red experiences are not themselves red, my experiences of time are, and must be, temporal. Are we sure? Or is it conceivable, even in the abstract, for external time to be a completely different animal than experienced time? When I consider, for example, my notion of motion, for an arc of a pop fly to be contained in its entirety in a single instant of "actual" time would mean that "actual" time would have very little in common with any conception of time that I understand. The mysterious essence of time, that which makes it inconceivable to compress into a timeless flash, may already be there in the subjective experience of time. Can everything we experience about time just be the paint we apply to sequences of timestamped retentions, the way red is the way we paint certain wavelengths of light? If so, then time presents no problems for us beyond the familiar problems with all qualia, and retention/time quale theory is plausible. If not, we are forced to the metaphysical strangeness of extentionalism.
Moreover, people who believe the version of retentionalism that holds that all perception is instantaneous (the "presentists") are failing, I think, to appreciate just how short a time 0.0000. . . seconds is. There is no action in zero seconds, no activity whatsoever; certainly no neurological activity. I claim that there is no phenomenological activity either. If you think of a 4 dimensional block universe, could there be consciousness in a perfectly "flat", durationless 3-D slice of it? If such a timeslice winked into existence for an infinitely short time and winked out again, and that were the only universe that ever existed, could there be consciousness in it? I think not, and even if you think the answer is yes, then I think the metaphysics of that "yes" are at least as problematic as the metaphysics of the extentionalist position - you are claiming a consciousness that floats completely free of any physical process. If the retentionalist claims that zero does not really mean zero, but just some pretty short time, then the genie is out of the bottle: time itself is necessary to perceive time, and you might as well call yourself an extentionalist.
As to the reluctance to bite a metaphysical bullet when we might be able to get away with biting a psychological one instead, I have already argued that we have to bite a metaphysical bullet anyway to see anything all-at-once, even a stick lying on the ground. Extending this into the realm of the temporal as well as the spatial and conceptual is not much more outrageous, and may actually clear up some of the mysteries surrounding time that have nothing to do with consciousness.
There is a lot that science does not understand about time, and consequently is silent about. Science generally treats the universe as a four-dimensional block, with the Big Bang at one temporal end. Leaving aside some wrinkles involving relativity, science speaks of points in time, just as it does points in space, and these points can be thought of as three-dimensional cross sections or slices taken out of this block universe. But nowhere in science, certainly not in physics, is there any mention whatsoever of a constantly moving privileged point or timeslice called "the present". What makes now now? Is it just a psychological trick? My point here is that the hard sciences are superb at describing the things they do describe, but there is a great deal of room in the places where they are silent for conjecture about what is really going on. Speculations about real live smeared-out presents, and different presents of different durations for different consciousnesses, do not so much contradict any scientific facts as they try to fill in some of those gaps.
If a thought or percept is temporally thick, what exactly does this mean? I have a strong intuition that my percepts exist through time, that I have direct experiential contact with something that spans a non-zero amount of time. Does this mean I see the future? Not really. That would imply that I have an experience at one point in time of something that takes place at another point in time. What I am suggesting here is that it does not really make sense to speak of any experiences at a point in time. They don't come in points.
I do not know how experiences or consciousnesses are individuated, or if there ever will be any hard and fast criteria for individuating them. But part of the point of calling my qualitative subjective experience qualitative is the claim that however an experience may or may not be individuated as you scale up, you certainly can not subdivide it by scaling down. Experiences tend to fuzz out around the edges, and it may be hard to tell exactly where their outer boundaries are, but I am certain that somewhere within those fuzzy boundaries, an experience must be what it is in its entirety, as a whole, not as a function of any "parts". I have said this before, but what I am now suggesting is that this indivisible, all-at-once whole exists as it does over time, in addition to whatever other sense in which it might exist.