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Granting Time Its Passage

Andrew W. Lamb
University of Notre Dame

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ABSTRACT: Many philosophers who support a four-dimensionalist metaphysics of things also conceive of experience as a state of a mind having temporal extension or existing as a momentary feature of the dimension of time. This essay shows that such a strict four-dimensionalism — suggested in works by D. M. Armstrong, Mark Heller, and David Lewis — cannot be correct, since it cannot allow for the passing of time that is essential to awareness. The argument demonstrates that the positing of any temporal process at all must compromise the strict four-dimensionalist view of the temporality of experience. This is not to say that the traditional endurantist view is left wholeheartedly endorsed. As I point out, this traditional view makes several questionable claims of its own that must be carefully scrutinized. Still, the criticism of the strict four-dimensionalist ontology indicates a direction to be followed in developing a successful metaphysics of experience.

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This essay presents a critique of what I call strict four-dimensionalism, a metaphysical view supported by David Armstrong, Mark Heller, and David Lewis.(1) Strict four-dimensionalism includes "things experiential" in the group of things that are temporal only insofar as they either have temporal extension or exist at some point upon the axis of time. I argue that experience cannot exist in this way. Its temporality must be of a different order. For experience must involve the passing of time,(2) and this is something that strict four-dimensionalism must exclude. This does not, however, disprove that ontology in toto. It does not venture beyond the theme of experience's temporal nature. What is at stake here is simply the securing of experience's temporality from a misleading metaphysical interpretation. The issue is simply the metaphysics of the seemingly non-thing-like entity of temporal experience.

Four-dimensionalism maintains that, strictly speaking, physical objects existing for more than an instant so exist only by being extended along the axis of time, just as common objects existing at more than one point in space exist in this way only by being extended along the three spatial axes.(3) As Lewis puts it: "Enduring things are timelike streaks" laid out across the fourth dimension, "wholes composed of temporal parts, or stages, located at various times and places" (Lewis 1976, 145). For a thing that lasts from one time to another, say from t1 to t2, it is thus not the case that the same thing once existing entirely at t1 exists later entirely at t2. According to four-dimensionalism, the only way for an object to "persist" from t1 to t2 is for it to have a temporal length extending from t1 to t2, so that it fills the available "temporal space." For such an object, what exists entirely at t1 and what exists entirely at t2 are simply two of its distinct, instantaneous temporal parts (cf. Heller, 5).(4) Strictly speaking no object endures through time according to four-dimensionalism, which is why some four-dimensionalists employ the following terminological distinction: objects with more than a momentary existence do not so exist by enduring through time, as traditionally thought; instead, they perdure through the dimension of time (Lewis 1986, 203).

Human beings like all psychological beings of the cosmos are not left out of this temporal scheme. And strict four-dimensionalism remains consistent in not making an exception of things experiential. For strict four-dimensionalism, experience itself is something stretched out across the dimension of time. This view is often arrived at by thinking of experiences as states of perduring minds states that must perdure with the minds that have them. This seems to be the case for Armstrong, Heller, and Lewis, all of whom go so far as to situate the human mind and its experiences in the perduring domain governed by a causal physics.(5)

How does this metaphysical view account for experience? Most strict four-dimensionalists would agree that no instantaneous mind could itself have what I will call a full experience an awareness, for example, in which some recognition of an object could occur.(6) Such experience takes more than an instant; recognition takes some time, and at least straightforwardly conceived, that is something that no "instant-mind" affords. Most strict four-dimensionalists account for this experience by holding that the momentary experiences of certain instant-minds lie within the temporal boundaries of a temporally extended experience, which is coextensive with the temporally extended mind whose state it is. It is this experiential expanse that provides the length of time needed for full awareness.

But while this appeal to the temporally extended mind might seem to overcome the inadequacy of the instant-mind, it does not of itself provide a sufficient metaphysical basis for full experience. More must be said specifically, how does this temporally positive length of experience support such awareness with its durational character, something evident in our everyday conscious life? Where in this account is there such experience? How does it take place? These questions are harder to answer than one might think. Does the length of experience occur bit by bit? How would that happen? Would the temporally extended mind experience each bit in sequence, so that it is at first mostly in the future in relation to the moment of its experience, but moment by moment becoming more and more past in relation to that moment? If this seems wrongheaded,(7) should we return to the instant-mind and wed one such mind alone to each momentary bit, with full experience emerging from the length within which such limit-minds lie? But would this latter solution (more characteristic of the strict four-dimensionalist camp) not return us to the problem with the instant-mind? If we linked experience and mind point-for-point, like train tracks, with every point of the temporally extended mind having only its momentary experiential state, what mind would there be to experience a duration with its passing of time? More importantly, where would there be any such passing? Is an axial length sufficient to grant time its passing?

Before trying to judge strict four-dimensionalism's ability to answer such questions, it will be helpful to set out carefully the basic features of any full awareness. This will make clearer what is at stake. Concerning our experience, one thing has often been noticed: it is never purely of what now exists. Rather, it everywhere involves some temporal context, which gives the present experience its meaning. For example, we react with frustration in encountering a traffic jam, with initially nothing "in mind" other than the immediate, lived-through feeling of frustration and the need to get by. What is involved in such an experience? Perhaps upon reflection we bring to mind that we need to get to a meeting. But in the initial experience of the traffic jam, this was not in mind: we were not recalling the past or thinking of where we were going, but simply feeling stuck. But though an explicit recognition of the temporal context was lacking, the very sense of the experience included a directedness toward something futural as already "binding" upon us. Even the explicit awareness subsequently brought about by reflection no doubt had its inexplicit context (I might have thought, "I have a pressing appointment," while leaving "understood" that this appointment is with my boss; further, that he is my boss in a context of work; and so on). Full experience is always the experience of a situated present, connected with an ultimately inexplicit temporal context that supports that present's identifiable meaning.(8) Secondly, we experience the traffic jam's duration: it continues to block our way as a bicyclist rides on by. This brings into view aspects of the phenomenon of experience other than its contextual character (these elements being separated only abstractively). Our experience bears witness to an availability of the passing of time as such within the domain of experience. It also manifests the successful disclosure in experience of time's passing as passing. Though usually unnoticed, these elements are always part and parcel of our full experience, as when we simply watch the bicyclist passing by. Some process of moments is clearly available to the experiential domain and our awareness is successfully disclosing that process. This description illuminates three features that I take to be essential to any full awareness: (1) a temporally contextualized experiential present, (2) the availability of a passing duration to the domain of experience, (3) the ongoing disclosing of that passing as such (which is not the explicit noticing of it). Can strict four-dimensionalism account for these features?

The first feature is already the subject of debate. Roderick Chisholm argues that strict four-dimensionalism cannot account for temporally contextualized awareness. He thinks that every instantaneous part of a temporally extended mind has no contact with the experiential context surrounding its now, such that a contextualized awareness of its present experience might have some raison d'Ítre.(9) Following Heller's response to Chisholm (Heller, 23), however, it seems that strict four-dimensionalism can appeal to causality to insure that the instant-mind has in its present not simply an impression of a now-content but an "experience" (not yet "full") that brings to bear a temporal context. Causal connections between instant-minds might insure that each instant-mind is "made" so as "to see," in its own small way, its present in terms of the temporal context lying beyond. Causality might thus provide a raison d'Ítre for instant-minds that support a coherent length of experience that is everywhere contextually savvy (cf. also Armstrong 1980, 151-154; Lewis 1976, 148).

But more is needed for a full experience, and it is with the second requirement of such experience that insurmountable problems begin to arise for strict four-dimensionalism. In our experience we have more than contextualized moments. We are involved in a passing duration that supports the ongoing aspect of awareness. It is by such an involvement in a passing of time that we can identify things like a soaring hawk or a persisting monotone pitch. No experience without such an involvement in time's passing is imaginable. This involvement is itself two-fold: it essentially implies (a) the existence of time's passing and (b) the availability of that passing as such to the mental or experiential domain (which supports the third feature of full experience the bringing-to-awareness of that passing).

When it comes to this essential two-fold feature, strict four-dimensionalism must fail. (a) For strict four-dimensionalism, the whole temporal cosmos including minds, experiences, and their causal connections is laid out along a static dimension of time. The fourth dimension is like the ground of an extended but entirely fixed landscape. This leads to the following difficulty: insofar as there is nothing "advancing through" the fourth dimension with the opposing "falling past" that this implies, strict four-dimensionalism provides no temporal passing at all. There is no time passing that might be available to the experiential domain.

But could not some such passing be posited as a brute fact? Some strict four-dimensionalists posit not only causal connections between instant-minds but an actual causal movement of an "experiential now" that "activates" one instant-mind after the other (cf. Heller, 23). This is supposed to account for the temporal "movement" of experience. Such a movement would certainly provide an existing temporal passing. But several problems emerge for this idea, given a strict four-dimensionalist ontology. First, allowing such a movement would require admitting something truly enduring through time namely, the present point of the movement itself. Movement is passage, of something through or past another, even where neither of these is really a thing. There can be just the progress of a movement itself like waves, which, although not things, still pass through both time and space. For a movement through time to occur, whatever that movement may be, it itself must pass time, and this implies its enduring through it.(10) Any movement through time compromises strict four-dimensionalism at its roots. But without some such movement (2(a)), there could be no temporal passing available to anything experiential (2(b)) the very thing needed for (3) an ongoing temporal awareness. Here alone is sufficient cause to overturn strict four-dimensionalism, since this shows that it cannot support several elements necessary for any full experience.

(b) The second problem with postulating a temporal passing as a brute fact brings up the other facet of an involvement in time's passing. For the problem here is that the postulation of the moving "experiential now" must make that movement as such available to the mental domain if there is to be anything able to support (3) an experience of time's passing. But this view's ontology of "things mental" states in perduring minds provides nothing in this domain able to bear the presence of time's passing as such. For time as passing to be present to something mental would require that something mental suffer that passing as passing, allow the passing to be available as such by bearing its happening. But this would be to endure time.

But why should any one "thing" have to undergo that passing? Could not this passing involve a series of mental entities, so that there is a passing but with nothing lasting through its passing? This, however, would leave the passing as such unavailable to anything mental. Different entities might each have their moment of that passing, but the passing as passing would be nowhere "received" in a sense because it would be everywhere "received," but exhausted bit by bit. For there to occur anywhere a "reception" of time's passing as passing requires that somewhere its process be "received." But receiving a process takes more than a moment of time. It, again, implies endurance.

But is not the whole process "received" by the extended mind that it traverses? Not as a process unless that mind lasts its passing as a passing. This mind would have to be at one time in one state then later in a different state with regard to that movement for the latter even to exist for that mind as a movement. This would be to encounter a temporal passing as such, but this would also be to last through a sequence of moments in turn and so to endure time.

Strict four-dimensionalism cannot accommodate any time passing or anything in the mental domain to which that passing can be available as such. But both are needed for the third element of experience the bringing of that passing to awareness. Again, since it cannot account for several features essential to full experience, strict four-dimensionalism must fail.

The very nature of experience calls for something more like traditional endurantism when it comes to experience. As ordinarily formulated, this view keeps pace with strict four-dimensionalism when it comes to our awareness of a temporal context, by positing a mind capable of such. It also promises to succeed where strict four-dimensionalism fails, by allowing for a passing of time and the availability of that passing as such to something mental by positing a temporal movement relative to a persisting mind's experiential present.

It might be thought, however, that this view must ultimately suffer a fate like that of strict four-dimensionalism. Does not the traditional endurantist see time as a stream encountered by the mind bit by bit, with the mind at no moment existing but at an infinitesimal moment of that stream? Endurantism seems caught in a paradox like that of Zeno's arrow and no better able to account for an awareness of time's passing. For such passing could never be given in any moment at which the enduring mind would exist. While the enduring mind might be involved in a passing of time, it might seem no more able than the strict four-dimensionalist mind to be aware of this as a passing.

It is important to note that this problem is not the problem that was raised against strict four-dimensionalism. That problem had to do with the lack of any temporal passing at all and with a lack of its availability as such to the mental domain (these shortcomings clearly making impossible an account of our awareness of time's passing). Certainly, though, if there is a problem here for endurantism, there is also one for strict four-dimensionalism at least if both views are formulated to provide a series of moments through which, in sequence (enduringly or perduringly), consciousness has its time.

But to say that the conscious mind endures through a temporal process that has moments at its infinitesimal limits and so to say that there is in this way an existence of that mind at the moment is not to say that the conscious mind ever simply exists at a moment. That would be an impossibility. The conscious mind, to be conscious, must have an ongoing experience that takes some duration. The conscious mind can exist only as existing. It is thus wrong to think of this mind simply at the limit and then to try to find out where it would experience time's passing there. The conscious mind is never simply there. It is there-in-the-process-of-an-ongoing- experiential-existence. Similar to Aristotle's response to Zeno, the response to the objection here is the conscious mind is to be conceived first as in process, with its moments being truly abstract limits at the infinitesimal depths of this process, which is not to say that these moments are unreal but that they are unthinkable and non-existent in isolation. The ontological foundation of consciousness is not the pure infinitesimal but an ongoing involvement in time and an ongoing bringing of time's passing to awareness.(11) To see this response as begging the question, escaping Zeno only by claiming what should be explained on Zeno's grounds, is in reality to make an unwarranted counter-assumption that values the infinitesimal as the ontologically basic. It is to remain blind to the possibility of another ontological basis one that is in fact demanded by the phenomenon of consciousness that we, continually, have.

Endurantism may be more plausible than strict four-dimensionalism in accounting for experience. But is traditional endurantism satisfactory? Should the enduring of time's passing be thought in traditional fashion in terms of a thing-like mind that passes through a stream-like time? Or does the phenomenon of temporal experience call for less spatial thinking? Would an endurantism without a thing-like mind, without a stream-like time, provide a better ontology of the process of experience? While much still needs examination, hopefully some progress has been achieved here in disclosing a way for further inquiry.

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(1) Those of their works referenced in this essay are as follows: Armstrong, "The Nature of the Mind," in The Mind/Brain Identity Theory, ed. C. V. Borst (London: Macmillan, 1970), pp. 67-79; Armstrong, "Identity Through Time," in Time and Cause: Essays Presented to Richard Taylor, ed. Peter van Inwagen (D. Reidel, 1980), pp. 67-78; Heller, The Ontology of Physical Objects: Four-Dimensional Hunks of Matter (New York: Cambridge UP, 1990); Lewis, "The Paradoxes of Time Travel," American Philosophical Quarterly 13 (1976): 145-152; Lewis, "Survival and Identity," in Philosophical Papers (New York: Oxford UP, 1983), pp. 55-77; Lewis, On the Plurality of Worlds (New York: Basil Blackwell, 1986).

(2) I recognize that the notions referred to by such phrases as "passing time" and "enduring through time," like the endurantist notion of a "mind" as a thing that persists and has experiences, are problematic and call for analysis. But for the sake of brevity I will need to make immediate use of such terms to present my critique of strict four-dimensionalism. A more thorough analysis of the phenomenon of temporal experience would be required to help clarify the proper sense of these terms. Still, they can be used without such an analysis at least to begin uncovering the problems at issue. (Endurantism as I see it need not conceive of experience in terms of a thing-like mind that persists through a fourth-dimensional, axial "stream." It might also conceive of it in terms of a persisting taking awareness, a "mental living." But how endurantism should be finally developed is something that this essay cannot hope adequately to address.)

(3) With whatever curves and warps that may undermine the straightness and continuity of these four axes.

(4) As Heller makes clear, to say that there are momentary parts of temporal objects is not to say that objects with temporal length have their length through a summation of these parts (a summation which would seem to yield no length at all). For Heller, the momentary parts are "no more ontologically fundamental" than the temporally extended object, which thus does not depend upon "being built up out of instantaneous objects" (Heller, 6). In a sense, the temporally extended object is to be thought of as "already there" with each instantaneous part simply being what might be found at the edge of a slice that exposes an infinitesimal limit.

(5) For Armstrong and Lewis, the human mind ultimately boils down to the central nervous system, such that every mental state is identical with some neurological or neurochemical state (cf. Lewis1, 99-101, and Armstrong 1970, 75). It should be noted that neither Lewis nor Armstrong identify the mind, generally speaking, with the brain or central nervous system, since the minds of other beings might need to be identified with systems of other kinds. According to Lewis and Armstrong, the mind generally is simply whatever causes behaviors of certain kinds. It is thus possible, given their definition of "mind," to identify a mind -- even the human mind -- with some spiritual substance (if that be what causes certain kinds of physical behavior) or with some combination of physical and spiritual "stuffs" (cf. Lewis1, 102-103). Still, both philosophers think that the central nervous system is what causes such behavior for human beings. (For a summary of Lewis's reasoning, see Lewis1, 106; for Armstrong's reasoning, see Armstrong 1970, 68-69.) Heller seems to have some identification of mind with brain in mind in his discussion of consciousness (cf. Heller, 24-25).

(6) I think that as far as the essential features of this experience go, it could even be "subconscious." But this need not be an issue for the purposes of this essay.

(7) Not only would this mind's awareness be hard to account for, as will be hinted at later any such sequential experience ultimately posits another dimension of time in which it experiences bit by bit what lies along its length.

(8) Edmund Husserl accounts for this direct, present experience of what lies beyond the now by conceiving of the mind as "constituting" its present through "retention," which holds, in the present, just-past contents as just past, and "protention," which anticipates in the present just-future contents. Neither retention nor protention gives us any impression; impression only gives us contact with what exists as now, what is actual (24 & 35). The unique, non-impressional presentation of retention and protention allows us to have an immediate awareness of our present temporal context by presenting to us what is clearly not now (cf. 16 & 40-41). (References are to On the Phenomenology of the Consciousness of Internal Time [1893-1917], trans. John Barnett Brough [Dordrecht, Neth.: Kluwer Academic, 1991]. Page numbers refer to the pages of Husserliana X, which are given in the margins of the aforementioned translation.) In this essay, I leave unaddressed whether we have an awareness of past and future in the present, or whether it would be better to say that the sense of our present awareness implies a past and a future. In order to leave these issues "open," I limit myself to speaking of some "connection" with a temporal context that gives the present its meaning (however that "connection" may be conceived).

(9) Chisholm, "Problems of Identity," in Identity and Individuation, ed. Milton K. Munitz (New York: Cambridge UP, 1990), pp. 10-15.

(10) And if what is moving is the now of experience, it is no great leap to see this in terms of some enduring present of mental life.

(11) This idea is similar to Heller's conception of temporally extended objects as having their length as what is ontologically primary to them, rather than having instantaneous parts as the most fundamental building blocks out of which all else must have its temporal being (see note above). In the present endurantist case, however, what is at stake is a sort of process and not simply an axial length.

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