Page 109, Quentin Smith, 1985, Philosophical Studies, 47, pp. 109-119.

 

QUENTIN SMITH

 

THE MIND-INDEPENDENCE OF TEMPORAL BECOMING

 

(Received 24 February, 1984)

 

Temporal becoming can be thought to consist in the occurring now of for­merly future events, and the subsequent belonging to the past of these events.[1] One of the central issues in 20th century philosophy of time is whether temporal becoming is a mind-dependent feature that events acquire or seem to acquire by virtue of being apprehended, or whether it is a mind-­independent feature that inheres in events irrespectively of their relation to a conscious organism. Philosophers like Russell, Smart, Weyl, Goodman, Quine, Williams and Grünbaum have argued for the mind-dependency of becoming, and Broad, Reichenbach, Whitrow, Prior, Lucas, Gale, Schlesinger and others have defended its mind-independency. In the present essay, I shall defend its mind-independency by responding to what is perhaps the most sustained attack yet developed against the thesis of mind-independency, that developed by Grünbaum in Chapter I of his Modern Science and Zeno s Paradoxes (versions of this chapter have also appeared under the titles 'The status of temporal becoming',[2] 'The meaning of time',[3] and 'The exclusion of becoming from the physical world'[4]). Since Richard Gale has previously responded to some of Grünbaum's arguments,[5] I shall cover new ground by responding to other of Grünbaum's arguments and by developing novel responses to the arguments Gale has criticized.

Section I examines Grünbaum's definition of the present, and Sections II to IV respond to Grünbaum's three main arguments.                                                      

 

 

I

 

Grünbaum sets forth his characterization of nowness or presentness as follows:

 

If a physical event occurs now (at present, in the present), what attribute or relation of its occurrence can warrantedly be held to qualify it as such? Speaking generically, what over and above its otherwise tenseless occurrence at a certain clock time t, in fact at a time t characterizes a physical event as now or as belonging to the present? It will be remembered from the Introduction why my construal of this question does not call for

 

 

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an analysis of the commonsense meaning of 'now' or of 'belonging to the present' but for a critical assessment of the status which commonsense attributes to the present. Given this construal of the question, my reply to it is: What qualifies a physical event at a time t as belonging to the present or as now is not some physical attribute of the event or some relation it sustains to other purely physical events; instead what so quali­fies the event is that at least one human or other mind-possessing organism M experiences the event at the time t such that at t, M is conceptually aware of the following complex fact: that his having the experience of the event coincides temporally with an awareness of the fact that he has it at all.[6]

 

In a later statement of his theory, Grünbaum characterizes presentness differently:

 

What qualifies a physical event at a time t as belonging to the present or as now is not some physical attribute of the event or some relation it sustains to other purely physical events; instead what is necessary so to qualify the event is that at the time t at least one human or other mind-possessing organism M experiences the event at the time t such that at t. M is conceptually aware of experiencing at that time either the event itself or another event simultaneous with it in M's reference frame.[7]

 

The first step in evaluating these passages is to determine the standpoint from which Grünbaum is offering this "critical assessment of the status which commonsense attributes to the present". Grünbaum begins the sentence in which this phrase occurs by referring the reader to the introduction to the chapter; the relevant passage in the introductory section reads:

 

Clearly, an account of becoming which provides answers to these questions is not an analysis of what the commonsense man actually means when he says that a physical event belongs to the present, past, or future; instead, such an account sets forth how these ascriptions ought to be construed within the framework of a theory which would supplant the scientifically untutored view of commonsense.[8]

 

Grünbaum seems to mean that the standpoint from which he is assessing the status commonsense attributes to the present is that of science or of a philo­sophical theory based on the sciences. He indicates some of the relevant scientific facts that must be taken into account in this critical appraisal:

 

That the commonsense view is indeed scientifically untutored is evident from the fact that at a time t, both of the following physical events qualify as occurring 'now' or 'belonging to the present' according to that view: (1) a stellar explosion that occurred several million years before time t but which is first seen on earth at time t, and (2) a lightning flash originating only a fraction of a second before t and observed at time t. If it be objected that present-day commonsense beliefs have begun to allow for the finitude of the speed of light, then I reply that they err at least to the extent of asso­ciating absolute simultaneity with the now.[9]

 

It should be pointed out that these scientific facts do not entail or even lend

 

 

 

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support to Grünbaum's analysis of the present in terms of a conceptualized awareness of one's own experiences. These facts can be interpreted in a way that is perfectly consistent with the view that the present is an intrinsic and mind-independent feature of physical events. The data about the finitude of the speed of light can be taken as suggesting that commonsense ascriptions of presentness to physical events are often in error about when these events are present. The commonsense person mistakenly ascribes the time at which the visual effects of stellar events are present to these events themselves. The relevant scientific facts dictate that these ascriptions ought to be subject to the following revisions, (1) the presentness ascribed by commonsense to the stellar events should be taken as a presentness of their visual effects, and (2) the presentness of the stelIar events should be calculated in accordance with the formula: the time at which the visual effects are present minus the distance in light-years to the stelIar events. If I am now experiencing visually a stelIar event 10 light-years away, it can be inferred that the stelIar event was present 10 years ago.

If commonsense is mistaken about associating 'absolute simultaneity with the now', the relevant revision need not be that the now be regarded as mind­-dependent, but that commonsense ascriptions of nowness to a physical event E be construed relativistically, so that 'E is now' means 'E is now in this reference frame'. If the simultaneity of two events is relative to. a reference frame and yet mind-independent, as Grünbaum believes. then there is no reason to doubt that the now cannot be also.

Grünbaum himself implies to some extent that this revision be made in the passage I quoted above (on page 110), in which he talks of the now in terms of a "reference frame". But it is not necessary to suppose that the further revisions Grünbaum offers are required by the Special Theory of Relativity this theory does not entail that physical events lack nowness even in a relativistic sense or lend support to the view that nowness is a conceptualized awareness of one's own experiences.[10]

Perhaps, however, it is not the facts about the finitude of the speed of light or the relativity of simultaneity upon which Grünbaum is resting his case, but a more general claim that physical sciences as a whole do not take into account nowness in their explanations. It is this claim that constitutes one of Grünbaum's three main arguments against the thesis that becoming is mind-independent. If we regard Grünbaum's "critical assessment" of the

 

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status which commonsense attributes to the present in this light, then we can allow that this assessment depends for its validity upon the validity of this more general argument, which I shall now examine.

 

II

 

Griinbaum writes:

 

It seems to me of decisive significance that no cognizance is taken of nowness (in the sense associated with becoming) in any of the extant theories of physics. If nowness were a fundamental property of physical events themselves, then it would be very strange indeed that it could go unrecognized in all extant physical theories without detriment to their explanatory success. And I hold with Reichenbach that "If there is Becoming (independently of awareness) the physicist must know it".[11]

 

Richard Gale offers this reconstruction of Griinbaum's argument, where "A­determinations" stands for determinations of presentness, pastness and futurity:

 

(1)   A-determinations are not taken cognizance of by physics.

(2)   Any non-mind-dependent property is taken cognizance of by physics. Therefore,

(3)   A-determinations are not non-mind-dependent properties.[12]

 

Gale says of premiss (2):

 

Why must any objective, non-mind-dependent property be taken cognizance of by physics? That it must be certainly is not advanced as an empirical claim, but if it is an analytic claim on what conceptual truth does it rest? I can think of none. Premiss (2) could be challenged by the following counter-example: A-determinations are objective properties, and yet they are not taken cognizance of by physics (in the above sense). To rule out this counter-example without any further justification is to beg the very point at issue.[13]

 

I agree with Gale that premiss (2) is not analytic, but I think it can be more charitably interpreted as an empirical claim, so that it along with premiss (1) renders probable rather than entails (3). Moreover, I think Grünbaum can be defended against Gale's accusation of begging the issue by replying that Gale no less begs the issue- A-determinations cannot count as a counter-example to premiss (2) unless it is independently proven rather than assumed that they are objective properties not taken cognizance of by physics.

I shall now argue (assuming that premiss (2) is an empirical claim) that premiss (1) is false since pastness, presentness and futurity are taken cog­

 

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nizance of by the physical sciences. It is instructive that Griinbaum does not attempt to defend his claim that physical sciences do without such notions by an extensive study or review of physical theories, for I think any relatively exhaustive study would reveal that these notions do play a decisive role. This is true not only on the pragmatic level of science (which concerns the disco­very and verification of laws), but also on the semantic level (which pertains to the formulation of laws and theories).[14] I will exemplify this fact by a consideration of a few concepts in current cosmological theories.

One of the basic concepts in cosmological theory is of the present value of the Hubble age, the time elapsed between the beginning of the universe and now. An oft-cited discussion of the Hubble age can be found in R. H. Dicke's 'Dirac's Cosmology and Mach's Principle',[15] the article usually heralded as the one introducing the anthropic principle into contemporary cosmological literature. Dicke explains "the present value of T"[16] (T being the Hubble age) by deducing it from" the biological requirements to be met during the epoch of man". Since humans require the heavy elements formed in stars, as well as planets orbiting stars, humans cannot exist except at a time after (1) the cessation of the first shortest-lived stars (which spew forth heavy elements upon their demise), and before (2) the cessation of all stars (which warm planets). Since humans are existing now, the value of the Hubble age now must be somewhere between (1) and (2). As nowness 'shifts' to later and later events, the "present value of the Hubble age" changes.

The concept of the present value of the Hubble age is not an isolated in­stance in current cosmological theory; this theory is based on the Big Bang cosmological model which is an evolutionary model and as such entails that past and future states of the universe have different parameters than the pre­sent state that is currently accessible to observation. This is why cosmological issues are frequently defined in reference to the present state of the universe; given the present day parameters X₁, ..., X_n, what must be the past or future parameters X₁ , ..., x_n? For example John Ellis and Keith Olive write:

 

The list of cosmological problems to be investigated has often included the homogeneity, isotropy, flatness and age of the present-day Universe. Why is the Universe now so homogeneous and isotropic on scales which have only recently entered our horizon and were previously held incommunicado by conventional big-bang cosmology? Why is our Universe nearly flat, having an energy density within 1 or 2 orders of magnitude of the critical closure density, despite having lived to the old age of 0(10⁶¹) Planck times? Why is the present-day vacuum energy density so small?[17] The distinction between present and past states of

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the universe is crucial to Dennis Sciama's theory of the density of the uni­verse:

 

... in its present state the universe is far too dilute to be able to thermalize radiation in the time available (10¹⁰ years). Since it is difficult to see how the radiation could have been produced already thermalized, we conclude that at sometime in the past the universe must have been sufficiently dense to thermaIize radiation in the time-scale then prevailing. According to the standard cosmological models this would require a universal density of at least 10^-14 gm cm^-3 (that is about 10¹⁵ times larger than the present mean density).[18]

 

Here, too, the idea that a past state of the universe has a different parameter than the present state of the universe is a part of Big Bang cosmological theory, so that the expressions' present' and 'past' are being used on a semantic level rather than pragmatic level.

A few more relevant examples can be gleaned from these quotes:

 

i)        P. A. M. Dirac: "... the present velocity of recession is 10^-3..."[19]

ii)      I. D. Novikov: "Observations primarily of the microwave back­ground radiation show that the Universe expands isotropically with a high degree of accuracy at the present time and that the matter distribution is homogeneous on a large scale... This is valid for at least some period of time in the past too."[20]

iii)    Piet Hut and Martin Rees: "... the persistence of our present vacuum for 10¹⁰ yr implies that a spontaneous transition via tunnelling is unlikely..."[21]

iv)    S. W. Hawking and G. F. R. Ellis: "... theorem 2 does not tell us whether the singularity will be in our past or in the future... We shall therefore give an argument based on theorem 3 which indi­cates that the universe contains a singularity in our past...,,[22]

v)      R. Brout, F. Englert and E. Gunzig: "... straightforward extra­polation of the present cosmological situation to the distant past, according to the laws of general relativity, leads to an initial singularity."[23]

 

Grünbaum might respond to the foregoing by claiming that the quoted re­ferences to the present ought to be construed in accordance with his defini­tion of the present as a conceptualized awareness of the person's own ex­periences. But why ought they? Because the physical sciences do not take into account presentness as an objective property of physical states, and therefore all references to the present ought to be construed in a mind­-

 

 

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dependent way? But that is manifestly a circular argument: it assumes what it needs to prove.

Moreover, these references to the present cannot be construed in Grünbaum's way without seriously altering the explanations of which they are a part. For example, "the present value of the Hubble age" cannot mean 'the value of the Hubble age at a time when I - the physicist - am conceptually aware of the fact that my awareness of the universe temporally coincides with my awareness of the fact that I am aware of the universe'. Such an analysis would restrict by definition the present value of the Hubble age to times at which there are mind-possessing organisms who are aware of the universe. And this means that it is logically impossible for the present value of the Hubble age to be any value. But that is inconsistent with the cosmological definition of the Hubble age. The classic view which Dicke is criticizing is that "the present value of T [the Hubble age, is] considered conceptually a ran­dom choice from a wide range of possible values of T'.[24] Now if the present value is restricted by definition to times at which there are mind-possessing organisms, it cannot be considered as a random choice from a wide range of possible values; rather it is necessarily restricted to values consistent with the existence of mind-possessing organisms.

Dicke's own criticism of this view is not that the present value by defini­tion is a value consistent with the existence of mind-possessing organisms, but that this value in fact (a contingent empirical fact) is consistent with their existence. Since it is an empirical fact that (1) we are alive at present and that (2) we require certain stellar life-spans in order to live, it follows that (3) the present value of the Hubble age is limited by the values of the stellar life­times. Dicke is clearly implying that the present value of the Hubble age could have been different, but that in fact it is not since we happen to be alive at present.

 

 

III

 

A second argument Grünbaum offers in support of the thesis that presentness cannot be a mind-independent property of physical events concerns the putative triviality of assertions of presentness:

 

What of the retort... that independently of being perceived, physical events themselves possess an unanalyzable property of presentness (i.e. nowness) over and above merely occurring at certain clock times? I find this retort wholly unavailing for several reasons:

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(1) It must construe the assertion 'It is 3 P.M., E.S.T., now' as claiming non-trivially that when the clock strikes 3 P.M. on the day in question. this clock event and all the events simultaneous with it intrinsically have the unanalyzable property of nowness or presentness. But I am totally at a loss to see that anything non-trivial can possibly be asserted by the claim that at 3 P.M. nowness (presentness) inheres in the events of 3 P.M. For all I am able to discern here is that the events of 3 P.M. are indeed those of 3 P.M. on the day in question![25]

 

In this passage Grünbaum misrepresents the import of 'It is 3 P.M. now'. This sentence is not uttered in order to communicate the assertion that when the clock strikes 3 P.M. this striking and all the events simultaneous with this striking are present. Indeed, so construed, the statement is trivial, for if presentness, pastness and futurity are intrinsic properties of physical events, then it is analytically or trivially true that physical events are present when they occur. It is a contradiction for example to assert that at the time when the clock was striking 3 this striking was not yet present or no longer present. However, 'It is 3 P.M. now' is not used to express this triviality, but to communicate the assertion that (I) 'The clock's striking 3 and all events simultaneous with this striking are present'. I shall now show that (I) differs from (2) 'The clock's striking 3 and all events simultaneous with this striking are present at 3', and from (3) 'The clock's striking 3 and all events simul­taneous with this striking occur at 3'. In order to prove that presentness is distinct from occurring at a clock time t, it suffices to show that (I) is not equivalent to (3).

Any statement that can be false is non-trivial. (I) is non-trivial, for it is false if asserted at 4 P.M. or at any time other than 3.

However, (2) and (3) cannot be false; they are mere tautologies (assuming that the clock is set to the correct time). (2) and (3) are true if asserted at 3 P.M. or at 4 P.M. Consequently, (I) must convey some information not conveyed by (2) and (3). Note particularly that since (I) differs from (3) primarily through the introduction of the predicate 'present', this predicate must convey some information lacking in (3). 'The clock's striking 3 and all events simultaneous with this striking are present' must say something more than 'The clock's striking 3 and all events simultaneous with this striking occur at 3'.           ­

Let us highlight some further differences between (I) and (3). (I) provides information relevant to practical action not provided by (2). (I) indicates that the events at 3 P.M. cannot be prevented from occurring, for events can be prevented from occurring only if they are not yet present. Since (3) gives