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Gordon Kennedy

Temporal Becoming and the A- and B- Theories of Time

It is interesting to note that many of Saint Augustine's concerns about time around 400AD are the same as we have today. For example, Augustine was puzzled about the nature of the distinction between the past, the present and the future. He was also concerned about the nature and status of the apparent flow of time.

In this essay we will consider a much more recent approach to time that came to the fore in the twentieth century. In 1908 James McTaggart published an article in Mind entitled 'The Unreality of Time', in which, as the title implies, he argued that there is in reality no such thing as time. Now although this claim was in itself startling, probably what was even more significant than McTaggart's arguments was his way of stating them. It was in this paper that McTaggart first drew his now standard distinction between two ways of saying when things happen. In this essay we shall outline these ways of describing events and then discuss the merits and demerits of each, and examine what has become known as the 'tensed versus tenseless' debate on temporal becoming.

One way which we speak, experience and conceive of time is that time is something that flows or passes from the future to the present and from the present to the past. When viewed in this way, events which are present have a special existential status. Whatever may be the case with regard to the reality or unreality of events in the future and the past, events that are in the present exist with a capital 'E'. It can then be postulated that it is the 'present' or 'now' that shifts to even later times. If events in time (or moments of time) are conceived in terms of past, present and future, or by means of the tenses, then they form what McTaggart called the A-series (from which the A-theory of time is derived). This type of change is commonly referred to as 'temporal becoming', and gives rise to well known perplexities concerning both what does the shifting and the type of shift involved, which we will discuss later.

On the other hand, we experience events in time as occurring in succession, one after another, and as simultaneous with other events. When viewed in this way, events stand in various different temporal relations to each other but no one event, or set of events, is singled out as having the property of being present or as occurring 'now'. Indeed, from the perspective of tenseless earlier and later relations no event is past, present or future. When events in time (or moments of time) are ordered by means of the concepts earlier, later and simultaneity, they form what McTaggart called the B-series (from which the name B-theory of time is derived).

The gist of what has become known as 'McTaggart's Paradox' is as follows. According to McTaggart time must possess the A-series, in other words be conceived of in terms of 'past', 'present' and 'future'. If this was not the case, then, according to McTaggart, time would not possess change and without change there would be no time. Also if we were to conceive of time solely in terms of the B-series, where each event in the series always bears the same relation to every other event, there would be no change. However, McTaggart asserts that the A-series concept of time is contradictory because if every event must be 'past', 'present' and 'future' then having these three characteristics is a contradiction. In response to the argument that having these characteristics is not contradictory since events possess them at different times, McTaggart says that if this was the case then these different times would form a new time series and that this series would be contradictory in the same manner as the first series, thus we are launched into a vicious regress.

Arising from these two ways of describing events there is a debate concerning the reality of tense, in other words, our division of time into past, present and future. One question that we must attempt to answer is that of whether time really is divided in this way. Another is whether this picture merely reflects our perspective on a reality in which there is no uniquely privileged moment, the present, but simply an ordered series of moments. Tensed theorists say that our ordinary picture of the world as tensed reflects the world as it really is i.e. that the passage of time is an objective fact. On the other hand, tenseless theorists would deny this. For them, the only objective temporal facts concern relations of precedence and simultaneity between events.

We can now look at some of the problems that arise if we were to hold the A-theory. These include the argument that it would seem to be absurd to assert that it is the 'present' or 'now' that shifts since the terms ' the present' and 'now' refer to a particular moment of time and to say that the present shifts to later times means that this particular moment of time, i.e. 'now', will become some other moment of time and therefore cease to be identical with itself.

Sometimes the entity that shifts is the property of 'nowness' or 'presentness'. The problem here is that every event has this property when it occurs. Thus, what must qualify some event as being now simpliciter is its having the property of 'nowness' now — and this is the start of an infinite regress that is vicious because at each stage we are left with an unexpurgated use of 'now', the very term that was to be analysed in terms of the property of 'nowness'. Further, since temporal relations between events and/or times cannot change and temporal becoming requires that events change from being future to present and from present to past then it would seem that they would have to do so in relation to some mysterious transcendent entity.

D.C. Williams in ' The Myth of Passage' poses what he considers to be two key questions to those who believe in the passage of time. The first is 'If time moves, what does time move through? If it moves through time of any sort, then there is a form of time which does not move. The second question is ' If time moves, we must be able to attach sense to the question of at what speed it moves. But speed is defined as distance covered over time. Hence the speed of time is the distance it travels in a given time. What does 'distance' mean here? If it is temporal distance, then the speed of time is the time it travels in a given time, which is absurd.

An interesting account of the B-theory perspective is given by Adolph Grunbaum, who states:

Instead of allowing for the transient division of time into past and future by the shifting 'Now' of experienced time, the theory of relativity conceives of events as simply being and sustained relations of earlier and later, but not as 'coming into being': we conscious organisms then 'come across' them by 'entering' into their absolute future, as it were. And upon experiencing their immediate effects, we regard them as 'taking place' or 'coming into being'.

The B-theorists sought to satisfy the demand from science to view the world non-perspectivally, and also evade the perplexities and mystical elements that arose from the A-theory and temporal becoming. To do this they attempted to reduce the A-series to the B-series through a linguistic reduction in which a temporal indexical proposition reporting an event as past, present or future is shown to be identical with a non-indexical proposition reporting a relation of precedence or simultaneity between it and another event or time. It appears to be generally accepted that this reduction fails. The reason being that, in general, no indexical proposition is identical with any non-indexical one due to the fact that one can have a propositional attitude toward one of them that is not had to the other. For example, I can say that it is now raining without believing that it rains (tenselessly) at t. Some A-Theorists seem to have drawn the wrong conclusion from this failure. i.e.. that there is a mysterious force out there doing 'the shift'. In reaching this conclusion they have overlooked the fact that two sentences can express different propositions and yet report one and the same event or state of affairs. e.g. 'This is water' and 'this is a collection of H2O molecules', although differing in sense, report the same state of affairs — this being water is nothing but this being a collection of H2O molecules. One thing that appears to be accepted by both A and B theorists is that translational analysis fails and therefore the criterion of translatability has to be rejected as the crucial factor in determining whether tensed or tenseless theory gives us the proper description of the nature of temporal reality.

One other approach is to attempt to hold a hybrid 'A — B' theory of time, where the ultimate metaphysical nature of time is to be understood in terms of both temporal becoming and temporal relations. One example of such a hybrid theory is that of Quentin Smith, which he postulated in the 1990's. According to Smith, the basic fallacy in arguments against the temporal properties of pastness, presentness and futurity is that they treat 'tensed' predication as either 'timeless' or 'simultaneous' predication. Thus he claims that it is never the case that an event E is (timelessly or simultaneously) past, present and future, but rather E is past, was present and was (still earlier) future, or E is present, was future and will be past or E is future and will be present and (still later) will be past. Smith maintains that the reality of temporal properties, as reflected in his analysis of the tenses, implies an infinite regress of inherences of presentness inhering in their own inherences. Smith's explanation is quoted by Nathan Oaklander in 'The Problem of Time and Change', as follows:

the first conjunct predicates presentness of the event E and each of the remaining conjuncts predicates presentness of a different inherence of presentness; the second conjunct predicates presentness of the inherence1 of presentness in E, the third conjunct predicates presentness of the inherence2 of presentness in its inherence in E, and so on.

Similarly, the correct analysis of 'E is past' and 'E is future' involves the inherence of presentness in an infinite number of inherence relations. Thus, although there is an infinite regress of inherence relations there is no contradiction in the predication of A-properties of events or predication of A-properties of inherence relations. Now, Oaklander sees this solution to McTaggart's Paradox as 'inelegant and phenomenologically false' since 'we are not acquainted with the infinite regress of inherence relations Smith's theory implies'.

From our discussion we can see that it is a contentious question whether the experience of tense — that is experiencing an event as past or present — is more fundamental than the experience of order, or vice versa, or whether indeed there is such a thing as the experience of tense at all.

Despite the formidable problems involved in explicating the way in which time passes, proponents of the temporal becoming theory or 'A-Theory' resolutely maintain that there is temporal passage and that it is ineradicable. Furthermore, they contend that tensed language is not anomalous or egocentric, but a reflection of the reality of passage. However, the A-theorist's case is certainly not helped by modern physics, wherein it is possible to describe time in terms of t1 or t2 etc., but there is no provision made for describing the 'present' or 'now'. The explanation of the 'present' or 'now' is the crux of the problem for the A-theorist since any explanation offered appears unable to define the elusive 'extra ingredient' that appears to separate the time of 'theory' from the time of 'our immediate awareness'.

The serious threat to the tenseless theorist is to explain why, if time does not pass in reality, it appears to do so. B-theorists argue that the experience of temporal passage can be discounted, contending that this pervasive and unrelenting illusion is attributable to the way in which tensed language is used, our increasing stock of memories, or the flow of information through our short term memories. Some other doubts that remain concerning the tenseless theory include first, perhaps the tensed theorist can produce a simpler explanation of our experience. Further, it may turn out that supposedly tenseless facts are dependent upon tensed ones, so that, for example, 'a' and 'b' are simultaneous by virtue of the fact that both are 'present'.


Audi, Robert (Ed.) The Cambridge Dictionary of Philosophy. Cambridge University Press.(1995). pp. 803-806.

Ibid. pp. 691-692.

Ayer, A.J. The Central Questions of Philosophy. Penguin.(1973). Chapter 1, pp. 15-21.

The Experience and Perception of Time. Stanford Encyclopedia of Philosophy.

Grunbaum, A. Philosophical Problems of Space and Time. New York: A.A. Knopf. (1963). pp. 318-319.

Lucas, J.R. Reality and Time. International Studies in the Philosophy of Science. 11, number 1, March 1997.

Lucas, J.R.A Century of Time. A contribution to the British Academy's Centennial Volume, The Arguments of time, ed. Jeremy Butterfield. Oxford.(1999).

Mellor, D.H. The Time of our Lives. Royal Institute of Philosophy.[In Press].

Mellor, D.H. & Lucas, J.R. Transcendental Tense. Aristotelian Society Supplementary Volume 72, pp. 29-43.(1998).

Mellor, D.H. & Lucas, J.R. Transcendental Tense II — J.R. Lucas. Aristotelian Society Supplementary Volume 72 (1998).

McTaggart, John Ellis. The Unreality of Time. Mind: A Quarterly Review of Psychology and Philosophy,(1908), 17, pp. 456-473.

Oaklander, L. Nathan. The Problem of Time and Change.Quidditas Essay Stoa Vol.1, No.1, Spring 1998.

Price, Huw. Time's Arrow and Archimedes' Point. Oxford.(1996). Chapter 1, pp.3-21.
Sandbothe, Mike. The Temporalization of Time. To appear in Time in Modern Intellectual Thought. ed. Patrick Baert. Amsterdam and New York, Elsevier.(1999).

Scruton, Roger. Modern Philosophy — An Introduction and Survey. Mandarin.(1994). Chapter 25. pp. 365-374.

Trisel, Brooke Alan. The Causal Attainment Theory of Temporal Passage. Sorites 10, May 1999, pp.60-73.
Westphal, Jonathan. Philosophical Propositions. Routledge.(1998). Chapter 6. pp. 72-88.

Williams, D.C. The Myth of the Passage. Journal of Philosophy. (1951). 48, pp. 457-472.