The Unreality of Time
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The Unreality of Time is an important paper on the philosophy of time written in 1908 by John McTaggart Ellis McTaggart. The paper was published in Mind: A Quarterly Review of Psychology and Philosophy 17 (1908): 456-473.
McTaggart's objective in this paper was to show that change can be understood in terms of events moving from the future to the present to the past and then to try to demonstrate that this change was not a property of events themselves, nor a relation between events; and that the time series in which this temporal change appeared to occur does not exist. He then declared that time was not a real thing in the physical world.
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[edit] The A, B and C series
McTaggart proposed that time could be described by three series, the A series, the B series and the C series. He defined these as follows:
The A Series: "..the series of positions running from the far past through the near past to the present, and then from the present to the near future and the far future.." McTaggart further declared that "the distinctions of past, present and future are essential to time and that, if the distinctions are never true of reality, then no reality is in time." He considered the A series to be 'temporal', a true time series because it embodies these distinctions and embodies change.
The B series: "The series of positions which runs from earlier to later.." The B series is temporal in that it embodies direction of change. However, McTaggart argues that the B series on its own does not embody change.
The C Series: "..this other series -- let us call it the C series -- is not temporal, for it involves no change, but only an order. Events have an order. They are, let us say, in the order M, N, O, P. And they are therefore not in the order M, O, N, P, or O, N, M, P, or in any other possible order. But that they have this order no more implies that there is any change than the order of the letters of the alphabet…" According to McTaggart the C series is not temporal because it is fixed forever.
[edit] The general structure of the argument
McTaggarts argument for the unreality of time has two parts. The first part argue for the reduction of the B-series (and the C-series) to the A-series. Basically time demands change, and both the B- and C-series do not involve change, therefore time must be described using the A-series.
The second part argue for the conclusion that the A-series is incoherent or contradictory. Events are contradictory because they exemplify all the A-properties of being future, present and past.
If both parts are true, there can be no reality of time.
[edit] The idea of change
McTaggart has defined two fixed series (the B and C series) and one series that is continuously created (the A series). This is pivotal to his argument about the way things change. In the B and C series things have fixed positions and fixed extents so they cannot change. They are defined as static from the outset.
Of events in the B Series McTaggart says: "no event can cease to be, or begin to be, itself, since it never ceases to have a place as itself in the B series. Thus one event cannot change into another." and "as the B series indicate permanent relations, no moment could ever cease to be, nor could it become another moment."
Given that the C series is, like the B series, a set of events cast in the same sequence forever it is also unchanging, he says of events in the C series: ".. that they have this order no more implies that there is any change than the order of the letters of the alphabet…"
McTaggart argues that what we consider to be 'change' is actually the inclusion of an event in the A series:
"But in one respect it does change. It began by being a future event. It became every moment an event in the nearer future. At last it was present. Then it became past, and will always remain so, though every moment it becomes further and further past."
He then asks whether such a change can really occur.
[edit] The nature of change
McTaggart asks if the change that occurs to an event in the A Series is a 'quality' of the event or a 'relation' between events. He considers that there is one relation that deserves consideration:
"a past event changes only in one respect -- that every moment it is further from the present than it was before"
In other words the relative position of an event in the A Series might be considered as an indication of change. McTaggart then uses this apparently obvious relation to show that the A Series itself cannot exist.
The basic argument against the A Series notes that if events change by a relation where they get further from the present in the A Series then one term of the relation would be in the C Series and the other term would be at the present moment of the A Series. This means that: "The relations which form the A series then must be relations of events and moments to something not itself in the time-series."
This concept then leads to other arguments against the A Series. In the first of these it is pointed out that the terms future, past and present are incompatible yet each event has all three of these relations. McTaggart notes that this might be avoided by describing an event as has been future, is present and will be past. But he considers that this involves a "vicious circle" because it assumes time to explain time (ie: assumes another A Series in the future or past).
In the second argument, related to the first, it is pointed out that if each event has been future, is present, and will be past, then when we are considering one A Series, there is yet another A Series where an event is present in the future and so on ad infinitum. McTaggart calls this a 'vicious infinite series' and considers that this shows that the A Series is untenable.
He concludes these arguments by stating that "Our ground for rejecting time, it may be said, is that time cannot be explained without assuming time".
[edit] Dismissal of any relativity of time
McTaggart considers the possibility that time is related to individual observers but he does not include any discussion of relativity and assumes that there is only one time, true for all observers: "The present through which events really pass, therefore, cannot be determined as simultaneous with the specious present. It must have a duration fixed as an ultimate fact." This viewpoint is now known to contradict special relativity theory.
[edit] Influence of "The Unreality of Time"
McTaggart's work has led to many productive areas in the philosophy of time. He laid the foundations for both the tensed and tenseless theories of time and, even though he dismisses a relativistic approach he notes how it would affect his analysis.
