February 1, 2008

Conceptual Models of Time

We speak of time and of temporally related things like events, moments, and instants in a ways that reflect different conceptualizations of time.

1. Time as a Line
First, there is the idea of the "timeline" that we encounter especially in history books. According to this model, all events are equally real and are differentiated by their dates and/or by their relative positions along a one-dimensional timeline. There is no unique present. The past consists of those events that are "earlier than" or "behind" a given "present" moment. The future consists of those events that are "later than" or "in front of" a given "present" moment.

2. Time as a Container
In theological circles it is not uncommon to encounter the question of whether God is "inside" or "outside" of time. According to this model, time is like a three-dimensional box. The container model can be blended with the linear model supposing that the contents of the box are arranged in accordance with a linear temporal metric.

3. Time as a Process
We say that time "flies", "passes", and "flows". He we conceive of time as a dynamic process of motion or change. This can be combined with the linear model by imagining something like a spotlight or pointer moving along the timeline.

4. Time as a Resource
We can "spend" it, "waste" it, "save" it, "lose" it, and so forth. On this model, time is a quantity of "stuff" that can be manipulated in various ways. This idea can be combined with the process model by quantifying the amount of "flow" or the rate of "motion". For example, I "spent" about half an hour on this post. It "cost" me that much time.

Philosophical discussions of the metaphysics of time typically pick one or more of these models of metaphors and elevate it over the others as being more accurately descriptive of the nature of time.
  • The tenseless, static, or 'B' theory of time emphasizes the linear model and rejects the process model s literally descriptive of the nature of time. Time, on this view, is just an "earlier than" ordering of events in a static block universe, kind of like the sequence of frames on a movie reel.
  • The tensed, dynamic, or 'A' theory of time emphasizes the process model and either combines it with the linear model (e.g., the "moving spotlight" and "growing block" models) or rejects the linear model altogether (e.g., "presentism"). Time, on the moving spotlight and growing block views, consists in some kind of a change taking place in the timeline. This is akin to either the actual playing of a movie reel (moving spotlight) or the addition of new footage onto an existing film (growing block). Time, on the presentist view, consists in the intrinsic dynamism of the present, which both "remembers" a past that is no more and "anticipates" a future that is not yet.
  • Proponents of divine timelessness typically take the container model very seriously. If time is like a container, then to deny divine timelessness is say that God is "in" time, which sounds objectionably like limiting God by placing him "in a box". Opponents of divine timelessness typically reject the container model. Rather than saying that God is "in" time they will say God "experiences succession", or something like that.
As far as I can see, the resource model doesn't play any role in metaphysical discussions. It is more relevant to the practical art of living and making decisions. No one thinks that time is really a kind of "stuff".