Philosophy of time
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The philosophy of time is a topic of philosophy that includes aspects of both epistemology and metaphysics.
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Persistence through time
Two fundamental questions asked by philosophers of time are
- what is the nature of time? and
- how do things persist across time?
For each of these questions there are two predominant answers.
What is the nature of time? Presentism and Eternalism
According to presentism, time is an ordering of various realities. At a certain time some things exist and others do not. This is the only reality we can deal with and we cannot for example say that Homer exists because at the present time he does not. An Eternalist on the other hand holds that time is a dimension of reality, on a par with the three spacial dimensions and hence that all things, past present and future can be said to be just as real as things in the present are. According to this theory then Homer really does exist, though we must still use special language when talking about somebody who exists at a distant time, just as we would use special language when talking about something a long way away (the very words near, far, above, below, over there and such are directly comparable to phrases such as in the past, a minute ago and so on).
How do things persist across time? endurantism and perdurantism
The positions on the persistence of objects are somewhat similar. An endurantist holds that for an object to persist through time is for it to exist completely at different times (each instance of existence we can regard as somehow separate from previouse and future instances, though still numerically identical with them). A perduranist on the other hand holds that for a thing to exist through time is for it to exist as a continuous reality, and that when we consider the thing as a whole we must consider an aggregate of all it's instances of existing. Endurantism is seen as the conventional view and flows out of our innate ideas (when I talk to somebody I think I am talking to that person as a complete object, and not just a part of a cross temporal being), perduranists have attacked this position. (An example of a perduranist is David Lewis). One argument perdurantists use to state the superiority of their view is that perdurantism is able to take account of change in objects.
The relations between these two questions mean that on the whole presentists are also endurantists and eternalists are perdurantists and vice versa, however this is not necessary and it is possible to claim, for instance, that time's passage indicates a series of ordered realities, but that objects within these realities somehow exist outside of the reality as a whole, even though the realities as wholes are not related. However such positions are hard to defend and rarely adopted.
Other questions
The philosophy of time also includes questions such as:
- Why do we observe time to flow at all?
- Why does time flow in a particular direction?
Another issue of debate is whether time is an ontological entity itself, or simply a conceptual framework we need to think (and talk) about the world. Another way to frame this is to ask, "Can time itself be measured, or is time part of the measurement system?" The same debate applies also to space, and an important formulation in both areas was given by Immanuel Kant.
Kant, in the Critique of Pure Reason, described time as an a priori notion that allows us (together with other a priori notions such as space) to comprehend sense experience. With Kant, neither space nor time are conceived as substances, but rather both are elements of a systematic framework we use to structure our experience. Spatial measurements are used to quantify how far apart objects are, and temporal measurements are used to quantify how far apart events occur.
External Links
- *The Impossibility of Temporal Relations Between Non-Identical Times: New Arguments for Presentism*. (http://www.abstractatom.com/new_arguments_for_presentism.htm) Published in Disputatio: International Journal of Philosophy, Vol. 1, No. 18, May 2005, pp. 91-125. Journal article available online about the philosophy of presentism, where only the present moment exists.