In the following, we are reading alongside Aristotle in his Physics: Book IV, Chapter 10.
Aristotle begins his approach to time by reviewing the things currently said on the subject. He then shows, through argument, why each of the things said prove to be unclear.
The contemporary opinions on what time is leave us in a state of confusion. This is precisely where Aristotle wants us to be. His approach is a process of catharsis. In order to proceed to a clear account of what time is, it is necessary that the confusions we have about it are first brought to a place of aporia.
To take us to this place of confusion, Aristotle begins with the following argument:
That time either has no being at all, or is only scarcely and faintly, one might suspect from this: part of it has happened and is not, while the other part is going to be but is not yet, and it is out of these that the infinite, or any given, time is composed. But it would seem impossible for a thing composed of non-beings to have any share in being.1
Aristotle is pointing to the fact that the past was but no longer exists and the future will be but does not yet exist. Then, since time seems to be a compositeof past and future, neither of its parts seem to exist.
At this point, however, we want to insist that time is composed of the present in addition to past and future. Aristotle sees this assertion as problematic.
Admitting the the now exists, if we assume it to be a part of time, it would seem to be the only part of time that exists. It is also infinitely small. The now, by itself, does not do justice to what we include when we speak of time. Also thenow is infinitely small and we cannot put our finger on it. The now is confusing, and the past and future seem to not exist.
People contemporary to Aristotle say that time is the motion of the whole in a circular pattern, but Aristotle rejects this. This is because we can take from this “circular whole” a certain portion of time. The section under our consideration is not in itself circular (that is, it does not work its way back to the beginning of the segment). Even though it might ultimately be part of a circuit, it seems that we are able to consider this segment of time as time without reference to the whole. This puts us in a state of epistemic aporia, because we have no way of accessing time as a circular whole. Rather, we only have access to time in segments.
People also say that time is the orbit of the celestial sphere. Aristotle rejects this because, if there were more than one heavenly sphere, the motion of eachwould be time. This would mean that there would be two separate times, each relative to a specific heavenly sphere. But we would not conceive these as being separate time, as it seems that we can correctly say that the motions of each heavenly sphere can coincide (that is, we can abstract a time in which both motions exist). Each sphere cannot be a separate time because this would mean there would be many times at the same time, which would be absurd.
It is as if we said that time is the setting and rising of the sun. But why is it not the orbit of the moon? If time is defined in such a way, we could take both to be time. But, of course, they cannot both be separate times; rather, they share a certain temporal relationship.
While we can measure time by either days or months, these celestial orbits are not what time is. Rather, they are what we measure time by. Time is something separate from what measures it.
Some people claim that time is change or motion. Aristotle rejects this on the grounds that, if time is change, change is only in the changing thing itself, or in the place where the thing changing occurs. This does not explain how time seems to be universal among changing things. That is, my kettle can boil at the same time as I finish making breakfast. These changes do occur at the same time, but are separate changes. Then, time cannot be change, although it is certainly related to it.
Also, change can be faster or slower. Time, however, can be neither faster or slower. Slow and fast, in fact, are defined in terms of time, which means that if change were time, time would be defined by means of itself (which is absurd).
While we can speak of changes as occurring at a certain time, these changes are not what time is. Rather, they are what is measured in terms of time.
This concludes Aristotle’s treatment of the opinions of his contemporaries on the subject of time.
3 I apologize for the shortage of footnotes; I will add more footnotes citing the relevant passages and line numbers (for each of the arguments) to my formulations in a later revision.
Chapters 11-14 of Book V of the Physics are on their way; as well as a review of the writings of Leibniz, Newton, Kant, Hegel, Einstein, Heidegger, (and others) on time. I also imagine that I will look at the mythology and poetry on the subject of time in Homer, Hesiod, Gilgamesh, (and the likes) at some point.