Time is a major bugbear for metaphysics. In this essay I will attempt to show what sense we can make of time using the methodology of tetralemmic polarity, and its outcome: mumorphism. [Note: if these terms are new to you, see the Tetralemmic Polarity essay.]
Time may be thought of in various ways. There are the famous A-series and B-series of McTaggart (the A-series being the concept of the present dividing the future from the past, with the future becoming the present and the present becoming the past, the B-series being the ordering of events into 'before' and 'after'). A variation of the B-series, with the complication that before and after may depend on the observer, is the classical physicist's model of time as a fourth dimension, with events being located on a real line as zero-dimensional points. This conflicts with psychological time, which seems to be a flow. All of these present muddles of one sort or another, leading McTaggart, for example, to declare time to be unreal. Which has also been said by many a mystic. And so, the first horn of the tetralemma ("time is real") must be rejected, not so much that it is shown to be untrue, but that one cannot make sense of it being true.
But to call time "unreal" is contradictory, in that it takes time to say "time is unreal". Hence one must reject the second horn of the tetralemma.
In order to consider the third and fourth horns, we need to consider what it means to say "time is real (or unreal)". To say that the third horn says "time is real and unreal" is just a contradiction. But if we rephrase "time is unreal" as "reality is timeless", then the third horn becomes "reality is temporal and timeless" (and the fourth horn "reality is neither temporal nor timeless"). The third horn as stated must be rejected as it implies a temporal realm existing side-by-side with a timeless realm, but that doesn't resolve any of the metaphysical problems described at the outset for the temporal realm. As with mumorphism, the way forward will be to bring in awareness. For one could simply note that to be aware of time passing requires timelessness. What follows is an elaboration of this remark.
Let us consider time as the defining feature of awareness of change, distinguishing awareness of change from awareness of static forms. Given that there is awareness of change, the Parmenidean option of regarding change as unreal must be rejected. For even if there are no changing substantial things, the mind that is aware of change is changing. While the changes apparently going on in the world that is seen may be illusory, the illusion itself is undergoing change. And so we have a data point: minds undergo change.
But for there to be awareness of a change, there must be a continuity in the mind to be aware of the before state and the after state of the change as a whole. Hence the (traditionally understood) Heraclitean option that there is only change must be rejected. And so we have an additional data point, that there is in the mind that which does not change, at least for the duration of a change.
Now comes the tricky part. It seems that the mind, when it is aware of a change, is divisible into an unchanging part that observes a change, and a part that is the observed change. This, however, is impossible, since to observe a change is to be changed, which is to say that postulating an unchanging part just regresses the problem. The entire mind is changing, yet it is staying the same through the observed change. Thus we have the apparently contradictory fact that when there is awareness of change, the mind stays the same as it does not stay the same. And yet there is no alternative. The mind works -- that is, observes -- by staying the same as it changes. Thus, we reject the third horn by replacing "there is time and timelessness" with "time is not other than timelessness, timelessness is not other than time".
To complete the tetralemmic refutation, we need only note that appealing to some state or whatever that is neither changing nor unchanging does not help. It would be simply irrelevant to our experience. We cannot reduce "changing and not changing" to something else, since both the changing and the not changing are essential to being aware of change.
Thus awareness of change can only be thought through as a tetralemmic polarity. Is it mumorphic? Yes, in that that which is unchanging is formless, and hence non-objectifiable, while change is (dynamic) form. But, as mentioned in the tetralemmic polarity essay, there is a curious aspect to it, which we can note best in considering the awareness of change that occurs when we think. It is that the unchanging pole of the mumorphism is that which drives change (produces new thoughts), while the changing part resists change (it takes effort to get past old thoughts). This, as I see it, further drives home the point of the identity of the poles, that is, further refuting the third horn.
What we have, then, is that the present "moment" is the mumorphic identity of change and that which does not change. I put "moment" in scare quotes, since it is an ambiguous term in this context. Is a "moment" a point, or is it extended? In this case, that is, in considering awareness of change, it must be extended. If it were a point (as in the physicist's model of time) then there is no way for there to be awareness through a change. Yet whenever we see a fly buzz by, we are perceiving change through some period of time -- we can even specify that the "present moment" lasts somewhere around a quarter of a second to a second or two. (Note: The phrase "present moments" may have undesirable connotations, as it suggests discrete events, while the experiential reality is that of a continual flow. A simile I find helpful is that it is like the contact that a tire on a moving car makes with the road. It is, first of all, extended: an area, not a point. But it is also continually being added to on one end as the other end drops off. Thus, one can't truly speak of one present moment following another as if one stops and another begins.}
Unfortunately, this does not settle everything, as we have only considered time within the present moment. What of the past and future?
Per idealism, there is no feature of the universe outside of experience, so the question becomes: does it make sense to speak of time outside of my experience of it? That is, is there a real past, and maybe a real future? What I think of as "past" is partly my memories, but also what I have heard of memories of others, and my experiences of historical records that I assume exist only because others had the experiences recorded in them. So the past is a cognitive construct. But, to quote the sage Albus Dumbledore: "Of course it is all in your head, Harry, but why on earth should that mean that it is not real?" For an idealist, there are only cognitive constructs. (What is to us pre-cognitive or apparently non-cognitive just means we are seeing the end-product of a thinking process without having experienced the thinking of it.) And so, I would define the past as a set of ideas that order my memories of present moments, and to the extent that these ideas are shared by others, they constitute history. Within these ideas of the past are many regularities, which can be extrapolated in one direction to provide ideas of pre-history, and in the other to provide ideas of what we call the future. These latter shape our present moments in that they can include expectations -- hearing two notes of a familiar melody includes the expectation of the next note, or learning that war has started includes the expectation of consequences of war.
To summarize, the perplexities of time come about through confusing time as experienced in the present moment with time as extrapolated from the cognitive constructs that develop from the experiences of the present moment. As I see it, these should be given separate names, perhaps experiential time and constructed time. Experiential time is real, in that awareness is real, and awareness is mumorphic -- the tetralemmic polarity of time and timelessness. Constructed time is real in that all mental constructions are real. But this does imply that constructed time is malleable. If all our present moments were to somehow include different memories, and reading different texts, history would be different. That is, constructed time is not absolute, rather it is fully dependent on the contents of our present moments. But it is real, in that it conditions our present moments to include expectations in our present moments.
[Note: the last paragraph of this essay has been amended -- previously I had different terms for what I am now calling experiential and constructed times.]