Hegel describes very intuitively the essential conceptual features of each of the three dimensions of time (Hegel, 1970, p. 235): how do we think of the future, how do we think of the present, and how do we think of the past? Or rather, what the most elementary logical content is that we meet in each of these three dimensions. Especially Being and non-Being have a particular meaning with respect to time, depending on the dimension of time in which they appear.
When we think of the future and the past, we think of two non-existent modes of reality. In the case of the future, we think of something that is not yet, but comes to be, and in the case of the past, we think of something that was and is no longer.
Of course, in the case of the present, we deal with something which is, in the sense that it is immediate, is around us; we can touch it, so to speak; we have sensations of it. Thus, the three dimensions of time are understood based on their relationship with the concept of being, with the way in which something is thought of as being or not being in it.
As we saw, the fact of being is not thought of in the same way in each of the three dimensions. While we deal with actual being only in the present, the non-existence or non-being specific to the past and the future are different.
We think something different concerning the conceptual couple of being and non-being in the case of the future and the past. The future is a combination of being and non-being in which the non-being is expected to transform into being, whereas the past is a combination of being and not-being in which the being is already transformed into non-being.
Let’s take an example: when I imagine that a friend will visit me tomorrow, this event has not happened yet. While I imagine and expect the event to happen, I think of something that, as a simple object of my imagination, can be considered to exist.
This imagined content is being: being projected into the future. But because it is only imagined, it has no reality yet; therefore, it is a non-existent event. However, the way we think of this non-existence has an additional feature: we think that this non-existence will transform into existence and will come to be.
With respect to the past, we have the same aspect of something existing only in my mind, and therefore, it can be said to be, but only as an ideal or mental content. But, unlike the case of the future, when we think of something belonging to the past, we think of an existence that will never return, that has completely fallen into non-existence without any possibility of coming again to be.
Let’s consider the example of my meeting with my friend again, but now thinking that the meeting has already happened. Then, when I remember the meeting, along with that remembering there is also the awareness that what I remember remains forever captive to non-existence, that that memory will never transform into reality again. Of course, I can meet my friend many times again in the future, but what my memory presents to me will never return as such.
In these explanations, we also can grasp Hegel’s view of the necessity of Notion and the relationship between philosophy and the science of nature. In order to understand what time is, you need to think of it in its relationship with being, non-being, space, and becoming as passing from one dimension of time into another. All these features are ignored by science.
Time is not simply the fourth dimension of space, as the science of nature considers it. Science can entertain such a view precisely because it ignores time as becoming, thinking of its objects as ‘points in motion,’ that is to say, as (to some extent) immutable entities devoid of any properties except those which allow mechanical explanation, i.e., spatiality and material consistency.
As a consequence, a whole universe of knowledge is overlooked by science. And not only with regard to the properties of real objects but also concerning how things can relate to each other through those neglected properties. For example, the phenomenon of becoming as a transformation of something while this something maintains its identity is necessarily ignored by the science of nature.
This is why, in Hegel, the necessity of thought or Notion involves considering all the features of real things (which the science of nature ignores) and showing how they logically relate to each other. The exposition of these logical relationships consists of showing how the more complex feature is built upon the simpler one and how, in order to understand the complex feature, we must start and use the simpler one.
Whereas in the science of nature, necessity means only the mathematical necessity displayed in the measurements of experiments, the deeper logical necessity of the investigated process is not taken into account. This logical necessity consists of – as we saw previously – the understanding of how the investigated properties presuppose the meanings of less complex properties or features of reality.
With respect to time, we can illustrate this idea through the fact that its three dimensions are intimately related to a particular understanding of how being and non-being occur in them, an understanding that you cannot change and is, therefore, necessary for your thought.
As a consequence, the approach of Hegel’s philosophy is akin to modern phenomenology: it is mainly a description of the meanings of our concepts. However, this philosophy assumes that all concepts of our knowledge are connected to each other, and the philosopher could thus derive a chain of concepts that grow from each other. In other words, he can show how the meaning of one concept contains the meaning of another less complex concept and adds to it a new feature or determination.
This activity has a systematic character in that the conceptual chain is thought of as consisting of concepts that cannot miss each other: that in order to understand one concept, you must understand the whole previous conceptual chain or the whole system of those concepts.
This is the meaning of a system, namely the idea of a totality of components that are ordered in a specific way (the structure of the system) and in which no component can be removed without necessarily destroying the systematic whole.
Hegel’s Philosophy of Nature, edited and translated by M. J. Petry, vol. I, London, George Allen, 1970.