Time is defined as the observation of reality based on the difference between past and future. Each system only ever exists in the present and simultaneously (synchronically) with its own environment. In this sense, past is not a starting point and future is not a goal, but rather both cases concern horizons of possibilities [→Meaning].
Meaning-constituting systems construct reality as the difference between actuality and potentiality. This difference can be temporalized through the doubling of the distinction. On the potentiality side, we can continue to distinguish between past and future. The present is always secured by the fact that the system reproduces itself autopoietically [→Autopoiesis]: the temporal orientation leads to the distinction between actuality of self-reproduction and what is not actual, i.e. it is not contemporary to the system. In this way, a paradoxical situation is created, in which what is contemporary and what is not contemporary appear at the same time. The paradox is unfolded through particular temporal differences, such as, for instance, the difference between past and future.
For each observer [→Operation/Observation], time exists because each distinction has two sides and that, in order to change from one side to the other, operations, and therefore time, are required. Thus, a difference emerges between the observer herself, who is always actual, and the difference between before and after, which is generated by the event that enabled the transition from one side to the other side of the distinction. The difference between synchronicity on one side, and the difference before/after on the other side, is time.
In the present, non-actual temporal horizons of the past and future are formed. This present moves through time, and with it the horizons move, too: in each moment, past and future are projected anew and there can be no move into the future or return to the past. As horizons, past and future are not quantities constituted from events, but rather selective performances of the system (of the observer). Not everything that happens is relevant to construct the past. This construction also depends on the system and cannot correspond with what “really” happened. The same goes for the future, because the projection of future possibility depends solely on the system.
The construction of the temporal dimension is based on the possibility to observe change and duration at the same time. Meaning-constituting systems can only observe events and changes in situations when they can hold something constant that serves as a background. Conversely, everything that remains constant only appears to do so against the background of events.
The present can be described in two mutually conditioning ways [→Meaning Dimensions]. First, the present is punctual and transforms the future into the past by moving: time passes irreversibly and inevitably. Under the second aspect, the present is observable as the duration that abstracts from the passing of events. The present makes it possible to remember past situations or to anticipate future situations. According to these two temporal points of view, meaning-constituting systems differentiate →structures and →processes, which in their interplay keep meaning accessible to social and psychic operations.
Since they are imaginary, the horizons of the past and the future are structurally determined constructions, which have no correspondences in the environment of the observing system [→System/Environment]: the system and its environment exist only in the present and only synchronically. However, the projection of temporal horizons means that the system can observe changes through constants in terminology without having to change itself. The system time is not in synch with what happens in its environment, because that would imply the dissolution of the system boundaries.
This complex construction of the temporal dimension reveals different characteristics depending on the societal structures: it corresponds to the type of primary societal differentiation [→Differentiation of Society]. Tradition sees time as movement, a concept that describes the unity of the difference between before and after. The temporal horizons of pre-modern societies refer to the distinction between time and eternity. Eternity indicates the divine position from which all times are given simultaneously: eternity guarantees that everything happens according to God’s will.
This is different from the finite time of creation, which has a beginning and an end whose meaning can only be interpreted in relation to eternity. In the functionally differentiated society, movement is replaced by the idea of the present: the primary temporal horizons become the completed past and the uncertain, open and contingent future into which the system can project numerous possible presents.
Selections are guided by the fact that the past is only a premise of the future: it is “capitalized” as the history of already completed selections that can be recombined depending on future perspectives.
This modern conception of time has had consequences for the historical description of society. History is produced whenever the events relevant to society are observed on the basis of the distinction before/after: from antiquity until at least the seventeenth century, the difference before/after was considered as a unity against the background of the temporal horizon itself, and was reflected by distinguishing between passing time and divine eternity. In the modern era, from the eighteenth century onwards, history is grasped as self- referential—it must be continually written anew depending on the historical moment in which the historians find themselves. Also history is, in other words, something historical: history re-appears in history through a →re-entry. Writing history today means recombining data depending on the chosen theoretical approach. Now, the need for data no longer depends on the sources that can be discovered and taken into account, but rather from the theoretical approach itself. From a sociological perspective, it is therefore not so much the coherence of the events to be described historically that is interesting, but rather the consistency of the theoretical approach that the theory of society can deliver.
**The distinction and connection between the past and the future is managed in the present by memory, which detects in the past the distinctions providing the frame in which the future can oscillate.**
Memory has the function of testing the consistency of system operations against its construction of reality, which it accomplishes through the double function of remembering and forgetting. Remembering recognizes repetitions as something already known, overcoming the need to learn the same thing over and over again. Forgetting prevents the system from blocking itself, and frees up processing capacity.
The forms of memory change with the evolution of society. In ancient societies memory was related to objects and rituals, while writing made it more mobile. Modern society, which is so complex that it has to remember and forget much more, has moved from forms oriented to identity (Gleichheit) to forms oriented to comparison (Vergleichbarkeit), realized as culture. The different functional systems have their own special memories, which are coordinated by the →mass media, but which cannot be integrated. The mass media operate as the overall memory of society, providing a reference reality that can be taken for granted. **Everyone knows that the second reality without obligation of consensus that is built by the mass media is also known to everyone else, no matter what they think, and at the same time is constantly renewed (forgotten).** [G.C.]
Social Systems (1995: Ch. 1.III, 5.III); Geheimnis, Zeit und Ewigkeit (1989); Gleichzeitigkeit und Synchronisation (1989); Theory of Society (2012: Ch. 3.13); The Re- ality of the Mass Media (2000: Ch. 11).