Systems have developed ways of managing conflict. For instance, a psychic system may experience conflict when incompatible desires arise at the same time–e.g., a person wants to go to the beach but knows he must go to work. The conflict can be managed in the temporal dimension by scheduling a beach trip for a later date. The past and future are observed as twin horizons, and when we postpone something until a later date we are using the future. But what happens when a child wants something right now and refuses to wait. She hasn’t yet learned how to use temporal horizons very well. As for the past, this is where things like promises and contracts come into play. If a promise is made and later broken, one party can point to the promise made in the past. In the case of a contract, the legal system makes the past quite real. Different systems treat the past and the future differently.
The chances for conflict increase when time is scarce. Extending the future horizon relieves the pressure to act or make a decision, but shrinking the horizon increases pressure.
Different systems use the time dimension differently. The economy has invented things like credit. So we can live in a house or drive a car while still paying for it. Politics has established term limits for political office and election cycles, which addresses the problem of everyone wanting to be in power at the same time. The legal system invented the contract, which only makes sense if we consider past and future. A contract is often an agreement to do something in the future, and signatures and dates on a contract make the past relevant. The education system invented twelve years of public schooling because everything can’t be learned at once. Basically when everything can’t be done at once, a system makes use of the temporal dimension.
All the temporal dimension really amounts to is the acceptance of a difference between before and after. The difference between before and after is meaningful.
Space is used very much like time. A simple way to resolve a conflict between two people is to separate them. Time and space are inseparable because it takes time for an object to move in space. This might be why Luhmann talks about the factual, social, and temporal dimensions but not a spatial dimension. A spatial dimension would be redundant.