I am writing a paper about fair division. When we divide, say, a piece of land among us, the division may be fair in the time of division, but may seem unfair at a later time, for example, if oil is found in one of the land-plots.
I am looking for a single word (a noun) that emphasizes the fact that a division is fair only in a specific point in time. Using Google translate, I found "momentariness", "instantaneity", "temporariness", but, I don't which of these words, if any, fits the context.
An example paragraph: "Our third assumption is _____________. This means that, when we check the fairness of a certain division procedure, we only check that the division is fair at the time it is made. We do not require that it remains fair forever."