Constitutions are incomplete contracts. What do I mean by this? Constitutions are basic laws that provide a legal framework for the management of a given entity. Good constitutions reflect the actual distribution of power in society. In other words, they merely codify what society accepts as legitimate distribution of power and responsibilities in public affairs. Enduring constitutions are also flexible. The only constant in life is change. Power distributions or values change over time. For constitutions to endure they should be flexible with regard to secular changes. This is why constitutions are not meant to detail specific statutory requirements. They provide general frameworks. And it is because of this that they are inherently incomplete contracts.
Two key reasons lead to incompleteness of constitutions qua contracts. First, no one is inter-temporally omniscient. We do not know what tomorrow might bring. And so we cannot account for every possible eventuality in future. Therefore, we must accept that there is a reasonable chance that we may need to amend the Constitution in future to make it match contemporary realities. Second, we need flexible constitutions. Even if we knew exactly what the future held, we would still want to allow ourselves room to maneuver in the actual implementation of constitutions.