Final answer:
The social contract theory, associated with Thomas Hobbes and his work Leviathan, was initially considered to be inadequate for explaining state formation due to historical evidence of more complex gradual evolutions from stateless societies and chiefdoms.
Step-by-step explanation:
One early theory for the formation of the state, known as the social contract, was initially found to be inadequate because it could not fully explain the variety of ways in which states actually formed throughout history. Historical evidence indicates that the process of state formation was often more complex and could not be wholly encapsulated by a single theoretical framework. For instance, the social contract theory popularized by Thomas Hobbes in his work Leviathan implies a deliberate and consensual transfer of power to preserve order and ensure protection; however, this overlooks the gradual evolution of political systems from stateless societies and other forms of pre-state organization, such as chiefdoms, which evolved into states over time due to integrative and conflict pressures without necessarily involving explicit consent.