Which aspect is crucial for a state's existence and operational capacity?

A clearly defined population is vital for a state's existence and operational capacity because it forms the foundation of the state's identity and sovereignty. A state is typically defined by a distinct territory, a government, and a population that recognizes that government as legitimate. Without a population, there cannot be a state in the traditional sense, as states derive their legitimacy and function through the consent of the governed.

Population is essential for various reasons, such as providing human resources for governance, economic activities, and maintaining order within the territory. Additionally, the existence of a defined population allows for the establishment of social contracts, which are fundamental in creating and sustaining a political community. A shared identity among the population can also contribute to national unity and stability, which are crucial for effective governance.

In this context, while elements like military defense, global trade agreements, and international recognition are important for a state's functionality and influence in global affairs, they depend upon the existence of a cohesive and clearly defined population that supports and sustains the state itself.