Why did Herbert Spencer believe societies became more complex over time?

Herbert Spencer believed that societies became more complex over time as part of a broader process of social evolution. He argued that human societies evolve from undifferentiated, primitive "hordes" into complex civilizations primarily through an increasing division of labour.1

Spencer viewed this development through the lens of social Darwinism, applying biological principles of evolution to social structures. He drew detailed analogies between biological organisms and human societies, suggesting that both require specialized systems for regulation, sustenance, and distribution to function and survive.231

In his framework, this evolution represents a movement toward greater "individuation," where society transitions from military-based systems—characterized by forced cooperation and despotism—to industrial societies, where cooperation is voluntary and spontaneous. Spencer believed this increasing complexity was a natural, adaptive process, leading toward a state of higher social development.14