Herbert Spencer, a prominent 19th-century philosopher and sociologist, approached the study of society through the lens of evolutionary theory. He believed societies, like biological organisms, evolve from simple to complex forms through a process of differentiation and integration. Spencer applied concepts like natural selection and survival of the fittest to social phenomena, arguing that societies adapt and progress over time. His work, though controversial, significantly influenced the development of sociological thought and sparked debates about the nature of social change.