Why is Herbert Spencer famous in the history of sociology and philosophy?

Herbert Spencer was a prominent English philosopher and sociologist known for his influential synthesis of knowledge and his early advocacy of the theory of evolution. He is most famous for developing the doctrine of social Darwinism, which applied evolutionary principles—including natural selection—to human societies, social classes, and individuals. He also coined the term "survival of the fittest".12

In philosophy, Spencer sought to create a scientific "summa" through his Synthetic Philosophy, aiming to replace theological systems with a unified understanding of development across cosmic, biological, and social realms.13

In sociology, he viewed society as an evolving organism, distinguishing between primitive "military" societies based on force and advanced "industrial" societies based on voluntary cooperation. A staunch advocate for individualism, Spencer argued that society exists for the benefit of its members, not the reverse. While his opposition to state intervention and social welfare was later criticized for its disregard for the realities of poverty, his ideas regarding limited government and individual rights have been revisited by modern libertarians.4