Spencer believed that change occurs according to the Law of Evolution, which dictates a progression from simplicity to homogeneity to uniformity to more complexity to heterogeneity to variety. At any stage, all of the parts that are changing are also part of one whole. Spencer cited as evidence examples from the physical, biological, psychological, and social sciences. Society itself evolves from primitive homogenous forms to complex advanced ones, he pointed out, whereby component parts have different functions.

Because Spencer thought that change follows its own internal rules, he believed that social progress cannot be the result of external actions, such as social welfare or the regulation of trade. In education, he believed that children should be taught skills that would best enable them to compete with others. Spencer’s views were taken up by Social Darwinists, who advocated the principles of the “survival of the fittest” for society, against social reform generally, and in favor of capitalistic competition, specifically.