In the nineteenth century, the foundations were laid for psychology and sociology to develop as distinct fields separate from philosophy. The reasons for their separation are differences in subject matter as well as methodology. Concerning the latter, Wilhelm Dilthey (1833–1911) put the case of his age best in claiming that human sciences such as history, psychology, philology, and philosophy were characterized by a need to understand, whereas the physical sciences sought causes.

However, in the twentieth century, quantitative methodology and experiments in search of causes were to characterize important parts of both psychology and sociology. Quantification and causal explanation were also to characterize economics, which did not become distinctly independent from political philosophy, sociology, and philosophy until the twentieth century. But in the nineteenth century, the establishment of psychology and sociology as separate from epistemology, ethics, and political philosophy, as well as revolutionary critique, was a major achievement.