Over time, history and sociology have developed into two distinct academic disciplines. Historical data is used, and has been used, mainly in these three ways: examining a theory through parallel investigation, applying and contrasting events or policies (such as
Verstehen), and considering causality from a macro perspective.
John Stuart Mill's method: a) principle of difference: a case with effect and cause present is contrasted with a case with effect and cause absent; and b) principle of agreement: cases with the same effects are compared in terms of their (ideally identical) causes. There is an important debate about the usefulness of Mill's method for sociological research, given that historical research often relies on only a few cases and that many sociological theories are probabilistic rather than deterministic. Today, historical sociology is measured by a conjunction of questions that are rich in detail. == Themes ==