While historically the discipline explored broad questions in political science through between-country comparisons, contemporary comparative political science primarily uses subnational comparisons. The name comparative politics refers to the discipline's historical association with the comparative method, described in detail below. Arend Lijphart argues that comparative politics does not have a substantive focus in itself, but rather a methodological one: it focuses on "the how but does not specify the what of the analysis." Peter Mair and Richard Rose advance a slightly different definition, arguing that comparative politics is defined by a combination of a substantive focus on the study of countries' political systems and a method of identifying and explaining similarities and differences between these countries using common concepts. Sometimes, especially in the United States, the term "comparative politics" is used to refer to "the politics of foreign countries." This usage of the term is disputed.
Methodology
While the name of the subfield suggests one methodological approach, political scientists in comparative politics use the same diversity of social scientific methods as scientists elsewhere in the field, including experiments, comparative historical analysis, case studies, survey methodology, ethnography, and others. Researchers choose a methodological approach in comparative politics driven by two concerns: ontological orientation and the type of question or phenomenon of interest.
Most Similar Systems Design/Mill's Method of Difference: This method consists in comparing very similar cases which only differ in the dependent variable, on the assumption that this would make it easier to find those independent variables which explain the presence/absence of the dependent variable.
Most Different Systems Design/Mill's Method of Similarity: This method consists in comparing very different cases, all of which however have in common the same dependent variable, so that any other circumstance which is present in all the cases can be regarded as the independent variable.
Substantive areas of research in comparative politics
By some definitions, comparative politics can be traced back to Greek philosophy, as Plato's Republic and Aristotle's The Politics. As a modern sub-discipline, comparative politics is constituted by research across a range of substantive areas including, but not limited to the study of:
While many researchers, research regimes, and research institutions are identified according to the above categories or foci, it is not uncommon to claim geographic or country specialization as the differentiating category.
