It can clarify and make more secure the analytical judgements which political economists – and more narrowly based economists, and other social scientists including historians—make. It can do so by establishing criteria independent of a particular context. Those significant analytical judgements, which are routinely made, are many, and they are familiar. They lie at the very heart of the everyday practice of political economists and economists. Comparison, then, in the workaday practice of economists and other social scientists, can, suitably pursued, prevent analytical closure by keeping one alive to the diversity and historical contingency insisted upon by Ben Fine. The former is desirable for all social scientists. The latter is a distinct branch of enquiry of its own, with discernible methodological principles. The comparative principle enunciated by these authors is as valid for any of the social sciences as it is for economics or history.