AbstractTaking as a starting point the book by Grundmann, Micklitz and Renner, New Private Law Theory, the author briefly examines the methods practised today in the most important legal systems for studying private law. There is no unanimous consensus on the definition of “private law”, nor on its functions. The formalistic method prevails, using terms, concepts, dogmas stratified over time, with an apparently technical content. In reality, as the three authors demonstrate, and as has been preached in Italy for more than half a century, law is a social science and its function can only be fully understood by combining the formalistic method with economic, sociological and political analysis and considering its historical development.