The gravity equation in international trade: an overview of the introduction of gravity to the study of economics and its systematic barriers

This article explores the evolution of the gravity model in international trade studies, emphasising systematic barriers to its acceptance. Employing a chronological and argumentative approach, it examines the emergence of the gravity concept, comparing Isard's original contribution with Tinbergen's econometric approach. It discusses how the heuristic nature of economics and a perceived lack of theoretical foundation initially hindered the gravity equation's use. The works of Tinbergen's contemporaries, including Linnemann and Anderson, are introduced. Lastly, recent findings in research will be reviewed, such as Krugman's New Economic Geography, which seeks to encompass Isard's intention to combine international trade with localisation theories.