Abstract:Is the study of international law an art or a science? Can the role of international law be explained by general rules, with predictive value? Or does it require the exercise of judgment, in order to account for the richness and complexity of international life? Traditionally, international lawyers have gravitated to the latter view, analyzing issues in an essentially ad hoc and eclectic manner. In their controversial new book, The Limits of International Law, Jack Goldsmith and Eric Posner argue forcefully for a more scientific approach, relying on the methodology known as rational choice theory. The article examine the book's ambition to develop an overarching theory of international law, which reduces the role played by international law to a few simple explanatory models. In the end, Limits makes a convincing case that rational choice theory can help us better understand the development and effectiveness of international law. But the book provides no compelling reason why noninstrumental factors might not also play a role. It presents a flattened picture of the world, drained of texture and nuance and color. It illustrates that, to understand international law, we need not only science, but also art.