Book excerpt: Over the past decade, a small group of economists has challenged traditional wisdom about international trade. Rethinking International Trade provides a coherent account of this research program and traces the key steps in an exciting new trade theory that offers, among other possibilities, new arguments against free trade. Over the past decade a small group of economists has challenged traditional wisdom about international trade. Rethinking International Trade provides a coherent account of this research program and traces the key steps in an exciting new trade theory that offers, among other possibilities, new arguments against free trade. Krugman's introduction is a valuable guide to research that has delved anew into the causes of international trade and reopened basic questions about the international pattern of specialization, the effects of protectionism, and what constitutes an optimal trade policy. In the four sections that follow, he takes a revisionary look at the causes of international trade, and discusses growth and the role of history, technological change and trade, and strategic trade policy.