It is interesting that the optimists, List and 6arey, supported tariffs, whereas the pessimists, such as Ricardo, generally supported free trade. This difference probably flowed from their view of theory and use of assumptions. Ricardo’s theoretical comparative advantage model directed thinking toward the advantages of a policy of free trade. But the static nature of the model also led to the view that once the gains of trade had been achieved, growth would stop. List and Carey focused less on theory and more on observation and history. Direct observation of the economy suggested the importance of technology and the possibility of continued growth. It also suggested that protecting that technology by tariffs was important. Smith’s argument that trade expands technology through expanding the division of labor and learning by doing, and therefore can be beneficial for all, is a much more complicated argument to make; it follows from a dynamic view of the economy that is difficult to capture in formal models.