Us family vacation destinations for It permits international specialization, hence greater prosperity. To insist on making everything domestically, such as producing wine in Scotland, would make no more sense than a farmer insisting on making his own shoes. A generation later, David RICARDO strengthened this argument with the principle of comparative advantage, which remains the core idea of international trade theory. BIBLIOGRAPHY. Wesley C. Mitchell, Types of Economic Theory, Volume 1 (Augustus M. Kelley, 1967); Joseph A. Us family vacation destinations 2016.