An examination of the Ricardian model of comparative advantage yields the clear result that trade is (potentially) beneficial for each of the two trading partners since it allows for an expanded consumption choice for each

However, for the world as a whole the expansion of production of one product must involve a decrease in the availability of the other, so that it is not clear that trade is better for the world as a whole as compared to an initial situation of non-trade (but efficient production in each country). Are there in fact gains from trade for the world as a whole? Explain.

If we were to combine the production possibility frontiers of the two countries to create a single world production possibility frontier, then it is true that any change in production points (from autarky to specialization with trade) would involve a tradeoff of one good for another from the world's perspective. In other words, the new solution cannot possibly involve the production of more of both goods. However, since we know that each country is better off at the new solution, it must be true that the original points were not on the trade contract curve between the two countries, and it was in fact possible to make some people better off without making others worse off, so that the new solution does indeed represent a welfare improvement from the world's perspective.