The location of comparative advantages on the basis of fundamentals only

One of the basic issues in trade theory is the determination of the sources of comparative advantage and hence of trade between countries. The early theories stressed one aspect at a time (such as differences in technology in the Ricardian model and differences in endowments in the Heckscher-Ohlin model). They neutralized the other possible sources of relative domestic price differences in order to prove their argument in the simple way. That is what theory should do.