What does the Heckscher-Ohlin theorem postulate? Which forces do Heckscher and Ohlin identify as the basic determinant of comparative advantage and trade? In what way does the Heckscher Ohlin theory represent an extension of the standard trade model presented in the textbook? What does the Heckscher-Ohlin theorem postulate? Which forces do Heckscher and Ohlin identify as the basic determinant of comparative advantage and trade? In what way does the Heckscher Ohlin theory represent an extension of the standard trade model presented in the textbook?