Original sentence: "  Two simple ways to understand the benefits of free trade are through David Ricardo's theory of comparative advantage and by analyzing the impact of a tariff or import quota
Edited sentence: " Two simple ways to understand the alleged benefits of free trade are through David Ricardo's theory of comparative advantage and by analyzing the impact of a tariff or import quota.However, critics point out that like astrology and feng shui, economics is not a science at all.Therefore, they ask whether people should take the opinions of economists seriously