Economic theory has been widely criticized since the beginnings of economic science in the eighteenth century due to the confusion between self-interest and selfishness. Israel Kirzner presents arguments that both support and oppose economics. He concludes that many of those that oppose economic theory confuse self-interest, meaning the freedom to do what one wants, and selfishness, meaning an exclusive concern with oneself. Kirzner compares the ideas put forth by Lionel Robbins, which hold that economics depends on the search for efficiency, and Ludwig von Mises, who develops the idea of rationality of purposefulness. He also describes the Austrian view of the market process, misunderstandings within microeconomics, and the importance of economic understanding.