A Quaker blog, Through the Flaming Sword, quotes the following opening paragraphs from an essay by Kenneth Boulding:
The history of the application of the Quaker experience in the realm of economic life presents a curious paradox. On the one hand we do not find the apparently clear-cut “testimony” which is found in the peace testimony, where a relatively simple standard of conduct has come down almost unchanged through three centuries. It is difficult to find any simple standard of economic conduct or judgment which deserves the name “Quaker.” Quakers have been both capitalists and socialists, bankers and civil servants. Friends have, of course, maintained a testimony for the “minor virtues” - honesty, truthfulness, fulfillment of promises, thrift, hard work, punctuality, and so on - in their economic activities as well as in other aspects of daily life. Such testimonies, important as they are, do not, however, constitute a specific attitude toward economic institutions or systems. On the great question of socialism versus capitalism, for instance, the Quaker trumpet seems to speak with an uncertain sound.
This is from The Quaker Approach to Contemporary Problems, a collection of essays by Quakers on Peace and War, Education, Race Relations, Health and Healing, etc.In spite of—or perhaps even because of—this apparent weakness in the clarity of the theoretical position, the practical impact of the Society of Friends on the economic life of the world has been enormous, and quite out of proportion to the small number of Friends. Indeed, it can be argued that the greatest impact of the Society of Friends on the world has been precisely in this sphere of economic life where the theoretical contribution seems to have been small.