Economic interdependence is a consequence of specialization, or the division of labor, and is almost universal. The participants in an economic system are dependent on others for the products they cannot produce efficiently for themselves. This physical interdependence implies corresponding linkages in the demands for products and the incomes of the participants. Economic interdependence was described as early as 1838, when A. A. Cournot wrote:

"...but in reality the economic system is a whole for which the parts are connected and react on each other. An increase in the incomes of the producers of commodity A will affect the demand for commodities B, C, etc., and the incomes of their producers, and, by its reaction will change the demand for commodity A."