This paper explores the significance of Potts's (2000) claim that the key difference between orthodox and heterodox economics lies in the former viewing the economy as a mathematical field in which everything is connected to everything else, and the latter viewing it as a complex system in which only some elements are connected. It focuses on the types of connections in economic systems that different economists have identified and the significance of the degree of connectivity for how economic systems function. Topics explored include separable consumer networks, separable utility functions, checklist-based decision rules, lifestyles, goodwill, the nature of business strategies and evolution.