There is growing awareness of the need for interdisciplinary research on complex issues, but also of the obstacles that historical boundaries between social disciplines pose to such dialogue. It is increasingly recognized that the somewhat constitutive autonomy, the progressive autonomization, and finally the "imperialism" of economics have severely reduced the possibility of interdisciplinary discussion. This paper is a first step towards developing a research program on the foundations of a non-imperialist economics. It investigates gift exchange as a missed opportunity for economics. It aims at showing that, by refusing to tackle the complexity of the gift, economics has not only lost an opportunity to develop a method suitable for the analysis of complex problems, but has voluntarily chosen not to follow a path which would have prevented it from colonizing other disciplines. Reintroducing the concept of gift into the economic discourse may thus represent a required precondition to produce an innovating discourse on economics.