These essays explore what happens when a skilful ecomist makes unconventional assumptions. Ecomic theory has traditionally relied upon a tacit and 'classical' set of assumptions that have gradually acquired a life of their own in defining how ecomists write and how they justify ecomic models. Similarly, these assumptions have acquired an automous character: they guide the way ecomists think about the world. In consequence, consideration of alternative assumptions has become taboo. These essays are substantively and stylistically vel because they break these taboos and bring new assumptions into ecomic theory. The papers apply this adventurous approach to a wide range of issues - from insurance markets and trade in underdeveloped countries to unemployment and discrimination. Some of the essays derive the implications for ecomic markets of costly asymmetric information. Others explore the findings of other social sciences such as anthropology, psychology, and sociology.