During the last ten years or so, contract economics and the transaction cost approach to economic organization have been strongly critizied by a body of theory that is called "the knowledge-based approach". Writers within this approach argues that it is possible to build a theory of economic organization that makes no use of the notion of opportunism (or related concepts). This lecture discusses the knowledge-based approach, compares it to the more traditional approaches to economic organization, and argues in favor of a synthetic approach.