Revising Knowledge: A Hierarchical Approach

小行星9309515 在过去的二十年里，经济学家在理解经济中不确定性和不完全信息的作用方面取得了巨大的进步。 宏观经济学、劳动经济学和产业组织学等不同的应用领域越来越多地关注一些经济参与者相对于其他参与者所拥有的上级信息。 这一进展之所以成为可能，是因为存在一个标准的、人们很好理解的经济决策者如何在不确定性下做出选择的模型。 假设经济决策者能够想象过去可能发生的和未来可能发生的每一个可能的相关事件。 他们缺乏完整的信息反映在这样一个事实上：虽然他们可以想象所有相关的情况，但他们实际上不知道哪些情况已经发生或将来会发生。 这种标准方法的一个含义是，每当一个经济决策者不知道某事时，他或她就知道他或她不知道。 这一模式提供了一个有用的起点。 但是，主要研究者和其他人最近的一系列工作都集中在不完全信息模型上，这些模型反映了这样一个事实，即经济决策者不仅不知道哪些情况已经发生或将要发生，而且他们也不一定了解所有相关的情况。 因此，我们考虑到这样一种可能性，即决策者可能不知道某些事情，也可能不知道他或她不知道。 因此，本研究项目的第一个目标是完成主要研究者的发展一个更现实的模型下的不确定性选择。 但是，在这种结构中出现了一个关键的概念问题。 经济学家试图解释选择，包括不确定性下的选择，作为决策者偏好的反映。 但在构建不确定性模型时，决策者的偏好是对世界相关环境描述的一部分。 该项目的第二个目标是提供一个绕过这种循环的偏好的层次描述。 这将为更现实地理解经济决策者如何科普不确定性提供坚实的分析基础。 ***

9309515 Morris In the last twenty years, economists have made tremendous strides in understanding the role of uncertainty and imperfect information in the economy. Applied fields as diverse as macroeconomics, labor economics and industrial organization are increasingly focussed on the superior information which some economic participants have relative to others. This progress has been possible because of the existence of a standard, well understood model of how economic decision makers make choices under uncertainty. It is assumed that economic decision makers can imagine every possible relevant event which may have occurred in the past and may occur in the future. Their lack of complete information is reflected in the fact that - while they can imagine all relevant circumstances - they do not in fact know which circumstances have transpired or will transpire in the future. An implication of this standard approach is that whenever an economic decision maker does not know something, he or she knows that he or she does not know it. This model provides a useful starting point. But a series of recent work, by the principal investigator and others, has focussed on models of incomplete information which reflect the fact that economic decision makers not only do not know which circumstances have transpired or will transpire, but also they do not necessarily understand what all the relevant circumstances are. Thus we allow for the possibility that a decision maker may not know something, and may not know that he or she does not know it. Thus the first objective of this research project is to complete the principal investigator's development of a more realistic model of choice under uncertainty. But there is a critical conceptual problem which arises in this construction. Economists seek to explain choices, including choices under uncertainty, as a reflection of the decision makers' preferences. But in constructing a model of uncertainty, decision makers' preferences are part of the description of the relevant circumstances in the world. The second objective of the project is to provide a hierarchical description of preferences which gets around this circularity. This will provide a solid analytic foundation for a more realistic understanding of how economic decision makers cope with uncertainty. ***