Abstract

The recurrence of financial crises in the last fifty years reveals a market coordination failure that regulation and economic policy were unable to prevent. While several explanations exist for the emergence of financial and economic crises, none seems to be fully satisfactory or conclusive. This text develops the idea that the theoretical assumptions that underlie policy and regulation are inadequate to fully map economic reality and that this explains the observed policy and regulatory failures. The paper suggests to assess the adherence of standard economic assumptions to reality from a probability viewpoint. It notes in particular that the no-arbitrage condition is the key assumption retained by modern finance for the pricing of financial assets. It is supported by the same set of logical premises that are associated to competitive markets in general equilibrium theory. Still today, this group of normative requirements remains central in policy advice and regulation, be it through Modern Finance or other applied fields such as Public Choice. Based on simple probabilistic arguments, the paper reminds that the domain of relevance of the above standard normative conditions is necessarily very limited. The inadequacy of the assumptions retained by regulators and policy makers to map actual economic reality can thus explain the regulatory and policy failures that allowed financial crises to develop. Public action should use more wisely normative conditions. A closer look at the adherence of the relevant assumptions to reality may be a way for improving policy and regulation effectiveness in the future.

摘要

过去 50 年金融危机的重演揭示了监管和经济政策无法阻止的市场协调失灵。尽管对金融和经济危机的出现存在多种解释，但似乎没有一个是完全令人满意或决定性的。本文提出了这样一种观点，即作为政策和监管基础的理论假设不足以全面反映经济现实，这解释了观察到的政策和监管失败。本文建议从概率的角度评估标准经济假设与现实的一致性。它特别指出，无套利条件是现代金融为金融资产定价所保留的关键假设。它得到了与一般均衡理论中的竞争市场相关的同一组逻辑前提的支持。直到今天，这组规范性要求仍然是政策建议和监管的核心，无论是通过现代金融还是公共选择等其他应用领域。基于简单的概率论点，本文提醒上述标准规范条件的相关范围必然非常有限。监管机构和政策制定者保留的假设不足以反映实际经济现实，因此可以解释导致金融危机发展的监管和政策失误。公共行动应该使用更明智的规范条件。