Decisions on Financial Markets

Recent financial crises have sometimes been blamed on the excessive use of mathematical tools on the stock exchanges. This article aims to deconstruct decision making on financial markets and to analyze the evolution of belief systems (signals, data, tools, etc.) by comparing them with standard probabilistic models, often considered “natural” models for random events. In doing so, it highlights the procedures (derandomization and detemporalisation) that contribute to tame uncertainty.