Abstract
The works of Knight (1921) and Keynes (1921, 1936) seek to clarify confusion about uncertainty. According to these authors, a precise analysis of uncertainty is required, in order to obtain a clear significance of the concept and understand the consequences for the decision process. Consequently, Knight and Keynes study the content of the decision process in uncertainty and converge towards similar views on the mobilization of confidence. Their works thus go beyond a simple examination of uncertainty, by also throwing light on the role and function of confidence in economic analysis. These works demonstrate that confidence is the prerequisite for individual action under uncertainty.