Expectation and Uncertainty in the Keynesian Theory

The purpose in this article is to investigate the relationship between probability and logics in order to understand the notion of expectation in Keynes, and to examine the contributions that a set of postkeynesian authors has made to clarify the sense and the meaning of the notion of expectation in the framework of both the theoretical and the economic policy. We will start by integrating Keynes's work on the theory of the probabilities into the construction of his theoretical corpus. We will emphasise the role of the expectation as the main contribution of Keynes to the economic thought in the theoretical framework of uncertainty. The article is divided in two parts. Firstly,it will examines the contribution of Keynes to the interpretation of the meaning of the expectations in a theoretical framework of Uncertainty. Secondly, it will examine the comments of Shackle and Kregel on the role of expectations in the theory and the economic policy and will consider the appreciations of Minsky on the volatility of the expectations in a framework of finantial instability