F. Muth and the emergence of the concept of rational expectations

In this article, we wonder at first to what extent the personality of Muth can explain his analysis of the question of the expectations. Then, to highlight the specificity of his approach, we compare it to that of the other economists who, before or at the same time as he, used the expression "rational expectations". Finally, we study the spread of his theory and the critical look that he took on his contribution at the end of his life.