Abstract. Although three years have passed since the onset of the deepest recession from 1929, the most world economies are still fragile, the slipping into another recession being imminent for many of them. “It is a sin to waste a crisis” without learning something of the causes that generated it, said Nouriel Roubini, but this time the problems facing the economic science are related even to the own concepts of the promoted model, while to change something in the economy it is need a reconceptualization of the economic science.

The context of the current economic model has failed to anticipate the economic crisis and fails to propose sustainable measure of the economic recovery and this because it starts from the wrong premises, such as assuming that the behavior of the subjects within the market is always rational.

In this work we will demonstrate that the irrational behavior of the participants to the economic life has led to imbalances of these markets and we will try to distinguish between the rational and the irrational economic behaviors, to identify the operating area of economic science at this time.

Keywords: rational/irrational behaviour; economic crisis; financial market.