In the last decade the Professor Elster has become one of the philosophers who have stand out in the vast field of Social Sciences. This is supported by the importance of his work that has grown admirably in the last years, but above all for his originality. The first researches of the Professor Elster dealt with the problem of the analysis of the types of scientific explanations, characteristic of the analytic philosophy that dominated the English-speaking world, and at the same time he worried about an alien aspect to that philosophy, as is to answer the question “in what sense you can be Marxist?”, which the failed attempt of Althusserian renovation, coming from France, bring to the forefront.

However, the methodological individualism of the Professor Jon Elster has led him to other ways far from the Marxist problematic. The originality of the Professor Elster is manifested again in this field as he has pointed out the limitations of the rational choice theory both in the field of social actors and in the sociologist who observe it.

Considering that before talking about theories that formulate regularities, similar to the general laws about human behaviour, what at the moment social sciences are not capable of explaining, the need is to talk about mechanisms, small mechanisms and medium size dimensions for considering actions and human interactions, plausible mechanisms. These were the frequent ways of understanding the study to which he has dedicated a part of his work.