[30 years' development of economic theories in confrontation with facts]

In 1969, R. Frish and J. Tinbergen received the first Nobel Price in Economics. 200 years after Quesnay's "economic tables", economics were at last considered as a science. During the last thirty years, economics haven't lost their scientific reputation, but, confronted with different situations in the world and in France, economics have been unable to bring appropriate solutions to every problem. Nowadays, economics are quite far from the promises born after the Second World War: indeed, until the 1974 world crisis, Keynes' theory (from a macro-economic point of view) and Walras' formalisation of the markets (from a micro-economic point of view) were sufficient to give satisfying representations of any economic reality and mechanism. Nevertheless, these theories were unable to deal with both growing unemployment and raising inflation in the late 70's and early 80's. Today, economics present a wide variety of efficient analysis of society. Game theory, behaviour theory or econometrics are new means used to found new kinds of reality representation. Therefore, if economics can no longer be considered as an exact science, it remains nevertheless scientific.