Economics is an essential knowledge for economists, politicians and managers of all levels.
An Inquiry into the Nature and Causes of the Wealth of Nation could be considering as the first step of the development of Modern economy in our leader decision process. Before this work, Economics is more the fact of feelings than a theory based on statistic studies (in France, for example : Colbert during the reign of Louis XIV). Since 1776, economy is becoming more and more important in our every-day life. Nowadays, none can ignore it. When you are watching TV or reading a newspaper, you may found parts on the evolution of GDB (the growth) or on the inflation. As a result, best economists are not anymore great anonymous people. J. Stiglitz leads last years in France a Commission about building new kind of measures and P. Krugman is both the 2008 Nobel Price of economy and one of the best editorialist of New-York Times. We will study why it makes sense to say Economics is an essential knowledge for taking decisions. Then, on the other hand, we will focus on the facts that highlight the default of this “science” and the important to use this “knowledge” with cautious.

Firstly, as a famous quote of J. M. Keynes told us, the main idea applies by our leaders used to be the ones of unknown economists. Our way of life is mostly based on earning lots of money. Economy is the Science that studies the way to optimize and to understand our production process. Moreover, the importance of markets and all the tools to insure their efficiency reveal us that Economy is not anymore a theoretical issue but the solution to life in prosperity. For years, Economy was linked and subjected to politics. The last events in the “euro crisis” drastically change this fact. Now, politics have to consider economists and have to fallow their advice (Greek crisis).

Nevertheless, each thirty years, the trendy economic theory is questioned. Keynesianism, Liberalism, Mercantilism seems old-fashioned