The purpose of the social sciences is, through the complementarity of their approaches, to reconstruct when it comes to the past, or to discover when it comes to the present, the ways of thinking, organizing society, and acting that characterized a given society at a given time or that characterize the diversity of contemporary societies today. To do this, we must take into account the representations that individuals and groups making up a society have of it and the place they occupy in it, as well as the values ​​they attach to it. Humans do not simply live in society like other social animals. They produce society in order to live, forms of social existence that each have their own logic and capacities to transform themselves either through their internal evolution or through external pressures. Why are the social sciences strategically important for understanding the world that is opening up before us? Because they are essential to understanding the gigantic transformations that have taken place in the world in the last century and the clashes that are looming before us for the decades to come. Among the social sciences, four are in some way their spearhead: history, anthropology, sociology and economics. History because the past of societies is always one of the actors of their present; anthropology because it is a discipline that requires immersion for a long time within a society to understand its representations, values ​​and structures; sociology because it allows us to statistically understand phenomena and social states that are majority, minority or emerging within nations or cities with enormous populations that will continue to grow; and finally economics because it analyses, without being able to anticipate them, the movements in the production and circulation of goods and the unequal accumulation of wealth that make up the globalised and divided world in which we are called to live. As for anthropology, the discipline practiced by the author of this note, it was born precisely from the military, commercial, political, and ideological expansion of the West that began in the 16th century. In order to administer the many societies with different customs and languages ​​that the West had conquered and subjugated, to convert them often by force to the true religion, Christianity, to trade in distant seas, Europeans had to learn languages, learn about local customs and the nature of local powers in order to achieve their goals. This information, of course biased by the intentions of those who collected it, constitutes the first materials of anthropology. It was in the second half of the 19th century that anthropology became a true scientific discipline thanks to the investigations of Lewis Morgan (1818-1881) on kinship systems and those of Edward Tylor (1832-1917) on cultural systems existing in the world. Anthropology is a discipline that compares ways of thinking and living, a comparative science based on data collected in the field. Its method is observation that arises from participation in the daily life of the group in which the anthropologist has chosen to immerse himself and work. But he must add to this the results of systematically developed and pursued surveys on various aspects of the organization of the society he is studying: its kinship system, its myths and rites, its production techniques of its material base, its forms of property and power, etc. Thanks to this data, the anthropologist seeks to detect the postulates and mental schemes that organize the social relations of this society and give them meaning and coherence. And as he continues his research in today's world, the anthropologist is one of the best placed to realize and report to us the transformations undergone or desired that appear in post-colonial states when they integrate more or less quickly into the capitalist world economy and equip themselves with forms of political power more or less similar to those of the West. To do his work, the anthropologist must therefore constantly decenter himself in relation to his own culture and society and commit to testifying in his own society to what he has understood and learned from the societies he has studied. Lycée d'État Jean Zay - Paris boarding school - CPG 2017. Speaker: Maurice Godelier, agrégé de philosophie. Anthropologist, professor at the École des hautes études en sciences sociales.