This conference will present an overview of the transformations of the relations between scientists, politicians and citizens since the Second World war. We will how the first “social contract” of science with society embodied in the famous American report “Science the Endless Frontier” presented by Vannevar Bush in 1945 to the President of the United States has been replaced at the end of the 20th century by a new social contract where “society” is considered as the new “endless Frontier” to which “science” must adapt and respond. This new conception of the relations between science and society has been prepared by the emergence in the 1960s and 1970s of a more critical view of the effects of science on society and the natural environment as well as by stronger relations between science and industry in the 1980s and 1990s which gave rise to situations of conflict of interests detrimental to the positive perception of science as a tool of progress. New communication technologies based on the internet made possible the emergence of new pressure groups promoting a better control of scientific research contributed to a diminished autonomy of the “republic of science” and a stronger political control of its priorities and development. We will conclude with reflections on the positive as well as negative aspects of the new structural relations linking scientists, politicians and citizens.