The article focuses on the relationships between science and policy in the light of critical science movements that emerged during the 1970s. Criticisms by scientists of their own activity are first analyzed as a process of politicization which diverges from the nuclear physicists’ commitment to peace after the Second World War. Having highlighted the diversity of this process, the lexicometrical analysis of activists journals published between 1970 and 1977 shows that the question of differentiation between science and society impregnates these movements and finally constitutes the foundation of the process of politicization. This conclusion leads us to point out the limitations of the idea that science and politics are necessarily inseparables.