Determinism, random, chaos, freedom. Henri Poincaré and the revolution of scientific ideas in the twentieth century

At the end of the nineteenth century the triumphant "scientism" left almost no room to consciousness and claimed that it will soon rule everything. The determinism was considered as the main property of scientific facts while freedom, will, free-will were considered by most scientists as illusions. The danger of this evolution was pointed by Henri Poincaré (1854–1912) who developed many philosophical considerations on the future of science and its relations with mankind. He was also a major scientist opening the gate to the theory of chaos that was for decades considered as an odd singularity and revealed its fundamental importance in the seventies when chaos was acknowledged in most domains of science and technology. The other main philosophical upheavals of science were of course the intrinsic presence of random, irreducible to determinism, (theory of quanta) and the trouble of scientists confronted with the terrible misuses of science. All this has led to new perspectives on consciousness and freedom while materialism is no more a must.