Why do we believe incredible things?

Throughout history, human beings have believed unbelievable things. Why does this happen? According to the thesis defended in this paper, because human beings give up the use of reason. Therefore, the use of human rational abilities, in particular in science, must be defended as the responsible way to cope with the problems besetting our own lifes and those of our fellow human beings. The paper closes by highlighting the close link between scientific rationality, when it is aware of its own limits and provisional nature, on the one hand, and democratic culture, on the other.