In this paper, the author, an ethics and political philosophy professor, wishes to pinpoint the dangers of inflating such words as ethics and morality in our present days vocabulary. He considers that the erosion of these terms, i. e. their indiscreet and indiscriminate use, reinforces the nihilism of values prevailing in modern society. As an exercise to recover these concepts in their proper condition, he brings forward a translation of the entry: moral science, as found in Diderot and D´Alembert's Encyclopedia. There lie the philosophical bases of the concept, from antiquity to modern times. Reading this entry may help establish more delineated patterns for morality, ethics and the values that define the social rights and duties... which...