Reductionism and relativism are like Siamese twins. Their history goes back to Protagorus, but in the West they find their origin in the 13th and 14th centuries. The objectives are this session are to be able to tell the story convincingly, to know the strengths and weaknesses of reductionism, especially where it morphs into scientism, and to know the weak points in the lives of modern students and their need for certainty and trust.