 Thus, according to Richard Popkin, Mersenne is not so much refuting skepticism as he is adopting an attenuated form of it. By openly discarding research on the causes and essences of phenomena, reducing the whole of physical science to mathematical knowledge of accidents, the study of external effects, and the establishment of the laws of appearances, he invents a “mitigated skepticism”, that Popkin considers as the first lucid expression of the modern scientific outlook, deemed to become dominant in the following centuries. This outlook conjugates an entire confidence in the virtues of physico-mathematical sciences, with a complete positivism (that is, a deliberate abstention) in regard metaphysical matters.