 Another important difference between Aristotelian and Cartesian deduction is that Aristotelian deductions do not yield any new knowledge. In the syllogism, “All men are mortal; all Greeks are men; all Greeks are mortal”, the conclusion is already known. We “learn nothing new form such forms of reasoning” (AT 10: 406, CSM 1: 36). For Descartes, the method “should […] extend to the discovery of truths in any field whatever” (AT 10: 374, CSM 1: 17; my emphasis). Descartes’ method is a method of discovery; it does not “explain to others arguments which are already known”.