In his book La Raison et les Remèdes, François Dagognet proposed a very original philosophy of pharmacology. He pays attention to the complicated situation in which modern pharmacology is placed. Modern pharmacology was freed from the past one which was characterized by magical thinking, simple empiricism, and contingency. But it fails to arrive at a positive, necessary and firm foundation on which to build itself. Pharmacology always remains as a region where individuality and generality, contingency and necessity, predictability and unpredictability are mixed up. The reason why pharmacology should always remain in the nebulous gray zone is that patients or diseases are precarious and labile. Through the rigorous analysis of placebo, Dagognet persuasively demonstrates the impossibility of eliminating all the uncertainties from remedy. However, he does not agree to the relativism as such. He thinks that pharmacology in the real world should be place somewhere between two extreme positions. He also finds the efficacy of remedy is related with potentialities and contingency, but not with certainty. This uncertainty is without doubt an obstacle and limitation to reason. But what he sees here is not only the limit of reason, but also the serpentine itinerary of reason that passes through material world.