The science around cannabis brings together the physico-chemical and experimental sciences (nature and matter, biology, and especially medicine). But also the human sciences, which concern Man, his history, his behavior, language, social, psychological, political.The acquisition of knowledge recognized as scientific passes through a series of stages. The data collected allows a theorization, the theorization makes it possible to make predictions which must then be verified by experimentation and observation.A theory is rejected when these forecasts do not fit the experiment. The researcher having made these verifications must, in order for scientific knowledge to progress, to make this work known to other scientists. These will validate or not his work during an evaluation procedure.