Accurate thematics is one of the requirements of sectarian operations, and a lack of correct knowledge of the subject of the Shari'a ruling leads to a wrong inference and consequently to a wrong ruling. Undoubtedly, jurists due to lack of expertise in basic sciences may not have the correct subject matter. One of these sciences is the science of chemistry, which the jurists may not have the correct subject matter of alcohol, and in such cases it is necessary to leave the subject matter to its expert, and if the subject is not met, go to the principles, and this issue can Lead to differences in their arguments and fatwas. In this article, the author examines the reasons for the purity of alcohol in four axes (principle, invalidity of the name, narrations of purity and renunciation to normal) and the reasons for the impurity of alcohol in four axes (principle, consensus, general narrations of impurity and specific narration). Has refuted and believes in the purity of alcohol. But in the end, in order to solve the problem according to the opposite basis (the basis of the impurity of all intoxicants), he studied the exact subject of alcohol and the intoxication of its types, and concluded that except for medical alcohol- which is intoxicating and toxic - other All types of alcohol are non-alcoholic and pure.