The article deals with the philosophy of medieval philosopher ZAKARIA al-Razi, one ofthe most original personalities in the spiritual life of the peoples of the Middle East.It is known that at the beginning of the twenty-first century challenges of spirituality andspiritual world of the individual become the subject of intense attention of modern philosophy.It should be noted, that nowadays, a great place in the writings of thinkers concerned withquestions of essence and value of knowledge, aspects of truth, the role of science in thedevelopment of society.The article reported that Al - Razi although was the largest rationalist in the theory ofknowledge, attached importance of the senses in the learning process of reality. In its medicaltheories al-Razi emphasizes the close connection existing between the human body andchanges in the state of his soul. Al-Razi does not subordinate the human mind for the divinecommand and considers the work of the mind - an active and creative human activity.The main idea of the article is the scientist recognized a huge role of mind, which was veryimportant under the rule of reactionary ideology of Islam. Convinced of the power of the humanmind and the knowability of the world, al-Razi only means of knowledge of the world considersthe scientific method of learning and encourages people to mastering science. Progressivenessof the theory of knowledge of al-Razi was expressed in the fact, that he denies the existence ofmiracles, attributed to various prophets and so-called imams.The author comes to the conclusion that a valuable contribution of al-Razi to the problemof knowledge was his denial of faith in the authorities; theory of knowledge and teaching aboutthe mind of al-Razi played a huge role in the Middle Ages and had a great influence on thefurther emancipate of science from the influence of religion and on the development ofmaterialist theory of knowledge.