The article presents a comparative analysis of the fundamental principles of the philosophy of knowledge of prominent representatives of the classical Russian philosophy of the XIX century Nikolai Strakhov and Peter Astafiev. The materials of their main philosophical works show how, based on Descartes' cogito ergo sum (rooted, in turn, in a tradition that goes back to Socratic self-understanding), both thinkers in their polemically-directed independent philosophical quests come to different conclusions on the nature of the cognizing subject. Assuming fundamentally necessary moment of objectification of the knowable, including the process of knowledge of their own spiritual experiences, N. Strakhov believes that the subject of consciousness as such is aught that does not possess any properties and qualities, since all these properties and qualities are objectified in the content of psychic life. P. Astafiev considered this split – on the subject of the experience and the experience itself – to be illegal; he insisted on the inseparability of the subject and his spiritual experience in the "total mental act", and interpreted the process of knowledge of the inner psychic life as a direct and natural.