Floating man experiential field shows that the self is not consequently a substance and thereby there is no subjectivity. On the other hand some scholars like Wisnovsky believe that the flying man argument proved the substantiality of the soul. Ibn Sina believes that innate awareness is completely independent of sensory experience. Before the French philosopher Descartes (1596–1650) pointed out the existence of the conscious self as a turning point in epistemology, using the phrase "Cogito ergo sum," the 11th century Iranian philosopher Avicenna had referred to the existence of consciousness in the flying man argument. Thus, long before Descartes, Avicenna had established
Cogito, ergo sum for thought". In other words, "the only claim that is indubitable here is the agent-independent claim that there is cognitive activity present". The objection, as presented by Georg Lichtenberg, is that rather than supposing an entity that is thinking, Descartes should have said: "thinking is occurring." That is, whatever the force of the "cogito", Descartes draws too much from it; the existence of a thinking thing, the reference of the "I," is more than the "cogito" can justify. Friedrich Nietzsche criticized the phrase in that it presupposes that there is an "I", that there is such an activity as "thinking",