Ma`rif Aqli

Fundamental questions about what a thing is, in Arabic is stated by »Ma hoo« and »Eyyo«. Given that their functions and Answers Completely distinct, Avicenna s definition of Eyyo is A little vague. Fakhr Razi s description shows that there is a problem in this phrase. Tusi s description not only added to its ambiguities, rather, it expresses inconsistency with the basics of logic. In the judgment between Fakhr Razi and Tusi, Qutb Razi supported Fakhr Razi s view and raised some criticisms about Tusi's point of view. Considering the importance of these criticisms, Mullah Abdullah Yazdi defended Tusi. In this research, the effort is based on that to answer this question: Does Tusi's view have those problems? The result of this research is that none of the Criticisms are true just as Yazdi's defense is not correct either. The source of Qutb Razi's problems is the misinterpretation of Ibn Sina's and Tusi's words. Therefore, this research tries to provide a correct interpretation of that statement.