On Defining 'I' "I logy"

Could we define " I " ? Throughout this article we give a negative answer to this question. More exactly, we show that there is no definition for " I " in a certain way. But this negative answer depends on our definition of definability. Here, we try to consider sufficient generalized definition of definability. In the middle of paper a paradox will arise which makes us to modify the way we use the concept of property and definability. Here, definability is defined based on the properties of objects and possessing the properties by objects. Throughout this article we don't define and consider property as precise as a mathematical Definition (by property here, we mean the property of a cognitive agent), but we try to make it as precise as possible. Indeed we suppose that, our intuition about property is sufficient to develop the subject here. Definition: p‐sentences are the set of sentences which are constructed by induction as following: ١. Every sentence in the form of " X has property p " is a p‐sentence ٢. The logical combinations of p sentences are p‐sentence. Here, a definable object is an object which there is a p‐sentence which defines and specifies (****) that object. Definition: For every property p, by A(P) we mean the set of objects which has the property p. The following definitions and theorems are based on the definitions and theorems in [١]. Possibly, In the first glance the subject seems a little odd, unless we read [١] first.