The usage of the pronoun I is not innate but acquired. At first, Infants use their proper names to refer to themselves. It is so difficult to master the usage of I that it takes a long time for infants to know how to use the first-person pronoun. When, how and why did we get to use the first-person pronoun?
1. Requisites for the usage of "I"
Before answering this question, let’s consider what conditions are necessary for an information system to use I correctly. The object referred by I is generally though to be the user that uses this word. How about the following cases?
Case 1. I record my voice I am a tape recorder onto a tape recorder and replay it, so that the tape recorder introduces itself.
Case 2. I input a certain amount of vocabulary and grammar to a computer and make it write a composition freely, so that it happens to output a sentence, I am a computer.
Case 3. A little girl, Betty, learns English and reads out a written sentence, I am a girl, without knowing what it means.
These sentences, I am a tape recorder, I am a computer and I am a girl, seem to be true, but in fact, they are meaningless, because the tape recorder, the computer and Betty do not have self-consciousness and they cannot understand their meaning.
Self-consciousness is a necessary, but not a sufficient condition for an information system to use I meaningfully. Without the first-person pronoun, self-conscious beings can use their proper names to refer to themselves. For example, instead of I use a computer, I can say, Toshiya Nagai uses a computer.
2. The nature of the pronoun
Let’s consider the difference between the first-person pronoun and the proper name. The proper name, Toshiya Nagai refers to the sole object, whoever may use it. There are, of course, many people that have this name, but I can make this name proper to mine by adding a limitation, say, the Toshiya Nagai born in 1965.
On the other hand, the object referred by the pronoun is indeterminate depending on who uses it. In this sense, I is similar to here or now. Though the phrase here and now indicates a unique spatiotemporal point, the phrase itself is universal, because every spatiotemporal point can be here and now. As here and now is a spatiotemporal point where I am, the ambivalence of uniqueness and universality characteristic of here and now can be reduced to that of I. Though I indicates a unique person, I can be anyone, therefore it is universal.
3. The role of "I" is to negate "I"
The word I is usually thought to be a symbol of egotism, but it has a rather public role. Thanks to this universal word, I can put myself in another’s shoes: for him I indicates himself, just as I indicates myself for me. So, two conditions are necessary for an information system to use I: to be self-conscious and to have intersubjective imagination.
Suppose the little girl Betty gets thirsty and says, Betty wants the orange juice, while there is only a glass of orange juice and another girl of an age also wants to drink it. If she can know Betty wants to drink the orange juice is equivalent to I want to drink the orange juice, monopolizing the orange juice denies another I want to drink the orange juice. The universality of I drives egotism to logical self-contradiction. When Betty notices that her friend wants to drink juice like me and share the orange juice with her, this it the moment Betty learns to know the usage of I.