In terms of logic, I would say “I think because I exist “ is more appropriate. It is because I must exist first, therefore I can think of my existence. Things about me or myself are impossible to happen before my existence and cause my existence. In the following paper, I would like to explain why “I exist because I think” is false and explain “I think because I exist” is true.
Let me first explain why ‘I exist because I think’ is false. If ‘I exist because I think’ is true, every time when I think I exist and when I do not think, I do not exist. As I mentioned, “Think” seems to be the cause of my existence in this case. How can my thinking exist before my existence and cause my existence. Therefore, I must exist first, then I can think about “I exist” or not. In fact, every minute whatever I am conscious or not, I am existing in this world, If my body physically is existing. For example, a person whose body functionally works but loss his conscious. He is still alive but he cannot think, we cannot say he is inexistent, because he is not dead. In other word, I can exist without “I think”, but “I think” cannot be without I exist.
Furthermore, as Descartes said “I think, therefore I am” to prove the indubitable truth of self-existence. He suggested that every time when we doubt that “I” exist or not, we can absolute certain that “I” am existing by this act. Then he said that the evil genius could not deceive us “I exist” because before the evil genius’s deception, “I” must exist first, then I can be deceived in some way by the evil genius. So “I exist”