Who am I? Do we really live in one reality or universe, or do we live in many realities that connect to this one existence? This essay will discuss the theories, concepts, and ideas about who we are in this world and in reality. Arguing the points that we are genuine living beings, who are not the brainchild of someone or something else, we are not copies of something that is eternal or in another reality. We, along with everything we see, hear, touch, taste and smell, are in this reality, not two, or three, or a hundred, just one reality. What I mean when I say this is that we only live in one reality or one world. An example of this would be how we live on planet Earth, we only live on Earth, we don't live on other planets like Mars or Venus. Known as the father of modern philosophy, René Descartes created the world-famous theory “I think, therefore I am”. Descartes developed this theory when he tried to consider what really existed and what did not. He arrived at three main truths, the first is that he exists because he thinks, the second that God exists and the third that external objects exist. God must exist because the idea of ​​an omnipotent being must come only from God, therefore God exists perception can deceive us. Does God want to deceive us? No, because he is perfect and would not. Therefore external objects must also exist. When Descartes came up with these three truths he was wondering what was real, he doubted everything because there wasn't one certain answer to nothing except the three truths of which he was certain. Since Descartes doubted reality, he invented the three truths, which made him certain that... middle of paper... Rickhouse, T., & Smith, N.D. (2009). Plato (427-347 BC). Philosophical encyclopedia on the Internet. Retrieved (2009, November 1) from http://www.iep.utm.edu/plato/#SH6bBurnham, H. D. (2005). Leibniz: Metaphysics. Philosophical encyclopedia on the Internet. Retrieved (2009, November 1) from http://www.iep.utm.edu/leib-met/#SH9cMcDonald, W. (2005). Søren Kierkegaard (1813-1855). Philosophical encyclopedia on the Internet. Retrieved (2009, November 1) from http://www.iep.utm.edu/kierkega/Call, L. (1995). Nietzsche critical and prisoner of the Enlightenment. Retrieved from http://www.scrye.com/~station/dissertation.htmlMcCormick, M. (2005). Kant: Metaphysics. Philosophical encyclopedia on the Internet. Retrieved (November 2, 2009) from http://www.iep.utm.edu/kantmeta/#SH1b(1997). Metaphysics: Immanuel Kant. Retrieved from http://www.spaceandmotion.com/metaphysics-immanuel-kant.htm