Questions about God, knowledge, freedom and immortality are asked not only by philosophers, but by all individuals. The answers to these questions are extraordinarily contradictory because everyone has different beliefs and opinions. One of the main philosophical questions is that of personal identity and immortality. Most commonly, philosophers attempt to discover what makes someone the same person they were ten or twenty years ago. Some argue that memory is the key to personal identity: others object. The problem of personal identity is difficult to solve, especially because the terms are ambiguous. Identity can mean the same person or the way one sees oneself. In any case, philosophers wish to evaluate this problem and find an adequate explanation, one of the motivations is responsibility. Humans will hold others accountable for acts such as murder, theft, and fraud. However, the person who will have to face the consequences must be the one who actually committed the wrongful act. A second motivation is interest in the future. An individual may worry or become excited about an event that will happen in the future. Surely, these emotions imply that they will be the same person once the event occurs. The ultimate motivation for resolving personal identity is immortality; basically, what will connect a person to what survives after their physical death. Something can be identical in two ways: quantitatively or qualitatively. To be quantitatively identical is to be numerically identical, and to be qualitatively identical is to share exact qualities. There are two criteria on which personal identity is based, but the most important is the metaphysical criterion, which attempts to explain “being” or existence, without the need for physical evidence… middle of paper…. .all the tables, but the next morning he can't remember what happened. Isn't it rational to believe that he suppressed these memories to avoid shame? The conscious brain can sometimes veil the memories of the unconscious mind. Psychology has demonstrated cases where consciously individuals could not remember past events, but during sleep the memories return. There have also been several cases of individuals who have been drugged and abused. The drugs impaired memory for some time, but slowly the memories returned. In short, we can conclude by deduction that body, brain and soul are not sufficient to explain personal identity. Personal identity and immortality will always raise questions from philosophers, as well as other individuals, and although many philosophers may object and disagree, the memory criterion offers the most sufficient explanation.