Personal identity has long been one of those riddles the human race has strived to unravel. Even the earliest philosophical works posed the questions of, ‘who am I?’, ‘what am I?’ or ‘what makes a man different to the other men around him?’ I have no doubt that every conscious and self-aware person on the planet has, at some point and to some level, delved in introspection and pondered the notion of their identity, whatever that may consist of. Identity, as defined in the Dictionary of Philosophy, is ‘the theory that mental states and events, such as dreaming, believing, hoping, fearing, feeling pain etc. are identical with certain states or processes in the central nervous system'. This definition provides a shallow idea of the concept of identity. A deeper and more complex understanding of identity in relation to survival will be extracted by examining the works and opinions of Derek Parfit and David Lewis. First, Parfit’s outlook on identity and survival will be explored accompanied by examples of fusion and fission. Following Parfit’s arguments on identity and survival, the contrasting views of David Lewis will be examined, specifically in relation to the identity of the time traveller.
Derek Parfit’s notion of identity is as follows: psychological continuity does not equal personal identity, which, in turn, does not equal survival. He describes identity as being all or nothing; matters of identity have a one-one relation. With regards to psychological continuity and connectedness, however, Parfit maintains that they do not have a one-one relation, and therefore are not an apt measure for personal identity. Furthermore, Parfit also holds the belief that personal identity does not imply survival, as survival is not a one-one relation and is, in fact, a matter of degree. He demonstrates these notions through examples of fusion and fission. When Parfit discusses fusion, he describes it literally as two separate brains and bodies, with accompanying memories,...