Personal Identity Over Time

Key Questions:

Are we the same person we were a year ago? Six months ago?
What criteria determine continued personal identity over various stages of life?

John Locke, a prominent 17th-century philosopher, asserted that personal identity is primarily grounded in the continuity of consciousness rather than physical attributes.
He emphasized the significance of psychological factors, arguing that changes to the physical body do not alter one’s personal identity.
Key Concept: Memory holds a central position in defining personal identity; the ability to remember experiences contributes significantly to one’s sense of self.

While individuals may experience alterations in desires, hopes, and beliefs over time, these changes do not compromise their personal identity. Rather, it is the continuity of memories that serves as the backbone of one’s identity through time.
Thomas Reid's Modification:
- Reid presented a compelling example featuring a sequence of identities: starting as a boy, then becoming an officer, and eventually an old general.
- The crucial argument is that as long as the chain of memories connecting these identities remains intact, personal identity persists.
- For instance, if the old general can recall being the officer and the officer can remember being the boy, it affirmed their psychological continuity and thus their identity throughout the changes.

Total amnesia leads to a profound transformation of identity; in such a scenario, an individual essentially becomes someone else entirely.
Example: The contrast between Jason Bourne and his original identity as David Webb illustrates this concept – they cannot be considered the same person due to the encompassing memory loss.

Consider a theoretical situation where an individual is duplicated (akin to the character Riker in Star Trek).
Both resulting beings (Will and Tom Riker) retain psychological continuity with the original Riker; however, they cannot both be seen as identical, as they possess different properties and exist in separate physical forms.

The philosophical discourse surrounding identity suggests it is a transitive relation (if A = B, and B = C, then A = C).
An illustrative case is Snoop Dogg, where identity necessitates identical properties, including spatial position, thus indicating that psychological continuity alone cannot sufficiently define personal identity, as two distinct beings (e.g., Will and Tom) cannot be identical.

Derek Parfit, a contemporary philosopher, contended that more emphasis should be placed on the concept of survival, rather than adhering to a rigid definition of identity.
Parfit argued that a person could survive through two distinct identities, which complicates traditional notions of personal identity.
Fission and Fusion Thought Experiments: These thought experiments explore scenarios in which two identities emerge from one or combine into a single identity, demonstrating that the process of survival can shift identity perception.
An example is when Goku and Vegeta merge to form Gogeta, exemplifying how the interplay of survival can influence one’s concept of identity.

The exploration of personal identity prompts critical inquiries: What fundamentally makes us the same person over time? Is the concept of survival more crucial than the strict adherence to personal identity?