Chains of memories that are connected to each other are the way of identifying a person offered by the psychological continuity theory. For example, if one person remembers being himself 10 years ago and 10 years ago he remembered that he had been the same person 5 years earlier, then it is the same person according to the theory. Nevertheless, psychological continuity does not fully answer the question of “who am I?” as Derek Partif pointed out in his critique. He offers a thought experiment called the split brain argument. It is based on the situation where are person’s brain is split in half in order to save a person’s life, and both of these halves are placed in different bodies. This leads to the question, what happens with the person’s identity after his brain lives in two different people?
Consequently, there are three possible answers to the question above. First is that John is going to be both people, second is that John is going to be one of those people, and the third question is that John is going to be neither of them. However, Derek Partif argues that none of those answers is correct. John cannot be both of those people because they will start to live separate lives with different experiences; hence, they cannot be considered one person anymore (Klaming and Haselager 530). The second question also cannot be answered because if one person can be considered John, why the other one cannot? Finally, the third one is considered grossly misleading by Partif because John, who had undergone an operation, had his dreams and aspirations and purpose of doing this. Hence, people after the operation will most likely have the same intentions and aspirations according to the psychological continuity theory.
Therefore, Partif’s critique identifies three problems with psychological continuity. The first problem is created because of the transitivity of identity – John cannot become two different people. The second problem is the fact that both people have an equal claim to being the original person. Thirdly, it is misleading to conclude that John has gone out of existence by virtue of having two later person-stages that have equal claim to being psychologically continuous with the earlier stage.
Hence, the solution to those problems offered by Partif’s critique lies within applying a measure of degree. Psychological continuity should differentiate between the numerical identity, which in the case of personal identity is a trivial truth (Parfit 18). Numerical identity admits that the person John is in 2021 was the same person as John in 2000. However, John in December of 2021 is much more of the same person compared to John in November of 2021, which puts trivial truth to the degree.
All those problems pointed out by Partif’s critique emphasize how contradictory the theory of psychological continuity is. However, other theories on personal identity are also problematic. For example, there is body identity theory and memory theory. Body theory is criticized for the changing nature amount of body parts such as DNA, which should be present for the person to be present. The memory theory proposed by Locke is challenged by the fragility of the memory. For example, if the person does not remember being a 2-year old that does not mean that it was not the same person. In conclusion, the amount of problems associated with psychological continuity and other theories leads to the conclusion that the concept of personal identity is also problematic, and there may not be such thing as identity.
Klaming, Laura, and Pim Haselager. “Did my brain implant make me do it? Questions raised by DBS regarding psychological continuity, responsibility for action and mental competence.” Neuroethics vol. 6 no.3, 2013, 527-539.
Parfit, Derek. “Personal identity.” The Philosophical Review vol. 80 no. 1, 1971, 3-27.