The Memory Theorythis Theory Claims That What
Makes One Person Identic
The Memory Theory posits that personal identity over time hinges on the retention of at least one of an individual’s memories. As articulated by John Locke, this theory asserts that what makes one person identical to another at a different time is the sharing of at least one experiential memory. The core strength of this theory lies in its ability to explain phenomena such as body switching without resorting to non-physical substances, emphasizing the significance of psychological continuity through memory in forming personal identity. However, it faces three principal objections:
Inconsistency Objection:
Reid’s brave officer example demonstrates that the memory theory violates the transitivity of identity, which is a fundamental logical requirement. For instance, an officer may remember a past event, yet later forget a related part, raising the question of whether the same person persists through such gaps. This issue can be mitigated by introducing intermediate “person stages” that account for gradual psychological changes over time.
Circularity Objection (Butler):
The theory appears to rely on a circular criterion for identifying genuine memories, as recognizing a memory as truly belonging to a person presupposes knowing that the person had that experience previously. To address this, some philosophers propose the concept of “quasi-memories,” which are less stringent and help break the circularity
Insufficiency Objection:
While memories are crucial, they do not fully define personal identity. Personal identity is also influenced by desires, intentions, and ongoing psychological states. Therefore, psychological continuity, which encompasses memory, desires, and other mental states, is proposed as a more comprehensive account.
To deepen our understanding, it is essential to clarify key concepts related to psychological continuity. A person possesses a quasi-memory if:
She seems to remember an experience;
Somebody actually had that experience; and
The seeming remembrance is caused by that actual experience.
Similarly, a quasi-desire refers to a desire that: She appears to have; Someone truly desires that thing; and Her desire is caused by that actual desire.
Two individuals are psychological connected if they quasi-remember and quasi-desire the same things, although this connection is not transitive. If a series of overlapping individuals are psychologically connected, then they are considered psychologically continuous.
Psychological Continuity Theory
The Psychological Continuity Theory suggests that personal identity persists over time because successive persons are psychologically continuous with each other. This theory offers several advantages: It is simpler than the Soul Theory because it relies solely on psychological factors, avoiding metaphysical assumptions about an immaterial soul.
It accounts for body switching phenomena, where bodily continuity is not necessary for personal persistence.
It allows for the possibility of an afterlife since psychological continuity might persist beyond physical death, depending on beliefs and definitions.
It overcomes the limitations of the memory theory by including broader mental states such as desires and intentions, addressing its violations of transitivity and circularity issues.
However, a significant challenge arises because psychological continuity is a "one-many" relation: many distinct persons can share overlapping psychological states, but only one can be the same individual over time. Examples such as the teleportation thought experiment and Williams’ “Guy Fawkes” illustrate this conflict. In the teleportation scenario, the person who reappears after teleportation is psychologically continuous with the original but not identical, raising questions about the criteria for one-to-one personal identity versus multiple psychological continuities. Consequently, while psychological continuity provides a compelling account, it struggles to adequately distinguish individual identities in cases of duplications or splits.
Conclusion
In conclusion, both the Memory Theory and the Psychological Continuity Theory offer valuable insights into personal identity, emphasizing mental continuity over physical. The Memory Theory's simplicity and explanatory power are matched by significant objections, particularly regarding transitivity and circularity. The Psychological Continuity Theory broadens the scope of personal persistence by incorporating desires and other mental states, providing solutions to the limitations of the memory-focused account. Nonetheless, the problem of distinguishing individual identity among multiple psychologically continuous persons remains unresolved. Therefore, a nuanced understanding of personal identity likely requires integrating these theories and addressing their respective challenges.
References
Locke, J. (1689). An Essay Concerning Human Understanding.
Reid, T. (1785). Essays on the Intellectual Powers of Man.
Butler, S. (1736). The Analogy of Religion, Natural and Revealed.
Parfit, D. (1984). Reasons and Persons. Oxford: Oxford University Press.
Shoemaker, S. (1970). Personal Identity: A Materialist Account. The Journal of Philosophy, 67(23), 713–727.
Husserl, E. (1931). Ideas: General Introduction to Pure Phenomenology.
Williams, B. (1970). The Self and Its Worlds. Cambridge: Cambridge University Press.
Parfit, D. (1987). Personal Identity. Insterprime Press.
Lewis, D. (1976). The Paradoxes of Time Travel. American Philosophical Quarterly, 13(2), 145-152.
Parfit, D. (2011). On What Matters. Oxford University Press.