What Secures Our Personal Identity Through Time?

Personal identity refers to the unique characteristics and qualities that make us who we are as individuals. One of the most fascinating questions in philosophy is how we maintain our personal identity through time, as we undergo various changes in our lives. In this essay, we will explore two main theories that attempt to answer this question: psychological theories, specifically Locke’s Memory Theory, and physical continuity theories, including Animal Theory and Brain Theory. We will discuss the arguments and examples proposed by philosophers to support each theory and evaluate their merits and limitations.

i. Psychological Theories of Personal Identity – Locke’s Memory Theory

Psychological theories of personal identity focus on mental states, such as memory, as the basis of our identity. One of the most influential psychological theories is Locke’s Memory Theory, proposed by the British philosopher John Locke. According to Locke, personal identity depends on a continuous chain of memories, and a person is the same individual over time if they can recall past experiences.

For example, if you can remember eating breakfast this morning, that memory connects you to the person who ate breakfast earlier. This chain of memories extends backward through your life, creating a continuous sense of identity. Locke’s theory has been influential because it accounts for the changes we undergo in our lives, such as physical growth or shifts in personality, while still preserving a sense of continuity.

However, critics of Locke’s Memory Theory argue that it is insufficient for establishing personal identity. The philosopher Thomas Reid points out that memory can be unreliable, as we sometimes forget experiences or remember things inaccurately. Additionally, imagine a person who suffers from amnesia and cannot remember their past experiences. According to Locke’s theory, this person would not have a personal identity, which seems counterintuitive.

ii. Physical Continuity Theories of Personhood – Animal Theory and Brain Theory

Physical continuity theories propose that our personal identity depends on the continuity of our physical bodies. Two significant physical continuity theories are Animal Theory and Brain Theory.

Animal Theory

Animal Theory suggests that our personal identity is based on the continuity of the living organism that we are. This view is supported by the philosopher Eric Olson, who argues that we are essentially human animals, and our identity persists through time as long as the same living organism continues to exist. For instance, as a child, you had a smaller body and a different personality, but you were still the same living organism as you are now, which secures your personal identity.

Critics of Animal Theory argue that it cannot account for thought experiments that involve body swapping or brain transplantation. For example, if your brain was transplanted into another person’s body, would you still be the same individual? According to Animal Theory, you would not be the same person since your living organism has changed. However, intuitively, we might feel that our identity is preserved in such cases, which challenges the adequacy of the Animal Theory.

Brain Theory

Brain Theory, on the other hand, posits that our personal identity is based on the continuity of our brains, specifically the patterns of neural connections that constitute our mental states. This view is supported by the philosopher Derek Parfit, who argues that the brain is the seat of consciousness and memory, and thus, the key to our personal identity. In cases of brain transplantation, Brain Theory suggests that your identity would be preserved, as the neural connections that define your mental states would remain intact.

However, Brain Theory also faces some criticisms. One challenge is the potential development of brain duplication technology. If an exact copy of your brain was created, would the duplicate have the same personal identity as you? Brain Theory struggles to provide a satisfactory answer to this question.

iii. Recapitulation

Both psychological and physical continuity theories offer valuable insights into the nature of personal identity, but each has its limitations. Locke’s Memory Theory highlights the importance of memory in connecting our experiences across time, but it struggles to account for unreliable memories and cases of amnesia. Animal Theory emphasizes the continuity of our living organism, but it fails to address thought experiments involving body swapping or brain transplantation.

On the other hand, Brain Theory links our personal identity to the continuity of our brains and neural connections, which seems more intuitively appealing in cases of brain transplantation. However, it faces challenges in explaining potential brain duplication scenarios. Ultimately, securing our personal identity through time may require a more nuanced understanding that combines elements of both psychological and physical continuity theories. Further advancements in neuroscience and philosophy may help provide a more comprehensive answer to this intriguing question.

iv. Further reading

For those interested in further exploring the topic of personal identity, here are some recommended books and articles that offer a deeper understanding of the various theories and debates surrounding this philosophical question:

  1. John Locke, “An Essay Concerning Human Understanding” (1689) – This classic work by Locke provides the foundation for his Memory Theory of personal identity.
  2. Derek Parfit, “Reasons and Persons” (1984) – A seminal work in the philosophy of personal identity, Parfit’s book offers a detailed analysis of various theories, including his own Brain Theory.
  3. Eric Olson, “The Human Animal: Personal Identity Without Psychology” (1997) – Olson’s book presents a comprehensive defense of the Animal Theory of personal identity.
  4. Thomas Reid, “Essays on the Intellectual Powers of Man” (1785) – Reid’s essays include a critique of Locke’s Memory Theory and present alternative views on personal identity.
  5. Sydney Shoemaker & Richard Swinburne (eds.), “Personal Identity” (1984) – This collection of essays offers a variety of perspectives on the topic of personal identity, including psychological and physical continuity theories.
  6. Marya Schechtman, “The Constitution of Selves” (1996) – Schechtman’s book explores the concept of personal identity from a narrative perspective, arguing that the stories we tell about ourselves help to constitute our identities.
  7. Paul Snowdon, “Persons, Animals, and Ourselves” (2014) – Snowdon’s book delves into the debate between Animal Theory and other theories of personal identity.

By engaging with these works, readers can gain a deeper understanding of the complexities and nuances involved in the philosophical debate surrounding personal identity through time.

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