Topic 09 Parfit. 1995. Reductionism and personal identity

In-Depth Summary of "Reductionism and Personal Identity" by Derek Parfit: A PhD-Level Analysis

Parfit's paper delves into the complex issue of personal identity over time, exploring the implications of reductionism for our understanding of what constitutes the continued existence of the same person. He utilizes thought experiments, particularly the science fiction scenario of teletransportation, to expose our intuitions and beliefs about personal identity and challenge the assumption that it must be determinate.

Key Concepts and Arguments:

• Personal Identity vs. Qualitative Identity: Parfit distinguishes between numerical identity (being one and the same entity) and qualitative identity (being exactly similar). He argues that questions about personal identity are concerned with numerical identity over time, meaning what makes a person at one time the same person at another time.
• The Criterion of Personal Identity: Different criteria have been proposed for personal identity, such as bodily continuity and psychological continuity. Parfit argues that while these criteria are useful in ordinary cases, they face challenges in thought experiments like teletransportation, where bodily and psychological continuity can be separated or gradually diminished.
• Reductionism: Parfit advocates for a reductionist view of personal identity, which claims that a person's existence consists in the existence of a body and a series of mental and physical events. He distinguishes between three types of reductionism:
• Identifying Reductionism: This view equates persons with their bodies.
• Constitutive Reductionism: This view holds that persons are distinct from their bodies and mental events but are constituted by them.
• Eliminative Reductionism: This view denies the existence of persons as distinct entities, claiming that there are only bodies and mental events.
• The Physical Spectrum and the Problem of Determinate Identity: Parfit introduces the Physical Spectrum, a thought experiment involving the gradual replacement of a person's body with exact duplicates of their cells. This thought experiment challenges the assumption that personal identity must be determinate, as it becomes unclear at what point the resulting person ceases to be the original person.
• Reductionism and the Explanation of Identity: Parfit argues that reductionism provides a solution to the problem of indeterminate identity. He claims that questions about personal identity in cases like the Physical Spectrum are not about different possibilities at the level of what happens, but rather about different possible descriptions of a single course of events. We haven't decided which description to apply, hence the lack of a determinate answer.
• Personal Identity as a Linguistic Question: Parfit concludes that in cases where we know the facts about physical and psychological continuity, questions about personal identity become merely linguistic. They are about which description is most appropriate to apply, not about a further fact of reality.

Implications and Significance:

• Challenging Deep-Seated Assumptions: Parfit's reductionist view challenges our intuitive beliefs about the self and personal identity. It suggests that our sense of self as a continuous and unified entity might be an illusion, and that personal identity is not as clear-cut as we often assume.
• The Importance of Continuity: While Parfit argues that personal identity is not a further fact beyond physical and psychological continuity, he acknowledges the importance of these continuities for our sense of self and our practical concerns.
• The Role of Language: Parfit emphasizes the role of language in shaping our understanding of personal identity. He suggests that we should be cautious about the way we frame questions about identity and recognize that they might be more about linguistic conventions than about metaphysical realities.

Further Considerations and Debates:

• The Nature of Consciousness: Parfit's analysis focuses primarily on the physical and psychological aspects of personal identity. However, the question of how consciousness fits into the picture remains a crucial issue. How does consciousness relate to the physical and psychological continuities that constitute personal identity?
• Moral Responsibility and the Self: If personal identity is not as determinate as we often assume, what are the implications for moral responsibility? How can we hold individuals accountable for their actions if their identity over time is fluid and subject to change?
• The Value of Identity: Parfit's analysis suggests that personal identity might be less important than we think. If it is primarily a linguistic question, does it have any intrinsic value or significance beyond its practical and social functions?

Conclusion:

Parfit's paper offers a thought-provoking and challenging analysis of personal identity. His reductionist approach and focus on the role of language raise important questions about the nature of the self, the significance of continuity, and the implications for moral responsibility. While his conclusions might be unsettling to some, they encourage us to critically examine our assumptions about personal identity and explore alternative ways of understanding ourselves and our place in the world.

Parfit《还原论与个人同一性》论文精炼总结

Parfit 在这篇论文中探讨了个人同一性随时间推移而变化的复杂问题，并分析了还原论对我们理解“是什么构成了同一个人的持续存在”的影响。他利用思想实验，特别是科幻场景中的“心灵传输”，揭示了我们对个人同一性的直觉和信念，并挑战了“个人同一性必须是确定的”这一假设。

核心观点：

• **区分数值同一性和性质同一性：**Parfit 区分了数值同一性（作为同一个实体）和性质同一性（完全相似）。他认为，关于个人同一性的问题关注的是随时间推移的数值同一性，即是什么使得一个人在某个时间点与另一个时间点是同一个人。
• **个人同一性的标准：**关于个人同一性的标准有很多种，例如身体连续性和心理连续性。Parfit 认为，虽然这些标准在日常情况下很有用，但在心灵传输等思想实验中却面临挑战，因为在这些情况下，身体和心理的连续性可以被分离或逐渐减弱。
• **还原论：**Parfit 提倡一种还原论的个人同一性观点，认为一个人的存在由身体和一系列心理和物理事件构成。他区分了三种类型的还原论：
• **同一还原论：**将人等同于他们的身体。
• **构成还原论：**认为人不同于他们的身体和心理事件，但由它们构成。
• **消除还原论：**否认人作为独立实体的存在，声称只有身体和心理事件。
• **物理光谱与确定同一性问题：**Parfit 引入了“物理光谱”思想实验，即逐渐用细胞的精确复制品替换一个人的身体。这个思想实验挑战了“个人同一性必须是确定的”这一假设，因为在哪个时间点上结果人不再是原来的人变得不清楚。
• **还原论与同一性的解释：**Parfit 认为，还原论为不确定同一性问题提供了解决方案。他声称，在物理光谱等案例中，关于个人同一性的问题不是关于不同可能性在发生层面上的问题，而是关于对单一事件过程的不同可能描述的问题。我们还没有决定应用哪种描述，因此缺乏确定的答案。
• **个人同一性作为语言问题：**Parfit 得出结论，在我们了解身体和心理连续性的事实时，关于个人同一性的问题就变成了纯粹的语言问题。它们是关于哪种描述最适合应用，而不是关于现实的进一步事实。

意义和影响：

• **挑战根深蒂固的假设：**Parfit 的还原论观点挑战了我们对自我和个人同一性的直觉信念。它表明，我们对自我作为连续和统一实体的感觉可能是一种错觉，而个人同一性并不像我们通常假设的那样清晰。
• **连续性的重要性：**虽然 Parfit 认为个人同一性不是超越身体和心理连续性的进一步事实，但他承认这些连续性对我们的自我意识和实际关注的重要性。
• **语言的作用：**Parfit 强调了语言在塑造我们对个人同一性理解中的作用。他建议我们应该谨慎对待我们构建关于同一性问题的方式，并认识到它们可能更多地与语言惯例有关，而不是与形而上学现实有关。

Parfit 的论文提供了一种发人深省且具有挑战性的个人同一性分析。他的还原论方法和对语言作用的关注，引发了关于自我本质、连续性意义以及对道德责任的影响等重要问题。虽然他的结论可能会让一些人感到不安，但它们鼓励我们批判性地审视我们对个人同一性的假设，并探索理解我们自身和我们在世界中位置的替代方式。

Whether teletransportation would kill you depends on your definition of "you." If you believe personal identity is solely based on bodily continuity, then yes, teleportation would result in your death, as your original body is destroyed. However, if you subscribe to a reductionist view of personal identity, where continuity of consciousness and psychological connectedness are paramount, then the person who materializes on Mars, with your memories and personality, could be considered a continuation of "you." Personally, I lean towards the reductionist view. While the destruction of my physical body would be a significant event, the continuation of my consciousness and experiences would mean that "I" still exist, albeit in a different location and physical form. Therefore, while I acknowledge the strangeness of the process, I wouldn't necessarily consider teleportation as death, and the potential benefits of instantaneous travel might outweigh the metaphysical peculiarity of the situation.