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Thesis Parfit was right: identity is not what matters in survival

Ethan Mercer Fellow
· 6 replies
Personal identityAnalyticBuddhistAbhidharmaDerek ParfitThe Buddha#duplication#parfit#relation-r#what-matters
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Where it stands

I'm the resident sceptic in my effective altruism group, but on this one I'm a believer, so bring your best objections.

Parfit's argument in Part III of Reasons and Persons (1984), roughly:

  1. Suppose your brain is divided and each half placed in a different body. Both resulting people are psychologically continuous with you.
  2. They can't both be you: they are two people with different futures. And there's no reason to say one is you rather than the other.
  3. So you don't survive as either, strictly speaking. But each of them has everything that ordinarily matters to you about survival: your memories, character, intentions, carried forward with the right kind of cause.
  4. Double success can't be worse than single success. So what matters is not identity. It's psychological connectedness and continuity, which Parfit calls Relation R.

I think this is right, and I think it has consequences. If R comes in degrees, then my relation to myself in forty years is weaker than I assume, which makes the gap between prudence and concern for others smaller than common sense says. Parfit himself said accepting this made him less concerned about his own death and more concerned about others.

Objections welcome. I suspect the strongest will come from people who think the duplication case is incoherent, or that being the same organism is what matters.

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6 replies

For the thesis 1

  1. Nirmala Jayasekara

    For Fellow

    I am mostly on your side, with a caution. Parfit noticed the resemblance to the Buddha's teaching himself, and quoted Buddhist texts in an appendix. But the resemblance can mislead. Anattā is not offered as a conclusion about what matters in survival. It is offered as a diagnosis of craving, as part of a path. The Buddha does not say "you will not survive, so care about others", he says that clinging to a self is the root of suffering. Same metaphysics, perhaps; different purpose.

Against the thesis 3

  1. Ikechukwu Anyanwu

    Against Fellow

    I'll take the organism. Step 2 assumes that if you have two equally good candidates, neither is you. But if what you are is a living human animal, then the brain-splitting case is one in which the organism you were is destroyed and two new ones made, and you did not survive. That is not double success, it is death with excellent successors. The thought that this is "as good as ordinary survival" only follows if you already accept that psychology is what matters.

    Helpful · 1
    1. Ethan Mercer

      Fellow

      Ikechukwu, that's the cleanest version of the objection, and I can't fully answer it. But consider: if your cerebrum were transplanted into another body and the old body kept alive in a coma, most people think they'd go with the cerebrum, not stay with the organism. That intuition seems to favour psychology over the animal.

      Helpful · 2
  2. Brian Otieno Ouma

    Against Fellow

    One man in my prison reading class, twenty-two years in, said of the boy who committed his crime: "I would not let that boy into my house." Parfit actually considered whether reduced connectedness could reduce desert for crimes long past. My men find that idea both a hope and an insult. A hope because they have changed. An insult because the victims' families have not stopped being the families. I'm against, but only half.

    Helpful · 3
  3. Arjun Iyer

    Against Fellow

    Against, from the Advaita side, though not for Ikechukwu's reason. Parfit's reductionism treats the self as nothing over and above the stream of psychological states. Vedānta holds that there is a witness to the stream which is not itself one of the states. You may say that is unverifiable. But Parfit's "what matters" is also a claim about value, not something read off from the cases.

Other replies

  1. Ethan Mercer

    Fellow

    Revised position: the duplication argument shows that psychological identity can't be what matters, because R can branch while identity can't. It doesn't by itself show that being the same animal is unimportant. So the argument is stronger against Locke's heirs than against Ikechukwu. Brian's point I'll have to sit with.

    Helpful · 1