2.3: Removing “identity” from “persons”- Derek Parfit

Reasons and Persons¹⁴

Reasons and Persons is a philosophical work by Derek Parfit, first published in 1984. It focuses on ethics, rationality and personal identity. His views on personal identity transformed how it is understood and used in philosophy, especially ethics. His view is briefly explained as follows:

At time 1, there is a person. At a later time 2, there is a person. These people seem to be the same person. Indeed, these people share memories and personality traits. But there are no further facts in the world that make them the same person.

Parfit's argument for this position relies on our intuitions regarding thought experiments such as teleportation, the fission and fusion of persons, gradual replacement of the matter in one's brain, gradual alteration of one's psychology, and so on. For example, Parfit asks the reader to imagine entering a "teletransporter," a machine that puts you to sleep, then destroys you, breaking you down into atoms, copying the information and relaying it to Mars at the speed of light. On Mars, another machine re-creates you (from local stores of carbon, hydrogen, and so on), each atom in exactly the same relative position. Parfit poses the question of whether or not the teletransporter is a method of travel—is the person on Mars the same person as the person who entered the teletransporter on Earth? Certainly, when waking up on Mars, you would feel like being you, you would remember entering the teletransporter in order to travel to Mars, you would even feel the cut on your upper lip from shaving this morning.

Then the teleporter is upgraded. The teletransporter on Earth is modified to not destroy the person who enters it, but instead it can simply make infinite replicas, all of whom would claim to remember entering the teletransporter on Earth in the first place.

Using thought experiments such as these, Parfit argues that any criteria we attempt to use to determine sameness of person will be lacking, because there is no further fact. What matters, to Parfit, is simply "Relation R," psychological connectedness, including memory, personality, and so on.

Parfit continues this logic to establish a new context for morality and social control. He cites that it is morally wrong for one person to harm or interfere with another person and it is incumbent on society to protect individuals from such transgressions. That accepted, it is a short extrapolation to conclude that it is also incumbent on society to protect an individual's "Future Self" from such transgressions; tobacco use could be classified as an abuse of a Future Self's right to a healthy existence. Parfit resolves the logic to reach this conclusion, which appears to justify incursion into personal freedoms, but he does not explicitly endorse such invasive control.

Parfit's conclusion is similar to David Hume's view, and also to the view of the self in Buddhism, though it does not restrict itself to a mere reformulation of them. For besides being reductive, Parfit's view is also deflationary: in the end, "what matters" is not personal identity, but rather mental continuity and connectedness.

The “Identity Doesn’t Matter View”¹⁵

David Shoemaker has written an excellent explanation of Parfit’s views and their implications. They are located in his entry on “Personal Identity and Ethics” in the free Stanford Encyclopedia of Philosophy, which is a wonderful resource that you should read if you are interested in doing so. The quoted sections from his article that follow below along with my commentary and explanation are from Section 2.5 on “The Identity Doesn’t Matter (IDM) View”

John Locke’s view on personal identity, often called the “Lockean Memory Theory of Personal Identity” is exactly as the name sounds: our personal identity is tied to our memories in one way or another, and we have periods where we are conscious and make memories and periods where we are not (when we are sleeping, for example), and our identity consists of the whole of these memory-making moments. Derek Parfit generally agrees with this view on personal identity since it seems to match up with how we conceive of ourselves. On top of this, as Shoemaker explains, “He is a ‘reductionist,’ according to which the facts about persons and personal identity consist in more particular facts about brains, bodies, and series of interrelated mental and physical events (Parfit, Reasons and Persons, 1984, 210–211). The denial of reductionism is called ‘nonreductionism,’ according to which the facts about persons and personal identity consist in some further fact, typically a fact about Cartesian egos or souls.” Basically, this means that Parfit denies anything like a “soul” and thinks we are identical to something we can quantify, measure, and point to directly that is associated with our memories.

To begin explaining why Parfit doesn’t think that identity matters in survival (that is, how “we” continue to exist as ourselves from moment to moment and day-to-day), Shoemaker says that Parfit “suggests at times that the most plausible reductionist criterion of personal identity is the Psychological Criterion. As we saw earlier, this criterion maintains that in order for X to be identical to Y, X must be uniquely psychologically continuous with Y. Psychological continuity is potentially a branching, one-many relation, i.e., it could conceivably hold between me-now and more than one person in the future. But identity is an equivalence relation — it is reflexive, symmetrical, and transitive — so it holds only one-one. Thus only by including a ‘no branching’ clause can this criterion of identity avoid a crippling contradiction.”

Along with the transporter experiment, Parfit outlines a “fission” experiment to help bolster his claim that identity doesn’t matter in survival. It works like this: assume that your brain exists in two halves (which they do, and they are called “hemispheres”) and that both of these halves are identical to each other (which isn’t a stretch, as this is hypothetically possible with how our brains can work). Now, you also happen to be one member of a set of triplets, and at the same time your body gets irreversibly damaged, your brothers’ brains get irreversibly damaged. Half of your brain is then transplanted into each of the brothers. “You” would not be “split” into two identical parts. So where did “you” go? As Shoemaker puts it, “If we lack the “no branching” clause, we are forced to say that, because both brothers are psychologically continuous with me, they are both me. But then (given the transitivity of identity) both survivors would also have to be identical to each other, which seems obviously false…” So, if identity means there can be only one of you, then there’s a problem. Are you both of them? Neither? Are you dead? You can’t be identical to either of them since picking one over the other would be arbitrary. However, it does seem that “you” survived in a very important sense.

Shoemaker continues,

“But is this like an ordinary case in which I don't survive, i.e., like death? Clearly not: both survivors will seem to remember my thoughts and experiences, they will fulfill intentions I had in action, they will have the same beliefs/desires/goals as me, and their characters will be exactly like mine. Indeed, it will be just as if I had survived. Everything that matters in ordinary survival (or nearly everything), therefore, is preserved in fission, despite the fact that the identity relation is not. What this must mean, then, is that the identity relation just is not what matters (or is not what matters very much) in survival; instead, what matters has to consist in psychological continuity and/or connectedness (what Parfit calls “Relation R”). As long as that relation holds between me-now and some other person-stage — regardless of whether or not it holds one-one — what happens to me is just as good as ordinary survival. Call this the Identity Doesn't Matter (IDM) view.”

What all this means is that our unique survival might not matter, and that identity then isn’t as important as we thought, and that what matters is that things that are closely related to us using “Relation R” are what matters. This could have a drastic impact on how we approach our lives, ourselves, others, and those things we value in the world. As Shoemaker explains the implications,

“So let us assume that Relation R grounds our patterns of concern. Consider, then, prudential rationality. While it is ordinarily thought to be imprudent to discount the interests of one's Much Later Self (MLS) just because that self will not come into existence for a long time, Parfit suggests that reductionism provides a different, more plausible reason to do so. Since one of the relations in R (connectedness) obtains by degrees, it is very likely it will obtain to a much reduced degree between me-now and my MLS than it will between me-now and my tomorrow's self. But if R grounds my patterns of concern, and a reduced degree of connectedness is one part of R, then a reduced degree of connectedness justifies a reduced degree of concern. Thus, I may be justified in caring much less about my MLS than about my tomorrow's self. This conclusion justifies discounting my MLS's (expected) interests in favor of my present interests.

Of course, given that we still think great imprudence is wrong, how might we criticize it if we made these revisions to our practices? One way to do so would be to recognize that, since my MLS would really be more like a different person than me, he should be treated as such, i.e., how I treat him should now fall under the rubric of morality, and insofar as it is wrong to harm others without their consent, it would be wrong for me to harm him as well. Great imprudence like this, in other words, would be immoral (Parfit 1984, 318–320).”

This results in something quite enlightening since it helps us understand why we might conceive of our past and future selves as very different than our current selves. It also gives real meaning to the phrase “he’s a different person than he used to be.” It also means that we can truly survive the death of our bodies and brains if we survive in others and through our works. Derek Parfit (the man) passed away New Year’s day in 2017, but he still survives in the ways he found most meaningful through his work and influence.