Parfit argues that personal identity and psychological continuity cannot both be what matters in survival because the former cannot admit a degree, whereas the latter can. Parfit takes a reductionist view of personal identity reasoning that what is of importance is facts concerning brains, bodies, and physical and mental events; we should not be concerned with another sense of identity that cannot necessarily be explained by physical brain activity.
I argue that psychological continuity and personal identity are not mutually exclusive, as Parfit might suggest. In fact, both are necessary for survival. Personal identity relies on psychological continuity and connectedness but it is also something else in itself, and it is Parfit`s failure to acknowledge this that renders his argument unsuccessful.
This essay will first look into Parfit's argument and his thought experiment presented in his essay Personal Identity, then discuss the successful aspects to his argument such as its ability to withstand criticisms such as the multiple occupancy view. I will then address the key issues to Parfitâs argument. Most prominently, I will reason that his approach is too reductive and fails to account for an essential pre-theoretic notion that we hold regarding our personal identity - that we intuitively define ourselves to be more than just the psychological connectedness and continuity of memory and characteristics.
Parfit on Identity
Parfit uses a causal theory, pioneered by Locke, to argue that psychological continuity, even when unaccompanied by personal identity, contains all that matters to us about our own survival. Note, the Psychological Criterion has given by Parfit:
- There is psychological continuity if and only if there are overlapping chains of strong connectedness. X today is one and the same person as Y at some past time 9 if and only if
- X is psychologically continuous with Y,
- this continuity has the right kind of cause, and
- it has not taken a branching form.
- Personal identity over time just consists of the holding of facts like (2) to (4).
On a surface level, the matter of continuity of memory makes logical sense and fits in well with our pre-theoretic notions of self: I am the same person as my younger self, not because I am physically identical, but because there are overlapping chains of memory. Even if I and earlier me don't share any specific memories, there's a chain by which old me had a set of memories, then a day later lost some and gained some, and so on going forward to the present.
For Parfit, the question of personal identity when it comes to survival is a non-issue because all that makes up a person is psychological continuity and connectedness. Parfit reasons that identity is a relation that does not admit a degree: you either are or are not yourself. Whereas a relationship of mental continuity and connectedness is not quite so formal. Instead, it allows degree and variety and we can imagine cases in which it is present to a degree so slight that survival is questionable. This seems more an adjustable approach to such complex topics.
The Problem of Fission
My body is fatally injured, as are the brains of my two brothers. My brain is divided, and each half is successfully transplanted into the body of one of my brothers. Each of the resulting people believes that he is me, seems to remember living my life, has my character, and is in every other way psychologically continuous with me. And he has a body that is very like mine.
Let the person who has the left hemisphere of my brain be Lefty. Let the person who has the right hemisphere be Righty. There are only three possibilities in a fission case: (a) I do not survive. (b) I survive as either Lefty or Righty. (c) I survive as both. Since there are overlapping chains of strong psychological connectedness between me (on the one hand) and both Lefty and Righty (on the other), the Criterion of Psychological Continuity predicts that I am both Lefty and Righty.
Parfit proposes that it makes sense to think of someone surviving after having his or her brain transplanted into a new body because the resulting person has [the original person`s] character and apparent memories Parfit thinks that we must say that the person survives as two persons, we should separate survival and an overarching sense of personal identity since the two resulting persons are clearly not identical.
This is problematic, it seems completely counterintuitive for us to suggest one person can survive as two distinct persons. David Lewis tackles this with his view of multiple occupancies. According to Lewis, before the brain transplant, both Lefty and Righty occupy the same body. After the transplant, they occupy different bodies. So, before the transplant, what I take to be myself is in fact two different persons - Lefty and Righty - who coincide.
Despite seeming to overcome the issue of one person's survival as two different people, this can be criticized. There is a consequence of this view which also seems counterintuitive and unresolved: In cases of fission, before the fission happens, when someone uses the first person I, it`s not clear whether they pick out any unique person. For instance, in the transplant example, before the operation, when I use the word I, it`s not clear whether I thereby pick out Lefty or Righty. This remains unexplained and therefore renders this approach unhelpful in our response to Parfit.
Perhaps a better way to deal with Parfit`s thought experiment is by revising the original criterion. We can say: a person X at t1 is identical to a person Y at t2 if; (i) there is an overlapping chain of strong psychological connectedness between X and Y, and; (ii) There is no other person Z at t2 such that there is an overlapping chain of strong psychological connectedness between X and Z. So, according to the Revised Criterion, I am neither identical to Lefty nor Righty I do in fact die after the transplant.
The Problem of Identity
Having analyzed the thought experiment, I will now deeper discuss the more prevalent issues Parfit`s reasoning raises. The first is - if there is no overarching identity to a person, to what degree can we say we survive or not? Despite praising psychological continuity for its ability to admit a degree, there is no specification of degree that is put in place by Parfit to say how much psychological continuity is necessary for your survival as the same person.
This brings us to the question of quasi-memories: the phenomenon where we believe memory to be our own but really it is fabricated from other experiences. Certain cases of source amnesia involve a subject who comes to believe, on the basis of hearing a story for example, that he or she has actually experienced the events of the story. Thus, it is possible to remember experiences that actually happened to another person. Similarly, it is common for character traits to rub off onto others with whom one has close contact. Imagine two friends, A, and B, such that both of these scenarios obtain. B has at least one of A`s traits and at least one of A`s memories. Parfit`s conditions lead to the unintuitive result that A will have survived as B. Parfit needs to supplement his account by saying to what degree of psychological connectedness must be obtained in order to count as survival, or his theory predicts that one can survive as another person without dying.
And yet, we are still left with a key question for Parfit: who, if anyone, is A? Take the fission example, is person A simply a combination of phycological and physical events that hold a certain level of continuity? Is person A a mix of both lefty and righty, even when they go on to live distinct and separate lives? If so, who was A to begin with, were they always two people in one? (the multiple occupancy view).
Parfit believes this question is unimportant: Certain important questions [regarding survival, memory, and responsibility] do presuppose a question about personal identity. But they can be freed of this presupposition. And when they are, the question about identity has no importance.
Parfit avoids the question of what exactly is personal identity. His response to this matter is not satisfactory and suggests things that go against our pre-theoretic notions of how we would define ourselves as surviving. Would we say that we, personally, survive as those shared character traits or memories in our family or close friends? Most commonly, people would say no. We would attribute something more to ourselves, that is to say, our personal identity, that would distinguish us as surviving as our individual selves compared to surviving as memory or trait. Parfit`s fatal flaw is in his avoidance of this fact, rendering his approach far too reductive for such a complex discussion of self and personal identity.