The concepts we are concerned with are those of responsibility andguilt,qualified as ‘moral’, on the one hand—together with thatof membership of a moral community; of demand, indignation,disapprobationand condemnation, qualified as ‘moral’, on the other hand—togetherwith that of punishment.
These sketches suggest the possibility, then, of a of relations between identity and ethics. If so, perhaps the way toproceed is to focus on one specific person-related practical concernat a time and work out its precise relation to identity (if any)before moving on to others. While this approach may not diminish thecomplexity of the relation(s) between identity and ethics, perhaps itwill at least provide the kind of settled views in some limited areaswhich we have thus far been missing.
For some authors, however, the role of our normative commitments in this debate is much stronger: they may actually authoritatively constrain, shape, or even be immune or irrelevant to one's theory of personal identity. This is a general methodological dispute about theproper direction of argumentation in the arena of personal identity and ethics. The assumption of many working in this arena has been evident in the discussion thus far: we work out or identify the correct theory of personal identity and then apply it where needed tothe world of ethics. What we will briefly explore in this section, though, are four importantly different approaches (these are not exhaustive of the alternatives, however).
Recall that both Reid and Butler objected to Locke's account of personal identity, in part, because they thought it had absurdly revisionary implications for our practices of moral responsibility. So rather than give up those practices, they said, we would be betteroff giving up Locke's theory. On this view, our normative commitmentsprovide an important check on our theories of personal identity. Nevertheless, the consideration about moral responsibility is only one of many objections both critics run against Locke. They also launch purely metaphysical objections as well, the thought being that Locke's view fails both on its own terms and in light of its absurd normative implications. So actually, while our normative commitments provide an important consideration that the theory of personal identity should account for, it remains open that such commitments could be overridden or revised, depending perhaps on the independent plausibility of the theory in question.
There are at least four other areas of applied ethics that seem to bear a relation to personal identity, and we will lay out the issues of each very briefly. First, there is a problem of justifying therapeutic treatment for patients with Dissociative Identity Disorder (DID, formerly known as Multiple Personality Disorder). The worry here comes from the attractive thought that each of the distinct personalities of someone with DID is in fact a different (Wilkes 1988; Dennett 1976). If so, then a therapy that aims at one or more of the alter personalities infavor of one of them would be, prima facie, immoral. (Morton Prince, one of the first psychologists to work with a DID patient, wrote thathis aim was indeed to kill off what he thought of as the “non-real” personalities of his patient, Christine Beauchamp. See Prince 1905.) But this verdict is quite counterintuitive: surely the therapist is the patient with DID when his work produces only one healthy personality, not doing anything immoral. The issue, then, is about the moral ramifications of cutting off personal identity in an unusual sort of way. In addition, there are intriguing issues regarding identity and both legal and moral responsibility in patients with DID. What if onealter commits a crime, say? Is the patient with DID responsible or isonly the offending alter responsible? If the latter, how is a fair punishment to be effected? (For further discussion of these issues, see Wilkes 1981, 1988; Hacking 1991, 1995; Lizza 1993; Braude 1995, 1996; Radden 1996; Sinnott-Armstrong and Behnke 2000; Kennett and Matthews 2002; and DeGrazia 2005).
This criterion of identity (and its variants) has been taken to fitparticularly well with our practical concerns, both self-regarding and other-regarding. For instance, what seems to matter for self-concern and rational anticipation is that my psychological life continue. Anticipation and self-concernare psychological states, as are their objects (future experiences),so a theory of identity that ties those states together by virtue oftying distinct stages of me together seems initially quiteplausible. In addition, concerns having to do with moralresponsibility are also about the relations between variouspsychological states — including intentions to perform actions,memories of past doings, desires and beliefs explaining actions, andso forth — and so if personal identity is a necessary conditionfor moral responsibility, the Psychological Criterion provides aplausible and satisfying account of that condition: I cannot beresponsible for the actions of some person if I'm not the inheritor ofthat person's psychology.
What could motivate alternative approaches to our identity, then,given the seeming successes of the Psychological Criterion? Oneimportant problem stems from worries about our essence. Forinstance, I am many things, including an adult, a professor, a driver,a voter, and so forth. None of these is my essence, however, for Ieither did or could exist without being them. If we could identify myessence, however (and generally the essence of individuals like me),we would be able to identify the conditions for my persistence acrosstime as well. Now the Psychological Criterion seems to implythat personhood is my essence, that I couldn't exist withoutbeing a person, and given that personhood is a psychological matter,psychological continuity is what preserves my identity. But as EricOlson and others have pointed out, this seems quite wrong (Olson1997a, 1997b, DeGrazia 1999a, 1999b, Carter 1982, Snowdon 1990,Wiggins 1980). After all, just as I was once a teenager, and beforethat an adolescent and a child, wasn't I also an infant, andultimately a fetus? Furthermore, suppose I were in a horrible accidentand went into a permanent vegetative state (PVS). Wouldn't Ithen be in a PVS? If so, then if personhood necessarily involveshaving a certain sort of developed psychology (e.g., a psychologycapable, at the least, of self-reflection), it can't be my essence;instead, being a person would be like being a child, or a teenager,something one becomes and may also outlive (called a “phasesortal” in the literature).
If personhood isn't my essence, then what is? The most plausible answer seems to be that I am a biological organism, a human animal. And if this is my essence, it will also provide the conditions of my persistence across time. From this move, then, we get the Biological Criterion of Personal Identity: if X is a person at t1, and Y exists at any other time, then X=Y if and only if Y's biological organism is continuous with X's biological organism (Olson 1997b, DeGrazia 2005). Note that Y may or may not be a person, which allows that X might be one and the same as a fetus or someone in a PVS. This view is also sometimes called animalism (e.g., Noonan 1998, Olson 2003).
Consider, then, this criterion of our identity. While it obviouslydoes well with the essence question, it seems to do less well when weconsider its relation to ethics. Again, what seems to ground therationality of my anticipation of future experiences is the fact thatthat future person will be the inheritor of my psychology. That he'salso the inheritor of my biological organism seems irrelevant. Indeed,our reactions to certain thought experiments strongly suggest that wethink rational anticipation, self-concern, moral responsibility, andthe like can be justified even in the absence of biologicalcontinuity. We can see this most dramatically in consideringthe transplant intuition (Olson 1997b, 43–51, DeGrazia2005, 51–54). Suppose my cerebrum were transplanted into adifferent living body and the resulting person turned out be exactlylike me psychologically. Suppose also that my cerebrum-less organismwere kept alive. What would have happened to me? Most people share theintuition that the recipient of my cerebrum would be me, simplybecause he would have my psychology and survival of my psychologyseems to be what matters in my survival. The advocate of theBiological Criterion, however, has to maintain that I remain thecerebrum-less donor, essentially in a PVS, while the other person— the person who seems to remember my experiences, and seems tobe carrying out my intentions, and seems just like me psychologicallyin every respect — is just a deluded imposter. But this is hardto believe. Suppose further that I had committed some crime and thendonated my cerebrum in this way. The person who woke up would seem toremember my crime and anticipate enjoying getting away with it for awhile, but if identity is what's necessary for responsibility, hecould not be responsible for my actions, on the Biological Criterion,and so he wouldn't deserve blame or punishment for the crime. Again,this seems hard to believe. What accounts for the practical concernswe have seems to be grounded in psychological relations, and theBiological Criterion thus targets a relation for identity that is justirrelevant for those concerns (a key exception will be discussedlater, however).
Putting all these replies together, then, we have The Psychological Criterion of Personal Identity: X at t1 is the same person as Y at t2 if and only if X is uniquely psychologically continuous with Y, where psychological continuity consists in overlapping chains of strong psychological connectedness, itself consisting in significant numbers of direct psychological connections like memories, intentions, beliefs/goals/desires, and similarity of character (Parfit 1984, 207). We will see the meaning and importance of the “uniqueness” clause later.