Obviously, the continuity of personal identity is not the same thing as absolute identicalness. No person is purely identical with his or her past self, neither physically nor psychologically. So it’s clear that “identity” here doesn’t have a mathematical sense.
It also doesn’t have the sense it has in claims that two words have the identical meaning, or that water and H2O are identical, etc.
Rather, we’ve got a slight conflation of identity as sameness, and identity in the sense of who I am, how I and others identify me. My identity is, among other things, the parts of myself, including my moral outlook, that I would think of as essential to who I am, and, alternately, the parts of a person that others think of as essential to who that person is. The question of personal identity then is somewhat complex, and somewhat confused in bringing together identicalness with who or what I identify with, or what others identify me with.
Since we can’t have absolute identicalness of a person across days or weeks or years, what we’re usually asking is about the degree of identicalness of a personal identity. That is, when a person changes, as we all do, we sometimes need to ask“how much sameness is enough?” And that question, because of its vagueness, is not something that there’s a pre-made answer for. Rather, we have to decide it on a case by case (or category-by-category) basis, and we have to know “enough for what?”
For legal purposes, a complete change in the material component of the body is not necessarily a hindrance to sameness, assuming the old saw about changing all the parts of one’s body after seven or twelve or some number of years is true. Rather, an organismic continuity and some degree of psychological continuity are what count.
But the forensic has perhaps been overused as the paradigm for the “enough for what?” question in continuity of identity. Recently, Jesse Prinz and Shaun Nichols did some survey research showing that people have less identity with continuity of memory or continuity of body than with continuity of moral principles and personality (unpublished as yet; this matches a claim I made in “You Are Not the Person I Knew” in Appraisal, vol. 9 no. 1) This would be a somewhat surprising result, since most of the philosophical literature points to memory or body as the basis for continuity. But, if this research and my guesses hold true, people don’t want to identify with an entity that carries on their memory and bodies but does not carry on their moral values and personality.
This change is almost certainly not relevant for legal culpability or forensic purposes in general. So when people said these changes were not “identity preserving,” they clearly had something else in mind.
Further, some change in moral perspective will not be identity destroying, whereas some changes will be. So this brings up the “enough” question. How much is enough?
Let’s take a case:
Myra and Enid are married. At the time, both are supporters of the rights of gay women to marry each other, both are strong libertarians, both attend a Baptist church regularly, and both believe that a loving adoration of Jesus Christ is the surest path to heaven, though, contrary to some church teachings, they hold that good works can be sufficient. Further, both do charitable work every weekend, and both are huge fans of the Star Trek franchise, attending Star Trek conventions at least twice a year.
Now suppose that Myra, in her exploration of libertarian ideals, begins to believe that Ayn Rand’s ideas on selfishness are proper. This contrasts with Enid, who thinks that libertarians should take responsibility for the poor by doing and giving to charity, even though she thinks the government should not be involved in this enterprise. We could imagine this causing a rift between Myra and Enid, but would it be enough for Enid to claim that Myra has changed beyond recognition, or has lost the identity that Enid fell in love with?
Maybe. Maybe they still go to Star Trek conventions, even though Myra no longer attends church (as a Randian atheist, she is opposed), no longer does charitable work, and no longer believes that loving Jesus or good works are paths to salvation. Clearly, a great deal of their shared identity has been severed. There were causes and goals and ideals that they identified with that Myra no longer identifies with.
And maybe Enid will say that that’s enough, that she can’t be with Myra anymore. If so, it’s because the Myra she fell in love with has changed so much that Enid no longer sees her in the Myra she is currently married to. She might well say, “It’s like I don’t know you anymore.” And in a sense that’s true: Enid used to know Myra’s moral landscape as though it were her own. Now it’s a puzzle, and a frustrating one. It really is true, in an important sense of “same person” (though obviously not in a forensic sense) that Myra is not the person that Enid married.
So in this case, my point is, “enough” comes down to the participants. It’s not for a philosopher to tell Enid that Myra is still the same person, or is not the same person. That’s up to Enid.
But imagine that Myra and Enid both became Ayn Rand advocates. They might change together. Then this question might not arise. However, they might look back on their charitable, church-going former selves and say, “I hardly recognize the people we were.” They may indeed have trouble identifying with their former selves, feeling embarrassment at their old moral code, and no longer understanding how they could have believed such things. Again, if they make this claim about themselves, that’s up to them.
Or, they might think of their journey to Randian “objectivism” as continuous with their early exploration of libertarianism, and may think of their earlier selves as continuous with their current selves, though a bit naïve. Or they may have trouble identifying with some of their beliefs, but not others, seeing themselves partially reflected in, and partially alien to, their former selves.
Sometimes, we are asked to identify ourselves, and sometimes we can rightly say, “I don’t even know that person anymore,” when referring to a past iteration of ourselves. And sometimes we are asked to identify a friend or lover, and we can rightly say, “I don’t even know that person anymore,” when she is standing right in front of us.
One last note on change: a parent recently told me that she missed her infant daughter and mourned her loss, as her daughter was now 5 years old. It’s not that she didn’t love the five-year-old. She did! But she missed the baby that, in a very real sense, had ceased to exist. There was no great connection between the five year old and the baby. They form part of the continuous history of an organism, but there was nothing in particular about the personality, appearance, or even the physical make-up (as I understand it, children move through the matter of their bodies fairly quickly) that necessarily linked them.
So I don’t think the mother was wrong in thinking that the infant was gone. I could, distantly I guess, not being a parent, understand that one would mourn the loss of the completely needy, sweet-smelling, bald, non-linguistic creature of 6 to 10 pounds weight and less than two feet length that always wants to be held, while still appreciating the more independent, 45-inch tall child with long hair that sometimes pushes away from a hug or tries to explore on her own, shutting out the mother.
What I’d like to get at here is a sense of the “enough” and “enough for what” that reflect what we value, and how people, in daily life, divide up the world. I’d like to say more, too, about the prospect of changing together, and the way in which we do identify ourselves across change. I think Parfit’s example of the Russian Nobleman (Reasons and Persons, 327-328) is a good starting point for this: Schechtman’s discussion of this in “Personality and Persistence” (American Philosophical Quarterly, Vol. 41, No. 2, Apr., 2004, pp. 87-105) and Christine Korsgaard’s discussion in Creating the Kingdom of Ends (p. 207-208; Cambridge, 1996) form interesting commentaries. I’ll try to tackle these in a later post, and expand on the question of how we maintain identity across change, while also losing identity across change.