by Tim Sommers
One time, this guy handed me a picture of him and said, ‘Here’s a picture of me when I was younger.’ Every picture is of you when you were younger. – Mitch Hedberg
There’s synchronic identity, what makes you, you at a particular moment in time – say, now. And there’s diachronic identity, what makes you, you over time. For example, why are you now the same person as when you were twenty-five years old or five (if you are)? These two perspectives – synchronic and diachronic – are deeply interdependent, of course, but philosophers tend to focus on diachronic identity since what is essential to you being you is, presumably, whatever it takes for you to continue to exist. Here are some theories.
You are your soul.
The trouble with this theory is not that it usually has a religious basis. That might be trouble later, but initially the trouble is that it is not very helpful. I am my soul. So, what’s my soul? Is the soul some mysterious, ghostly thing or a Platonic form or is it just whatever is essential to who I am? If the answer is that the soul is whatever is essential to who I am, this seems like just a restatement of the question.
Keep in mind, the great innovation of Christianity was not the soul, an idea that’s been around at least since Plato and Aristotle (who thought we had three souls). The Christian innovation was bodily resurrection.
You are your ego.
The ego may just be the secular soul. Descartes’ version of the ego theory, the most influential, is that a person is a persisting, purely mental, thing. But like the soul it’s hard to unpack the ego in an informative way. It is whatever unifies our consciousness. We survive as the continued existence of a particular subject of experiences, and that explains the unity of a person’s life, i.e., the fact that all the experiences in this life are had by the same person. This is circular, of course. Further, on this view, what happens if I fall into a dreamless sleep? Or get hit on the head and black out? Go in and out of a coma? Am fully anesthetized? When I wake up and start having experiences again, how do I know I am the same ego? How do I know that the ego is a persistent thing at all? Later, we will see what Hume has to say about this.
In the meantime, we are going to need a better theory of the ego or soul before either is going to be useful as a theory of personal identity.
You are your body.
Believe it or not, in Modern Philosophy, “animalism” – the view that you are your body – is a latecomer to the party. It’s easiest to explain by comparison. Suppose we take the anti-animalist view that identity is some kind of psychological, rather than physical, continuity. Here’s one animalist counter argument. Fetuses, at least early on, have no mental capacities. You can’t be psychologically continuous with a being that has no such capacities. But you used to be a fetus. So, whatever you are, it’s not a matter of psychological continuity.
I am not sure about this argument. Carl Sagan used to say, “We are made of star stuff…The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars.” But notice, he doesn’t say that we used to be star stuff. Did we also use to be an unfertilized egg and a sperm at the same time?
I am not sure that settles the argument, but here’s a broader challenge.
You are your brain.
I like to call this view reductive neuro-animalism. But no one else in the world calls it that, so I probably shouldn’t.
Suppose identical twins are in a car crash together. Twin A has their body destroyed, except for their brain, and Twin B has their brain destroyed, but their body is fine. Surgeons manage to put Twin A’s brain into Twin B’s body and save one of them. But which one?
By volume, Twin B makes up the bulk of the survivor. But the brain is A’s brain. If you think that A is the survivor, that suggests that you believe that you are not your body as a whole, but one specific subpart. You are your brain.
You are your memories.
There are a number of pretty science-fictional challenges to the view that you are your brain. If you can be uploaded into a computer, teleported, or bodily resurrected, then you are probably not your brain. But let’s keep it simple.
Suppose one day we can treat certain brain issues by swapping out some biological neurons with artificial ones. Suppose over a long period of time you are treated until the point where none of your neurons are your original neurons. If you remain psychologically identical (or differ only in small, natural ways), are you still the same person? If so, you are not your brain.
The most influential psychological theory of identity is John Locke’s memory theory. You are the same person over time because of your memories. They make you, you. Here are two problems with that.
You don’t remember so much. You probably don’t remember being five, maybe, not even twenty-five (if you are old enough). We could just say if you lose enough memories, you are not you. But one worry is that most of us don’t have enough memories to count as a continuous person over our complete life. A possible fix is the idea of chain-connectedness. I don’t have to remember being five to be that person. I can remember being a twenty-five-year-old person who remembered themselves as five.
There’s a weirder problem. As it stands, the memory theory, like the ego theory, is circular. What makes me, me, is the memories that I have. Notice the “I.” I need the memories to be mine. But that means I need to define “mine” before I attribute memories to me.
One of the most influential responses to this problem is still weirder. Psychological continuity might be based on quasi-memories. Quasi-memories provide knowledge and/or acquaintance with past experiences without assuming that the rememberer and the experiencer are the same person. Maybe, all quasi-memories are also, in fact, regular old memories. Or maybe one day we will be able to share memories in some way. Either way, it’s not circular to say that psychological continuity is based on quasi-memories, rather than memories. Or, anyway, that’s what I have been told.
So, we could say…
You are your chain-connected, quasi-memories.
But memories hardly exhaust the categories of psychological continuities plausibly connected to our identity, including basic desires, character traits, tastes, thoughts, beliefs, and intentions. Since we don’t have to sort and pare this list down today, let’s keep it vague and say…
You are your chain-connected, quasi-psychological continuities.
So, there you go. That wasn’t as hard as you thought, right? Wait. Hume wants to say something.
“For my part, when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe anything but the perception…. If anyone, upon serious and unprejudiced reflection thinks he has a different notion of himself, I must confess I can reason no longer with him. All I can allow him is, that he may be in the right as well as I, and that we are essentially different in this particular. He may, perhaps, perceive something simple and continu’d, which he calls himself; tho’ I am certain there is no such principle in me.”
Derek Parfit calls this view the Bundle Theory. Buddha may have been the first bundle theorist. He taught “anatta” or the No-Self view.
The bundle theory does not deny that we are the confluence of a number of chain-connected, quasi-psychological continuities. They deny that these persist over an entire human life and that we can always distinguish continuities across person. We have quasi-psychological chain-connections with people who are not us, after all. Which means that there’s not always an answer (much less a binary answer) to the question of whether you are the same person over time. In fact, being you turns out to be a matter of degree.
I have said more about this elsewhere. But I will end here now. Or anyway the person that replaced me while I was writing this will end it here.