Surviving Death. Take the Hibernators (see yesterday's post). They think they don't survive hibernation. The person who falls asleep dies, they think, and a new person wakes up three months later. By contrast, in Star Trek the crew thinks they do survive teletransportation. The Hibernators have a much more demanding notion of what it means for a person to be the same over time than the Star Trek crew. We (Johnston assumes--and I'm really not sure why) have a third notion--we would not want to get into the transporter, because we think it would kill us while generating a copy of us at our destination.
Johnston says the Hibernators, the Teletransporters, and us Human Beings differ in their dispositions. The Hibernators presumably feel bad about dying when they get ready to hibernate, instead of planning the next stage of their own lives, as we would. The Star Trek crew isn't concerned about stepping into the Teletransporter, as we might be. So...which of the tribes is right about personal identity?
Johnston says they're all really right in a fashion--the dispositions make for three forms of personal identity. Basically, there's no disposition-independent fact of the matter about whether any person survives hibernation or teletransportation. Should we go along with this?
A bit of medical anthropology might be useful here. A child from an exotic community has a bad stomach ache. The doctors say he must have an operation. The boy has heard talk in his community about how operations put an end to persons and replace them with new persons, but he never really understood this. So he wonders what will happen. When he wakes up, he remembers his question, and feels he got his answer. "I survived!"
Now imagine he had been well trained in the theory, so he was terrified before the surgery, and willingly participated in a christening when he woke up. He begins calling himself by his new name and buys into all the strange theories the group has about why he feels so much like the boy who went into surgery,
Since the boy really has no dispositions in the first scenario (he just wonders what will happen) are we really to say he neither survives nor doesn't survive? In the second scenario, do we really want to say that the boy doesn't survive, because of his dispositions?
Come on. The boy survives, and he knows it in the first scenario. In the second, he's been brainwashed into having unnecessary fears. Though at the edges, personal identity is murky and there are very hard cases, there are also clear cases of survival and non-survival. Johnston's dispositional view of personal identity doesn't have room for this.
Sadly, I think I'm getting close to jumping off this boat before it reaches it's destination--a story about how I can survive the death of my body, if I just develop a certain set of dispositions.