Again, coming back to the distinction between persons and animals,
we might want to collapse, that we might want to say maybe we don't need that distinction.
Maybe we should just go with identity of physical organisms. We can see that way in the 17th and 18th centuries.
They might not have been keen to do that because it does seem to ruin the prospects for an immortal soul or new material.
So. And that, of course, could be a reason for people not wanting to do that nowadays.
But suppose we don't mind about that. Suppose we do not believe in immaterial souls.
In that case, we might be tempted to collapse. The distinction between person and organism.
But this does have significant implications. If I was once a foetus.
And this human organism was once. It seems to follow that I once wasn't a person.
To be a person, you need to have some significant mental life, or at least that is how most people wouldn't understand the notion of person.
Maybe there will come a time when this physical organism is still operating as an organism that has no conscious life.
Maybe at the end of my life. This will be a physical organism after the person who has gone.
So it might seem to follow that being a person is, as it were, an accidental property of mine rather than an essential property.
And that might seem to be rather an uncomfortable position to think of myself as not necessarily a person.
OK. Suppose we bring these together. Suppose we're impressed by that thought.
Could we not then identify the person with the developed functioning brain rather than the whole organism?
So in other words, maybe we want to say that a person only comes into existence,
not when the embryo is formed, not at conception, not even when there's a very early foetus.
But when the brain starts developing, when consciousness emerges,
that's when a person comes along and the person is to be identified with the developed functioning brain rather than with the whole organism.
So that can make sense of the Williams cases where the brain gets transplanted, blunted.
Maybe they're we fairly unproblematic. We want to say that my brain, your body is one and the same person as my brain.
My body. So when you have a brain transplant, actually, it's a body transplant, not a brain transplant.
And you can imagine some devious,
clever person approaching somebody who's a bit simple but happens to be blessed with an extremely good body and
persuading them that it will be greatly to their advantage to have this wonderful brain transplanted into their body.
And thus the the old genius gets rejuvenated.
OK, so this solves some of the problems. But unfortunately, things aren't so simple.
Split brain cases, for example. If the nerves between the hemispheres of the brain are surgically cut.
That is a procedure that can be done. I think a treatment can be an extreme treatment for epilepsy, for example.
Then you can have a single brain giving rise to two conflicting behaviours.
You can find the two hands do different things. They no longer coordinate.
OK. Let's build a problem case from this.
Suppose we have a single brain that split and putting two bodies, each half of the brain can in certain circumstances survive alone.
Suppose that that is if part of the brain is destroyed.
One can make do with less. Suppose it became possible to transplant the two halves into separate bodies.
In that case, you'd have two new persons, both having brain and memory continuity with the original.
OK, so both the two persons would remember being me. There would be at least significant continuity over both of both brain and thought.
What do we say then? Well, maybe if this happened, we'd actually give up the notion of strict personal identity.
Maybe if this became a common thing, we would no longer think of personal identity as all or nothing.
And Derek Parfit actually suggests this as the way we ought to think about personal identity.
It's a matter of degree. And we can bring loks forensic thought in here.
If what matters is our concern, both moral.
And utilitarian, as it were, about our future self, what matters about personal identity,
what matters about me tomorrow is that I today care about that person and will make plans on the assumption.
That that is me. Then that seems to reflect the way we would judge about split brain cases.
Suppose I knew that I was going to my brain was going to be split and put into two separate bodies.
I mean, let's suppose I've got some medical condition. My have done too much philosophy and my brain is beginning to fall apart.
And the solution is to cut it in two and give each half a separate life.
I don't know quite how I'd negotiate things with my wife in these circumstances, but maybe, maybe we decide that's the best thing to do.
I think I'd want to make sure that both of those individuals were provided for.
We would care about both future selves.
So maybe thinking of personal identity as a matter of degree would be an appropriate thing to do in those circumstances.
And I want to leave you with a concept which I think is a particularly useful one for thinking about some of these problems.
Not only personal identity, but other concepts in philosophy as well.
Friedrich Weisman, who spent many years at Oxford, in fact.
Yeah, a lot of them did. Coyte coined this term for concepts which become vague in radically novel situations.
And he actually suggested that most empirical concepts are like this, that with most of our ordinary everyday concepts,
if you dream up dramatically radical novel situations, it becomes very unclear how to apply them.
And the thought here is not. That there is that it's a difficult question how to apply them, we have to think a lot about it to get to the truth.
Rather, the thought is that maybe there is no correct way to apply them.
It raises a new question. So let me give you an example. He used to be when I was growing up.
Taken for granted that marriage always could only involve one man, one woman.
Of course, you could have things like divorce and so forth, but marriage applied straightforwardly to a man and a woman you couldn't marry.
You couldn't have marriage between two men, you couldn't have marriage between two women.
That simply wouldn't be marriage, whatever it was. OK.
Lines have been blurred. But think yourself into that situation.
And then ask. Okay. Suppose somebody is had a sex change operation.
What then? Can a man marry a sex change woman?
Born a woman, now a man, can they marry? What about the other way round?
Born a man, now a woman kind of man, men marry her.
And you can see that it's just left radically unclear. When people, as it were, invented, the concept of marriage,
the idea of a sex change or someone changing their sex during the course of their life was simply out of the question.
So there wouldn't have been any thought about this situation, the concept of marriage took for granted that sex was stable.
And if it isn't, maybe there's no right answer as to how that concept should be taken forward.
Maybe one could answer in different ways. Maybe we're going to invent have to invent a new concept to deal with this kind of situation.
But in many cases, what we do when we have a radically new situation, we reinterpret our old contact, let's say having a conversation.
We know what having a conversation with someone is like. Okay. And then the telephone comes along.
Is that having a conversation? Well, sort of, yes. It seems pretty close.
What about e-mail, is that having a conversation? You can see that as technological change takes place.
It may become radically unclear how we should adapt our concepts to cope with it.
And it may be that personal identity is a concept which takes for granted all sorts of things, which in the vast majority of cases are true of us.
We do retain the same consciousness in the same body, continuously developing through life.
It may be that when we dream up these puzzle cases, we are inventing situations to which there is in fact no right answer.
If such things were to become commonplace, then maybe we'd have to adapt our concepts.