Here’s a common objection to psychological
continuity accounts of personal identity. As a result of a rather disastrous
spell, Harry Potter’s body is destroyed, though fortunately his psychological
states are imprinted in life-size statues of Peregrin ‘Pippin’ Took and
Meriadoc ‘Merry’ Brandybuck, which subsequently become active, moving around
and insisting, rather stroppily, that they are Harry Potter. Had Harry’s
psychological states simply been implanted in (the statue of) Pippin, then
psychological continuity theorists would have no trouble saying that Pippin is
Harry. The situation, from their perspective, is be little different to if
Harry had been the victim of a particularly eloquent Transmogrification spell.
But Merry causes a problem. For, the argument goes, Merry is not Pippin, so we
cannot both say that Harry is Pippin and that Harry is Pippin. Perhaps though,
as Douglas Ehring (1987) has suggested, we should deny the claim that Merry is
not Pippin, and instead insist that we have a bilocated person. Here I want to
set out a couple of arguments in favour of Ehring’s claim.

One
of these arguments ends up supporting a slightly stronger claim than Ehring
explicitly endorses. One can accept that Harry is now bilocated, but deny that
‘psychological duplication’ leads to bilocation. Psychological duplication is
the process where a person’s psychology is mapped onto an external object while
the body currently hosting their psychology is preserved, and maintains that
psychology. As it happens, the spell that started this story led to Hermoine
Granger’s psychology being mapped in this way onto a statue of Samwise ‘Sam’
Gamgee, and that statue is now discussing the delicate philosophical issues
with Hermoine. There are four moving objects in the room. It’s a live option to
say that there are four people in the room. Indeed, that’s the common opinion.
It’s a live option to say that although Merry and Pippin are the same
(bilocated) person, Hermoine and Sam are different people, so there are three
people in the room. That’s what a defender of a ‘closest continuer’ view of
personal identity might say. And I think it’s defensible to say there are just
two people in the room. What would be very hard to motivate is the view that
although Hermoine is Sam, Merry and Pippin are different people. If we are
prepared to say that two bodies that are asymmetrically related to an earlier
person are parts of the same person, then why would we deny that two bodies
that are symmetrically related to an earlier person are parts of the
same person? I can’t imagine a reason why we would say this. So I will simply
argue here that in cases of duplication the end result is a bilocated person,
and assume that from this it follows that in fusion we also end up with a
bilocated person.

1. Ehring’s Argument

In “Time Travel and Personal Identity”,
Douglas Ehring argued that the common arguments for ‘dualism’, the view that
fission results in two people, were invalid. Those arguments usually turn on
the fact that the two bodies don’t have a shared consciousness, don’t have a
common body and are causally independent (Ehring 1987: 427). Ehring noted that
this kind of argument for dualism proves too much, since similar considerations
show that dualism is true in the case of time travel.

To
take a well-known example, consider what happens at the end of ‘Harry Potter
and the Prisoner of Azkaban’. (The plot of the relevant section is set out here.)
On one side of the lake, Harry, Hermoine and Sirius are being attacked by
Dementors. On the other, Harry Potter (who has travelled back in time to figure
out how they were rescued) casts a spell to see off the Dementors. The ‘two’
Harrys here lack a shared consciousness and a common body, and are to some
extent causally independent. As Ehring notes, the last point isn’t exactly as
clear as the first two since issues about causation get complicated when time
travel is involved. But to some extent the actions of the two bodies are
causally independent of each other. Whether one or the other coughs at a
particular time is independent of what the other does, for example.

Ehring
argues that even though all these characteristics hold of the two time travellers,
they are still the one person. Hence the fact that the bodies that come out of
the fusion are independent in these ways cannot show that they are not the same
person, because their relation to each other is no more distinct that the
relation of the two Harry Potter bodies in this story. This all seems right to
me, but note that this just shows that an argument for dualism fails, not that
dualism itself is false. Let’s now turn to two arguments for that conclusion.

2. The
Hard Working Argument

Bilocation is conceptually feasible. It may
be desirable in some circumstances. In ‘Azkaban’ Hermoine wants to be bilocated
so she can take twice as many classes. Casanova may want to be bilocated
because he has two appointments this evening. It seems conceptually possible
that Hermoine’s and Casanova’s desires could be satisfied, that they could each
be in two places at one time. Given this, it seems conceptually possible that
they could do something about making their desires come to fruition.

How
could each of them make their desires come true? Hermoine’s method was a time
travel spell, but Casanova can’t cast spells, and doesn’t know where any closed
timelike curves are. It seems the most natural thing for him to do would be to
create a duplicate of himself. Ideally this would be a psychological and
physical duplicate, although as long as the other parties to the appointment
didn’t ask too many questions he need not get all the physical characteristics
exactly right. Let’s assume he makes such a duplicate and sends it along to one
of the appointments. The next morning he fuses the memories each body carries
with it from the time apart. It seems to me that Casanova succeeds in his quest
to be in two places at the same time.

Here
then is the quick argument against dualism in the case of duplication.

(P1) It
is possible to make ourselves be bilocated.

(P2) If
it is possible to make ourselves be bilocated, then one way to do this is by
creating a psychological duplicate.

(P3) Whether
the creation of a psychological duplicate leads to bilocation or not is
independent of whether the duplicate was created so the source person could be
bilocated.

(C) Whenever
a psychological duplicate of a person is created, that person is bilocated.

3. The Alibi Argument

Most readers will be familiar with the
story in Waltzing Matilda. A drifter steals a sheep to eat for the next
few dinners. He is spotted by the local police, and drowns himself in a nearby
creek to avoid justice. Naturally, he became an Australian hero. Let’s change
the story a little bit. Just before he drowns himself, he creates a
psychological duplicate of himself. He stays around to check that the duplicate
has all the right features, that it really is him, then jumps into the creek.
Call the person who the police capture when they turn up Swag and the person
who stole the sheep Man. Then the following argument looks plausible.

(P4) Swag
can be properly punished for stealing the sheep.

(P5) Swag
can only be properly punished for stealing the sheep if he in fact stole it,
i.e. if he is Man.

(P6) If
Swag is Man when the police turn up, then Swag is Man when Man stands beside
the creek checking that the duplication machine worked.

(P7) Whether
Swag is Man does not depend on whether Man actually does drown in the creek.

(C) Whenever
a psychological duplicate of a person is created, that person is bilocated.

(P4) is intuitively right given the
description of the case. If this were not true it would be too easy for anyone
who owns a duplication machine to avoid responsibility for their actions. (P5)
follows from a natural principle of punishment – a person can only be punished
for his own actions. (P6) and (P7) are more contentious, but the idea is that
Man’s drowning doesn’t change the facts about whether Swag is Man. (P6) says
that it can’t be the case that while Swag was a different person to Man while
they chatted on the creek bank, but he became the same person as Man once Man
drowned. That would be a very odd view to have. (P7) says that whether Swag and
Man are two people or one as they chat can’t depend on whether Man (or a part
of him) ends up drowning in the creek. Like the other premises this is
intuitively plausible, though I imagine a determined dualist could argue that
it relies on a questionable intuition that facts about identity are ‘local’
facts, not dependent on what happens at later times or other places. I doubt
such an objection can be made to hold up, but it’s worth noting this is not a
knock-down refutation of dualism.

The
important point about (P7) is that it makes the case of Swag and Man suitably
arbitrary. If in this case Swag is Man, and the later facts of the case, in
particular the drowning, are not relevant to whether we have one person here or
two, then the case is arbitrary. All that matters is that Swag is the output of
a duplication machine applied to Man. And that’s enough, it seems, to justify
the conclusion that Swag is Man. So in general, duplication leads to
bilocation, not to the creation of a person.