Carefully outline and explain Parfit’s view that identity is not what matters. What does
matter? Critically evaluate his argument for this. Does his account help make sense of
the concerns raised by Williams? If so, which ones and how?
Prior to assessing Parfit’s take on identity, I think it is important first to define identity
carefully and completely in such a way that the elements which Parfit’s model addresses
are understood, and also so that it is phrased for everyone in such a way that it is neutral
with respect to Parfit’s model – we do not want our definition to force us down any
particular path. Wilkes (1993) splits the “question of identity” into two key problems:
identification, and reidentification. The problem of identification is tangential to Parfit’s
model, and so will not be covered in this essay. Put simply, it is the problem of deciding
by what standards an entity could be considered a person. Summarily though, based on
how liberal his model is, Parfit would almost certainly take a liberal approach to the
question of what qualifies as an intentional agent, (what Wilkes refers to as a “person”,
phrasing that could be considered too anthropomorphic). An answer to this problem of
identification is a precondition of any answer to the problem of reidentification. An
answer to the reidentification “sub-question of identity” simply establishes the criteria by
which we can both spatially and temporally unify the discrete components of something
into an atomic entity – what makes the pitcher in the first inning and the 3rd baseman in
the 9th members of the same baseball game? It is these two dimensions of unification, but
almost solely that of temporal unification, which Parfit focuses upon. Note here too that
there is obviously no requirement that the answers to the questions of spatial and
temporal unification need to be the same, although many physically-based models (e.g.
those espoused by Olson, 1997 and Johnston, 1987) do entail an answer to the two parts
in the same way.
What could be termed the traditional standards of identity1 are those proposed by
Williams2, and enumerated by Parfit (1986, p267). They are limited standards, in that
they refer only to the spatial and temporal unification aspects of the reidentification subquestion of identity and do not attempt to address the problem of identification at all.
Quoting Parfit, who quoted Williams, they are:
1) Whether a future person will be me must depend only on the intrinsic features of
the relation between us. It cannot depend on what happens to other people.
2) Since personal identity has great significance, whether identity holds cannot
depend on a trivial fact.
Parfit argues against both these standards and any theory of identity “in general” (e.g.
Parfit, 1986, in the physics student argument, p245-247; and also on p264 and the
following pages). For example, on Williams’ physical model he says: “this version…
assumes that personal identity is a further fact that requires, rather than consists in,
1
Note though there is a very subtle supposition of the existence of identity as a further fact in the first
criterion (“must depend on” is included when it need not be if the criterion were rephrased only slightly).
Because of this, we cannot use the first criterion in evaluating Parfit’s model. Parfit recognises this and
revises (1), which I will later refer to as (3). Rewording (2) can be done by a simple substitution of
whatever it is decided matters in place of the word “identity”, and so is trivial and I will not cover it.
2
I would reference Williams directly, but unfortunately I could not figure out from which work Parfit is
quoting him.
1
physical continuity” (Parfit, 1986, p268). On psychological models, he says: “a similar
argument can challenge this view” (Parfit, 1986, p268). Both of the arguments of his that
I will assess can be used to argue against either Williams’ standards or the concept of
identity. I will largely pass by his other arguments directed only against Williams’
standards though, simply because any of his arguments against identity necessarily argues
against the requirements of it as well, and also to keep this essay to a reasonable length. I
will firstly cover the arguments themselves, before then going over the claims they make
against the criterion and the case for identity in general, the physical or psychological
criterion aside.
Parfit puts forward two key arguments against identity. The first of these is the case of
the divided subject of experience in one brain and one person. This thought experiment
builds off of the empirical data coming from epileptics who have undergone a
commisurotomy and who appear to exhibit two streams of consciousness at any one time
- one on the left, and one on the right. Relying on the assumption that the two halves
could be equipotent with respect to the undivided original (each half possesses all
memories, all abilities, and so forth) – an ungrounded assumption that I will ground later,
when assessing Parfit's argument as a whole – Parfit then goes on to posit a person (a
physics student in an exam, in his instantiation of the argument) who has voluntary
control of their minds division and “undivision”. Or rather - and here the language
becomes complex! - the entities3 that live in him have complete control of the division.
No thing not spatially unified with them needs to be involved. Presumably when the
consciousness and decision making capacity is undivided, it requires only a simple
thought to divide the mind. Rejoining things may be a more complex operation though,
requiring agreement or the same intention from each entity in the body. These details are
not specified by Parfit, and as Wilkes (1993) points out, perhaps he should have done. I
will do my best to do so briefly later in such a way as to salvage the theoretical possibility
of the argument, but presuming it stands we are left with a situation difficult for any
adherent of identity theory to answer: how many people are in the body?
The second argument is that of a standard fission. I won't bother to specify this in
significant detail, except to show that it is at least theoretically possible, as fission
arguments are fairly common, and all result in much the same consequences: at a
particular moment in time, one person becomes two. Each of these people is exactly
similar to the other, and they can in turn either be completely identical to (as in Parfit's
formulation) or completely different to (as in Williams' Guy Fawkes Reduplication
formulation) the original person who was in the body, if the body existed prior to the
fission. Unfortunately, Parfit’s assumption that one brain could be split into two equipotent halves which could then be split into another body falls down on empirical
grounds, even if we could split the lower brain, resulting in the argument being not just
technically impossible in this world, but theoretically impossible in all interesting
possible worlds4. The reason for this is that the brain consumes roughly 40% of the
3
Whether or not they are persons, or sub-persons or Humean bundles or Cartesian sub-Egos (as Parfit
argues) is far beyond the scope of this essay!
4
See below for a more detailed definition of which subset of all possible worlds constitute the set of
interesting possible worlds.
2
resources the body needs, and in any evolutionarily operating system, such a prodigious
waste of resources that could be used for “fighting or fleeing” would evolutionarily
cripple the organism. The grounding of Parfit’s argument to theoretical possibility I will
give here is simply that often alluded to in science fiction: the position of each neuron,
axon and dendrite is precisely recorded by some non-invasive procedure (ala RADAR or
a very high resolution fMRI5), relative to all of the others. The precise firing state and
frequency of each neuron is presumably recorded as well, and in addition to this, any
other aspect critical for psychological continuity is recorded as well - the locationspecific level of the various neurochemicals, the state and position of the various spinal
nerves, or whatever else is necessary. Such a recording will be more than sufficient to
recreate the entire brain (and spinal cord, which also looks to be empirically important) of
one, two, or any number of entities in such a way that they are psychologically
continuous with the entity they were “copied from” at the time the recording was made.
There is no need, despite the claims Wilkes (1993) makes, for the precise position of
every atom to be recorded and recreated - in fact, there could even be quite a reasonable
amount of error in the recreation, and psychological continuity would still probably
result. After all, as will be relevant again later, it is estimated that one of our brain cells
dies at least every 3 minutes in the normal course of life, and some sources estimate it as
being as frequent as one a second (Chudler). Furthermore, a single neuron – of which it is
estimated we have anywhere between 1011 and 1012 in the brain! – weighs some 0.000001
grams (Chudler). Based on this, Avogadro's constant (6.02214199x1023 – Google1) and a
very conservative estimate of the average atomic weight of a neuron (of 25 – see footnote
6, below:6), we come to the conclusion that the average neuron contains at least
24,088,567,960,000,000 atoms, or roughly 2.4x1016 atoms. Given the astronomical rate at
which our brain cells and the atoms they contain change or die every moment anyway, I
find it utterly counter-intuitive that we would need to copy the precise location of every
single atom or molecule. More than a simple claim is needed to establish this
requirement, and until a persuasive argument is put forward, we have to regard fission via
the method I describe (and the confusing consequences) as theoretically possible at least.
Based on these two “stepping stone” arguments, what arguments does Parfit use to argue
against the conception of identity, particularly the “further fact beyond the relation”
inherent in the formulation of the first requirement of the question of identity7, given
above? Parfit suggests instead that the entire construction is a situation where each
possible outcome (in both arguments) simply redescribes the same situation (in that
argument, not in the other, obviously). Answering the question is thus empty, since it
provides no information. For example, in the case of fissioning A into A’ and A’’ there
are four possible descriptions of the outcome:
 A becomes A’
5
Functional Magnetic Resonance Imaging
Carbon, one of the primary atomic components in biological matter, has an atomic weight of 12.
Hydrogen, another primary component, has an atomic weight of 1. For the average atomic weight of the
atoms in a neuron to be above, or even close to, 25 would require that neurons be the sole consumer of the
milligram quantities of the various exotic metals and molecules our body needs – for example lead, and
arsenic – too much of which is almost always fatal or harmful to the brain.
7
These requirements, as mentioned above, of course only refer to the problem of reidentification, but they
are often argued about as if they encompass the entirety of the question of identity.
6
3
 A becomes A’’
 A becomes A’ and A’’
 A becomes neither (and dies)
Likewise, in the case of the division within the mind in which A becomes A’ and A’’,
which then rejoin into B, some combination of the following outcomes must be true (as
they logically exhaust the possibilities):
- At the time of the split, A becomes A’ or A’’ according to the four possibilities
outlined above.
- And at the time of combination, A’ and A’’ become B in the following possible
dimensions:
 Both become B, and whichever ones possessed the property of being A pass it
on to B.
 Neither becomes B, and both die, as does A (if A is still alive).
 One or the other becomes B. If this one possessed the property of being A,
this is passed on to B. Otherwise A now dies (although A had survived until
the time of combining).
 One, the other, both or neither become B, but even if one or both of them
possessed the property of being A and this one then becomes B, this “Aness”
is not passed on.
Parfit raises the question, one which must be answered by any identity theorist and one to
which I can conceive of no answer, as to what the difference is between each of these
outcomes. Given the near-certain impossibility of a Cartesian Ego or immaterial mind
(from empirical evidence) Parfit concludes that each of these outcomes is in fact a
description of precisely the same event. Thus, it cannot be a conclusion regarding “who
will be me” that we care about (Parfit, 1986, p260). Rather, it must be the survival of our
selves psychologically, which, most critically, is the survival of our intentions (which we
do care about). This distinction within psychological continuity is a perspective I will
return to later in evaluating Parfit’s model.
Parfit also argues that in many respects the question in a case of fission and fusion –
whether I survive or not – is badly phrased. It is not, he argues, a binary choice, a
question to which there are only two answers. You are not, he says, either completely
dead or completely “survived” and alive, although both extremes certainly are possible,
and it may be possible to be “worse than dead” or “better than survived”. A key factor in
determining your place on the continuum in situations of fission, on how well you might
regard yourself as you are currently to have survived, is generally dependent on your
“uniqueness factor”. This, which Parfit refers to as U, simply measures how one-one the
relationship between you-now and you-then is. His argument for this viewpoint, that of
adopting a continuum, centres on how our intuitions show what we really care about. One
of his thought experiments on the nature of this question is that of a man who undergoes
fission (Parfit, 1986, p264), grounded and detailed above. Which of the resulting people
(or entities, if we don’t want to ascribe “peopleness” to them) gets to marry the women to
whom the original, un-fissioned man was engaged? Clearly, both cannot, and even if both
could marry her, the division, in a very real sense, “brings too much” (Parfit, 1986,
p264). Even in the best case, with that of the women undergoing a fission as well, there
are problems. True, each man can now marry the women he loves – but for all four
4
people involved in the two marriages, there most definitely exists outside of the marriage
someone who they themselves love, and someone who loves their partner. This does not
sound like a recipe for long and happy marriages! In this case, clearly the fission results
in something a little worse than survival, due to the extra complications it brings. Yet it is
not death – I assert that if anyone were given the choice, choosing either to die painlessly
or to undergo a fission8, every rational person would choose to be fissioned, even if they
were in the same situation as the imaginary man in Parfit’s thought experiment. Indeed,
in some situations it may even be better than normal survival – consider someone who
has two conflicting goals, a situation I’ve certainly found myself in. If I were fissioned,
whilst it would be true that there would now be two people, both of whom had the two
intentions (a point and potential problem ignored by Parfit, who seems to assume the
intentions would be split), it is quite possible that they would be able to resolve them in
such a way that one did the first whilst one did the second. Of course they would be
numerically distinct, and so no one would think to say that I had done both – but both of
my intentions were met, and so were the unfissioned me still around, I would be happy.
In some small, minute way, being fissioned in such a situation is better than ordinary
survival! The immediately obvious objection to this process pointed out and addressed by
Parfit (1986, p265) is that it is not that I want someone to become an Olympic wrestler –
it is that I want me to become an Olympic wrestler! Here though, we have made the
mistake of thinking that the question of which of the post-fission people I become is not
an empty question9. Of course, we could arbitrarily call one of the post-fission people
“Christo Fogelberg”, and if that one became an Olympic wrestler, we could say that I had
won gold – except of course that to say so whilst referring to pre-fission Christo
Fogelberg is a mistake, just as it would be a mistake to say that I had not achieved it
because the post-fission me was given or took up the name “Bob Smith” instead – here,
Lewis’ (1983) conceptions may help, as would (later on) his conceptions of person-stages
as applied to the biblical Methuselah. Unfortunately, space precludes me from going into
these two topics. From these two arguments though, Parfit thus concludes that there can
be nothing more to identity than the relation – and if there is, it must be an empty
question10, and one about which we do not care. In the case of fusion, Parfit agrees that it
is easier to think “when faced with fusion, ‘I shall not survive’” (Parfit, 1986, p298).
After all, there will be no one completely like me after the fusion. To this there are two
responses:
1) Are you wholly like the person you were yesterday anyway? Certainly, fusion
brings dramatic changes in an extremely short span of time, but almost all of us
have certainly had experiences where we find ourselves completely changed –
perhaps we give up the religion we were born into; perhaps we pick up a new one;
maybe we get married – or divorced – and go through all the changes associated
8
Till now we have assumed this fission was painless, but even if it was quite painful, or even if there was
some overlap before the original died, I think the argument still stands. If there was both some overlap and
pain though, I am less certain of how it would stand with most people, although it would still stand with me
personally.
9
In part, I think this mistake stems from taking a perspective which is too first-person – a topic I will touch
on again later – in part due to believing that we are more continuous than we actually are – a topic I will go
over following the discussion regarding identity and Occam’s Razor.
10
Because if there is a difference, it is presumably (given its queerness) completely unverifiable. This is
one situation where I think verificationism is perfectly OK.
5
with such a dramatic alteration of ones’ circumstances. In all of these cases, no
one would say that you have died. Fusion however lies so far outside out cultural
conception of reality that it chaffs in unpleasant ways and this (I strongly believe)
helps precipitate the negative intuition. This chaffing may well have also helped
precipitate the Olympic Wrestler objection above. After all, due to the
approximity I will argue after discussing an application of Occam’s Razor, how
will it be you-today who wins the Gold Medal at the 2008 Olympics anyway?
2) Parfit again argues that “there is no fact involved which is all-or-nothing” (Parfit,
1986, p298). Depending on the magnitude and direction of the changes and their
“goodness” or “badness” when compared with the old you, you again may find
yourself anywhere on the continuum between “worse than dieing”, death,
survival, and “better than survival”.
In closing this summary of Parfit’s arguments and their conclusions, I will touch briefly
on Parfit’s challenge to the second criterion (1986, p269-271). He agrees with its intent,
that identity should never depend on something trivial. However, given he postulates that
an equi-potent brain split is possible (extending the split of consciousness seen in some
commissurotomy recipients), it would seem clear that any physical identity theory must
rely on at best a trivial fact: the possession of “half + 1 neuron”’s worth of brain – yet 1
cell is trivial! He refers to previous work11 in which he outlines similar criticisms against
psychological theories of identity. From this perspective he concludes that every theory
of identity must depend on a trivial fact, and therefore either identity depends on trivial
facts – an intuitively very uncomfortable conclusion – or the question answered when
identity is achieved is insufficient in some respect. This triviality argument I will return
to momentarily when I discuss approximity.
There are however further arguments that can be made against any theory of identity. Is
this a time to apply Occam’s Razor? I can think of no situation in which a further fact of
identity beyond the criterion (be they physical or psychological) is either manifest or
would be useful or verifiable. Here I must digress slightly to the purpose of identity, but
at its core I think we think identity exists purely so that we have something on which we
can hang intentions. We wish to do this primarily because we wish to ascribe
responsibility, both for punishment and reward. Yet we can often ascribe responsibility
quite comfortably regarding things that are clearly not intentional agents, which have
regularly changing parts12, and which no one would argue have a further fact which
constitutes their identity: “my computer just deleted all of my essay drafts”; “World War
II motivated a significant amount of research in rocketry”; or “her anger drove her to
this” are just some of the more immediately obvious examples. We need no further fact
of identity here to ascribe responsibility. Why is it required at all and only for intentional
agents? To conclude, I would say that one of the mistakes in the debate on personal
identity is requiring or positing such a further fact of identity itself, when no argument is
given for it.
11
Unfortunately, I was unable to locate this work and so could not reference it directly.
And so cannot be one-one matched perfectly, only approximately – approximity again alluded to prior to
its explanation.
12
6
There is however a third good argument against the second criterion in particular and
against any approach requiring strict numerical identity in general. Prior to going through
this argument though, which comes from a similar base as Parfit’s triviality objection to
the second criterion and identity-in-general above, I will first describe the thought
experiment in more detail to ensure its grounding: Imagine I give you a big bucketful of
sand to empty onto Table 1, enough that we both agree without a shred of discomfort or
disagreement that, emptied upon the table, we now have a pile of sand. Imagine I take a
single grain of this sand and move it to Table 2, on which until now there was nothing. I
think it fairly clear that there is now no pile of sand on the second table, and still one on
the first. I now repeat many times that transfer of a single grain of sand from the first
table to the second. Surely at some point, prior to the shifting of the last grain of sand
from Table 1 to Table 2, there is no longer a pile of sand on Table 1? By extension
(although potentially after a different number of sand grains had been moved13) there is
surely a pile of sand, at some point, on Table 2 as well. Imagine that it is after moving the
i'th grain of sand that there is now no longer a pile of sand on Table 1. Even with i-1
grains moved, there was still a pile of sand on Table 1, but not when i grains have been
moved. Surely the movement of a single grain of sand, one of millions, is a trivial fact?
This “grain of sand” can of course be the smallest of sub-atomic particles (be it strings,
quantum loops, or something as yet unconceived of – whichever the physicists decide
upon); or it can be the smallest psychological “chunk” 14, which, after moving i of them,
leaves the theorist forced to say that the entities identity has changed. Clearly, identity
depends on the most trivial of facts. More than that though, arbitrarily assigning a
particular point in time as being a time at which you are “complete” and wholly you, in
only a short time – e.g. by the time you’ve read this essay – you will in fact no longer be
wholly you. In fact, even now, having just finished that sentence, you are no longer
wholly you. Pretend you are a supporter of a physical identity theory. One of your brain
cells has almost certainly died, and it would not be at all surprising if one of the stem
cells, of which your body generates a few, and some of which turn into neuroplasts, has
completed the final transition and become a neuron or glial cell. Or pretend you adhere to
a theory based on psychological continuity. Here, the change is intuitively far more
obvious – we’ve all had the experience of knowing we once knew something, someone’s
name or the location of a store, but can no longer remember it – and we don’t know at
what time we lost it. This is simply Parfit’s triviality argument, simply in more detail. Yet
this problem is a critical one for identity in general in a different way, because it always
assumes a perfect one-one mapping, something empirically known to be simply
impossible in this world, and arguably the same in any possible world similar enough to
ours to be of interest (e.g. same laws of physics and the same evolutionary pressures). Put
simply, you are less than you were a moment ago in some ways, in other ways more.
Following this brief explanation and the discussion on the physical and psychological
change we all definitely and unavoidably undergo, I hope that you have reached the same
Potentially there are now two piles of sand, one on each table – we come here to one of Parfit’s empty
questions.
14
These chunks may be memories, personality traits, tics, or whatever the continuist selects. They will,
presumably be so small as to be atomic. My liking of muesli, burnt toast, and philosophy is presumably not
just one chunk. My personal inclination would in fact be to break my liking of philosophy down across
multiple dimensions – both the “feel” of the various elements of it, such as of deduction and of induction,
and also across the various types of philosophy, - of mind, of ethics, and so forth.
13
7
conclusion I have, which is that any attempt at holding on to strict identity is one doomed
to failure, simply because of its impossibility outside the world of abstract thought. Parfit
recognises this problem and responds to it in part, in his discussions of an anonymous
race of immortals, and Lewis’s (1983) person-stage conceptions could also be valuable
here.
Clearly then, identity is not what matters. More than that, identity is unachievable – the
best we can do is only approximate any one-one relationship over time. This
approximation is in fact how I suspect most of us would want to answer the question
about the pile of sand: “there’s a pile there, now, on Table 1, but it’s less pileish than the
one (that was) on Table 1”, since the one on Table 1 is bigger. This approximity inherent
in the actual world for identity is not a problem with the requirements, as no set of
requirements can work around this vagueness – rather it is a problem with the topic of the
debate. The only thing which we can argue meaningfully about is “what do we care
about” – a topic I will return to later.
Parfit argues though that what we actually really care about, what is important, is not
identity at all – it is the “R relation”. The R relation is simply nothing more than
psychological continuity, and not the psychological-continuity-plus-personal-identity
which is the goal in a standard theory of identity based on psychological continuity15.
However, as I stated above, the important part of psychological continuity that we care
about above almost all else is the survival of our intentions. This distinction is
particularly important in the consideration of thought experiments centred on the question
of identity. It is also a perspective I will return to later, in evaluating Parfit’s argument.
To digress momentarily though: It is here that I have said “nothing more than
psychological continuity” quite deliberately: Parfit discards the strict requirements of
numerical identity, not because they are unachievable (although they are, particularly a
perfect one-one matching, and so it is fortunate he does), but because they are something
he argues we simply do not care about – we only think we care about them because of the
conflation of personal identity with R. At this point though, the assertion of the
importance of only R is difficult to swallow and so I will spend some brief time
explaining Parfit’s reductionist model, before moving on to the arguments which suggest
we should follow it.
Effectively, as just covered, Parfit argues that the only thing that matters is psychological
continuity with something, by any cause. The requirements of numerical identity –
transitivity, reflexivity and symmetry – can be discarded. The argument for this begins by
giving the four possible things about which someone could selfishly care for the future
person who will be them: physical continuity (with either normal, reliable, or any cause),
R with its normal cause, R with any reliable cause, and R with any cause (Parfit, 1986,
p283).
I call Parfit’s model a “theory of identity” purely so that its abstract location in the structure of the debate
can be understood. It is not in fact a theory of identity at all – it is, as the theories of identity also are, a
theory about what we care about.
15
8
The argument against physical continuity is primarily a denial of the problem based on
how it was precipitated. Parfit argues against Williams’ torture cases, in effect by saying
that his second description, from the first person (“torture for me” and so forth, Williams,
1976, p51-52), prejudices us – Parfit argues “[i]f we give one of these descriptions in
order to imply some view about what matters, our description might be a bad description.
It might imply an indefensible view about what matters” (Parfit, 1986). In many ways,
this is the same point made by Wilkes (1993) – our intuitions are being pumped, and they
can be, as in fact Williams did in his first description of the situation, made to point in
exactly the opposite direction as well. Parfit’s conclusion here though I will return to
later, in the discussion of the standard by which we can and do measure identity.
In a similar way, Parfit argues against the requirement for the normal cause (which is
physical continuity). He argues (1986, p284-5) that what we really care about is not some
persons particular body or body part, but rather it is the relations between them and others
and their intentions. For example, he argues that nobody would rationally reject artificial
eyes which worked as well as normal human eyes if their own did not any longer – why
do we care particularly about the brain? “[I]f it is the cause of the holding of Relation R”
Parfit suggests. If it is not though, the brain must clearly lose its importance, as it would
in the case of teletransportation.
His argument against the need for a reliable cause again returns us to teletransportation,
but this time it is a process which almost always fails, but which, when it works, works
perfectly. Clearly, as Parfit points out, using it is not a sensible decision. If however one
did use it, and if it did work, why would the resulting body, which would be
psychologically continuous with old-me, not be me? In many ways, Parfit argues here for
a position with a similar structure to that of requirement one, and I would tend to agree
with him: Whether or not A at time t+1 is the same person as A at time t should not
depend in any way on what might have happened.
In addition, as given above, his fission argument or his mind division argument, gone
over earlier, show that psychological continuity is what we actually, really care about.
Thus, as a consequence of this, of the logical possibilities (physical continuity, be it with
any, reliable or normal cause; R with normal cause; R with reliable cause; R with any
cause) Parfit concludes that we should care only about relation R, regardless of its cause.
Whilst I will leave the majority of my evaluation for later, I will tangent to it briefly here,
to simply say that I do not think any cause is sufficient – I think it must be a cause which
is connected with the old me. In this way, a duplicate of me, formed out of a random
accumulation of molecules in a galaxy far far away, would not become me, even if the
body which holds the relation R which is me were to die at exactly the same instant the
freak accumulation was formed, simply because there is now no causal connection
between me and this new entity. This distinction is a refinement to Parfit’s model, simply
to bring it in line with my intuitions, which is that R should be causally connected in
some way, but that then any cause is sufficient.
9
Parfit makes other arguments though to support his thesis that what really matters is
relation R. One of these is his thought experiment of a village in which people are
replicated every few years to keep their bodies healthy. I will summarise this thought
experiment, modified only for conciseness. Imagine you fall in love with a person who
lives in this intriguing village. After a year or so though, it is time for Mary (clearly, the
village is in an English-speaking nation) to be reduplicated. She undergoes this process.
Her old body is destroyed, and her mind at the time she was destroyed is copied into her
new body, which looks (and presumably is, genetically and so forth) exactly identical
with her old body – just a few years younger. What would your reaction be to Mary`?
Parfit argues that, if your love is true, and not just an obsession about a particular bodytype, you must still love the new Mary, despite the fact that she is certainly not physically
numerically identical with the old Mary16 – love after all, is primarily about someone’s
character and traits, not just their body (although few would deny that it does play a role).
As we say – “It’s not just her body! I love her as a person too!”
I will now briefly summarise Parfit’s position from the arguments he gives, some of
which I have gone over above. His conclusions are three-fold:
1) There are only the facts the criterion for identity (or its replacement) assess –
there is no further fact of identity.
2) A complete answer to the question of identity, spanning both physical and
psychological spheres, is unimportant. All that matters is psychological
continuity, and critically within this, survival of our intentions.
3) This psychological continuity does not need to have the properties of numerical
identity – it can fission or fusion. Within a fairly loose definition of “identical”, I
can be identical to two future people, or one future person can be identical to me
and another now. The degree of the relationship varies along the continuum
running between and slightly beyond survival and death, as described above.
Prior to proceeding with a wider look at Parfit’s model in more depth though (particularly
in light of the concerns Williams’ raised in his 1976 article The Self and the Future, and
also some general concerns I have and which I have touched on already) I will look at
what standard might replace the first requirement – (1) – given by Williams, above.
I suspect here that Parfit would argue for a first criterion along the lines of:
3) The degree to which a future person will be me is only the degree to which we are
R related. In addition, it cannot depend on any R relations either of the parties
have with other people.
This is a step in the right direction; however Parfit still seems from his work to believe
that a one-one matching can be achieved over a usefully long time period. This is clearly
empirically false in this world, and in fact in all interesting17 possible worlds, although a
near perfect matching can be achieved in the very short term (a few minutes at most). At
the least, this fact should be acknowledged – a topic I will return to after looking at
And after only a few moments Mary in the new Mary-body won’t be psychologically identical either.
By “interesting” here, I simply refer to the same subset of all possible worlds partially defined above. As
well as being subject to the same laws of physics and evolutionary pressures we believe to be present in this
actual world, I think it important that the other possible worlds be ones to which we feel we can apply our
intuitions reliably.
16
17
10
Parfit’s model, not just in terms of Williams’ requirements, as done so far, but in looking
at it within the context of the concerns Williams raised.
Williams’ two concerns match to his two arguments: the very first person perspective we
take when forced to look at a potential future involving us from the first person, and the
problem apparent when we allow reduplication – when a fission occurs with exact
similarity resulting between each of the “fissees” and the “fisser”. Looking first at the
case of reduplication, Parfit’s response to this is simple: it does not matter – the question
does not (because it is empty and thus meaningless), and neither does the outcome. As
explained in some depth above, Parfit shows how our intuitions really reveal to us a
reasonable conclusion – that it may not be as good as perfect survival, but that it can also
be slightly better. This is, in almost all respects, exactly identical to how we respond to
any other change in our lives. For example, we go to a interview for a day-to-day job in
our career, nothing particularly inspiring or unusual, something about which we care, but
not about which we care beyond all else. If we get the job, things will be slightly better
and we could say that we had “more than survived” the interview. On the other hand, if
we do not get the job, no one would ever say “that interview killed me” in all but the
most metaphorical sense! Fission is precisely the same situation, and as one grows
accustomed to an alternative world in which it is possible, ones’ intuitions mellow away
from the almost fight-or-flee response of “I will die!” Likewise, in fusion, Parfit (1986)
points out that in some cases we might regard it as better than survival, if the person with
whom you fused had very similar goals, but good traits which cancelled out some of your
bad ones. In others, he admits, it may well be a lot less than survival – but at its worst, it
could be no worse than half-surviving, if all of your “chunks” conflicted with the chunks
of the person with whom you fused. To sum up: Parfit in effect denies the problem raised
by Williams, instead arguing that what we really care for is only the survival of our
intentions, and that to phrase it as a question of “who will be me” is foolish and empty.
Parfit does not address Williams’ argument about our differing perspective when forced
to take a first person perspective in any depth, instead only (accurately) pointing out that
the intuition we have depends entirely on which version of the story is told18. His
conclusion from this echoes Wilkes (1993), although he does not go into as much depth
regarding the methodological problem. Instead, he simply concludes that the description
of the situation must be a bad one, and so we cannot form any strong conclusions from it,
despite our strong intuitions. In this, he is right, as I believe he is right that the survival of
our intentions is what matters primarily, whereas numerical identity does not. In addition,
Parfit could certainly argue that Williams’ torture cases are empty questions, since each
distinct outcome is in fact simply a redescription of the same situation. This is certainly a
reasonable conclusion, and Williams’ thought experiments do not change my feelings
regarding what really matters (Parfitian survival19). All this said though, I think it foolish
to deny the intuitions Williams precipitates either. But this leaves us in a conundrum –
psychological survival and physical survival cannot both be most important! Yet clearly,
in different situations (those of torture and mind swap versus that of loving or not loving
In more detail, it is an example of how perspective-dependent our conclusions can be in general – see
later.
19
With reference to or including some aspect of the approximity inherent in the actual world.
18
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your replicated sweetheart) our intuitions conflict. Given this conflict, we could decide
that our intuitions simple aren’t reliable guides. I think though that such a conclusion
would be a difficult one to swallow in this particular situation. Instead, I think the
problem lies in the standard formulation of identity. As well as not being something that
can ever be determined in absolute terms I don’t see it as just a binary choice or ranking
between psychological and physical survival. It might either be a triad-or-more, including
at least the “Cartesian theatre” along side the survival of our intentions and physical
continuity; or it could be something akin to Block’s (1997) mongrel conception of
consciousness. By this I mean it could be that what we care about is a blurry mix of terms
ambiguous in such a way that the different definitions can be mixed and matched freely
and approximately whilst still resulting in a coherent outcome20. I will deal with each of
these possibilities separately.
If identity is the intuitive simpler of the two – a triad (or tetrad, or…, i.e. basically either
a cluster or disjunctive concept of some size) rather than a mongrel, then at the last it
should involve the Cartesian theatre alluded to above. Whilst no serious physicalist
model of the mind21 can assume the existence of a material Cartesian theatre (at least in
this world, in possible worlds, it is certainly plausible, but in those worlds it simply hides
the problem of mental functioning and consciousness behind an infinite regress),
something very much like it – call it the “first person perspective”, simply to avoid the
negative connotations that anything Cartesian carries with it – is important in the question
of identity. This is so even if it exists as nothing more than a subjective fiction (as
Dennett, 1991, argues) – fictional things can certainly be important to us, even if in some
senses they do not exist22, and in the end, the question of identity is only a topic about
which we bother to discuss so much because it is so important to us. Whilst I am
constrained by space and so unable to give an in-depth analysis of the cluster/disjunctive
approach as a possible solution, I would at least initially argue that the question of
identity is a ranking of six things (I consider initially things from a purely first-person
perspective23 only):
1. Avoiding physical or psychological pain and discomfort to my first person
perspective to a certain degree24, as would occur in Williams’ torture cases
2. The survival of my intentions – to me, this is more important than my memories
or my character traits. Put another way, I think it fairly common across people
that they see it as more important that that which they desire is achieved than that
they remember something or that they are a specific kind of person
The easiest way I have found of understanding Block’s concept “mongrel” is by understanding what it is
not: “bank” is an ambiguous word. It is either a financial institution or the side of a stream. However, there
is no coherent definition of the word “bank” which is some mix of the two definitions. In a mongrel
concept, this mixing is possible and in fact occurs, often resulting in confusion.
21
And I know of no serious dualist models – most dualist perspectives on the materiality of the mind focus
on how some aspect of it, typically related to qualia today, is impossible, and so it must be dualist, but what
this dualist stuff is and how it works is never made clear.
22
Not my area of expertise – I merely hedge here, rather than committing to an opinion on their existence
of non-existence.
23
With thanks to Michael Cawley for explaining this concept of the perspective – first, second, or third –
and its importance to me and the rest of the class in PHIL227/327 lectures.
24
Not completely – we all do things knowing that they will cause us pain. As they say: “no pain, no gain”.
20
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3. The survival of my memories. These are only important in that they make up
some part of who I am, and obviously contribute both to the retention, formation
and achievement of intentions.
4. Of all psychological traits, I think that from a purely selfish perspective, being a
certain kind of person is completely unimportant, if only because we never have
to “put up” with ourselves. That said, who I am is still more important than…
5. Bodily appearance (or body-type) is not critically important, but is a factor – both
health and general fitness fall into this category I think.
6. Bodily continuity is, to me anyway25 at most only something to be desired when
having it costs nothing – I would trade it away for any quantity of the above in
any situation.
From a second or third person perspective, I would leave the ranking generally in that
order, modifying it only slightly in very limited circumstances (bodily appearance, if not
bodily continuity, may have higher weighting, despite still being in the same order, with
respect to one’s spouse for example). The only permanent change that I would make is
simply that I think that others being a certain kind of person and having certain memories
would be at least as important to me as them having the same intentions. I would not say
higher, simply because so many friendships and relationships are built around having
goals which involve the two spending time together doing something both enjoy, but a
friends memories and character can certainly be as important as their intentions. Drawing
this potential solution to a close after this brief skim though, we can now consider the
conception of identity as a mongrel.
The elements that constitute this mongrel at this stage I would limit simply to the
physical and psychological, since all of and more than the 6 given above can be derived
from some melding of the physical and/or psychological. The question here then is
whether we gain sufficient value and understanding from this “mongrelisation”,
effectively an application of Occam’s Razor, to offset the vagueness it necessarily
introduces. This is not a discussion into which I can go any depth, but I think that, yes,
we do gain such value, simply because I would not be surprised if in depth thought led to
the 6 aspects of identity above multiplying 10 fold – yet I would still expect an absolute26
ordering (or ordering so near to absolute from any one perspective as to pose only trivial
problems) to be applicable. Mentally “holding” all of this in the mind’s eye would be an
utter nightmare. Thus, the simplification that “mongrelisation” allows, as well as the
freedom it gives in accommodating different peoples’ differing intuitions (I was very
surprised, for example, to learn that my fiancé is “naturally” someone who leant towards
physical continuity, for example) far outweighs the vagueness introduced, and I would
argue for a mongrel conception of identity, over and above any cluster or disjunctive
conception.
25
The intuitions of others vary here of course, and to them it may be more important, but I would be
surprised if either the specific atoms which constitute the body or the body-type were more important than
the psychological nature of someone.
26
By absolute, I simply mean an ordering in which, in all possible situations which are properly detailed
and grounded, we rank the aspects of identity in the same order of importance.
13
Between them, it is fairly clear to me that Williams and Parfit have opened a rather large
can of worms, no matter which way we attempt to resolve our conflicting intuitions in the
question of identity. With all this said though, there are still further concerns that I
personally have with Parfit’s model and the whole debate on personal identity in general,
which I’ve gone over above, and which show that a purely physical or purely
psychological approach must leave something out, whether we resolve identity (or
something like it) to be a mongrel, cluster or disjunctive prospect. On top of this, Parfit’s
argument does have empirical theoretical problems which made the original formulation
of them empirically impossible. However, in the overview of his arguments, I regrounded
the standard fission one in such a way that it was (to me at least) more plausibly
empirically possible. His argument involving the voluntary division of one brain with one
stream of consciousness into such streams two, not gone over in any detail there (as
within Parfit’s structure it was mostly a stepping stone) needs only similar “Sci-Fi”
tweaking grounded in empirical science as we understand it. There was however a
fundamental problem raised by Goodenough (1996), which is that of a Sorites paradox
being applied to Parfit, as in fact it could be applied to any identity theory. Goodenough
titled his argument the “Subtraction Argument”, and it runs analogously to the triviality
argument gone into in some detail above explaining how identity must depend on a trivial
fact. In an extremely shortened form it runs:
My body has i cells
If I remove one cell, I am still me and my body is till alive
If i-1 cells sustains my body, then i-2 cells sustains my body
Therefore, no cells sustains my body, and consequently, me
The conclusion of this argument is effectively that we need no bodies to exist (implying
dualism, in conflict with Parfit’s rejection of Cartesian Egos27) – or that identity must
either depend on a trivial difference, or that it must be a perfect one-one matching.
Having it depend on a trivial difference is intuitively something we detest (as covered
above), just as we feel identity shouldn’t be approximate, and so it is not surprising to me
that all of the models of identity have relied on a perfect one-one matching. Yet, as I
pointed out, a purely one-one relationship is impossible in this world or any possible
world of interest to us. So we are left with a rather uncomfortable situation: we need to
discard absolute identity and replace it with a blurry edged smear28. Presumably this
smear is one which would be “measured” psychologically, by the survival of our
intentions. This psychological bent I take as a given, since Parfit’s arguments in favour of
psychological continuity still generally stand, but a physical model would work as well.
In some ways, this reality is recognized in the wider community already – for example,
the statute of limitations on some crimes – but metaphysically I doubt that it will sit well
with many philosophers.
Focusing ourselves more tightly on Parfit once more though, what conclusions can we
draw from his psychological reductionist model? Based on the problems identified with
Parfit, 1986, p270: “If we were separately existing entities, like Cartesian Egos, our criterion might meet
these requirements. But we have sufficient reasons to reject this view.”
28
Not just temporally, but spatially too. Consider our use of language, e.g. “guns don’t kill people, people
kill people” – this is true, but it is also true that the instrument used to carry it out was in some sense,
spatially unified with the person.
27
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the question of identity in general above, our conclusions must be contingent. They are of
course contingent on at least two things, the first of which is that Parfit’s model – as it
currently stands – must be restricted only to the extremely short term (less than a day I
would estimate), which dramatically limits its usefulness and applicability. The second of
which is that the enumeration of the factors impacting on identity is still unclear and
incomplete – I am leaning towards that it is a mongrel concept, involving both physical
and psychological factors right now, simply because the physical and the psychological
factors almost certainly interact29. With some not-insubstantial reworking of the model
though, most of these otherwise impossible conclusions could be resurrected so that they
still applied. Summarily, and in bullet points, simply because space so constrains:
 Parfit makes clear that what is really important to us is the survival of our
intentions, above almost all else, and that this applies, even in the case of fission
or fusion (or fission and fusion, as he went into in some detail, but which I have
not had space to include).
 We need to be wary of empty questions, and in some cases (but not all, as I
argued above in the discussion on the standards by which we measure identity or
its replacement) we can discard our intuitions as a result of the question and the
answer we arbitrarily select.
 He has also made clear that it is a mistake to think of the answer to the question of
identity as one which must be either “I survive” or “I die” – instead, it is a
continuum between and beyond survival and death.
 Whether we care about identity or not, it must depend on a trivial fact.
In addition, we can also conclude:
 A model by which we answer the question of identity does not need to be, and
almost certainly should not be, one of two binary choices – some physical
continuity or psychological continuity model. Instead, it is probably a mongrel
concept, comprised of factors involving both what happens to our selves,
psychological continuity, and physical continuity. Even more, it is probably a
concept we apply differently from the first, second and third-person perspectives,
a topic I have not had the space to go into at all.
 There seems to be no need of a further fact of identity beyond the relationship
anywhere else in the world – why here, for persons?
 Our answers to the question of identity differ dramatically and to a significant
extent depend on our perspective, as Williams (1976) torture examples point out.
 The question of identity must account for the approximity inherent in any world
of interest to us, including the actual world from which we gather empirical
evidence. I would refer to an approach which accounted for this approximity,
“mongrelness” and perspective-dependency a “hyper3-reductionist” approach,
unless of course it has already been conceived of and has an existing name which
I have merely been unable to find. Reductionism discards some of the properties
of numerical metaphysical identity. I advocate discarding three more – hence
“hyper3”.
29
I doubt there are many who are so strongly epiphenomenalist today that they would claim that all of our
mental functioning (and not just our consciousness) is epiphenomenal.
15
Block, N. 1997 On a Confusion about a Function of Consciousness
In The Nature of Consciousness: Philosophical Debates
Cambridge, Massachusetts: MIT Press
Chudler, E. H. Brain Facts and Figures
http://faculty.washington.edu/chudler/facts.html
(Wednesday, October 27, 2004)
Dennett, D. 1991 Consciousness Explained
Boston, Massachusetts: Little, Brown & Company Ltd
Goodenough, J. M. 1996 Parfit and the Sorites Paradox
Philosophical Studies, v83 (1996) – p113-120
Google1 Avogadro’s Constant
http://www.google.co.nz/search?hl=en&q=avogadro+constant&meta=
(Wednesday, October 27, 2004)
Johnston, M. 1987 Human Beings
The Journal of Philosophy, v84 (1987) – p59-83
Lewis, D. 1983 Philosophical Papers...30
Oxford, England: Oxford University Press
Olson, E. 1997 Was I Ever A Fetus
In The Human Animal: Personal Identity Without Psychology
Oxford, England: Oxford University Press
Parfit, D. 1986 Why Our Identity Is Not What Matters
In Reasons and Persons
Oxford, England: Oxford University Press
Nozick, R. 1981 Personal Identity Through Time
In Philosophical Explorations
Oxford, England: Clarendon Press
Wilkes, K. 1993 Thought Experiments
In Real People: Personal Identity Without Thought Experiments
New York, New York: Clarendon Press
Williams, B. 1976 Problems of the Self
Cambridge, England: Cambridge Press
Unfortunately, the photocopying elided the rest of the title, and I wasn’t able to look up the rest of the
reference – sorry!
30
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