Thesis - Chapter 10 (Thought Experiments)
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Write-up2 (as at 14/02/2026 00:41:46): Thesis - Chapter 10 (Thought Experiments)

Chapter Contents
  1. Abstract3
  2. Methodology4
  3. Introduction5
  4. Note Hierarchy6
  5. Main Text7
  6. Concluding Remarks8
  7. Links to Books / Papers to be Addressed9
  8. Works Read10
  9. Further Reading11
  10. References & Reading List

Abstract
  1. Any discussion of personal identity needs to give an account of what is going on in the various thought experiments that have been considered relevant to the topic.
  2. It’s also the area that’s most fun. Indeed, I think that the entire Thesis will be an exercise in inference to the best explanation of what’s going on in these thought experiments.
  3. Any theory of Personal Identity needs to account for our intuitions (if there is a universal response) or explain them away as confused.
  4. I will briefly consider the propriety of using thought experiments in this domain of enquiry, and then consider the usual suspects.


Research Methodology
  • Follow this Link12 for a generic statement of how I intend to pursue each Chapter.
  • The method is broken down into 16, possibly iterative, stages, some of which have sub-stages.
  • Follow this Link13 for my progress dashboard on these tasks.


Chapter Introduction14
  1. In this chapter we will consider all the usual suspects, as itemised in the list of Notes and text below.
  2. This is a long Chapter, and starts with a general discussion of Thought Experiments15 – though further consideration will need to be given at the end of the Chapter in the light of the discussion of examples – because some philosophers maintain that our Concepts were not designed to work in situations far from those in which they were developed. This objection does – in this context – seem to suggest that questions of Personal Identity are merely Semantic rather than matters of fact. So, it’s worth giving the method a go, to test our Intuitions16 – though I think these should be modifiable in the light of this theoretical experience as well as well as guiding our interpretation of these TEs.
  3. The TE that I have found the most useful – and the first I came across – is Bernard Williams’s Future Great Pain Test17, as it forces us to take maybe glib intuitions seriously.
  4. It is to be noted that some – for instance Commissurotomy – are more actual experiments than thought-experiments, though quite a lot of armchair thinking is involved in working out their import. Consequently, I’ve made this distinction in the list below. We start with the ‘actuals’.
  5. Clones18 are relevant in distinguishing Identity from exact Similarity, and for confuting those who think that we are Information.
  6. This leads directly on to Fission19, including a natural example thereof, namely Twinning20, which may be a special case of Duplication21. This whole nexus is important to the Reduplication Objection22 to certain putative cases of persistence, where there is, or can be, more than one Survivor.
  7. Pregnancy and birth in placental mammals – as we discussed in Chapter 8 – might be described as Fusion23 (when the Zygote implants) followed by Fission (when the umbilical cord is cut).
  8. Organ Transplants24 are clear – though maybe not very exciting – examples of Fusion involving Human Animals, which nevertheless need to be given an account by Animalism.
  9. Otherwise, it is not clear whether there are any further naturally-occurring cases of Fusion relevant to personal Identity. The obvious possibilities are the pathological cases of conjoined twins covered by my Note on the extreme case of Dicephalus, though it’s unclear whether these are cases of incomplete Fission or incomplete Fusion.
  10. Finally under this discussion of ‘natural’ TEs are Psychopathological25 cases. I have a general Note on Clinical Observations26 to cover this area, with specific Notes on Commissurotomy27 and Multiple Personality Disorder28. Both are putatively examples of Fission on the Psychological View, but of little concern to Animalism. Multiple Personality Disorder might be better situated in Chapter 9 as a critique of the idea of an individuating First-Person Perspective.
  11. We then move to the various ‘artificial’ TEs, starting with Brain State Transfers29. Then come Brain Transplants30, which come in various forms. We need to distinguish Whole-Brain Transplants (WBTs) from single or double Cerebrum transplants, and these from brain-tissue transplants. Brain Transplants are vastly more difficult to perform than Head Transplants, which have allegedly been around the corner for some years. All these options are covered by the same Note but I have another on Brains in Vats which fall into the same general area.
  12. The above TEs maybe shade off into Siliconisation31, which is the gradual replacement of organic brain tissue by computer chips, though what can be deduced from such TEs without begging lots of questions is unclear.
  13. For a bit of light relief, I’ve added a general consideration of Dracula32, particularly of the various metamorphoses he’s supposed to be able to undergo.
  14. We then get to my favourite – Teletransportation33, which – at best – I take to be an example of Replication34 (which may be the same as Duplication, only more tendentiously-termed).
  15. Finally, I’ve added the hopes of Transhumanism35 as a coda to the Chapter, though it might be combined with the previous section. Transhumanism is a very wide topic, and is different to the other notions, in which we are and remain wholly organic. I’ve divided these hopes into those that are ‘nearby’ and those that are ‘far off’.
  16. The ‘nearby’ hopes include Chimeras36, which involves a kind of Fusion of animals of different species; either xenotransplants – which have been ‘actual’ for many decades – or the importation of human DNA into non-human animals for organ forming, or other reasons. The latter raise questions about the Ontological and Moral status of the DNA-recipients.
  17. The second case in this section is that of Cyborgs37, which have inorganic somatic augmentation; this may also be ‘actual’ to a limited degree, though not to the degree sought by the Transhumanists.
  18. Finally, we have the less imminent hopes – in particular Uploading38 to Computers39 – which I find very unlikely, and not even desirable. But if it turns out to be possible, we might end up as Androids40; just adding a robot body to a computer mind. If uploading turns out to be practically or metaphysically impossible, we might still have Androids completely discontinuous from human beings, though modelled on them.


Note Hierarchy
  1. Thought Experiments41
    1. Intuition42
    2. Future Great Pain Test43
  2. Principal Examples - Natural
    1. Clones44
    2. Fission45
    3. Fusion49
    4. Psychopathology53
  3. Principal Examples - Artificial
    1. Brain State Transfer57
    2. Brain Transplants58
    3. Siliconisation61
    4. Dracula62
    5. Teletransportation63
  4. Transhumanism65
    1. Nearby Hopes
    2. Far Off Hopes


Main Text
  1. Thought Experiments71
    1. In general, I’m in favour of using thought experiments in philosophy.
    2. However, I’d like to consider – following "Wilkes (Kathleen) - Real People: Personal Identity Without Thought Experiments" – whether some thought-experiments in pursuit of clarifying issues in personal identity
      1. Propose impossible scenarios,
      2. Trade on under-specification, or
      3. Put us in circumstances where our concepts72 no longer apply (or where we could no longer play the appropriate language-game using them – see "Gale (Richard) - On Some Pernicious Thought-Experiments").
    3. Sometimes our intuitions73 are unreliable as to the truth or possibility of what we intuit.
      1. Some doubt the possible phenomenal consciousness74 of artificial systems75, however complex, but is this anything other than a fallacious argument from personal incredulity?
      2. Descartes76 argued for the real distinction77 between mind78 and body79 by thinking he could imagine their separation, but could he really?
      3. Sometimes, our intuitions80 may give us no clue one way or the other, or only a gentle lead (as Williams seems to be suggesting in "Williams (Bernard) - The Self and the Future").
    4. "Snowdon (Paul) - Personal Identity and Brain Transplants" gives a helpful critique of Wilkes’s and Johnston’s (see "Johnston (Mark) - Human Beings") arguments against thought experiments.
    5. "Wilson (Jack) - Beyond Horses and Oak Trees: A New Theory of Individuation for Living Entities" thinks that TEs should be avoided where possible, and real examples used. At least in actual circumstances we know that the situation is possible81 (“actual implies possible”), and we know, or can discover, all the background conditions.
    6. The trouble is that there may not be enough naturally-occurring situations, or practically or ethically available experimental circumstances, to provide the occasions to put maximum pressure on our concepts82.
    7. Then again, were our concepts83 designed to be put on the rack? What would their failure really tell us?
    8. The topic of Transhumanism84 is replete with TEs, given that the expected advances are yet to take place.
    1. Intuition85
      1. The topic of Philosophical Intuition is somewhat related to that of Thought Experiments86.
      2. I decided to give this topic its individual note in response to "Clark (Andy) & Kuhn (Robert Lawrence) - Aeon: Video - Andy Clark - Virtual immortality". Therein, Andy Clark has the strong intuition that we87 are “patterns in information space88”, and he specifically contrasts this with the “me, here, now, animal” intuition shared by animalists89 such as myself.
      3. There are – of course – arguments for animalism90. Are there corresponding arguments for Clark’s view, or is it a foundational belief, like belief in God has been said to be?
      4. Philosophical intuitions occur in all sorts of philosophical arguments. One central to my own concerns is the “brain transplant91 intuition” – that “we go where our brains go”. I’m not sure whether to share it or not.
      5. The primary source for this topic is probably "DePaul (Michael) & Ramsey (William) - Rethinking Intuition: The Psychology of Intuition and Its Role in Philosophical Inquiry".
    2. Future Great Pain Test92
      1. This is a test invented by Bernard Williams in "Williams (Bernard) - The Self and the Future" though the actual terminology seems to be due to Peter Unger.
      2. It is a means of teasing out whether or not we really think – either by Intuition93 or through some convoluted reasoning – that we will be some future individual94. It is cashed out in terms of the prospect of “being mercilessly tortured in the morning”.
      3. If we think that the unfortunate individual will be us, our attitude will be qualitatively different to if we think it will be someone else (though maybe there are exceptions – mothers and their children, maybe – but even there, it may depend on what is to happen – reference Winston Smith and the rats in Room 101 in "Orwell (George), Davison (Peter), Taylor (D.J.), Ed. - Nineteen Eighty-Four: The Annotated Edition" – Wikipedia: Ministries of Nineteen Eighty-Four - Room 101).
      4. Of course, while this may tease out what we think will be the case in any situation, this doesn’t imply that it will be the case. Lots of people think that teletransportation95, were it to be technically feasible, would be a form of travel, rather than death96 and duplication97. I happen to think their view mistaken. But it either is or isn’t irrespective of anyone’s view. If I was forced to go through the procedure and found my First Person Perspective98 persisted – as only I could know99 – I’d change my mind, and my philosophy of PID.
      5. In my view, this is important when alloyed to the FPP100 in rebuffing Parfit101’s view that identity doesn’t matter102 in survival103. The footnote earlier raises epistemological worries, but the metaphysical certainty remains.
  2. Principal Examples - Natural
    1. Clones104
      1. Cloning features in105 several TEs106.
      2. We need to contrast two forms of cloning:-
        1. The metaphysical possibility of atom-by-atom cloning.
        2. Biological cloning which uses existing structures, and interferes unnaturally in a fairly minor way.
      3. I am not concerned (as far as my thesis goes) with the medical ethics of biological cloning. There is never any suggestion that clones in this sense are logically identical, any more than so-called identical twins are.
        1. That said, there is something of a link – in the metaphysics, if not the ethics – with a critique of Parfit107’s “identity doesn’t matter” account of personal identity.
        2. Since my clone has my (innate) properties and capacities, Parfit might think I have all that matters (or much of what matters) to me if my clone, rather than I myself, survives and I do not.
        3. The following papers seem to follow this approach:-
          → "Agar (Nicholas) - Cloning and Identity", and
          → "Brennan (Andrew) - Survival"
        4. In particular, the paper by Andrew Brennan suggests that persons might be types rather than tokens which – while an interesting proposal – is about as far from the truth as you can get. Tokens suffer, types do not, qua types. One token of the same type may be luxuriating while another is being tortured.
      4. What I am interested in is whether atom-by-atom cloning (where the original exemplar is destroyed) can ever preserve identity108. Because of the logical possibility of the non-destruction of the “original”, I take it that it cannot. This argument depends on modal logic109 – and the rejection of the possibility of contingent identity110. For further discussion, see under Teletransportation111.
      5. We may also need to discuss causality112 to further explain why identity is not preserved during a cloning event. This is particularly the case when discussing Dean Zimmerman’s Falling Elevator model of resurrection113, where – it is supposed – there is a causal connection between the expiring body114 and its clone in the next world.
        1. Is it agreed that this is indeed a clone, as it seems to be, or …
        2. Is this body supposed to be the same body, created by supernatural processes by immanent causation – albeit across space and maybe other dimensions – much as a body at one time is self-identical to a body at a later time by natural metabolic processes?
        3. This would imply – in the absence of perdurantism115 – the non-identity of the living organism116 and the post-mortem corpse117.
        4. See "Hershenov (David) - Van Inwagen, Zimmerman, and the Materialist Conception of Resurrection" for the argument that Zimmerman’s resurrected body is a duplicate118.
        5. For Zimmerman’s arguments, see:-
          → "Zimmerman (Dean) - The Compatibility of Materialism and Survival: The “Falling Elevator” Model", and
          → "Zimmerman (Dean) - Bodily Resurrection: The Falling Elevator Model Revisited".
      6. The very term ‘Cloning’ seems to deny the possibility of the logical identity of an original and its clone. It implies that there are two things – the original and the clone – and two things can never be one thing, so cannot be logically identical119.
      7. I note here – for want of a better place – that there’s a “no-cloning” principle120 in Quantum Mechanics121, which forbids the making of an exact copy of an unknown quantum state. This – it seems – is relevant to the difficulties for error-correction in Quantum Computing.
    2. Fission122
      1. Fission is important in the philosophy of identity – especially of personal identity – in that it provides many thought-experiments123 (TEs), and some real-life examples, that test out the various theories.
      2. The paradigm case of Fission is of two half-brain124 transplants125.
        1. It is difficult to consider this case without slipping into the “psychological view126”. Each hemisphere seems to preserve what matters127 to the fissioned individual128, and a perdurantist129 account can maintain identity130 after fission.
        2. An alternative account is to claim that the two half-brains131 always were separate persons132 (and Roland Puccetti has maintained that they are separate persons, in all of us, even prior to the commissurotomy133 in this TE and in everyday life), in a way slightly different from the usual Lewis134 view of non-identical spatially-coincident135 individuals136 (because the hemispheres aren’t spatially coincident, though the shared body137 is).
      3. We need to consider how the original person138 was unified139. We can press the realism of the thought experiment140 by asking how important are the spinal cord and Peripheral Nervous System generally to the psychological141 integrity of the human organism142? The case of dicephalus143 twins may be relevant – where the functions of walking and even typing seem to be carried out perfectly adequately despite the coordinated limbs being controlled by different brains144.
      4. We also need to consider whether the two half-brains145 continue to constitute a single scattered146 person147, just parked in separate bodies148. A single embodiment is important because it ensures synchronisation of experience, and external communication between the hemispheres (in the absence of the usual internal communication across the corpus callosum). Presumably, this could be achieved in other ways.
      5. We can – as in "Dennett (Daniel) - Where Am I?" – imagine a Brain in a Vat149 linked by radio transmitters/receivers to a remote body150.
        1. The brain151 is part of the body152 – so a single physical thing can be spatially discontinuous.
        2. Why, if A fissions into B and C, can’t we consider B & C to be parts of the same person?
        3. They could fight / argue … but so can someone in two minds153 about things.
        4. What if one killed the other?
        5. They would have different perceptual experiences, but so (presumably) does a chameleon, with its eyes pointing in different directions (and sheep and other herbivores, and fish, with eyes on the sides of their heads).
      6. I need to consider in detail what is supposed to be going on in fission – ie. press the original thought experiment154: there needs to be segregation / redundancy prior to separation – this can happen over time (or we would have plain duplication155). At some point the person will split into two, with incommunicable consciousnesses156 (cf. Locke157’s day-person and night-person).
      • Duplication158
        1. Duplicate objects are – to use the definition in "Sider (Ted) - Naturalness, Intrinsicality, and Duplication" – “exactly similar, considered as they are in themselves”. That said, it misses off the question “which is the original?”. A “duplicate” is – by implication – a copy of the original. I don’t think there’s the same implication in the term “double”, though saying that person X is person Y’s “double” – while it doesn’t imply precedence of one over the other – doesn’t even imply exact similarlity159 – just that one might be mistaken for the other (and maybe not even that, quite).
        2. There is considerable overlap between this topic and two other topics:-
          1. Replication160, which is really the same thing (though not restricted to a mere doubling), and
          2. Reduplication Objections161
        3. The motivation for this discussion – and those above – comes mainly from the above (Re-)duplication objections – where some putative change appears to preserve identity, but cannot for logical reasons162.
        4. In Teletransportation163, something distinguishes the forward going psychological continuity164 of the original and the initial backward-looking psychological discontinuity of the duplicate, but I don’t know what it is. Handwavingly, it’s the “wrong sort of causal chain165”, and it’s this causal-chain failure that defeats such Thought Experiments166.
        5. If I were to accept Lewis’s perdurantist167 thesis, the straightforward objection to the identification of the duplicate with the original is undermined – they simply share stages. However, there are still causal chain168 problems to address, and those of physical continuity169.
        6. While cloning170 falls under this head, there is no identity171 preservation, even under a perdurantist172 thesis, as there are no shared stages, just shared genetic material.
        7. Also, philosophical Zombies173 are supposed to be physical duplicates of their conscious174 analogues. But this is a TE that cannot really be conceived of.
      • Twinning175
        1. There are two forms of twinning:-
          1. Dizygotic twinning ("Wikipedia - Dizygotic (fraternal) twins"), wherein two separately-fertilized eggs simultaneously develop (to term), is uninteresting from the perspective of my Thesis.
          2. Monozygotic Twinning ("Wikipedia - Monozygotic (identical) twins") wherein a single fertilised egg splits into two separately-developing fetuses176 is a special case of Fission177.
        2. Monozygotic Twinning is an important factor – modally178 even when there is no twinning in fact – in the topic of Personal Identity.
        3. The possibility of monozygotic twinning is said to be the reason why no existing individual179 can be numerically identical to an earlier zygote180:-
          1. A zygote is capable of fissioning into two qualitatively identical, but numerically distinct daughter zygotes.
          2. So, a particular zygote has the modal property of developing into two monozygotic twins.
          3. Given that it cannot be identical to both of them – see the Logic of Identity181 – it cannot be identical to either (given that they are exactly similar there is no reason why one should be its closest continuer182 rather than the other).
        4. Conjoined-twinning would appear to be a case of fusion183 (maybe with prior fission184). This case is also be touched on in the discussion of Dicephalus185, which is the most extreme case of conjoined twinning.
      • Reduplication Objections186
        1. The problem of reduplication relates to a systematic problem in the logic of identity187, that of fission188, whether actual or potential.
        2. I have another Note in this general area, that of Replication189. Is this the same issue? The latter Note will deal with what Replication is and how it differs from Identity, while this Note will deal with the problems it causes for potential solutions to the problem of Personal Identity.
        3. So, this Note is about an objection. An objection to what?
        4. The case is probably best put in "Seibt (Johanna) - Fission, Sameness, and Survival: Parfit’s Branch Line Argument Revisited". Reduplication objections arise in various Thought Experiments190, especially:-
          1. Teletransportation191: you couldn’t survive because either the information192 can be used multiple times, or the original “you” might be left behind (the “Branch-line” case).
          2. Brain-state Transfers193: you cannot be the mental contents194 of your brain195, because they could be copied onto multiple “wiped” recipient-brains. This might seem to defeat the Psychological View196.
          3. Cerebrum Transplants197: You cannot be a brain198, because idempotent cerebra199 (or maybe half-brains) could be donated to two recipients, who would have equal claims to be your closest psychological continuer200.
        5. These responses to the TEs201 argue that we would not survive202 certain the vicissitudes in question. The force of these objections rests on the logic203 of identity as classically understood.
        6. Joanna Seibt herself thinks that Reduplication objections – in particular the “Branch Line cases” – “entail according to Parfit204 a conceptual distinction between the notion of identity205 and the notion of survival206”.
        7. As noted elsewhere, I hope this is a misunderstanding of Parfit. What he ought to be saying – and probably is – is that we can have most of what we want207 from survival without surviving208. Because you - that very individual209 – don’t survive unless you are the very same individual pre- and post- whatever contingency is under consideration.
        8. Reduplication objections also arise in the abortion210 debate, and the argument over when “we” – assumed to be human animals211 – begin212. The reduplication objection implies that this cannot be before the possibility of twinning213 is past.
        9. All these Reduplication objections are – I think – fully answered by adopting Perdurantism214, though there might be other objections to the stances adopted.
    3. Fusion215
      1. Like Fission216, though to a lesser degree, Fusion is important in the philosophy of identity – especially of personal identity – in that it provides many Thought Experiments217 (TEs), and some real-life examples, that test out the various theories.
      2. We need to consider the merger of the two psychologies218: Parfit thinks we might like to inherit some of the better characteristics219 of our partner, as in a marriage – but the creation of a single consciousness220 from two seems difficult to conceive of (much more so than the creation of two consciousnesses from one, as in fission221). Do we end up with a single first-person perspective222, or with two? This needs to be related to multiple personality disorder223.
      3. Also, consider Parfit224’s seasonal people that alternately fission225 and fuse. How conceivable are these TEs226?
      4. We also need to consider physical as well as psychological fusions, as in the case of the dicephalus227 and brain transplants228. These are in any case easier to imagine – or to think we can imagine – and apply to real and hypothetical cases.
      5. A non-pathological case of fusion – also discussed under Pregnancy229 and Chimera230 – is that of the very early fusion of non-identical twin231 embryos232. Then, the adult may contain cells with different genotypes, which would normally have ended up as two individuals233. Things get slightly odd when the twins234 were of different sexes as the organs can develop from one or the other (or both). There’s also the normal case where ‘foreign’ cells (mostly red blood cells) wander across the placenta and end up in the body of either the mother or the fetus235. All this is covered in "Ball (Philip) - How to Grow a Human: Reprogramming Cells and Redesigning Life", pp. 81-5.
      • Transplants236
        1. From the standpoint of Personal Identity, the most significant transplants are Brain Transplants237. While the transplantation of cerebrums238 and larger brain239-parts, including WBTs240 will be covered elsewhere, here we should cover Thought Experiments241 involving smaller brain-tissue transplants, which are supposed to transfer psychological242 elements from one person243 to another and not identity as such.
        2. In the context of animalism244, however – where it is said (by Olson245) that the brain246 is just another organ – there is less reason for Brain Transplants to receive centre-stage. Some animalists247 resist the “Transplant Intuition” – which is that “we go where our brains go”, but I will discuss that when discussing Brain Transplants.
        3. But, the animalist must still consider whether an organism248 can survive249 the transplant of “lesser” organs, and which – if any – transplants it cannot survive. We certainly accept that major-organ transplants – and even a complex of organs such as heart/lungs – preserve the Human Animal250 (and person251).
        4. Are there any limits beyond which we cannot go? Do we have to allow for a case of fusion252 in extreme circumstances? Is there a “core” of the animal253 that preserves identity while peripheral organs are swapped out?
        5. What about inorganic transplants? Is the Human Animal254 preserved, and does it incorporate the transplanted organs, or are they useful appendages (like clothes) that are external to it? Alternatively, do we then have a cyborg255? What about implants that affect our mentation256?
        6. I can’t delve far into the ethics of transplantation, but only the metaphysics thereof. That said, I’ve read, enjoyed and briefly commented on "Ishiguro (Kazuo) - Never Let Me Go".
    4. Psychopathology257
      1. Psychopathological cases are useful as real-life Thought Experiments258 for teasing out issues in the topic of personal identity, as in psychology259 generally, though it’s strictly-speaking of more interest to those espousing varieties of the Psychological View260 than to animalists261 like myself.
      2. The underlying assumption is that pathological cases have lessons for the general non-pathological case. It is only when a hidden process goes wrong that we get clues as to how it works.
      3. It is somewhat moot – though maybe not hugely relevant to my concerns – just what conditions count as pathological. Not everyone agrees that the latest edition of DSM262 has it right, as many social and political factors enter into the choices.
      4. The topic of aphasia – loss of the ability to speak – is of particular interest given the inclusion of language263 – on some accounts – as a defining characteristic of persons264.
      5. The same might be said of deficits of memory265 or of sense of self266 (autism, maybe controversially).
      • Clinical Observations267
        1. Clinical observations may be a better guides than Thought Experiments268 (TEs) as test cases for our theories of personal identity, because at least we know they represent a real possibility.
          • One of the main objections to TEs is that they are underspecified and confused.
          • However, even with actual clinical observation, we still have the trouble of the correct interpretation of the clinical data, which affects the conclusions we can draw from it.
          • See "Wegner (Daniel) - The Illusion of Conscious Will" for the sort of controversy that arises in these circumstances. Briefly, B. Libet’s experiments supposedly revealing that we act before the experience of willing the action can be variously interpreted.
        2. Examples of relevant clinical cases are
          1. Commissurotomy patients269 and
          2. Those with Multiple Personality Disorder270 (MPD).
          Is a commissurotomy or MPD patient “home to” one or two Persons271?
        3. I will argue elsewhere that PATIENT272 – like PERSON273 – is a Phase Sortal274 of the Ultimate Sortal275 HUMAN BEING276.
          • One Human Being277 can simultaneously be multiple patients (dental and chiropody, for instance), or a multiply-enrolled student.
          • Does this situation mirror those of our more seriously damaged human beings?
        4. One thing can’t be two things (in the sense of “be identical to”), even if the two things are of a different kind278 to the one thing.
      • Commissurotomy282
        1. A commissurotomy involves cutting the corpus callosum, the bundle of nerve fibres connecting the two cerebral hemispheres283 of the brain284. The procedure is used to treat epilepsy, but is invoked by philosophers as a Thought Experiment285 (TE) to provide an alleged real-life example of Fission286. The real-life situation usually has to be improved upon to overcome the laterality of the brain, and the two hemispheres are assumed to be idempotent, with nothing of philosophical significance alleged to ride on this idealisation.
        2. As with all TEs287, what we can learn from this one depends on our level of description of what is supposed to be going on. The idea is that each hemisphere fully supports the mental life of the subject(s), and consequently that there are, or can come to be, multiple subjects (Selves288) – and hence multiple persons289 – within the same human animal290.
        3. Commissurotomy is therefore used as an objection291 to animalism292. Some philosophers argue that (for modal293 reasons) there are always two Persons294 within the same Human Being295.
        4. Clearly, this is not obviously the case in the normal asymmetric brain296. See, no doubt, "Kinsbourne (Marcel) - Asymmetrical Function of the Brain", though this is rather an old book. So, in these Thought Experiments297 – and prior to this idealised idempotency – there has to be a period of equalisation and duplication298 of function. This sounds like it would lead to causal over-determination, but maybe the way it could be described is as with fault-tolerant computer299 systems, so that one hemisphere always takes the lead (or maybe they alternate) – in fact, this is said to be the case with marine mammals, to enable them to sleep300 without drowning: see, for instance, "Hecker (Bruce) - How do Whales and Dolphins Sleep Without Drowning?". The non-dominant hemisphere is just kept up to date – either continuously or periodically – with whatever data and current state is represented in the dominant hemisphere. In such a situation, there are already – prior to the commissurotomy – two exactly similar (other than that they are mirror images of one another) but non-identical half-brains301.
        5. Of course, the last sentence above begs some questions. It is only the cerebral hemispheres302 that are separated and duplicated303 – but they are still physically connected via the brain-stem – even if the logical connections are greatly reduced. It is said – see "Rosen (Victoria) - One Brain. Two Minds? Many Questions" and the references therein, which summarises the controversy between Yair Pinto and Michael S. Gazzaniga – that severed hemispheres can still communicate with one another via cues passed externally to the brain304. Indeed, the case of the dicephalus305 suggests that this co-ordination is possible with two complete brains, where the hands can be coordinated to drive a car and even type, despite being controlled by different brains.
        6. A recent paper – "Pinto (Yair) - When you split the brain, do you split the person?" – has suggested that the research for which Sperry received a Nobel Prize has not been replicated306 – in the case of two patients – and that this raises questions about the nature of consciousness307. I have my doubts. Might the corpus collosum not have been entirely severed in these cases, or might one of the above situations apply? Rosen claims that Yair Pinto thinks that other fibers are involved.
      • Multiple Personality Disorder308
        1. MPD – otherwise known as Dissociative Identity Disorder – is a condition traditionally viewed as psychopathological309, to be treated by therapy, though there are dissenting views. It occurs where a Human Being310 is, or appears to be, “home” to more than one Person311, or at least more than one Personality312.
        2. These Persons313 / Personalities314 may be radically dissimilar, and are (as the alternative designation implies) dissociated from one another. They can be like Locke315’s night and day man “incommunicable consciousnesses316”, unaware of one another’s existence – hence being in Lockean317terms different Persons318; or, they can be aware of one another, but as of distinct Persons319.
        3. No doubt one could complain that the clinically320-recorded cases are exaggerated, fabrications or otherwise unreliable. But there seems nothing wrong with them as TEs321, and ones least open to cavil given their approximation to reality.
        4. Effectively, we are supposed to have a Brain322 running more than one “Mind323-program” (on the “mind-as-software” approach); or a brain segregated into more than virtual machine (on the “mind as hardware”) approach to the mind-brain relationship.
        5. MPDs pose no problems to those espousing the Psychological View324 of Personal Identity – other than ethical issues concerning “therapeutic” suppression or unification of the alleged multiple Persons325 (see "Shoemaker (David) - Moral Issues at the End of Life"), but what is the response of the Constitution View326? Can we have more than one Person327 – with more than one First Person Perspective328 – constituted by the same human Body329? Animalism330 ignores psychological331 factors altogether as far as identity is concerned, so won’t be troubled.
  3. Principal Examples - Artificial
    1. Brain State Transfer332
      1. The idea behind a Brain State Transfer is that we can – at least in principle as a Thought Experiment333 – copy the Information334 from a Brain335 to a backup device and then restore it to another (or the same) brain – as in "Williams (Bernard) - The Self and the Future" – without changing the identity of that brain.
      2. This seems fanciful to me, as I’m sure it does to most people not enticed by Transhumanism336, but seems to be a natural Intuition337 to them.
      3. My scepticism is partly because I am antipathetic to functionalism338. The Information339 stored in Brains340 appears to be in highly distributed representations along connectionist lines rather than according to classical AI. The very physical structure and topology of the brain changes along with what it represents. There is no simple software / hardware distinction in a realistic Psychology341 of Human Beings342. Of course, even in a digital Computer343 there are physical changes to the various gates and storage media. But there is no growing or disassembling of connections.
      4. Consequently, this is a case of an under-specified TE344 that Kathleen Wilkes so objects to. When we try to flesh out the details, we find that the TE doesn’t really work. Any backup will need to be molecule by molecule to retain the informational richness of the original, and consequently any restore will not really simply modify the existing brain, but will destroy it and replace it with a replica345 of the brain whose contents are supposedly being transferred. It will not simply feed information346 into a pre-existing brain.
      5. Hence, I now think that Bernard Williams’s intuitions347 about the post-transfer A-body-person remaining a “mixed up” A-person are incorrect. Nor does A-body-person end up as B, but as a fusion348 of a replica349 of B’s brain350 and A’s body351. The situation is best described as a transplant352 of (maybe only part of) a replica of B’s brain into A-body-person’s head. A-body-person may end up confused, but only because – it seems to him – he’s obtained a new body.
      6. Of course, this TE353 retains all the difficulties associated with Brain Transplants354. A particular brain355 is wired up to control a particular body356, and won’t work adequately with a new one.
      7. Note that “uploading”357 differs from – and builds on – BSTs because it requires the person358’s psychology359 and phenomenal consciousness360 to be realised (I would say merely simulated) on a digital computer361, making a two-phase project, whereas BSTs – superficially at least – just require the copying phase.
    2. Brain Transplants362
      1. Brain Transplants, even if currently technically infeasible, are considered to be important Thought Experiments363 in the philosophy of Personal Identity. They seem to give the same answer to both the holders of the Psychological Continuity364 View and the Bodily Continuity365 View of what ensures the persistence366 of the person across time. Both say that the Person367 goes where the Brain368 goes.
      2. This assumption is the “Transplant Intuition”. However, some animalists369 (say they) fail to share this intuition. They (Eric Olson for instance) consider the Brain370 to be “just another organ”, albeit a very important one. I find this counter-intuitive371.
      3. In evaluating these claims it is important to understand just how the Brain372 works, so that we can determine just how fanciful our TEs373 are. I will discuss this under the Note on the Brain374. An assumption I make is that as we are interested in the question What We Are375, it is important to be empirically accurate.
      4. Note that there are three conceptually distinct versions of the idea of a brain transplant376.
        1. The first is a Whole Brain Transplant (WBT), though it becomes somewhat arbitrary quite where the brain377 is supposed to terminate – ie. just how much of the Spinal Cord is included. I include “head transplants” in this category. Note that these might otherwise described as “Body378 Transplants”. Both descriptions are tendentious and theory-laden.
        2. The second is the Cerebrum379 Transplant (single or double).
        3. Finally, there’s a “Brain Tissue” transplant, presumably with the intention of transferring particular psychological380 properties381.
      5. It might be objected that the TEs382 of WBTs are under-specified. A lot of motor-control is delegated to the non-brain parts of the Central Nervous System (CNS); apart from the brain, the CNS is, mostly, the spinal cord (see "Wikipedia - Central Nervous System"). To ensure motor-control, the brain and the CNS – and even the Peripheral Nervous System (PNS) need to work in tandem. The PNS consists in those elements of the nervous system other than the brain and the spinal cord (see "Wikipedia - Peripheral nervous system"). Yet a transfer of the entire CNS - which includes the spinal cord, let alone the PNS – which includes all the peripheral nerve endings (both sensory and motor) – stretches credulity somewhat.
      6. We need to consider just what the TEs383 are supposed to prove, and just why we sometimes consider WBTs rather than just Cerebrum384 transfers. I presume the preference for WBTs may stem from the presumed assurance that the seat of consciousness385 is transferred, which might not be the case if only a cerebrum or two are transferred.
      7. It may be we don’t care too much whether the recipient of the transferred brain is fully functional – though if we want assurance that this individual is an animal386, we might want the regulatory functions of the brain387 to remain intact. But whatever brain parts perform these tasks, provided the resultant individual has a full brain, however cobbled together, we might have what we want if the wiring problem can be solved.
      8. A Whole Brain Transplant might better be described as a maximal body transplant, while it is much less clear what’s going on in a Cerebrum388 Transplant. The latter are useful for cases of fission389 (with the added assumption of the idempotency of the two hemispheres), but it’s not fully clear just what psychological390 functions are left behind in this case. Because not all regulatory functions are in the cerebra391, it’s more difficult to argue that the human animal392 is transplanted with one or more cerebra393 than it is with a WBT.
      9. I’ve not heard of anyone arguing for animal fission394 by a fission of the whole brain395, but maybe they have. I suppose the simplest case of Animal Fission would be the separation of Dicephalus396 twins, taken (rather implausibly) to be a single Animal397 with two heads. But this case might better be described as two animals sharing parts, which are then apportioned in the process of achieving separation.
    3. Siliconisation398
      1. “Siliconisation” is a name – there may be others – for Thought Experiments399 involving the gradual replacement of neural tissue by silicon computer400 chips.
      2. An example is Peter Unger’s “zippering”. Unfortunately, I can’t find the reference for this, so it is possible I’ve either misremembered the term, or forgotten the author. Unger does discuss the gradual replacement of neurons by silicon in pp. 122-123 of "Unger (Peter) - The Physical Approach To Our Survival", but I couldn’t see the term used there.
      3. Anyway, this is a subtle argument. We don’t – of course – know whether this TE401 is metaphysically402 possible403. We don’t know whether silicon can sustain consciousness404, though functionalists405 assume that it can. Gradually, it is said, we no longer have a human animal406, but one that will – behaviourally at least – be indistinguishable from one.
      4. I think the situation is best viewed as an increasingly mutilated human animal407 with an ever-growing prosthesis. The term for such is a “Cyborg408”.
      5. I doubt that the silicon would maintain phenomenal consciousness409 but just be a “zombie410” simulacrum.
      6. Any replacement that would maintain phenomenal consciousness411 would be indistinguishable from natural part-replacement. But I think this is a contingent, empirical matter, a long way off from an answer.
      7. A question I’ve considered is whether siliconization would preserve the First Person Perspective412, irrespective of whether it impacts on consciousness413.
      8. I just note here that “silicon” is used as a proxy for any non-carbon-based intelligence414. Germanium, or Qubits might do as well (or better), though quantum415-computing416 might change the game somewhat.
    4. Dracula417
      1. In October 2022, while tossing and turning with Covid in the dead of night, it occurred to me that the fictional Dracula might be a useful case study for various issues in the general area of Personal Identity. This Note is the end result.
      2. Count Dracula is only a Fiction418, but the vicissitudes he is supposed to be able to survive may be worth some brief considerations to determine whether they are metaphysically possible – or even make logical sense.
      3. I have no great interest in what supposedly causes vampirism – whether it’s a virus or whatever, nor on how it’s passed on. Nor do I care about Dracula’s abilities to climb walls or fly through the air. Nor about his supposed aversion to garlic or crucifixes.
      4. However, the vampire is supposed to only maintain his Existence419 by drinking blood – preferably human, but animal blood – particularly of rats – will do at a pinch. I presume there’s some refection of ancient ideas that ‘the Life420 – or Soul421 – is in the blood’, which was not to be eaten.
      5. Dracula is described as ‘undead’. That is – he has died at some point – in fact at many points in later retellings in order to keep the sequels running – but is neither claimed to be alive nor dead. We might reflect on how such an idea squares with our normal ideas of what Life422 and Death423 are.
      6. The fictional claims that really interest me relate to Dracula’s Metamorphoses424. The first question is what he ‘really’ looks like. In the book, and film thereof, Dracula in has castle looks as you might expect someone over 400 years old to look. But when he appears in public, he looks young and handsome. Then – in the dénouement – when he is mortally wounded in the guise of his ancient self – he reverts to his youthful self in response to Mina’s kiss, after which he is ‘released’ by beheading. A question is – is he metamorphosing, or supposed to be influencing the vision of his beholders? As the latter would be needlessly complicated in busy London streets, I assume the former, especially as he is supposed to be able to transform himself in other – more radical - ways. Enough to say there’s nothing metaphysically problematical about such identity-preserving Metamorphosis425, as it’s presumably ‘just’ a rearrangement of Matter426, with some need for an energy source to effect the same. One needn’t worry about the details.
      7. The more interesting metamorphoses involve Dracula’s supposed Metamorphosis427 into a large dog-like animal on leaving the ship at Whitby, and into a mist, into bats, and rats.
      8. Transformation into a dog (and back) would be a trans-species Metamorphosis428. I’ve not much special to add here. If Dracula still falls under the Natural Kind429 concept Human Being430, and the natural kind is an essential property of the Individual431, then he would cease to exist as the dog, but – if Intermittent Existence432 is allowed – might subsequently ‘exist again’. The same might apply to the other transformations.
      9. It is supposed that Dracula transforms himself into many bats (or rats). Bats and rats are much of a muchness. The interesting common feature is the one-to-many ratio. If Dracula cannot survive – logically speaking – Metamorphosis433 into a dog, he certainly can’t survive transformation into a single rat or bat, let alone many of them. Each rat – we may suppose – is an independent sentient being. Can they collectively constitute another being? Would this ‘distributed’ being be an Individual434? Are we to suppose Dracula to be conscious in this state? It is true that Organisms435 are constituted by a multitude of cells, but these cells aren’t independent beings. More could be said – maybe along the lines of Societies436.
      10. Transformation into a mist is very odd. Presumably this is disassembly into microscopic constituent parts. Can an Organism437 – as distinct from a bicycle438 – survive such an adventure? "Olson (Eric) - Life After Death and the Devastation of the Grave" thinks not. Would he cease to exist in the interim or exist as a Scattered Object439?
      11. It’s not in the book, but – at least in Hammer Horror – human blood dropped onto his ashes allows Dracula to regenerate. This would seem to be an example of Resurrection440. At least there’s some physical Continuity441 mediated by the ashes.
    5. Teletransportation442
      1. In what follows, I’ve used the term “Teletransportation” because that is the term used by Derek Parfit443 in "Parfit (Derek) - Reasons and Persons". However, in Star Trek, the function is performed by the “Teleporter”. See:-
        → "Wikipedia - Teleportation" and
        → "Wikipedia - Teletransportation paradox"
      2. I also note that "Dennett (Daniel) - The Mind's I - Fantasies and Reflections on Self and Soul: Introduction" uses the equally tendentious term “Teleclone444”.
      Original Case Study - “Beam me up Scottie”
      1. There are two obvious supposed mechanisms for teletransportation:
        1. Transferring both matter and information; or simply
        2. Transferring information, utilising local matter.
      2. I gather that in the Star Trek series itself, it's plasma that's transmitted, but as this is unlikely to get to its destination without causing havoc, the information-only transfer is more reasonable. However, even in the plasma-transfer case, I'm unconvinced that I'd survive445, for two reasons:
        1. Some things (eg. bicycles, and analogous artifacts446) can survive disassembly and re-assembly, but only if they are disassembled into recognisable parts. If a bicycle is disassembled into iron filings and latex goo, and then re-manufactured, we might be reluctant to say it's the same bicycle.
        2. As a matter of empirical fact, fundamental particles are not distinguishable, so the labelling cannot be undertaken even in principle. If it doesn't matter which particle fits where, provided they are of the right sort, the case seems to collapse into the information-transfer variant. On consideration, I’m not 100% confident on this point. In any case, since we are biological organisms447, the particular atoms that make us up aren’t important, provided they are replaced gradually, and the structure is maintained.
      3. We now turn to the information-transfer case. My main worries initially here have to do with the possibility of duplicates448. We all know that a counterfeit, however well done, isn't the same as the original. The logic of identity449 is constraining. A thing is identical to itself and to nothing else, so if a thing is identical to two "other" things, these "two" must be identical to one another. Given that my two beamed-up versions aren't identical to one another, at least one of them can't be identical to me. And, since they are exactly similar450, why choose one rather than the other? So, neither is me. Both are exactly similar451 to me, but identity is to be distinguished from exact similarity. This situation is comparable to the case where the "original" human being isn't destroyed. This sort of thought experiment452 is referred to as the “Branch-line Case”: see section 75 in "Parfit (Derek) - What We Believe Ourselves To Be", in "Parfit (Derek) - Reasons and Persons". Canonically, it's where I've only a few days left to live (because the scanner has done me a mischief). Would I be happy in the knowledge that my duplicate453 would go on and on, and take up with my partner and career where I left off? Is this as good as if I survived? Not likely, unless we’re Parfitian454 saints! Note, however, that the case is tendentiously described (ie. as teletransportation) to lead to this seemingly obvious conclusion that this is a form of transport. Note that the technology is described tendentiously with the opposite intuition as “Telecloning” in "Dennett (Daniel) - The Mind's I - Fantasies and Reflections on Self and Soul: Introduction". The "main line" candidate would be perfectly happy that his rival back home was about to perish.
      4. Philosophers split into two main camps in response to these situations (though - jumping ahead a little - even if perdurantism455 is true, we still might not have the teletransportation of a persisting456 individual457, because of the wrong sort of causal458 link leading to a lack of forward continuity459 of consciousness460, or even of physical continuity). So there are multiple bifurcations, but we keep things simple here and just follow those who think that I either survive461 or have what matters462 in survival:-
        1. 4-dimensionalists (Perdurantists463): A thing is really a 4-dimensional worm through space-time, which consists in a set of instantaneous 3-D stages. In this situation, where multiple teletransportations occur, all copies are me. They are different 4-D worms, but they share all their pre-beaming-up stages. There were always at least 2 people present.
        2. 3-dimensionalists (Endurantists464) claim that while I'm not identical to the beamed-up person, yet I have what matters465 in survival466.
      5. Note that there's a modal467 argument to the effect that even in the usual case where only one copy is beamed up, and the original is destroyed, because there might have been multiple copies, this means that identity isn't preserved even in the case where there's only one teletransportation-result created. This seems to lead to paradox. Imagine the situation - I'm beamed up and think I've survived468, and am then told that the machine has malfunctioned and produced a duplicate469, and hence, contrary to my experience, I haven't survived after all! Unfortunately, some philosophers go along with a "closest continuer470" theory of identity across nasty cases of fission471 or fusion472. I'm identical to (or even “survive as473”) the continuer that most closely continues me, either psychologically474 or physically475, according to taste. How can my survival depend on what happens to someone else, the thought goes? See the “Only 'X' and 'Y' Principle476”. While this does seem odd, in fact you can’t trust the feelings of the teletransportees – for even if multiple copies are made, they all subjectively feel like the original.
      6. There are two questions outstanding.
        1. Do I survive the transfer? And, if I don’t,
        2. Does it matter that I'm not identical to the post-beamed person?
        I’m here ignoring the (as it seems to me) illogical “survival477 without identity” option.
      7. We have seen that it is possible that it appears to me that I survive, yet I do not. On the endurantist478 view, the logic of identity479 means that I cannot trust my experience. So, it seems possible that the person “waking up” is not me. I never wake up – in the sense that I lose consciousness, but never experience a re-awakening - but someone else with my past in his memories is created in my stead.
      8. So, is survival480 itself what matters481? Well, on the perdurantist482 view, survival is not even sufficient for me to have what matters in the sense Parfit483 intends. Imagine the case where the machine goes haywire and 1,000 exactly similar teletransportees are created. All these share my pre-teletransportation stages, so are all me (except that “I” was always 1,000 co-located individuals – and maybe more – who knows how often the machine may go wrong in the future!). In this case 1,000 individuals would be squabbling over the same friends, relations, job etc, and that might be rather a nuisance, and it seems that I wouldn’t really have what most matters to me, though no doubt I would be able to rebuild my life from scratch. However, this isn't fundamental to whether I do or don't survive, and it seem that what really matters to me is survival itself. If I'm a violin virtuoso or a body-builder, I might not find it much fun surviving as a brain in a vat484, but that would just be tough. The standard philosophical test is the "future great pain test485". I believe that the future continuant will be me, whether I like it or not, if I'm as terrified of that continuant being tortured as I would be if I were to be tortured in the normal course of events. Our BIVs486 would be even more upset at the prospect of torture-simulation being fed into their brains than at the loss of their beautiful bodies. Our fears have to be moderated by logic, however. But this is no worse than ignoring a revivalist rant on Hellfire. If I’m not identical to a particular teletransportatee, I won’t survive487, and if I don’t survive488 I won’t feel anything. I may have a moral obligation not to land others in a pickle, but it won’t be the selfish problem of avoiding landing myself in one.
      9. I can imagine fissioning489, by the bungled-beaming-up process, into 1,000 continuants, none of which (on a 3-D view) is identical to me, but all of whom seem to themselves to continue my first-person perspective490. I can imagine (just about) going into the machine, and coming out again 1,000 times (when the life-histories of the 1,000 then start to diverge). While the psychologies of the 1,000 are initially identical, they are not connected to one another, though they are each connected continuously to the pre-beamed-up person. So, if even one of them were to be threatened with torture, I'd be terrified if I thought that that one (even amongst all the others) would be me, in the sense that my experience continues into that body.
      10. But, do I survive491? I don't think I do, for reasons given above. It’s not that I reject perdurantism492, it’s just that even accepting perdurantism there’s too radical a discontinuity. It's clear that a duplicate493, looking backwards, wouldn't be able to tell apart the situation from the normal one of (say) just having woken up after a dreamless sleep. However, I imagine it's possible (even in a supposedly successful teletransportation) for – moving forward494 – there to be nothing it's like for me after the beaming - it's as though I never woke up, though someone else woke up thinking he was me. This would be a tragedy but, we'd never know about it, because (on this hypothesis) I wouldn't be around to tell the tale, and my duplicate495 would claim everything was fine (he remembered going to bed and waking up, as it were).
      11. This worries me slightly about our every-night bouts of unconsciousness. How do I know that “the me” that wakes up is “the same me” that went to sleep, and would it matter if it wasn't? Was my mother right in saying “it’ll be all right in the morning”, in the sense that I’d have no further experience of the current problem, or indeed of anything at all? Is this worry parallel to beam-me-up case? Or is sleep a pain-free death?
      12. I suspect the answer to these questions is that for a physical thing to persist, there needs to be appropriate physical continuity, and this continuity guarantees its persistence (though this intuition is a bit of a feeble response). On the assumption that my brain496 supports my conscious experience, this is enough to reassure me that, as it's the same continuing brain in my skull overnight, it's the same me that's conscious in the morning. I don't have the same reassurance in the case of beaming-up. So, I wouldn't go in for it, even if it came to be seen as a cheap form of transportation.
      John Weldon's "To Be"
      1. This is a 10-minute animated cartoon497 that discusses the question of teletransportation.
      2. In it, a mad scientist invents a teletransportation device as a means of free travel. The necessity of destroying the original is discussed, initially to avoid overpopulation, and then to prevent disputes as to who is who. The branch-line case, where the original is destroyed five minutes after the replication498, also features. There, it is clear that the original is a different individual to the teletransportee, and clings to life. Destroying the original is (in retrospect) murder – but what’s the difference between this situation and the one where the original is immediately destroyed? There’s obviously the anticipatory angle – in the “normal” case, the original thinks of the situation as one of travel, and no-one thinks that identity is not preserved in the process, whereas in the branch-line case the confusion is exposed, and the original knows that the teletransportee is a clone499. So, maybe the branch-line case is clearly a case of murder, whereas the “normal” case is a case of accidental homicide where the perpetrator is unaware that he’s killed someone?
      3. The twist in the tail is that the heroine, overcome with guilt after the branch-line case (which she’d originally just thought of as a logical demonstration) – and now understanding the metaphysics of teletransportation – thinks she can now
        1. atone for her crime,
        2. escape the guilt and
        3. escape her creditors by being herself teletransported.
        For (i) she dies and is cloned500 and (ii) / (iii) the teletransportee is a different individual to the original, so why should this individual have any moral connection to the other? There seems to be something fishy about this, but maybe it’s perfectly sound reasoning. However, …
      4. In the animation, the original and the teletransportee get muddled up (after all, both look alike and think alike), so for practical purposes we are in a situation similar to Locke’s “amnesiac drunkard” case – society501 has to find the drunkard guilty for his forgotten crimes (in that case because of the possibility of dissimulation); so, maybe the possibility of dissimulation or devious intent (as in the animated case) would for practical purposes mean that the teletransportee would inherit the moral and legal baggage of the original – and surely they would, or the practical consequences of people routinely escaping their debts would be grave.
      5. Yet, metaphysically, it’s no different from escaping your debts by committing suicide, because the teletransportee is not the same individual. And, I think the Branch-line case shows that it’s not the same person either, unless we allow the non-substance term “Person” to have multiple instances – as immediately post teletransportation, both the original and the teletransportee would seem to be the same person (however this is defined non-substantially) even though they would rapidly diverge into two different persons. Just as in the case of suicide, society502 has in the past tried to show that you “can’t really escape” – because of the prospect of Hell, so in the teletransportation case the same myth would be propagated. The teletransportee would be deemed to inherit the moral baggage of the original and, if not up to speed on the metaphysics, would think rightly so. But the original would have escaped for all that!
      • Replication503
        1. Replication arises where an obvious copying process takes place. I would claim that Teletransportation504 falls under this head. I'm currently not clear whether there's a distinction between replication and duplication505, other than that duplication would seem to be restricted to doubling, whereas replication is more open-ended.
        2. Does amoebic division count as replication? When an amoeba divides, this is not a case of fission506 but of reproduction. So, there are three amoebae involved – the original one and the two daughters. This is not the same situation as in fission.
        3. The above said, does this case depend:
          1. on how the case is described507 and
          2. on how – empirically – the replication occurs?
        4. If the amoebic division occurs by budding of a daughter, so that we can continually "track" the parent, then we have straightforward reproduction. If the division is symmetrical, the case could be correctly described as replication, though maybe on a perdurantist508 view we originally had two coincident509 amoebae that both persist.
        5. We need to watch out for closest continuer510 descriptions of the case.
        6. I feel I need to investigate the science of all this a bit more.
          1. On amoebae: see "Wikipedia - Amoeba (genus)"
          2. Their standard division is as all eucaryotic cells – by Mitosis ("Wikipedia - Mitosis") and Cytokinesis ("Wikipedia - Cytokinesis")
  4. Transhumanism511
    1. Transhumanism is the thesis that we human beings512 can – in principle at least – transcend our animal513 nature and escape or at least augment – in whole or part – our animal bodies514.
    2. The movement hopes – amongst other things – to extend our lifespans – either considerably or indefinitely.
    3. One particular strand of this hope is to escape our mortal bodies altogether by “uploading515 ourselves” to a digital computer516.
    4. Of course, there’s lots more to the movement, especially with somatic and mental augmentation to expedite our evolutionary517 progress via Cyborgisation518.
    5. I’m very doubtful about the possibility – practical or theoretical – of most of these aims, as well as their desirability. However, while this topic is on the borders of sci-fi, it is a challenge to animalism519 in that it presupposes that “we520” can transcend our biological origins521 in some way or other.
    6. The premier transhumanist of my acquaintance is Nick Bostrom. He has also argued that we might be (and indeed probably are) living in a computer522 simulation. See:-
      1. "Bostrom (Nick) - Are You Living in a Computer Simulation?",
      2. "Weatherson (Brian) - Are You a Sim?", and
      3. "Bostrom (Nick) - The Simulation Argument: Reply to Weatherson".
    7. Light-hearted introductions to the ideas and personalities are:-
      1. "O'Connell (Mark) - To be a Machine", and
      2. "Tegmark (Max) - Life 3.0: Being Human in the Age of Artificial Intelligence"
    8. And the main text for this topic is "More (Max) & Vita-More (Natasha) - The Transhumanist Reader". It’s probably best to start with the Introductions to the book’s nine Parts.
    9. Enough to say here that I’m not sympathetic to these aims, nor to the possibility of Uploading523, even in principle.
    1. Nearby Hopes
      • Chimeras524
        1. Chimeras are animals525 – or maybe humanoids – the mythical centaur is an example – made up of parts of animals from different species.
        2. The original Chimeras were mythical beasts ("Wikipedia - Chimera (Mythology)"), improbable amalgams of lion, goat and snake, though mules ("Wikipedia - Mule", the progeny of a male donkey and a female horse) are chimeras as the parents are of different species with different numbers of chromosomes.
        3. My only reference for this topic was originally "Savulescu (Julian) - Should a human-pig chimera be treated as a person?". This brief paper focuses on the ethics of using (future) pig-human chimeras as sources of (human) transplant526-organs or neural527 matter.
        4. The paper’s rhetorical question is rather ludicrous as there would never be any intention of engineering pigs with the attributes needed to qualify as a person, nor the need to do so even in the case of neural tissue (which would remain in the petri-dish). However:-
          1. Admittedly, "Ishiguro (Kazuo) - Never Let Me Go" considers the cloning of human beings so their organs can be harvested, but this is presumably because it is deemed to be the technologically simplest solution.
          2. I’m admittedly unclear about the question of neural tissue. But the idea of developing neural structures within a pig-human chimera and transplanting these structures into a human head is as far-fetched as brain transplants528, so can be ignored for now.
        5. Whether such a beast – whether hybridised with a human or not – were to qualify as a person529 ought to be based on its cognitive capacities and not merely on its chromosomes.
        6. It is possible that this topic might relate to transhumanism530. Rather than adding small quantities of human to pig, we might add quantities of animal to human. This would be the case in organ transplants – where an essentially normal organ is transplanted – but it might be the case that augmentative strategies could be adopted whereby humans are enhanced with bodily features (or, say, the physiological infrastructure) of animals, much as in the case of cyborgs531, but with organic rather than inorganic parts.
        7. I’ve noted the extended usage of the term “chimera” to designate human beings with body parts or cells originating from different human beings. I’m not sure this is helpful, or that it has much significant to say about identity conditions. Genetic uniformity is not sufficient for numerical identity (because of identical twins532) and I doubt it is necessary either. Examples given are women after (or possibly during) pregnancy and human-human transplant recipients.
        8. The following useful material comes from notes made on the RIP-version of "Kingma (Elselijn) - Were You Part of Your Mother?".
          1. Micro-chimerism (See "Wikipedia - Microchimerism"): Fetal-maternal & Twin-twin transfer. Pregnant women usually pick up fetal cells during pregnancy, which remain in their bodies for decades.
          2. Macro-chimerism: Kidney donation; blastocyst fusion (see "Wikipedia - Chimera (Genetics)"). This link distinguishes Chimeras from Hybrids and Hybridomas. In a Chimera, each cell is genetically uniform, whereas:-
            • Hybrids: form from the fusion of gametes from two species that form a single zygote with a combined genetic makeup. See "Wikipedia - Hybrid (Biology)".
            • Hybridomas: result from the fusion of two species' cells into a single cell and artificial propagation of this cell in the laboratory. See "Wikipedia - Hybridoma Technology".
            In the latter case, two blastocysts (of non-identical twins) fuse non-pathologically (the pathological cases are of conjoined twins – where there’s incomplete fusion and integration) – for all Kingma knows this might be true of her – so that some organs are formed from one blastocyst and the others, or the skin, are formed from the other. It’d be bonkers to think that such cases weren’t each a (single) organism.
        9. I’m indebted to "Ball (Philip) - How to Grow a Human: Reprogramming Cells and Redesigning Life", pp. 81-5, for further information on the above case where, because of very early fusion of non-identical twin embryos533, the adult may contain cells with different genotypes, which would normally have ended up as two individuals. Things get slightly odd when the twins were of different sexes as the organs can develop from one or the other (or both). There’s also the normal case where ‘foreign’ cells (mostly red blood cells) wander across the placenta and end up in the body of either the mother or the fetus.
      • Cyborgs534
        1. Briefly, a Cyborg (Cybernetic Organism) is a human being (or any organic being) with some inorganic parts (see "Wikipedia - Cyborg").
        2. Compare and contrast with Android535, which is a humanoid robot.
        3. See also Siliconisation536, the Thought Experiment537 wherein we have the gradual replacement of (human) neural tissue with microchips while – allegedly – preserving consciousness538 and mental539 function.
        4. And again, connect to Chimeras540. In this case, biological material from other animals is merged with human tissue to provide an enhancement, and there are other situations where human tissue is to be harvested from other animals – after genetic modification or other means – for the purpose of implantation541.
        5. All of the above is beloved of the Transhumanists542, who want to enhance the human condition by all means possible, even if this means that humans are no longer – strictly speaking – human beings543.
        6. My interest in Cyborgs stems from the impact of their possibility on the truth of Animalism544.
        7. If we are (human) animals545, would we continue to exist if increasingly enhanced by technological implants546 and extensions. I see no immediate problem – just a bit more along the lines of spectacles & hip replacements. But no doubt there would eventually become a tipping point when we become more inorganic than organic547. Our persistence conditions548 would then be mixed between those of organisms549 and artefacts550. Or is the situation better described by us shrinking (if our parts are replaced) or – if the technological parts are add-ons – remaining unchanged. Currently we’re unchanged by our spectacles, but hip replacements become part of us. Is this not so?
    2. Far Off Hopes
      • Uploading551
        1. This Note will discuss the Transhumanist552 fantasy of uploading you553 (or your mind554) to a computer555.
        2. For this to be possible, the “Computer Model” of the mind – which seems to be the dominant paradigm in neuroscience – needs to be true of us, and not just a model. This is the view that the brain operates like a digital computer556 and is disputed by, for example, "Epstein (Robert) - The empty brain".
        3. "Miller (Kenneth D.) - Will You Ever Be Able to Upload Your Brain?" points out the formidable technical obstacles to building a full model of the brain, and that consequently Uploading is not to be anticipated any century soon. The author does, however, think that it is metaphysically possible557.
        4. I don’t believe this, for the same reason that I don’t think Teletransportation558 – even if technically feasible – is identity-preserving. Rather than uploading you, we’d only achieve a simulation. But even if the individual ‘in’ the computer were to be conscious559 and a person560, it would not be you but someone else.
        5. Additionally, this Note should cover the – more realistic but still technologically very remote – possibility of uploading information561 into our brains562, though this overlaps with Brain State Transfer563, though the latter is the uploading of an entire psychology rather than information.
      • Computers564
        1. This discussion will be restricted to the role Computers play in the philosophy of Mind and Personal Identity. While I am an animalist565, the mind566 and brain567 are important topics in alternative accounts – in particular the Psychological View568 and the Constitution View569.
        2. The “Computer Model” of the mind seems to be the dominant paradigm in neuroscience. This is the view that the brain operates like a digital computer. This is disputed by, for example "Epstein (Robert) - The empty brain".
        3. There’s a cross-over in much of the above topic with Functionalism570.
        4. Where this gets exciting is in the Transhumanist571 hope of uploading572 (you573, or your mind574) to a computer. This will be dealt with under the head of Uploading575.
        5. A related issue – also currently noted under Transhumanism – is whether we are (most probably) living in a computer simulations, whether or not we might have been uploaded576 there.
        6. Also, there’s the whole question of Artificial Intelligence577, and in particular whether computers – or maybe even computer programs – might ever become persons578.
        7. This topic might get caught up in the “Connectionism” debate, and whether connectionism – which seeks to adopt the neural connectionist architecture of the brain – can account for the “systematicity of cognition”. I don’t want to stray too far down this interesting path.
        8. I might also add the question whether the success of self-teaching game machines579 has anything to say about the innateness controversy – whether human beings are born with a “language580 instinct” or whether generic associative learning capabilities are sufficient to explain the near-miraculous acquisition of language by toddlers. I used to think not – see the Poverty of the Stimulus Argument581.
        9. The above comment is now rather outdated given the rise of ChatGPT and other Large Language Models (LLMs) which need to be discussed.
      • Androids582
        1. Briefly, an Android (Wikipedia: Android) is – or would be were one to be built – a robot with no organic parts that looks and acts like a human being; those looking otherwise are simply “droids”.
          • The Android needs to behave as if it had an appropriate psychology583 – at least one that passes the Turing Test.
          • This psychology need not involve phenomenal consciousness584 – indeed it is one of the problems of philosophy to consider how we could ever know whether or not an android is phenomenally conscious.
          • Could it not be a zombie585?
          • Compare and contrast with Cyborgs586.
        2. The relevance of Androids to the topic of Personal Identity stems from whether or not Androids would be persons587.


Concluding Remarks
  1. Having now discussed Thought Experiments in general, we now in our next Chapter596 turn to the question of Resurrection – the matter that first motivated Locke (and – I suspect – Lynne Rudder Baker and many others) in their discussions of Personal Identity.


Links to Books / Papers to be Addressed597
  1. This section attempts to derive the readings lists automatically from those of the underlying Notes, but removing duplicated references. The list is divided into:-
  2. There must be many more papers on Brain State Transfers than the classic one by Williams (and commentaries thereon) – I just haven’t got them correctly categorised. Under this head should be included references to “Brain Zaps” and the like.
  3. Siliconisation must be covered somewhere in "Unger (Peter) - Identity, Consciousness and Value", where it is referred to as “zippering”. I intend to re-read this book as part of the work for Chapter 1600, so I will find it then, I hope.


Works on this topic that I’ve actually read601, include the following:-
  1. Thought Experiments
    1. Thought Experiments602
    2. Intuition606
    3. Future Great Pain Test609
  2. Principal Examples - Natural
    1. Clones611
    2. Fission
    3. Fusion
    4. Psychopathology
  3. Principal Examples - Artificial
    1. Brain State Transfer635
    2. Brain Transplants638
    3. Siliconisation646
    4. Dracula649
    5. Teletransportation650
  4. Transhumanism
    1. Transhumanism660
    2. Nearby Hopes
    3. Far Off Hopes

A further reading list might start with:-
  1. Thought Experiments
    1. Thought Experiments678
    2. Intuition680
    3. Future Great Pain Test689
  2. Principal Examples - Natural
    1. Clones690
    2. Fission
    3. Fusion
    4. Psychopathology
  3. Principal Examples - Artificial
    1. Brain State Transfer704
    2. Brain Transplants705
    3. Siliconisation706
    4. Dracula707
    5. Teletransportation708
  4. Transhumanism
    1. Transhumanism710
    2. Nearby Hopes
    3. Far Off Hopes


In-Page Footnotes

Footnote 2:
  • This is the write-up as it was when this Abstract was last output, with text as at the timestamp indicated (14/02/2026 00:41:46).
  • Link to Latest Write-Up Note.
Footnote 14:
  • The hyperlinks in this Introduction – as in the other Chapter Introductions – are intended to help motivate the various Notes used in the construction of the Chapter.
  • So, a link appears once and once only per Note in the Note Hierarchy below and appears – as far as possible – in the order of the Hierarchy, even if this is not its first mention.
  • Links to other Notes are omitted in the Chapter Introduction but appear passim in the Main Text.
Footnote 52:
  • This Note will be excluded from the Reading List for this Chapter.
  • It is included in the Reading List for Chapter 8.
Footnote 60:
  • This Note will be excluded from the Reading List for this Chapter.
  • It is included in the Reading List for Chapter 2.
Footnote 99:
  1. Oh dear! I’m now uncertain about this! Maybe this is a good thing, from an Animalist perspective. Or not.
  2. The point is that – after a period of unconsciousness – say normal sleep – when I awake can I really be sure that it’s I who awake, or merely that whoever it is in my bed awakes.
  3. That it is I in my bed can only really be ascertained by reference to third parties, who assure me that there has been no intervention (so I’ve not been replaced by a simulacrum complete with my memories).
  4. Of course, in the current state of technology, such worries would be highly irrational.
Footnote 105:
  1. No doubt it does, but I need to specify which!
  2. See "Gale (Richard) - On Some Pernicious Thought-Experiments", which is also a vague reference!
Footnote 111:
  1. Teletransportation is sometimes rather tendentiously referred to as “Telecloning”.
  2. Yet, calling it “Teletransportation” is equally tendentious, and
  3. “Telecloning” has at least the virtue of being the correct description!
  4. See "Brennan (Andrew) - Survival".
Footnote 120:
  1. See "Ball (Philip) - Beyond Weird: Why Everything You Thought You Knew About Quantum Mechanics is ... Different", pp. 267 – 272.
Footnote 262:
  1. I have DSM3
    → "American Psychiatric Association - Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R)", and
    → "Spitzer (Robert), Skodol (Andrew), Gibbon (Miriam) & Williams (Janet) - DSM-III Casebook: A Learning Companion to DSM III",
  2. But the latest edition is DSM-5-TR (Text Revision), published in March 2022.
  3. See Wikipedia: DSM.
Footnote 272:
  1. This seems confused. A patient with MPD is still one patient, though may be multiple personalities, or even Persons.
Footnote 418:
  1. While Dracula is today a Fictional character, there is of course a historical antecedent in Vlad the Impaler. See Wikipedia: Vlad the Impaler. I have no professional interest in the historical facts, however.
  2. My considerations include not only the inventions of Bram Stoker but also the later additions of Hammer Horror. See:-
    → Wikipedia: Dracula,
    → Wikipedia: Count Dracula,
    → Wikipedia: Hammer Film Productions - Dracula,
    → Wikipedia: Hammer Film Productions - Dracula 2., and others,
    → Wikipedia: Bram Stoker's Dracula (1992 film),
    … and also, as an indication of what senior vampires are supposed to be able to do …
    → Wikipedia: Interview with the Vampire (film).
  3. Unsurprisingly, I had nothing philosophical on this topic when I first considered it. Even a trawl of JSTOR revealed nothing of relevance. There was lots on the history, politics, sociology and sexuality of Dracula, but nothing I could see that discussed the Metaphysics.
  4. There is a Cambridge Companion to Dracula which I have access to via Cambridge Core but this has little of interest to me. See The Cambridge Companion to Dracula. The editor is Roger Luckhurst, from Birkbeck – though not from the Philosophy Department. See Wikipedia: Roger Luckhurst.
Footnote 438:
  1. Actually, it is doubtful that a bicycle can survive ‘atomisation’ followed be ‘reconstitution’.
  2. The disassembly and reassembly of bicycles and watches are paradigm cases of the persistence of artifacts. But this isn’t the same as being turned into mulch and then being re-manufactured.
Footnote 497:
  1. I originally came across this on YouTube, but it was periodically taken down with the legend “This video is no longer available due to a copyright claim by National Film Board of Canada”.
  2. However, it now seems to be freely available from the source. John Weldon’s "To Be".
  3. It seems to be aimed at 12–18-year-olds, but is none the worse for that.
Footnote 579:
  1. AlphaGo and AlphaZero.
  2. I have "Sadler (Matthew) & Regan (Natasha) - Game Changer: AlphaZero's Groundbreaking Chess Strategies and the Promise of AI", but it is mostly about chess!
Footnote 597:
  • See the section on Research Methodology for what is to be done with these.
Footnote 612:
  • This is even less relevant than Nussbaum – being a novel. It raises ethical questions in a futuristic situation.
Footnote 621: Footnote 631: Footnote 633:
  • MPD is referenced in my comments only!
Footnote 639:
  • While mostly about other matters, this article reminds us that “brains and bodies develop together”, so simply removing a brain and trying to plug it into another body won’t necessarily work, however good we are at the wiring.
Footnote 641: Footnote 648:
  • Tye seems to be discussing brain-partition, with silicon transceivers. But he uses Unger’s term “zippering”.
  • He is indebted to Arnold Zuboff, who may be worth following up.
Footnotes 651, 661, 668:
  • Also look through other works by Andy Clark to get a handle on what he means by 'patterns in information space'.
Footnote 653: Footnote 654:
  • This is a useful head-count on contemporary philosophers’ views on surviving teletransportation.
  • See my comment therein.
Footnote 657:
  • Restrict a close reading to Part 3 (Personal Identity).
Footnote 664:
  • Some vaguely interesting historical background.
Footnote 669: Footnote 671:
  • I’ve read this book, but it’s insufficiently philosophical for its arguments – such as they are – to be worth considering as a priority.
Footnote 672: Footnote 674: Footnote 679:
  • This paper is of much wider import than TEs, but it shows a famous TE in action, together this trenchant criticisms and defences thereof.
Footnotes 681, 683, 684, 685, 686, 687, 688:
  • Philosophy of mathematics & logic.
Footnote 682:
  • I’ve not listed the individual papers in this book.
Footnote 691:
  • This book is concerned with the ethics of medical cloning, so is mostly tangential to my concerns.
  • However, the items in Part I: Science, and Part II: Commentary are likely to be of use.
Footnote 697:
  • This looks like an important paper, which rejects the “proofs” of 4D based on the “coincidence” TEs.
Footnote 702:
  • There are other papers on this topic by Michael S. Gazzaniga that I’ve not had time to collect yet.
Footnote 715: Footnote 716:
  • This paper no doubt considers the use of computers for simulating situations other than minds, so might not be directly relevant.
Footnote 717: Footnote 718:
  • This seems somewhat tangential, as it’s not focused on simulating persons, but it might be useful background.
Footnote 719:
  • There’s quite a lot by Searle that is relevant, but it’s important not to get dragged in too far into his “outlier” perspective – unless, of course, he’s right!
  • It may be best to start with the whole of the book from which this paper is taken, ie. "Searle (John) - Minds, Brains and Science: The 1984 Reith Lectures".
Footnote 720: Footnote 722:
  • This is very elementary, but short and maybe entertaining.

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