Thesis - Chapter 08 (Arguments against Animalism)
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Write-up2 (as at 16/02/2026 09:59:02): Thesis - Chapter 08 (Arguments against Animalism)

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. A discussion of the arguments against animalism, as given by those of anti-animalist persuasion and defended by the principal animalists (with a focus on Eric Olson), with a critique.


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. There is effectively a 1-1-match between this Chapter and the Note Animalism – Objections15, though I imagine that this Chapter will be more focussed and less exploratory than that Note.
  2. The main objections to Animalism are those of incredulity to the Animalist claim that “matters of psychology are irrelevant to personal identity”, when most philosophers have thought – and still do think – that it’s constitutive of it. As I’ve said previously and often – this is to confuse What Matters to us with What we Are.
  3. Then we have the Brain Transplant Intuition – that we go with our brains. It is very difficult to resist this intuition – for reasons I’ve given under my Note on Forward Psychological Continuity, though Eric Olson insists that the Animalist must deny it as a brain isn’t an Organism.
  4. Then, there are awkward pathological cases where it’s not clear quite what the animalist should say. I’ve collected these under the Note on Dicephalus16.
  5. Finally, there’s the question of what’s going on during Pregnancy17, which Animalists have allegedly failed to address. Is the Fetus18 a part of the mother? If so, we’d have a case of Fission at birth. Traditionalists would deny this, so the problem ‘goes away’, but it needs to be considered carefully from the actual biology (covered in the previous Note and those on Zygotes19 and Embryos20).
  6. I’ve also included the topic of Abortion21 as part of this Chapter, though it’s maybe either misplaced, or not sufficiently relevant.


Note Hierarchy
  1. Animalism22. Excluded23
  2. Arguments against Animalism24
  3. Dicephalus25
  4. Pregnancy26
    1. Zygote27
    2. Embryos28
    3. Fetuses29
    4. Abortion30


Main Text
  1. Arguments against Animalism31
    1. A convenient starting-point for reviewing objections to Animalism is in "Olson (Eric), Etc. - Abstracta Special Issue on 'The Human Animal'", reviewed in this Note32.
    2. The most obvious objection is to the initial implausibility of Animalism’s basic contention that – because I was once a fetus33 and may one day be a vegetable34 – psychological continuity35 or connectedness36 can have nothing to do with my persistence criteria37. Animalists can be accused of not taking persons sufficiently seriously38.
    3. Additionally, Animalists are said to have a “corpse problem39”. Because I am co-located with my “corpse-to-be”, the Animalist is hoist by his own petard, in that he has the analogue of the “fetus problem40” he alleges against the Constitution View41.
    4. A spin-off from the alleged irrelevancy of psychology for human identity is the need to deny the Brain Transplant42 intuition – that “I go where my brain goes”. The Transplant Intuition has been defended from an animalist perspective in "Madden (Rory) - Human Persistence".
    5. In "Olson (Eric) - Human Atoms", Olson mentions four “favourite objections”, though these strike me as being rather feeble, and I suspect them of being straw men:-
      1. If you were an animal, you would be identical with your body (or at any rate with some human body). But no human body can think or feel or act, as you can.
      2. Persons and animals have different persistence conditions: the organism that is your body could outlive you (if you lapsed into a persistent vegetative state), or you could outlive it (if your brain were transplanted and the rest of you destroyed). But a thing cannot outlive itself.
      3. Persons and animals have different criteria of synchronic identity: any human animal could be associated with two different persons at once (as cases of split personality). Thus, no person is an animal.
      4. These experiences – the ones I am having now – are essentially mine. But they are only contingently associated with any particular animal. Hence, I have a property that no animal has.
    6. The above paper is intended, however, to rebut the argument against animalism in "Lowe (E.J.) - Subjects of Experience", which have the unlikely consequence that we are “mereological atoms”.
    7. "Hudson (Hud) - I am Not an Animal!" argues against animalism via the “Elimination Argument”, which I’m yet to investigate and understand. "Bailey (Andrew M.) - The Elimination Argument" seeks to rebuff it.
    8. Elselijn Kingma has accused animalists of not taking Pregnancy43 as an important issue for Animalism. She thinks that the Fetus44 is a part of the mother. My view is that animals can share parts, as seems to be necessary for Conjoined Twins45, which are another supposed objection to animalism if it could be successfully argued that there is only one animal in these cases.
  2. Dicephalus46
    1. This Note is more general that Dicephalus, but I can’t think of a better title. There are several related pathological conditions in which the number of animals47 and the number of individuals48 may fail to align. In order of increasing severity of the “condition”:-
      1. Conjoined Twins: "Wikipedia - Conjoined Twins". Varies from a fairly loose conjunction of individuals, who may be separated, to more severe forms with shared organs and limbs. This article is of interest not least because it discusses the issue of fission49 versus fusion50, with the latter now the favourite suggestion.
      2. Craniopagus: "Wikipedia - Craniopagus Twins". The babies are joined at the skull. Contrast the case where both twins are persons51 with the degenerate case "Wikipedia - Craniopagus Parasiticus".
      3. Polycephaly: "Wikipedia - Polycephaly". Animals or humans with apparently more than one head. Dicephaly is the limiting case. Usually an extreme version of conjunction. See, for example, BBC - Rare two-headed snake. Note that the description “two headed” seems more plausible in the case of reptiles than humans, given their presumed reduced mental experience. That said, given that dicephaly is – according to this article – a case of incomplete fission52 of an original single individual – this descriptive decision may be correct.
      4. Diprosopus: "Wikipedia - Diprosopus".
        1. Animals, including humans, with two faces. There may be one or two brains, but only one skull. The important thing – and what differentiates the diprosopus from the dicephalus – is that there is much less duplication of body parts, so it is very much two brains sharing one body – though it can also be the relatively superficial – though tragic – case of one brain, one body and two faces.
        2. For more on diprosopus53 see:-
        3. The Mail Online diprosopus article above quotes the following “Medical Facts” from the Embryo Project Encyclopedia:
          • The rare condition diprosopus is also known as craniofacial duplication.
          • Diprosopus refers to a baby born with a single torso, normal limbs and facial features, which are duplicated54 to a degree.
          • In mild instances the baby may have a duplicated nose and the eyes may be spaced far apart. But in extreme cases the entire face can be replicated55, hence the name diprosopus - Greek for two-faced.
          • Most babies born with diprosopus are stillborn, and there are fewer than 50 cases documented since 1864.
          • Where a baby is born with two complete identical faces, the condition is considered a rare variant of conjoined twinning.
          • But while conjoined twinning is the result of an incomplete separation of two embryos, diprosopus is caused by abnormal activity of the protein Sonic Hedgehog (SHH).
          • The protein is responsible for signalling craniofacial patterning during embryonic development, and among other things governs the width of facial features.
          • Where the protein is found in excess, a baby will have wider facial features, and in extreme cases it can cause the duplication of those features.
          • Diprosopus can be detected via ultrasound in pregnancy, or via CT scanning.
          • One of the first indications of the condition is the detection of abnormally high amount of amniotic fluid present within the amniotic sac.
          • There is currently no treatment to cure the condition and because of its rarity few treatment options or corrective surgery techniques exist.
        4. This doesn’t seem to explain why there should be two brains, however. An actual search of the Encyclopedia delivers a much briefer and less informative article.
    2. All these situations – and in particular the paradigm case of dicephalus, wherein it appears that we have a human animal56 with two heads – are often cited as a prima facie problems for Animalism57.
    3. The claim is that while we have multiple persons58, we only have a single animal59, so the animalist60 claim that persons are numerically identical to their organisms61 is false.
    4. Of course, the above claim is somewhat bald. Animalism62 – at least in the form expounded by Eric Olson – has no truck with psychology63 as necessary for our persistence64. While Olson often refers to “people” this is just shorthand for “some of us65”, rather than “persons”, the plural of person66.
    5. So, if the animalist claim is that we are human animals, then the question is – in the case of dicephalus and related conditions – how many of us67 are present, and how many human animals68 are present. Animalism69 needs the numbers to be equal.
    6. That said, these cases add to the prima facie case for animalism – that we are human animals – as our animal nature is pointed out by the unfortunate errors that have arisen during the gestation of the animal.
    7. The cases under consideration have the advantage over standard Thought Experiments70, in that they are real-life cases. What is actual must be possible, and a standard argument against TEs is thereby avoided, namely that some of them, at least – whatever our intuitions may say – may not in fact be possible71 because the TEs are under-described.
    8. That said, there’s still a temptation to push the boundaries, and to consider cases in this general area that are not actual yet are not quite as science-fiction as the usual TEs72.
    9. Cases of dicephalus are fairly rare, and often one “twin” is degenerate (contrast "Wikipedia - Craniopagus Parasiticus" with "Wikipedia - Dicephalic Parapagus Twins") so it’s not clear that we have two persons73 or two of “us74”. However, the case of the dicephalus twins75, Abigail and Brittany Hensel, where one body appears to be coordinated by two brains (see "Wikipedia - Abby and Brittany Hensel") shows that this is not necessarily the case. Here we definitely have two persons76, but maybe only one animal77. This is probably a real-life case of either incomplete fission78 or of fusion79.
    10. There are two issues with these cases:-
      1. How should they be best described?
      2. How should the animalist respond?
    11. Description:
      1. I need to research this further, but it seems to me that we have a sliding scale of pathological cases – from that of Siamese twins (who are often fairly loosely connected, and can often be surgically separated) to the much more extreme cases of diprosopus.
      2. I presume, also, that we can have either fission80 or fusion81, or indeed both serially – as the case may be – an empirical matter.
      3. In the case of (incomplete) fission82, the twins83 will be identical, as the situation is one where the twinning process has not completed.
      4. But (I imagine) we can also have a case of fusion84, where the twin-embryos85 – whether identical or fraternal – that were separate have subsequently partially fused. Note that if the twins are identical, we will have had a case of fission86 followed by fusion87. I don’t know whether there have been any actual cases of this.
    12. Response:
      1. The most likely response from the animalist88 is that the dicephalus is not a single organism89, but two organisms that share some body-parts.
      2. The force of the arguments in this kind of case depends on “relevant similarity” – if the dicephalus-case is sufficiently similar to the general case, it can be used to show things about the general case. But this claim can be rejected.
      3. In the case of diprosopus, it is more difficult to claim that there are two organisms90. Now – in practice – there are never two persons91 either (as in all the 30-odd cases recorded since 1860, the condition has proved quickly fatal, so there were no persons92 present). But this might not always be so. Also, Lynne Rudder Baker might claim that the rudimentary persons were indeed persons93 – as there was a possibility that they would develop into robust persons. Failing that, it might be the case in the future there is a case where the diprosopus survives to develop personality94. There does seem to have been an actual case of survival into adulthood, but there was only one person, and one disfigured individual. Finally, we have to decide how to describe the situation where there is one brain stem but two ‘brains95’ (presumably two sets of cerebral hemispheres96). There don’t seem to have been any actual cases of this in humans, but there might have been97.
  3. Pregnancy98
    1. At first sight, this topic sounds utterly tangential to my research interests, but I’ve included it because Elselijn Kingma complained – in "Kingma (Elselijn) - BUMP: Better Understanding the Metaphysics of Pregnancy (B1)" – that "Olson (Eric) - The Human Animal - Personal Identity Without Psychology" contained not even a footnote on the topic of pregnancy and the metaphysical issues it raises, in particular for animalism99.
    2. Following Kingma, the discussion will focus on the relationship throughout pregnancy between the mother and the fetus100. The key question is whether the fetus is a part of the mother or is a separate individual101 inside her. Additionally, we need to consider whether this status changes as pregnancy progresses.
    3. I have to admit immediately that (contra Kingma) – my initial view102 is that the relationship is more “bun” (the “container model”) than “bump” (the “part model”), though this separation seems clearer as pregnancy progresses, following the implantation of the Zygote103 (prior to which there is clear separation – though I suppose we might consider the zygote a small bundle of maternal cells, despite their genetic distinction – a situation that occurs in other cases).
    4. It looks like Kingma’s view is of pregnancy as a case of fusion104 (at the point of implantation of the Zygote; I will discuss the ontological status of the zygote shortly) followed by fission105 (at birth).
    5. Another point to consider is the possibility of technological developments to enable gestation in an artificial uterus (see Wikipedia: Artificial womb). Would the same arguments imply that the fetus is a part of the machine? Is this plausible?
    6. Having said all the above, just what is the problem for animalism?
    • Zygote106
      1. A Zygote ("Wikipedia - Zygote") – is the immediate post-fertilisation product.
      2. In humans, the zygote develops by division until it implants as the embryo107. Until then it is called a pre-embryo ("Wikipedia - Pre-embryo"); a morula (Wikipedia: Morula) after 4 divisions – 16 blastomeres – and a blastocyst ("Wikipedia - Blastocyst") by the 5th day. The implanted embryo is called a fetus108 after 11 weeks.
      3. In the philosophy of personal identity, the question arises when the human being109 or the human person110 arises. Additionally – and relatedly – was I111 ever a zygote (or an embryo112, or a fetus113).
      4. Most philosophers agree that a zygote isn’t a person114, because it does not possess the appropriate psychological115 attributes.
      5. Many philosophers contend that a human zygote isn’t a human being116 either – in that it hasn’t the appropriate set of organs.
      6. In addition, the question whether I was ever a zygote is complicated by two considerations:-
        1. Twinning117: is a special case of fission118. Why should the zygote be numerically identical to one – rather than the other – of a pair of monozygotic twins? Modal119 considerations apply if I am in fact not a monozygotic twin.
        2. Difference over the definition – or maybe ontological120 category – of “person121”. Some philosophers insist that an individual122 can be a person123 on account of its expected future capacities124, or actual or once anticipated past capacities, irrespective of its present capacities.
      7. A question raised by the philosophy of Pregnancy125 is – in the case of human beings and mammals generally – what is the ontological status of the Zygote? Is this bundle of free-floating cells a part of the mother or is it a separate individual? It is genetically diverse from the vast majority of the mother’s cells, which would suggest a separate individual – but there are cases of Micro-Chimerism126 where genetically-diverse cells would be considered part of the mother (I suppose).
      8. As a footnote, in single-celled animals the zygote may constitute the entire animal. I once had “necessarily asexually-reproducing” here. The Wikipedia entry has it that such single-celled organisms reproduce asexually by mitosis. But if all such organisms arise in this way, in what way are they correctly described as “zygotes” which involves the “yoking together” of two distinct and differentiated gamete cells? Is it possible that some organisms reproduce both sexually and asexually? And – if so (as I believe) – is it true in this case? Do I care?
    • Embryos127
      1. In humans, the immediate post-fertilization product – the zygote128 – develops by division until it implants as the embryo ("Wikipedia - Embryo"). It is called a fetus129 after 11 weeks.
      2. In the philosophy of personal identity, the question arises when the human being130 or the human person131 arises. Additionally – and relatedly – was I ever an embryo?
      3. Most philosophers agree that an embryo isn’t a person132, because it does not possess the appropriate psychological133 attributes134.
      4. Many philosophers contend that a human embryo isn’t a human being135 either – in that it hasn’t the appropriate set of organs.
      5. In addition, the question whether I was ever an embryo is complicated by differences over the definition – or maybe ontological category – of “person136”, as was noted in the discussion of Zygote137.
    • Fetuses138
      1. A Fetus is a developing but unborn mammal subsequent to implantation and some further development. See my notes on Zygotes139 and the Embryo140.
      2. In humans, the implanted embryo ("Wikipedia - Embryo") is called a fetus ("Wikipedia - Fetus") after 11 weeks which remains the favoured term of reference until the individual141’s birth – whether full-term or induced – when it is referred to as a neonate (or a baby!). Referring to the fetus as a “baby” is tendentious but common in the pro-life movement.
      3. Fetuses feature a lot in the philosophy of personal identity. Are they persons142, or merely potential persons, given that they probably fail the conditions for personhood143?
      4. Was I144 ever a fetus? At least, was I an early-term fetus?
      5. This latter question is addressed by animalists145 – who think that we were indeed fetuses – as a poser for supporters of the psychological view146 (or constitution view147) of personal identity (since fetuses lack psychological connectedness148 to adult persons, and even lack psychological continuity149 to them on the presumption that early-term fetuses lack all psychological experience).
      6. But, it’s also alleged as a problem for animalism150, or at least a matter that has not been properly addressed by them. What was the relation of the fetus to its mother. Was the mother merely a container, or was the fetus a proper part151 of the mother, who thereby fissioned152 on the baby’s birth? See Elselijn Kingma and "Finn (Suki) - Bun or bump?".
      7. It strikes me that153 the “fission at birth” view is too implausible – the fetus – especially near term – certainly looks like an independent being that’s being hosted on life support by the mother.
      8. So, maybe we can come to a compromise understanding whereby the fissioning154 happens earlier, though the separation would clearly be more vague155 than the cutting of the umbilical cord. ‘Viability’ would be an appropriate point – something like 21-24 weeks’ gestation – though the earliest viability depends on the state and availability of medical technology (see Wikipedia: Fetal viability).
    • Abortion156
      1. The morality of abortion is a large and important issue, but is not my major concern except insofar as it impinges on the topic of Personal Identity.
      2. Our views on Personal Identity will have an impact on our views of the morality of abortion, though not in any straightforward manner.
      3. More importantly – and regrettably so in my opinion – views on the morality of abortion can have an impact on one’s views of personal identity. This is the wrong way round, and violates the fact / value distinction. While ethical, political or religious157 views might influence our preference for certain metaphysical views, they should not constrain our actual beliefs, which should be responses to how things are, and to which our other beliefs should conform, however disappointing that might be.
        1. This remark assumes that there is a “way things are” that is independent of the desires and motivations of human beings. This is denied by – for instance – Yuval Noah Harari; but see – for a robust realist view – "Blackburn (Simon) - Truth: A Guide for the Perplexed".
        2. I do not wish to deny that our ethical, political and religious views can be responses to how things are, just that they were often responses to how things seemed to us – or to people we respected – at formative times of our lives, and then got entrenched and we remain impervious to evidence to the contrary.
      4. I’ll leave further discussion for now. Enough to say that I’ll not intend to wade in too far into this moral morass, though I will need to review the foundational papers on the moral implications of abortion.
      5. The note on Pregnancy158 raises questions of what (to put it rather positively) abortion actually achieves. According to the standard “container model”, abortion kills a distinct, though temporarily dependent, being. However, according to the “parthood model”, abortion only removes a part of the whole (removing the so-called “foster” from the “gravida”: see "Kingma (Elselijn) - Were You Part of Your Mother?").


Concluding Remarks
  1. Having now discussed the arguments against Animalism, we now in our next Chapter159 turn to the arguments against the Constitution View.
  2. This is work in progress160.


Links to Books / Papers to be Addressed161
  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. I’ve not been overly careful to segregate the reading-list of this Chapter from that of Chapter 6164. I will address the segregation in due course. There will, in any case, be some overlap.
  3. Many aspects of these papers will need to be either ignored or reserved for other chapters.


Works on this topic that I’ve actually read165, include the following:-
  1. Arguments against Animalism166
  2. Dicephalus180
  3. Pregnancy
    1. Pregnancy182
    2. Zygote183
    3. Embryos184
    4. Fetuses185
    5. Abortion189

A further reading list might start with:-
  1. Arguments against Animalism192
  2. Dicephalus196
  3. Pregnancy
    1. Pregnancy198
    2. Zygote201
    3. Embryos202
    4. Fetuses204
    5. Abortion205


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 (16/02/2026 09:59:02).
  • 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 23:
  • This Note will be excluded from the Reading List for this Chapter.
  • It is included in the Reading List for Chapter 6.
Footnote 53:
  1. All this needs tidying up.
  2. It’s probably best to take the Wikipedia article in full and link it to these reports and extract the relevant biological facts and cut out all the social stuff that is irrelevant to the metaphysical issues.
Footnote 161:
  • See the section on Research Methodology for what is to be done with these.
Footnote 188: Footnote 190:
  • See Chapter 5: “In the Beginning: What's going on in there?”
Footnote 191:
  • This is a well-known and important book that I read a long time ago, but which doesn’t seem to have been referenced hitherto.
Footnote 199:
  • The item that my algorithms drew my attention to is the possibility of “post-mortem pregnancy”.
  • This anomalous notion is motivated by the adoption of “brain death” as the legal or clinical definition of death, where the mother is deemed dead but is evidently sufficiently biologically alive to carry the fetus as far as viability.
Footnote 200:
  • Doubtless of very dubious relevance, but you never know.
Footnote 203: See, in particular, Footnote 206: Footnote 207:
  • This paper might be as well considered in the Note on Pregnancy.
Footnote 208:

Text Colour Conventions (see disclaimer)

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