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Personal Identity

Zygote

(Work In Progress: output at 27/12/2025 19:20:38)

Plug Note¹

• Thesis Text:
  1. A Zygote ("Wikipedia - Zygote") – is the immediate post-fertilisation product.
  2. In humans, the zygote develops by division until it implants as the embryo². 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 fetus³ after 11 weeks.
  3. In the philosophy of personal identity, the question arises when the human being⁴ or the human person⁵ arises. Additionally – and relatedly – was I⁶ ever a zygote (or an embryo⁷, or a fetus⁸).
  4. Most philosophers agree that a zygote isn’t a person⁹, because it does not possess the appropriate psychological¹⁰ attributes.
  5. Many philosophers contend that a human zygote isn’t a human being¹¹ 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. Twinning¹²: is a special case of fission¹³. Why should the zygote be numerically identical to one – rather than the other – of a pair of monozygotic twins? Modal¹⁴ considerations apply if I am in fact not a monozygotic twin.
     2. Difference over the definition – or maybe ontological¹⁵ category – of “person¹⁶”. Some philosophers insist that an individual¹⁷ can be a person¹⁸ on account of its expected future capacities¹⁹, or actual or once anticipated past capacities, irrespective of its present capacities.
        
  7. A question raised by the philosophy of Pregnancy²⁰ 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-Chimerism²¹ 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?

References

• Relevant Works cited above:
  1. "Wikipedia - Blastocyst", 2023, External Link, Read = 25%
  2. "Wikipedia - Pre-embryo", 2023, External Link, Read = 50%
  3. "Wikipedia - Zygote", 2023, External Link, Read = 25%
• For a Page of Links²² to this Note, Click here.
• Works on this topic that I’ve actually read²³, include the following:-
  • General:
    1. "Anscombe (G.E.M.) - Were You a Zygote?", 1982
    2. "Baker (Lynne Rudder) - When Do Persons Begin and End?", 2005, Annotations, External Link, Internal PDF Link
    3. "Carter (William) - Do Zygotes Become People?", 1982, Annotations, Internal PDF Link
    4. "Kazez (Jean) - Life Doesn't Begin at Conception", 2017, External Link, Internal PDF Link
    5. "Kazez (Jean) - The Philosophical Parent: Asking the Hard Questions About Having and Raising Children", 2017
    6. "Lockwood (Michael) - When Does a Life Begin?", 1987, Annotations
    7. "Wilson (Jack) - Beyond Horses and Oak Trees: A New Theory of Individuation for Living Entities", 1999, Annotations
• A further reading list might start with:-
  • General:
    1. "Baker (Lynne Rudder) - When Does a Person Begin?", 2005, External Link, Internal PDF Link, Read = 5%
    2. "Damschen (Gregor), Gomez-Lobo (Alfonso) & Schonecker (Dieter) - Sixteen Days? A Reply to B. Smith and B. Brogaard on the Beginning of Human Individuals", 2006, External Link, Internal PDF Link, Read = 22%
    3. "Ford (Norman) - When Did I Begin: Conception of the Human Individual in History, Philosophy and Science", 1988, Book, Read = 3%
    4. "Guenin (Louis M.) - The Nonindividuation Argument Against Zygotic Personhood", 2006
    5. "Hershenov (David) & Koch-Hershenov (Rose J.) - Anscombe on Embryos and Persons", 2016, External Link, Internal PDF Link, Read = 22%
    6. "Smith (Barry) & Brogaard (Berit) - Sixteen Days", 2003, External Link, Internal PDF Link, Read = 7%
    7. "Strong (Carson) - Preembryo Personhood - An Assessment of the President’s Council Arguments", 2006, Internal PDF Link, Read = 6%
    8. "Tacelli (Ronald) - Were You a Zygote?", 2006, Internal PDF Link, Read = 11%
    9. "Wikipedia - Blastocyst", 2023, External Link, Read = 25%
    10. "Wikipedia - Pre-embryo", 2023, External Link, Read = 50%
    11. "Wikipedia - Zygote", 2023, External Link, Read = 25%

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• For a list of Works that have been considered, but have missed the cut for inclusion in this Section of my Thesis, see the following:-
  1. Read: No items to list.
  2. Further Reading: No items to list.
• This is mostly a place-holder²⁴.

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Table of the Previous 8 Versions of this Note:

Date	Length	Title
06/07/2023 00:43:12	4120	Zygote
20/09/2022 11:24:00	3712	Zygote
11/05/2022 18:59:02	3331	Zygote
19/02/2021 00:23:02	3116	Zygote
01/10/2020 00:24:29	2757	Zygote
18/07/2018 15:04:19	4955	Zygote
31/08/2017 19:35:02	3126	Zygote
14/01/2017 20:18:14	3211	Zygote

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Note last updated	Reading List for this Topic	Parent Topic
01/06/2026 05:16:32	Zygote	Fetuses

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Summary of Notes Referenced by This Note

Awaiting Attention (Personal Identity)	Chimera	Embryo	Fetuses	Fission
Human Beings	Human Persons	I	Individual	Modality
Note Links Explanation	Ontology	Person	Plug Note Apologia	Pregnancy
Properties	Psychology	Twinning	Works Read - Explanation

To access information, click on one of the links in the table above.

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Summary of Notes Citing This Note

Abortion	Embryo, 2, 3	Fetuses	Olson - What Are We? Animals	PID Note, Book & Paper Usage, 2, 3
Pregnancy, 2	Thesis - Chapter 08 (Arguments against Animalism), 2, 3, 4, 5, 6, 7, 8, 9	Thesis - Chapter 10 (Thought Experiments)	Thesis - Chapter 12 (Conclusion)	Thesis - Current Stance
Thesis - Personal Identity, 2, 3, 4, 5, 6, 7, 8	Twinning	Website Generator Documentation - Functors, 2, 3, 4, 5, 6

To access information, click on one of the links in the table above.

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Authors, Books & Papers Citing this Note

Author	Title	Medium	Extra Links	Read?
Anscombe (G.E.M.)	Were You a Zygote?	Paper	2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33	Yes
Baker (Lynne Rudder)	When Do Persons Begin and End?	Paper	2, 3, 4, 5, 6, 7	Yes
Blatti (Stephan)	Animalism and its Implications	Paper		Yes
Blatti (Stephan)	Animalism, Dicephalus, and Borderline Cases	Paper		Yes
Damschen (Gregor), Gomez-Lobo (Alfonso) & Schonecker (Dieter)	Sixteen Days? A Reply to B. Smith and B. Brogaard on the Beginning of Human Individuals	Paper
Ford (Norman)	Fertilization and the Beginning of a Human Individual	Paper	2, 3
Gasser (Georg)	Personal Identity and Resurrection: Introduction	Paper		Yes
Grobstein (Clifford)	Science and the Unborn: Choosing Human Futures	Paper
Guenin (Louis M.)	The Nonindividuation Argument Against Zygotic Personhood	Paper
Hartl (Daniel L.)	Our Uncertain Heritage: Genetics & Human Diversity	Book	2
Hershenov (David)	A Hylomorphic Account of Thought Experiments Concerning Personal Identity	Paper
Hershenov (David) & Koch-Hershenov (Rose J.)	Anscombe on Embryos and Persons	Paper	2
Kazez (Jean)	Life Doesn't Begin at Conception	Paper		Yes
Kazez (Jean)	The Philosophical Parent: Asking the Hard Questions About Having and Raising Children	Paper	2	Yes
Oderberg (David)	Modal Properties, Moral Status, and Identity	Paper	2
Olson (Eric)	What Are We? Animals	Paper		Yes
Todman (Theo)	Thesis - Abortion	Paper		Yes
Todman (Theo)	Thesis - Chapter 08 (Arguments against Animalism)	Paper	2, 3, 4, 5, 6, 7, 8, 9	Yes
Todman (Theo)	Thesis - Chapter 10 (Thought Experiments)	Paper		Yes
Todman (Theo)	Thesis - Chapter 12 (Conclusion)	Paper		Yes
Todman (Theo)	Thesis - Current Position	Paper		Yes
Todman (Theo)	Thesis - Embryo	Paper	2, 3	Yes
Todman (Theo)	Thesis - Fetuses	Paper		Yes
Todman (Theo)	Thesis - Personal Identity	Paper	2, 3, 4, 5, 6, 7, 8	Yes
Todman (Theo)	Thesis - Pregnancy	Paper	2	Yes
Todman (Theo)	Thesis - Twinning	Paper		Yes
Wilson (Jack)	Beyond Horses and Oak Trees: A New Theory of Individuation for Living Entities	Paper	2, 3	Yes

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References & Reading List

Author	Title	Medium	Source	Read?
Anscombe (G.E.M.)	Were You a Zygote?	Paper - Cited	Anscombe (G.E.M) - Human Life, Action and Ethics	Yes
Anscombe (G.E.M.)	Were You a Zygote?	Paper - Referencing	Anscombe (G.E.M) - Human Life, Action and Ethics	Yes
Anscombe (G.E.M.), Geach (Mary), Gormally (Luke), Eds.	Human Life, Action and Ethics	Book - Cited (via Paper Cited)	Bibliographical details to be supplied	10%
Anscombe (G.E.M.), Geach (Mary), Gormally (Luke), Eds.	Human Life, Action and Ethics	Book - Referencing (via Paper Referencing)	Bibliographical details to be supplied	10%
Baker (Lynne Rudder)	When Do Persons Begin and End?	Paper - Cited	Distinguished Faculty Lecture, December 5, 2005	Yes
Baker (Lynne Rudder)	When Do Persons Begin and End?	Paper - Referencing	Distinguished Faculty Lecture, December 5, 2005	Yes
Baker (Lynne Rudder)	When Does a Person Begin?	Paper - Cited	Paul, Miller & Paul - Personal Identity, 2005	5%
Blatti (Stephan)	Animalism, Dicephalus, and Borderline Cases	Paper - By Subtopic	Philosophical Psychology 20 (2007): 595–608	Yes
Carter (William)	Do Zygotes Become People?	Paper - Cited	Mind, 91.361 (Jan. 1982), pp. 77-95	Yes
Damschen (Gregor), Gomez-Lobo (Alfonso) & Schonecker (Dieter)	Sixteen Days? A Reply to B. Smith and B. Brogaard on the Beginning of Human Individuals	Paper - By Subtopic	Journal of Medicine and Philosophy, Apr. 2006, 31.2, pp. 165-175	22%
Ford (Norman)	Fertilization and the Beginning of a Human Individual	Paper - By Subtopic	Norman Ford - When Did I Begin, 1988, Chapter 4	No
Ford (Norman)	Implantation and the Beginning of a Human Individual	Paper - By Subtopic	Norman Ford - When Did I Begin, 1988, Chapter 5	No
Ford (Norman)	When Did I Begin: Conception of the Human Individual in History, Philosophy and Science	Book - Cited	Ford (Norman) - When Did I Begin: Conception of the Human Individual in History, Philosophy and Science	3%
Gasser (Georg)	Personal Identity and Resurrection: Introduction	Paper - Referencing	Gasser (Georg) - Personal Identity and Resurrection: How Do We Survive Our Death? 2010	Yes
Gasser (Georg), Ed.	Personal Identity and Resurrection: How Do We Survive Our Death?	Book - Referencing (via Paper Referencing)	Bibliographical details to be supplied	96%
Guenin (Louis M.)	The Nonindividuation Argument Against Zygotic Personhood	Paper - By Subtopic	Philosophy - 81, Jul2006, Issue 317	No
Howsepian (Avak Albert)	Who or What Are We?	Paper - By Subtopic	Review of Metaphysics, Vol. 45, No. 3 (Mar., 1992), pp. 483-502	6%
Kazez (Jean)	Life Doesn't Begin at Conception	Paper - Cited	The Philosophers' Magazine, 3rd November 2017	Yes
Kazez (Jean)	The Philosophical Parent: Asking the Hard Questions About Having and Raising Children	Book - Cited (via Paper Cited)	Bibliographical details to be supplied	Yes
Kazez (Jean)	The Philosophical Parent: Asking the Hard Questions About Having and Raising Children	Paper - Cited	Kazez (Jean) - The Philosophical Parent: Asking the Hard Questions About Having and Raising Children	Yes
Kenny (Anthony)	Life Stories: When an individual life begins - and the ethics of ending it	Paper - By Subtopic	Times Literary Supplement, 2007	No
Lockwood (Michael)	When Does a Life Begin?	Paper - Cited	Lockwood - Moral Dilemmas in Modern Medicine, 1987	Yes
Lockwood (Michael), Ed.	Moral Dilemmas in Modern Medicine	Book - Cited (via Paper Cited)	Bibliographical details to be supplied	29%
O'Hear (Anthony), Ed.	Philosophy - 81/317 (July 2006)	Book - By Subtopic (via Paper By Subtopic)	O'Hear (Anthony), Ed. - Philosophy - 81/317 (July 2006)	2%
Olson (Eric)	What are We? A Study of Personal Ontology	Book - Referencing (via Paper Referencing)	Bibliographical details to be supplied	Yes
Olson (Eric)	What Are We? Animals	Paper - Referencing	What Are We? A Study in Personal Ontology, Chapter 2 (November 2007: Oxford University Press.)	Yes
Paul (Ellen), Miller (Fred) & Paul (Jeffrey), Eds.	Personal Identity	Book - Cited (via Paper Cited)	Bibliographical details to be supplied	0%
Smith (Barry) & Brogaard (Berit)	Sixteen Days	Paper - By Subtopic	Journal of Medicine and Philosophy, Feb. 2003, 28.1, pp. 45-78	7%
Strong (Carson)	Preembryo Personhood - An Assessment of the President’s Council Arguments	Paper - By Subtopic	Theoretical Medicine and Bioethics (2006) 27:433–453	6%
Tacelli (Ronald)	Were You a Zygote?	Paper - By Subtopic	Revista Portuguesa de Filosofia , T. 62, Fasc. 2/4, Entre Razão e Revelação: A'Lógica' da Dimensão Semíta na Filosofia / Between Reason and Revelation: The 'Logic' of the Semitic Dimension in Philosophy (Apr. - Dec., 2006), pp. 889-899	11%
Todman (Theo)	Thesis - Zygote	Paper - By Subtopic		Yes
Wikipedia	Blastocyst	Paper - Cited	Wikipedia; Extract taken 23 May 2023	No
Wikipedia	Pre-embryo	Paper - Cited	Wikipedia; Extract taken 23 May 2023	No
Wikipedia	Zygote	Paper - Cited	Wikipedia; Extract taken 23 May 2023	No
Wilson (Jack)	Beyond Horses and Oak Trees: A New Theory of Individuation for Living Entities	Paper - Cited	Wilson, Jack - Biological Individuality: The identity and Persistence of Living Entities; 1999, Chap. 1, pp. 1-21	Yes
Wilson (Jack)	Beyond Horses and Oak Trees: A New Theory of Individuation for Living Entities	Paper - Referencing	Wilson, Jack - Biological Individuality: The identity and Persistence of Living Entities; 1999, Chap. 1, pp. 1-21	Yes
Wilson (Jack)	Biological Individuality - The identity and Persistence of Living Entities	Book - Cited (via Paper Cited)	Bibliographical details to be supplied	Yes
Wilson (Jack)	Biological Individuality - The identity and Persistence of Living Entities	Book - Referencing (via Paper Referencing)	Bibliographical details to be supplied	Yes

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Text Colour Conventions

1. Blue: Text by me; © Theo Todman, 2026

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