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Personal Identity

Brain Criterion

(Text as at 14/07/2013 23:02:24)

(For earlier versions of this Note, see the table at the end)


There will naturally be some overlap on this topic with the topics of brains1 and criteria2.

The question is whether the brain – for human persons – is the be-all and end-all of the matter of personal identity for human persons. It is acknowledged by most that – conceptually at least – there can be persons3 that are not humans (ie. not members of the species homo sapiens) – whether these persons be non-human animals, computers, God, angels, aliens or whatever. Non-animals presumably have no brains, though aliens presumably have a brain-analogue, so brains cannot be identity-criteria for personhood as such (indeed, we might argue that there are no criteria for persons as such4). But for animal-persons (human or otherwise), the brain seems to occupy a central place, both as the seat of psychology (in the absence of an immaterial soul5) and as the regulator of the body.

So, the story would go, X is the same person as Y iff6 X has the same brain as Y.

The trouble is – even if this claim is along the right lines – we can press matters further, and ask whether the whole brain is strictly necessary. If what impresses us is a brain-based psychological view, when what we imagine is “really the minimal me” is the pair of psychology-bearing cerebral hemispheres, then we might imagine (as some philosophers have) a case of fission7, where – after equalising the hemispheres in psychological potency, we transplant8 one into another body lacking both hemispheres. Or, without needing anything so radical, me sever the corpus callosum in a commissurotomy9, thereby (on this view) creating two persons in one body.

However, if we are animalists wondering what the “minimal animal” is, and it’s the command-and-control functions of the brain that impress us, then the paring-down process might10 be able to do without the cerebral hemispheres (or at least the psychology-bearing parts) altogether. So, brain-based views from different perspectives might come to different conclusions about the importance of the cerebral hemispheres – one view might make them essential, the other irrelevant to questions of identity (if not to “what matters11”). It is an empirical question whether the brain-stem can be divided, and hence that the brain-based animalist approach is also subject to worries12 about fission.

Anyway, the appropriateness of the Brain criterion of personal identity depends on what we13 are – in particular whether we are (most fundamentally, or in the sense of numerical identity, which is not the same thing) human animals or persons constituted by them (or various other things). Only if we are brains14, though I reject this idea under that head, will we adopt the brain criterion.

This is still mostly a place-holder15. Currently, see the rather diminutive categorised reading-list.



In-Page Footnotes:

Footnote 4: Hasn’t someone said this? Who? Wiggins (Click here for Note)? This is not to be confused with there being no criteria for identity, which is due to Merricks (eg. in "Merricks (Trenton) - There Are No Criteria For Identity Over Time").

Footnote 6: And, of course, “X and Y are both persons”, to cover the case where the brain is insufficient to support the property of personhood (Click here for Note).

Footnote 10: Much of this discussion has empirical aspects to it, and depends on the capabilities of real brains – though we might get into the choppy waters of more intricate TEs (Click here for Note), and wonder what might be the case if the biology went differently – but then we would most likely not be talking about our identity criteria, but of some other being.

Footnote 12: These worries about fission are essentially set to rest by adopting a perdurantist (Click here for Note) account of persistence. But, some consider the costs (mainly semantic, I think) of adopting this approach are too great.


Printable Versions:



Previous Version of this Note:

Date Length Title
25/05/2010 14:58:34 84 Brain Criterion



Note last updated Reading List for this Topic Parent Topic
14/07/2013 23:02:24 Brain Criterion Logic of Identity

Summary of Note Links from this Page

Awaiting Attention (Personal Identity) Brain Brain Transplants Commissurotomy Criteria of Identity
Fission Perdurantism Person Souls Thought Experiments
What are We? What Matters Wiggins    

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




Summary of Note Links to this Page

Brain Death Mereology Snowdon - The Self and Personal Identity Thesis - Current Stance  

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




Authors, Books & Papers Citing this Note

Author Title Medium Extra Links Read?
Olson (Eric) Animalism and the Remnant-Person Problem Paper Medium Quality Abstract   Yes
Olson (Eric) Psychology and Personal Identity Paper High Quality Abstract   Yes
Olson (Eric) Why We Need Not Accept the Psychological Approach Paper Medium Quality Abstract   Yes
Snowdon (Paul) Persons, Animals, Ourselves: Introduction Paper High Quality Abstract   Yes
Snowdon (Paul) The Self and Personal Identity Paper Medium Quality Abstract   Yes
Todman (Theo) Thesis - Brain Criterion Paper Medium Quality Abstract   Yes
Todman (Theo) Thesis - Brain Death Paper Medium Quality Abstract   Yes
Todman (Theo) Thesis - Current Position Paper Medium Quality Abstract   Yes
Todman (Theo) Thesis - Mereology Paper Medium Quality Abstract   Yes



References & Reading List

Author Title Medium Source Read?
Garrett (Brian) Criteria of Personal Identity Paper - By Subtopic Medium Quality Abstract Garrett - Personal Identity and Self-consciousness, 1998, Chapter 3 Yes
Garrett (Brian) Personal Identity and Self-consciousness Book - By Subtopic (via Paper By Subtopic) Medium Quality Abstract Garrett (Brian) - Personal Identity and Self-consciousness Yes
Manninen (Tuomas) Review of Alva Noe's 'Out of Our Heads: Why You Are Not Your Brain' Paper - By Subtopic High Quality Abstract Metapsychology Online Reviews, Sep 15th 2009 (Volume 13, Issue 38) Yes
Merricks (Trenton) There Are No Criteria For Identity Over Time Paper - Cited Noûs, Vol. 32, No. 1 (Mar., 1998), pp. 106-124 No
Noe (Alva) Out of Our Heads: Why You Are Not Your Brain, and Other Lessons from the Biology of Consciousness Book - Referenced Medium Quality Abstract Noe (Alva) - Out of Our Heads: Why You Are Not Your Brain, and Other Lessons from the Biology of Consciousness 23%
Noonan (Harold) An Initial Survey Paper - By Subtopic Low Quality Abstract Noonan - Personal Identity, 2003, Chapter 1 Yes
Noonan (Harold) Personal Identity Book - By Subtopic (via Paper By Subtopic) Low Quality Abstract Noonan (Harold) - Personal Identity Yes
Olson (Eric) Psychology and Personal Identity Paper - Referencing High Quality Abstract The Human Animal, September 1999, Chapter 1, pp. 7-21 Yes
Olson (Eric) The Human Animal - Personal Identity Without Psychology Book - Referencing (via Paper Referencing) Low Quality Abstract Bibliographical details to be supplied Yes
Olson (Eric) Why We Need Not Accept the Psychological Approach Paper - Referencing Medium Quality Abstract The Human Animal, September 1999, Chapter 3, pp. 42-72 Yes
Snowdon (Paul) Persons, Animals, Ourselves Book - Referencing (via Paper Referencing) Medium Quality Abstract Bibliographical details to be supplied 21%
Snowdon (Paul) Persons, Animals, Ourselves: Introduction Paper - Referencing High Quality Abstract Snowdon (Paul) - Persons, Animals, Ourselves - Introduction Yes
Thomas (Janice L.) Mind and Person in the Philosophy of Religion Book - By Subtopic (via Paper By Subtopic) Medium Quality Abstract Thomas (Janice L.) - Mind and Person in the Philosophy of Religion Yes
Thomas (Janice L.) The bodily criterion Paper - By Subtopic High Quality Abstract Thomas (Janice L.) - Mind and Person in the Philosophy of Religion Yes
Todman (Theo) Thesis - Brain Criterion Paper - Referencing Medium Quality Abstract   Yes



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