Taela asked:

We have to write an essay from this scenario:

A talented neurosurgeon removes Andrea’s brain and puts it into Beth’s body, and removes Beth’s brain and puts it into Andrea’s body. We end up with two living humans. Which of these is Andrea? Or is neither of them Andrea? Or are they both Andrea? Or is there no answer to the question? Or do you need more information about the case before you can answer? Explain.

I’m very confused as to what to write. I have talked about dualism and Descartes idea of a thinking thing, but this is not enough, and I am not sure if I am on the right track.

Answer by Craig Skinner

Descartes wont help much here. But Locke will.

The key text is the famous chapter (27) ‘Of Identity and Diversity’ in Book 2 of Locke’s An Essay Concerning Human Understanding (2nd edition 1694). Do read it, at least 27.8 to 27.29, it is one of the most important, influential, and still relevant parts of his philosophy.

Locke is concerned with fair praise/blame, both in this life and at the Last Judgment, what he calls ‘forensic’ issues. Clearly praise/blame can only be fair if the individual getting it is the SAME individual as the one who did the good/bad deeds.

So, what is it that makes me the same individual as yesterday or last year?

Locke distinguishes between being the same Human Being (‘same Man’ as he puts it) and being the same Person.

Being the same Human Being, like being the same plant or animal, is to be the same living, organized body, to be ‘the same continued life communicated to different particles of matter, as they happen successively to be united to that organized living body’ (27.8). In short, I am the same Man as twenty years ago even though none of the atoms constituting me then is part of me now.

Being the same Person is to have continuity of consciousness — one presently remembers one’s past experiences. Locke’s famous definition of ‘Person’ (27.9):

‘A thinking intelligent being, that has reason, and can consider it self as it self, the same thinking thing, in different times and places; which it does only by that consciousness, which is inseparable from thinking’

So, Personal identity is not identity of substance (a person could swap her material body, or, Locke feels, her immaterial soul, without loss of identity) No, it is identity (continuity or connectedness) of consciousness.

Of course, being the same Human Being and being the same Person usually go together. But not always, as in your brain-swap scenario, or in Locke’s analogous mind-swap thought experiment. He describes the mind of the Prince entering the body of the sleeping Cobbler (whose own mind departs). The individual who later wakes up is the same Man as was (the Cobbler) but a different Person (the Prince).

So in your scenario, if you think we are essentially Human Beings, Andrea and Beth get brain transplants. If you think we are essentially Persons, Andrea and Beth get body transplants.

Which is the more coherent view, Human Being or Person? You must make up your own mind.

On the Human Being view, YOU were once a zygote, then embryo, foetus, child, adult, and may sadly sustain brain damage and pass into a persistent vegetative state (PVS). If you were to get a brain transplant, you would be the same Man with a new brain, even though this brain thought as it did in the donor, just as a transplanted heart pumps blood as it did in the donor.

On the Person view, YOU were never a zygote or an embryo, nor could you be a human in a PVS, for none of these has consciousness, far less continuity of consciousness, and so can’t be a Person.

I favour the Human Being approach. I think I am essentially an animal, that I AM this individual sitting typing this answer, that I was once an embryo, and that if I enter a PVS it will still be me lying on the bed, and my relatives wont think I no longer exist.

Irrespective of whether we think Person or Human Being best describes our essence, Locke’s memory criterion for Personal Identity has problems.

First, discontinuities in consciousness such as an old man remembering nothing of his boyhood. According to Locke the old man is not the same person as the boy, but he clearly is. On the other hand, is it fair to punish a demented person for something she can’t remember doing?

Secondly, the definition is circular, begging the question. How do you know that the memories you have are genuine rather than false or quasi-memories? To suppose they are YOUR memories presupposes there is a YOU.

Thirdly, uncertainties about preservation of identity in split brain/fission/duplication cases (more thought experiments). We end up with more than one individual psychologically continuous with the original (who is no more). Which of these new individuals IS the original. Of course, on the somatic Human Being view, none of them. And I think this is the right answer. The original is dead but psychological continuity with her is preserved in the new individuals, so that survival (in this way) may be more important to us than identity, as Derek Parfit argues for.

I hope I’ve said enough to get you on the right track.