If your brain, along with your memories and personality, is transplanted into another human body, would you now inhabit that new body? If someone was in a car accident and suffered amnesia, can we still consider that to be the same person? On 23 February, Michelle Maiese shared her ideas about the connection between the psychological and biological self. Below, Michelle continues a deeper exploration into human existence and questions which factors make up our personal identities.
The dominant approach to personal identity says that a person persists over time by virtue of facts about psychological continuity. However, this approach faces a so-called duplication problem: a single person can be psychologically continuous with two or more persons. Derek Parfit’s solution is to suppose that what we care about in survival is psychological continuity and connectedness, which is a form of continued existence that does not imply identity through time. Even when psychological continuity is lacking, though, we still might regard someone as the same person in a moral and legal sense, due to the persistence of their living body, suggesting that our perception of survival is both biological and psychological.
Is there some other way to resolve the duplication problem that acknowledges this insight? Remember that according to Parfit, we all agree that if my brain is transplanted into someone else’s brainless body, and the resulting person has my character and apparent memories, then this resulting person is me. But should we agree, or do these intuitions rest on questionable assumptions?
It is worth noting that the very way in which the thought experiment is framed presupposes that an individual’s psychology can come apart from her body and that psychological continuity is separable from the continuity of the living body. This assumption is evident again in Parfit’s later work when he discusses the surviving head case: imagine that your head and cerebrum are detached from your body, attached to an artificial support system, and then later grafted onto another human body. Parfit maintains that you, the very same conscious being, would exist throughout; it’s just that you would switch from being the thinking, controlling part of one human animal to being the thinking, controlling part of a different human animal. Here Parfit identifies the person as the part of the animal that does the thinking, namely the part whose physical basis is the cerebrum.
But can our psychological profiles truly be prized apart from our bodies, and is it true that “the body below the neck is not an essential part of us”? Like so many philosophers, Parfit seems committed to what Andy Clark has labelled “a BRAINBOUND view of the mind“. The working assumption of BRAINBOUND is that mind and cognition are disembodied computational processes taking place in the brain. While the non-neural body does act as the sensor and effector system of the brain and central nervous system, neural activity is only ‘instrumentally dependent’ on human bodily activity. Cognition, on this view, is simply a matter of computing information according to the brain’s internal rules that then instruct the body how to act. According to BRAINBOUND, where your brain goes, you go.
However, recent work on embodied cognition challenges this prevailing view that mentality is a purely neural phenomenon. To claim that mindedness is fully embodied is to suppose that the capacity for consciousness and cognition are spread throughout our living bodies, and also shaped and structured by the fact of our embodiment. But if mind and consciousness are fully bound up with bodily dynamics, and the mind is not simply a set of contents that can be transferred from one brain to another, then it is not possible, as so many theorists have supposed, that one could undergo a sudden body transplant and still count as oneself. Nor would it be possible for one’s stream of consciousness to continue smoothly, its subjective character remaining much the same, if it were housed in a succession of distinct bodies.
Obviously, this is not to deny that the brain plays a crucial role in one’s mental life! However, it would be a mistake to suppose that one’s brain “stores” one’s memories and character traits, or that the brain can be isolated as the source of all of someone’s cognitive achievements. If the mind is fully embodied, then there simply is no way to extract your mind, implant it in a different body, and have you persist as one and the same person. To acquire a whole new living body would be to acquire a new set of operative neurobiological dynamics, which would so radically change the nature of consciousness that it’s unclear such a being could be just like you, psychologically speaking.
Such considerations suggest that what matters in survival is both psychological and biological, and that understanding personal identity across time requires that we appreciate how the psychological aspect of existence is fully bound up with our whole living bodies.
Featured image credit: Spirit by Josh Marshall. CC0 Public Domain via Unsplash.