By Lukas J. Meier
Patients who do not emerge from coma are not dead – at least not in a biological sense. Their hearts are beating, their skin is warm, and many of them even breathe without external assistance. But are these patients also alive mentally, that is, is there anything going on in their heads? Are they aware of themselves or their environment? For the friends and families of these patients, it is essential to know whether they are still sitting with a psychological being – with a person – or whether the body in the hospital bed is more like an ‘empty shell’, devoid of all mental characteristics.
One may try to answer this question on a purely medical basis, namely, by analysing the amount and the location of damage to the patient’s brain and comparing it to the functional deficits commonly associated with the respective condition. But this can only be half of the story. We must also somehow interpret the significance of the presence or absence of these functions; in other words: we must establish whether they are indicative of the existence of a mental subject. Patients who have sustained massive damage to their upper brain, for instance, often open their eyes and seem to be alternately awake and asleep. Does this mean that cognitive processes are still going on in their heads? Conversely, patients who suffer from a very small lesion in a certain area of the brainstem, while the rest of their brains remains entirely intact, appear to be in a deep state of irreversible unconsciousness. But does this entail that no psychological features are associated with their bodies?
To be able to make sense of such disorders, we need concepts of personhood – models that describe what conditions must be met for the mental persistence of entities like us. In this paper, I take the two most prominent of these models from the philosophical literature on personal identity – each focusing on a different aspect of our psychological architecture – and apply them to common clinical profiles of brain damage. This enables us to determine which type of cerebral lesion is compatible with the mental survival of the patient, and which is not.
Author(s): Lukas J. Meier
Affiliations: University of St Andrews
Competing interests: None
Social media accounts of post authors: Orcid