In a recent post, I summarized two opposing arguments over the concept of brain death. The minority view, (re-)articulated by Dr. Alan Shewmon in the context of the Jahi McMath case, is that the concept is philosophically incoherent. People with total brain failure sometimes maintain physiologic homeostasis and undergo wound healing, proportional growth, sexual maturation, etc. for some time. To the extent that some of these capacities depend on hypothalamic or pituitary function, it is not even correct to state that their entire brains have stopped functioning, much less that their bodies have dis-integrated. Regardless, such persons are are extremely disabled, but not dead.
The President’s Council on Bioethics, in their 2008 white paper “Controversies in the Determination of Death” accepted the argument that total brain failure does not inevitably lead to somatic dis-integration. Instead, they identified an organism’s death with the loss of its capacity to perform its “fundamental vital work . . . the work of self-preservation, achieved through the organism’s need-driven commerce with the surrounding world.” Such need-driven commerce is most basically expressed in the act of breathing: “. . . even when the drive to breathe occurs in the absence of any self-awareness, its presence gives evidence of the organism’s continued impulse to live. This drive is the organism’s own impulse, exercised on its own behalf, and indispensable to its continued existence.” When the organism can no longer engage in its fundamental vital work, it has died.
A commonality between these two arguments is that they both invoke a person’s capacities. Dr. Shewmon, et al. argue that the retention of certain capacities is proof of life. The President’s Council argues that the loss of what they consider to be fundamental capacities is proof of death. This focus on capacity reminded me of Aristotle’s concept of psuche as described in De Anima (On the Soul) and reviewed in one of my favorite books, Philosophical Foundations of Neuroscience. For a non-philosopher like me, Aristotle is tough reading. I’m going to make a few observations about how the current debate might be understood in an Aristotelian framework, but welcome any clarifying thoughts from sharper philosophical minds.
Aristotle actually gave three definitions of psuche; the most accessible and pertinent one to our discussion is “. . . the form of a natural body having life potentially within it” (De Anima 412a20; emphasis added). The relationship between matter and form is key. Aristotle uses the axe as an example. When its constituent wood and metal are formed properly, the resulting body attains the capacity to chop wood. This composite of wood and metal, combined into a form conferring the capacity to chop, results in an axe. Similarly, a natural body, en-formed in such a way as to confer upon it certain capacities, is alive.
Importantly, the matter and the form of a thing aren’t separable–they are aspects of the thing. Wood-chopping capacity is not a part of an axe. For Aristotle, psuche (anima, soul) is not a part of a person, standing in some relation to the person’s body, as Plato understood it to be before him and Descartes and many others understood it to be later. Soul is the form of a body that has life. A body having such form is empsuchos–ensouled–and therefore alive: “. . . what has soul in it differs from what has not in that the former displays life.” (413a20)
As a neurologist, I find this understanding of soul to be highly resonant. The body, and of particular interest to us, the brain, must maintain a certain form (really, a range of forms) in order for a person to function. As the brain is progressively injured, as its form deviates more and more from a healthy norm, the person loses more and more of his capacities until consciousness itself is diminished or lost. This understanding comports well with our everyday neurologic practice, where we so often diagnose bihemispheric dysfunction as a cause for altered mentation or coma and so often explain to our patients’ families this general correspondence between the severity of a patient’s brain injury and the degree of lost mental capacity. We are continually called upon to disabuse families, and occasionally other physicians and nurses, of the notion that despite severe brain injury, the patient “is still in there” in the particular sense of having largely retained mental capacities. Excepting the rare patient “locked in” by a pontine lesion or total neuromuscular failure (advanced ALS, severe Guillain-Barré, and the like), most neurologically devastated patients do not retain normal consciousness, their souls only unable to effectuate their wishes due to severe bodily/brain injury. Rather, to the extent that severely brain-injured patients retain consciousness at all, it is likely fleeting and fragmentary.
If a person’s brain injury is even more severe such that his ability to engage in his “fundamental vital work”, i.e. breathing, is permanently abolished, then, in the overwhelmingly predominant view of physicians, ethicists, and legislatures, the person is considered to have died. How does this modern concept of brain death fit in the Aristotelian framework? Aristotle actually posits that there is a hierarchy of three types of soul. The lowest is nutritive, associated with the capacities for nurishment, growth, and reproduction. The second type of soul is sensitive: “. . . it is the possession of sensation that leads us for the first time to speak of living things as animals . . .” (413b1) The highest type of soul is (in Aristotle’s understanding) unique to humans–the rational soul, which confers the powers of reasoning and volition. Regarding these three types of soul, Aristotle wrote that “. . . provided any one alone of these is found in a thing we say that the thing is living.” (413a21; emphasis added) Underscoring the point that nutritive soul alone is sufficient for life, he wrote “Hence we think of plants also as living . . . This is the originative power the possession of which leads us to speak of things as living at all . . .” (413b1; emphasis added) These passages suggest that the “fundamental vital work” of organisms might not be breathing (since not all organisms, e.g. plants and bacteria, have even the potential to breathe) but rather nourishment, growth, and reproduction, which are common to all. “Since nothing except what is alive can be fed, what is fed is the besouled body . . .” (416b8)
Thus, in an Aristotelian framework, bodies we declare to be dead based on neurological criteria could be considered to retain their nutritive souls. They don’t breathe, but if mechanically ventilated, cellular respiration may continue to occur. They don’t eat, but if infused with food, digestion and growth may continue to occur. It would follow that the term “vegetative” may actually be better suited to these neurologically devastated bodies than to the class of people to whom it currently applies; those whom we currently deem to be in persistent vegetative states would be considered to retain nutritive and sensitive souls, while lacking rational souls.
Now, I want to emphasize that the foregoing is completely contrary to the overwhelming, albeit not unanimous, consensus of the physicians, medical ethicists, and law makers in this field. Patients whose brains are destroyed, who are permanently comatose, apneic, and lacking brainstem reflexes, are considered to be dead. Living patients who have sleep-wake cycling and other primitive behaviors but no consciousness are considered to be persistently vegetative. De Anima is not De Bible (sorry, couldn’t resist) and surely we must look beyond a 2000 year-old secular text for philosophical guidance in modern times. Nonetheless, I think it fair to examine these weighty issues from multiple perspectives (next up: some religious perspectives), if for no other reason than to try to fully understand what we’re doing when we declare a person dead using neurological criteria.