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Table 4 Conceptual and empirical arguments in favor of brain death, and problems with those arguments

From: A survey of American neurologists about brain death: understanding the conceptual basis and diagnostic tests for brain death

The conceptual or empirical arguments in favor of brain death Problems with the argument
The concept of death fulfilled by the brain death criterion  
Irreversible loss of integrative unity of the organism as a whole Integrative unity continues during BD: there are many reports of gestation of a fetus, waste detoxification and excretion, assimilation of nutrients, fighting of infections, wound healing, proportionate growth, and sexual maturation [6, 14]. Without intensive care, BD patients will surely die quickly; but this is similar to many intensive care patients who are clearly live integrated organisms, such as those with cervical spine injury, on extracorporeal life support, etc.
  A central integrator is not required: embryos are alive [3, 17].
Irreversible loss of personhood, consciousness, or moral agency (higher brain) Consciousness is not the dividing line between life and death: irreversible vegetative state, anencephaly, and if moral agency is required, infants and the severely demented are not considered already dead (appropriate for burial, cremation, autopsy, or organ recovery) [3, 4, 17].
  Although consciousness may be a sign of ongoing integration, it can be lost with continued integration of the organism as a whole [3, 4, 6, 17].
Poor quality of life or certainty of cardiac arrest Conflate prognosis of death with a diagnosis of death. A prognosis of lack of recovery of neurological function is not a diagnosis of death.
Irreversible loss of the vital external work of an organism interacting with the environment to obtain what it needs Brain-dead bodies are receptive to stimuli/signals from the surrounding environment (e.g., clot blood at and heal tracheostomy and gastric tube incisions; have withdrawal spinal reflexes; react with hypertension and tachycardia to organ recovery).
  Brain dead bodies do act upon the world to obtain selectively what they need (e.g., assimilate nutrients/electrolytes from fluids/feeds; eliminate unneeded wastes in stool/urine; exchange gases with the world in ventilated lungs).
  Brain dead bodies do have basic (non-conscious) felt needs that drive the organism to obtain what it needs (e.g., the drive to circulate blood with oxygen/nutrients to sustain its vital organs, to absorb needed nutrients and eliminate unneeded wastes from the bowel, to acquire needed oxygen from the lungs) to allow growth, sexual maturation, and recovery from complications.
  The goal of external work is to sustain the "capacity for internal integrative unity": external work is "a second-order activity mandated by the primary work of an organism, the maintenance of internal homeostasis [19]."
Irreversible loss of the function (or the critical functions) of the entire brain, irreversible destruction of the brain, or irreversible loss of the capacity for consciousness and breathing. These simply restate the criterion of brain death; they do not give a concept of death to justify the criterion being death itself.
Empirical continuing brain activity after a valid clinical diagnosis of brain death is pronounced  
Residual functions detected in brain death are actually mere activities (of "nests" of cells) and not functions. The brain is too complex an organ to simply make this ad hoc and likely incorrect claim [3, 17]:
  The spatial resolution of EEG suggests there is widespread neuronal activity when EEG activity is detected, potentially performing functions 317.
  Evoked potential activity is due to transduction of ambient energy into electrochemical signals conducted to the brain, suggestive of a function 317.
  Neuroendocrine control maintains free water homeostasis, suggestive of a function 34617.
Residual functions detected in brain death are insignificant functions. This claim is ad hoc (without a clear reason): why are pupillary and corneal reflexes significant functions reflecting integration of the organism as a whole, while EEG activity, evoked potential activity, neuroendocrine control, and breathing at a PaCO2 of 80 mmHg are not [3, 15, 17]?
Residual functions are neither critical nor clinical functions, and BD is a clinical diagnosis. This claim is ad hoc (without a clear reason): how to define critical, and why these must be clinical functions is not explained [3, 15, 17].
  The clinical versus nonclinical distinction is irrelevant: neurologists' epistemic access to a function is not a relevant consideration to diagnosis of a critical function [3, 17].
  The clinical versus nonclinical distinction is false: neuroendocrine control can be diagnosed at the bedside by observing lack of polyuria [3, 17].
  The critical versus noncritical distinction is circular: critical functions are necessary for maintenance of life, and death is the loss of critical functions, is a trivial tautologous argument [3, 17].
Residual functions are not critical because they are replaceable mechanically. Breathing can be replaced mechanically and, therefore, is not a critical brain function. Like the dialysis machine replacing spontaneous kidney function, the ventilator replacing spontaneous brainstem control of breathing is irrelevant as to whether an organism is dead [3, 4, 15, 17, 18].
  Only consciousness cannot be replaced mechanically and, therefore, this is only an argument for a consciousness based (not integration, or vital external work based) concept of death [3, 4, 15, 17, 18].
  1. BD = brain death; EEG = electroencephalogram.