Ramesh argues that using the current standard of brain death to establish the end of personhood, and therefore to define brain “birth” as the criterion for the beginning of personhood, fails because of his offered distinction between “cerebral death” and total brain death. I disagree, though I admit that there are medical and philosophical complexities involved.

The most obvious problem with my proposed solution is that brain death is more-or-less a discrete, identifiable event, whereas in pregnancies the arrival of a “brain” is not so clear-cut. It is gradual. Some routine functions of the embryo are governed directly by the genetics of cells, then by strands and bundles of nerves reacting to stimuli, then by what might be called a proto-brain (that’s about as good as this layman can render the facts as I understand them, so consider this an apologize in advance to all the docs and med students flexing up their email-trigger fingers).

But remember that my proposal is intended simply to find a criterion that seems likely to attract a political consensus. It doesn’t pretend to achieve anatomical precision, or to address at all any religious or spiritual conviction as to when the soul enters the body (or, indeed, whether it is created at conception or instead pre-exists the body). A wise professor once warned me against falling into “line-drawing traps” by observing that while there has been dispute for many centuries, sometimes violent dispute, about the precise border in the Aegean Sea between Greece and Turkey/Anatolia, few would argue that as a geographical matter Athens is in Anatolia or Ankara is in Greece. The fact that lines may be blurry or even somewhat arbitrary does not constitute an argument against drawing them, or against their practical usefulness. Sometimes you just have to draw the line as best you can in a way that satisfies the largest number of interested parties.

The reason one should not use “higher brain functions” as an indicator of the life or death of a human person is, as Ramesh implies, that such a rule could easily be used to deny basic human rights to the handicapped or infirm. A decent government must necessarily err on the side of doubt here — if the brain is functioning in any significant sense, it is at least conceivable that a thinking person exists somewhere within an otherwise incapacitated shell. But inverting that rule to decide when personhood begins cannot reasonably be said to lead to the conclusion that one must err on the side of doubt all the way to conception, since unless we are all very much mistaken it is impossible to think without a brain of some kind.

Ramesh further implies that human personhood simply exists when there is a genetically distinct human organism engaged in some kind of living functions. Sorry, but that’s just too broad a definition. Brain-dead individuals have distinct genetics, their cells can be performing basic life functions or even dividing, and yet we don’t consider them living persons. On the other hand, someone who is almost entirely paralyzed, requires mechanical assistance to conduct basic life functions such as eating and breathing, and yet has a functioning brain is not considered dead. For most civilized people, the decision rule about personhood seems clearly to be the capacity for thought, however rudimentary.

The best government can do right now, it seems to me, is to a draw an admittedly arbitrary line at some point in the average pregnancy at which a functioning brain is evident. Eventually, technology may allow for a more specific determination. As for enforcing a law against all attempts to terminate a pregnancy after the moment of conception, that may still be in many people’s minds a noble goal but, as Podhoretz seems to argue, would require a widespread religious consensus or conversion. It cannot be accomplished purely on medical, legal, and natural-rights grounds, because they offer no legally enforceable guidance about the existence and nature of the soul.