Response from Professor Green

Steve,

You write, "As to Professor [Green]'s point that aliens from other planets can be persons without having brains or nervous systems. Certainly the latter is true (and angels can lack both), but they can not be human beings. And the question remains, how do you prove that an embryo is a human being (or, if you prefer, a human person) rather than a mere human organism)?"

The aliens example was only part one of my suggested response.  Step one, a brain itself is not required for personhood (even for materially-embodied beings).  That's where the aliens come in.  Step two, the human embryo has the moral equivalent of a brain.  Why?  Because the human embryo contains the physical material that will build a brain through the embryo's self-directed processes, and so the embryo contains within itself the physical basis for behavior characteristic of persons.  I don't claim that I have given a proof, but I do challenge those attracted to brain-&-nervous-system criteria of human personhood to explain the moral difference between a brain--the brain possessed by a reversibly-comatose person who will not wake up for a month, say--and the epigenetic primordium of a brain possessed by the embryo.  It doesn't seem to me that there is any moral difference between the two, and I haven't seen anyone explain what the moral difference might be.

 

There are other interesting things to say about "human beings," but I don't think the term is essential to an argument for the moral status of the embryo.  The short form of my argument is simply that embryos are morally equivalent to reversibly-comatose people, who are obviously persons.  (If a being's past exercise of capacities becomes an issue, I'll turn to replicated reversibly-comatose people, who also seem to me obviously to be persons.)

 

In general, I don't think that anything more is required for thinking about the moral status of the embryo than the same sort of distinction-drawing and case-to-case reasoning that drives discussion about any other secular philosophical or legal topic.

 

Chris