Yet another post on embryos and fetuses

Michael says, “The point is, you have switched from saying that the human organism has worth because of what it is to saying that a human organism has worth because it happens at the moment to possess certain characteristics, and this does undercut the argument that infants possess full moral worth and dignity.” But the question to be decided is what an embryonic human organism “is” namely is it yet a human being. Is it a human being when it possesses neither a nervous system nor a brain? Michael says that the nervous system/brain approach opens one up to other line drawing challenges as to when humanity begins. Perhaps so, but the presence of other challenges does not itself justify any particular different starting point; and every claimed starting point is open to challenge (including Michael’s).

I, of course, understand that those who opt for the nervous system/brain option can not prove they are right. But that does not show they are wrong. It may well be that no one can prove that the starting point they think is correct is in fact correct. In other words, Michael believes an embryo without a nervous system or brain is a human being and deserves to be treated as the moral equivalent as an infant. My question remains: can you prove it to people whose intuitions are different?

As to Professor Hill’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)?

To summarize some points I have put forward in this thread. The view that an embryo or first trimester fetus is a human being full stop is not shared by an overwhelming majority of the American people. If they really thought the fetus was a human being, they could not possibly support some of the exceptions to abortion that they do. They apparently believe that the interest in life of such an entity is entitled to substantial moral weight but not to absolute weight. Consistent with this, many millions believe that Roe v. Wade should be overturned. But very small percentages of those on that side of the culture divide support the view that an embryo or fetus is a human being full stop. If a fetus or embryo is a human being full stop, the idea that abortion or embryonic stem cell research is the major civil rights issue of our time (as stated in Rick’s church bulletin) or an overriding political issue (as stated by Father Araujo or Robert George) follows naturally.  Moreover, the failure of embryos to attach to uterine walls resulting in their demise would be regarded as a major worldwide health problem. If I understand Robert George, he so regards it. But he is surely joined in the latter by relatively few. This does not mean he is wrong. It is a function of the Church to be prophetic. But, if the truth is written on our hearts (Evangelium Vitae, 2.2), I still believe more explanation is needed as to why so many people have contrary intuitions. Perhaps, however, contrary to the Pope, this is not an area in which the truth is written on our hearts. The question I have pursued may or may not reveal the limits of secular reason in this area (which in no way means there is not a right answer). I apologize for the repetition on my part. I am wondering whether we are near the end of this thread.  If so, I am happy to let others have the last words (at least, in the absence of severe provocation). I am grateful for the many excellent contributions.