Are moral obligations derived from function or family?

As Thomisticguy (aka Pastor Van Oosten) points out, we had a discussion on the issue of terminating life support for individual in a persistent vegetative state ("PVS") at the Thursday night Aquinas Circle. The thesis discussed based on the following syllogism:

1. According to the Catechism, the purpose of human life is to "seek, know and love" God.

2. Individuals who are in PVS are not able to "seek, know and love" God.

3. Therefore, such individuals are not - and we assume never will be capable of - living a human life.

4. Accordingly, there is no moral or human purpose in maintaining such individuals in such a non-human life, and it may be the case that moral harm is being done to such individuals by delaying their union with God.

I am not sure that the move from "3" to "4" is obvious, and it seems that the moral harm point may be countered by speculating that the person's final end is not Heaven, in which case, delaying their ultimate destiny does them a lot of good.

On his Blog, Thomisticguy has addressed from a Thomistic perspective whether we can be sure that people in a PVS are not capable of seeking, knowing and loving God and whether "purpose" can be narrowly defined as the individual's purpose, as opposed to the purpose of other people or the community itself. (See my comment on Thom's post here.)

This argument seems novel at first glance, but is really just a variation on the secularist argument that defines human "functionality" as the sine qua non for determining moral rights and obligations. The secular argument based on functionality usually argues that the ability to reason and experience is the essence of humanity, and that someone without those capacities has the moral status of animals, which lack those essential human capacities.

This is not an extreme position. I think that the intuition of most people is to feel a horror at the the situation of people in PVS. Those in PVS seem to have entered a "post-human" life devoid of everything that the sentient finds meaningful. The death of those in PVS naturally seems a mercy for the family, society and the individual himself.

On the other hand, there is another intuition that we have. We still see those in PVS as being "human." We would have to descend into a presently unrecognizable culture to countenance the medical experimentation on the PVS, or harvesting their organs, although that fits into the notion that function determines status. Moreover, while we are willing to remove feeding tubes and watch them die, we are not willing to smother them with pillows or expose them to the elements.

The intuition then is that even without their human functions, individuals in a PVS are still humans.

Obviously, this latter intution is premised on the buried notion that we are not humans because of what we do, rather we are human because of who we are: we are humans - and entitled to the rights of all other humans - because we belong to the human community as a matter of our birthright, which can't be taken away by the accident of disability.

On which point, Mark Shea points to a book by Robert George and Christopher Tollefson called "Embryo," which makes the same kind of family over function analysis as a matter of embriology. This review describes the argument of the book as follows:

This book is likely to make a lot of people crazy: It is a radical, even audacious, assault on the emerging technologies that would harvest living human embryos for medical research purposes. It is absolutist in its claim that human life begins at fertilization, when the male and female gamete, each bearing 23 complementary chromosomes, combine to create the single-cell zygote that will implant itself in the uterus and, in due course, become a man or woman. The argument's implications, not only for embryonic research but for abortion and some forms of contraception, are obvious: If it's human, you shouldn't kill it. That the argument relies on no sectarian religious tenet will only further aggravate those who disagree — it is much easier, these days, to dismiss religious scruple than scientific fact and logic.

And continues:

But once the embryo is defined as human — as the science of embryology clearly defines it — the sentience argument falls short. Why not also harvest organs from the severely retarded or the comatose? The history of assigning value to individual human lives based on perceptions of inferiority or inconvenience has not been a pretty one, and the "greater good" argument is undeniably stronger, provided that the extravagant claims made for embryonic stem cells are not exaggerated. (The authors and many others believe the claims are, in fact, exaggerated.) But it, too, falters when one considers the history of reckless medical experimentation — the notorious Tuskegee syphilis trials, for instance, or the radiation tests performed on the unsuspecting by the military.

Moral principles are imperialistic. They conquer the surrounding territory until they are checked by an equally strong principle. Grant that function determines moral status and it is not clear where the stopping point of that principle can be found.