Vatican Issues Instruction on Bioethics

From NYTimes.com.

The Vatican issued its most authoritative and sweeping document on bioethical issues in more than 20 years on Friday, taking into account recent developments in biomedical technology and reinforcing the church’s opposition to in vitro fertilization, human cloning, genetic testing on embryos before implantation and embryonic stem cell research.

Even though I disagree with it, let's take as given the Catholic position on souls. What I find interesting and uncertain is how that position justifies the positions in this document—at least as reported in the Times.

The most obvious issue is in vitro fertilization. Why is that banned? The article quotes Josephine Johnston, a research scholar at the Hastings Center, an independent bioethics research institute in Garrison, N.Y. as follows.

“For a married couple who go to get in vitro fertilization, the Vatican’s idea that it’s not done with a serious amount of love and commitment is very bizarre to me, because it’s such a deliberate act, done in the cold light of day, with enormous amounts of thought and intention attached to it,” she said. “The idea that it’s not done within the spirit of marital love, I find very strange.”

I wonder what the Catholic response to that is.

Although according to the Times the Vatican opposes human cloning and embryonic stem cell research it does not oppose "research on stem cells derived from adults; blood from umbilical cords; or fetuses “who have died of natural causes.” Why not? What's the difference (in soul terms) between a stem cell derived in an acceptable way and one derived in an unacceptable way? Probably more difficult is the distinction between a stem cell and a clone. As I understand it, stem cells can be programmed to become any type of cell but they cannot be programmed to become full-fledged human beings. I wonder how absolute that limit is. Will we ever be able to turn a stem cell into a human being? And if we learn how to do that will the Vatican object to research on stem cells that they now accept?

The closer we get to being able to construct a human being "from scratch" the more difficult it is likely to become for the Catholic church. What if we are able to take a bunch of chemicals, mix them up to create a cell and then nurture that cell until it is a baby. Which step in the process is the line that the Catholic church will say is the line that shouldn't be crossed?

I agree that this possibility raises some very serious ethical issues. But I don't think the answer is to be found by asking when during that process the proto-baby becomes endowed with a soul on theological grounds.