There are two principles in Catholic sexual ethics that the CDF must keep in mind: “(a) unconditional respect for the human being as a person from conception to natural death; (b) respect for the originality of the transmission of human life through the acts proper to spouses.”Anderson notes the parallels between Benedict's call and the work done by Paul VI prior to Humanae Vitae's publication: new reproductive technology arises, the Church must apply Christ's "eternal truths" to new moral quandaries in which the faithful find themselves.
You will remember that Humanae Vitae--the 1968 encyclical definitively condemning artificial contraception--came rather as a shock to the hierarchy as well as to the laity. One can easily see the CDF's forthcoming response to IVF, the manufacture of "three-parent" embryos, etc... to be equally shocking.
On one level, I can sympathize with infertile couples seeking to conceive their own biological children. Thus far, Catholic teaching has largely been articulated in terms of "treating the child as a someone, not a something." The couple desperately trying to conceive will respond: "We certainly will receive this child as a person. We don't see it as another possession--that's why we're so desperate." The connection between what our actions say objectively ("I will create life that belongs to me!") and what we're feeling emotionally and in relationships ("This child is its own person, of course!") is simply not clear to us in our fallen condition.
Similarly, arguing from consequences--however right your prediction may turn out to be--usually fails to move hearts. The Church puts herself--again, necessarily--in the role of "harbinger of dire warning." Sometimes, this is necessary. But is there another way? Are there arguments against IVF and embryo-manufacture that stem from the very act of procreation itself? Is there something about the sexual relationship that says to all men of good will, "This is how we are meant to come into being?"
Anderson suggests several lines of argument the CDF may take:
Like Anderson, I favor the latter approach, always remembering that it is not arguments that will convince infertile couples. It is the cross.