The Bones has a good post about the way the eugenicists float 'shocking' ideas, wait for the fuss to die down, and then impose the reality. They get people used to the idea of contraception, abortion, screening for the disabled, euthanasia, by endless debate, and their chums in the media are always on hand to keep the defenders of the status quo on the back foot. The matter is never settled until they get their way; when that happens, suddenly it is very settled indeed, one might think it was handed down from the Almighty, the fuss they make about 'attacks on abortion rights' and so on.
This procedure is aided enormously if the response of Catholics is not to oppose the evil with arguments from Natural Law, but to beg to be allowed to shelter Catholic institutions and Catholic medics from having anything to do with it. The progressives are always willing to make this concession to win the main issue, after which they can remove our precious protections at their leisure. This has happened so often now it would be tedious to list the cases, but it started with Cardinal Heenan reining in opponents of abortion in exchange for a 'conscience clause' which in the long term has proved totally worthless.
There is another aspect of the progressive strategy which is worth highlighting. The Catholic Medical Quarterly has just published a short paper of mine, which the editor commissioned, on the widely used medical textbook by Beauchamp & Childress. This was first published in 1979, and is now in its fifth edition. It is a truly appalling book, a disgrace to academia, deriving not from serious moral philosophers but a self-regarding group of 'applied ethics' people who find it very easy to get grants and sell books without actually thinking anything through clearly.
The Catholic Medical Quarterly very decently lets people download pds of articles, and you can read mine here. One very striking thing about the Beauchamp and Childress approach is that they encourage medics to view every decision as a matter of balancing considerations. Not, as you might imagine, medical pros and cons to a proposed treatment, or anything as sensible as that, but 'on the one hand, Kantian ethics would suggest option (a); on the other, the patient wants (b); and then again my feeling is that we should go for (c).' This describes what may indeed be the reasoning of a medic with absolutely no ethical formation; Beauchamp and Childress want to keep medics that way, even after they've done a course in 'medical ethics'. Instead of making a decision on the basis of a coherent account of ethics which is itself subject to rigorous debate, they want medics to balance innumerable such accounts against each other and against inchoate feelings and even social pressure.
The genius of this account is that it can disguise the victory of materialism and utilitarianism indefinitely. One of the most powerful arguments against these theories is that they have extreme implications which are completely implausible. Murder five innocent people to save six? Cause great pain to one to save a large number from pin pricks? Give extra food to an indolent epicure while ignoring the needs of contented paupers? Instead of confronting these cases and concluding that Utilitarianism is simply wrong, Beauchamp and Childress say: keep it in the background, just balance it against your intuitions. So as time goes on, and healthy moral intuitions are undermined by relentless Utilitarian propaganda, not least in medical ethics courses, it can continue its relentless advance. The unthinkability of contraception, abortion, IVF, screening, euthanasia, and infanticide disappear one after the other because it hasn't been made sufficiently clear that the only reason to ignore these traditional moral prohibitions is a moral theory, Utilitarianism, which no sane person would actually adopt, without massive and arbitrary conditions, in real life.