The Pope and AIDS

A friend recently remarked on the difference between religious law and secular law: the former being what she called backward looking (looking to an authority as the basis for the law), and the latter being forward looking (looking to the consequences as the basis for the law). This distinction comes out fairly clearly in an op-ed piece by Nicholas Kristof. His last paragraph includes the following.

[I]f Pope Benedict wants to ease human suffering, then there's one simple step he could take that would save vast numbers of lives. He could encourage the use of condoms, if not for contraception, then at least to fight AIDS. That choice between obeying tradition and saving lives is stark, and let's all pray he'll make the courageous choice.

Obeying tradition is backward looking; considering the consequences of the no-condom rule is forward looking.

In discussing this issue, I started to wonder how the Catholic church got itself into this position with respect to sex. I suggested that perhaps the Catholic church's position on sex is that it is ok if one intends to procreate, but not otherwise. But I was reminded that the Catholic church approves of the "rhythm method" of birth control.

So sex is apparently ok even if one is intentionally attempting to avoid procreation. So now I'm confused about the basic philosophy. Is it really a claimed distinction between "natural" and "unnatural" means of avoiding procreation that makes the difference? Is sex ok according to the Catholic church even if one is attempting to avoid procreation while having it as long as one is using "natural" methods to avoid procreation?

But what does natural mean? Certainly counting days is not something we were born doing? That's a pretty deliberate act. It's the sort of deliberation that can get one convicted of conspiracy in other circumstances. Typically in moral issues, it's the thought that counts. Why not here? So in what way is that natural?

It seems to me that it would be very difficult to make a principled distinction between natural and unnatural means of avoiding procreation while having sex. So now I'm confused about what the basic philosophy of the Catholic church is toward sex.

Also, what is the Catholic church's position with respect to vasectomy — and sex afterwards. What about the removal of a woman's ovaries? What if she has (or doesn't have) ovarian cancer? What about sex afterwards. What about simply having one's tubes tied?