On Triablogue there's an out of context quote from Alexander Pruss and comments which should be answered...
Pruss writes: In fact, the biological union does not even require the couple consciously to will the striving towards reproduction. The biophysiologically united man-woman organism instinctively and automatically on a biological level strives toward that end. What is required is only that the couple should not place an obstacle in its way, because the act of placing the obstacle is an act of disturbing the union. The act of contracepting is opposed to the end of the teleological process by which union is constituted. A distinction between permitting and causing is relevant here.
The couple that contracepts is the intentional cause of their infertility. The NFP-using couple, when infertile, is not the cause of the infertility: the natural cycles of the female body are the cause of the infertility, which cycles are independent of the couple’s decision to use NFP. The couple permits the infertility, and draw good from it, even though it would be wrong for them directly to will this infertility. That the distinction between permitting and causing is a significant one can be seen in at least two other examples. One is the distinction between letting die and killing, often discussed in the context of euthanasia.
Note please, Pruss does indeed state that it is WRONG to directly will this infertility. Thus a couple who directly wills infertility is wrong and mortally sins in doing so - by WHICH EVER MEANS they choose to be infertile. With NFP the couple cannot willfully refuse one another - regardless of the time in the woman's fertility cycle. They may "plan" to participate in "the marriage act" during the time of infertility - and that's the "planning" part - but I reiterate, they cannot refuse each other during the time of fertility. If the desire is there, then they must allow "the marriage act" to go on unimpeded - by ANY means of contraception.
On to the illogic on Triablogue:
It’s odd that someone as astute as Pruss would leave it at that. It’s of course true that the distinction between causing and permitting can sometimes be morally relevant or exculpatory. But it’s easy to come up with counterexamples where that distinction is morally irrelevant or culpable.
But Pruss didn't "leave it at that!" If one investigates the link provided by Mr. Hays they can see that Pruss indeed explained further:
The other example is that of theodicy. God never causes an evil. However, in order to draw a greater good out of it, He sometimes permits evils. The greatest and clearest example of this was the crucifixion. God did not cause Judas to betray Jesus and Pilate to condemn Him, but He permitted it, in order to bring a greater good out of it. It is essential to the way that sexual union as one body is constituted that while willing the union one not simultaneously unwill the end (reproduction) the biophysiological striving towards which constitutes the union. However, it is not necessary that one explicitly will this end, only that one not will anything contradictory to it. The implicit willing of the unitive meaning of the sexual act, in the absence of a contradictory willing, suffices to make the teleological striving that constitutes the union be a willed striving—and hence a striving of the person, and not merely of the body, thereby effecting a willed personal union.
It is a bit disingenuous of Hays to say Pruss left it "at that." Hays even quotes that Pruss says there are "at least two other examples" and then only quotes one of them - and has the audacity to accuse him of "leaving it at that."
In The Little Foxes, Regina doesn’t cause her husband to die from a heart attack. Rather, she permits him to die by withholding his heart medication. In that situation, letting him to die is morally equivalent to murder, even though she didn't positively bring about his demise.
Sorry, but "withholding medicine" which is not an extra-ordinary means of keeping someone alive DOES CAUSE HER HUSBAND TO DIE! Certainly "the cause" is the underlying heart condition - but if one willfully withholds the medicine from another against his will - that would be murder. A clearer example of this would be a mother refusing to feed her newborn infant... that is negligence and murder for the mother has caused the death of her baby. No rational human being with any sense of charity or concern for the helpless/innocent would simply say the baby died of starvation and leave the mother's culpability out of the picture. Clearly in The Little Foxes, Regina does kill her sickly husband by withholding his medicine, which IS Hays' point here - but the point Hays misses is the fact that "planning" to participate in "the marriage act" during infertile times is not the same as "doing it" during fertile times and then killing the seed by some chemical or physical barrier.
Natural family planning has a contraceptive intent, and–where successful–a contraceptive effect.
This illustrates the problem with Catholics who use natural law to ratify a conclusion they arrived at by other means.
I'm sure that those who condone contraception believe this to be the case, but if the intent is contraception then the couple is in mortal sin. The intent is to have "planned" participation in the period of infertility of the female cycle. If either party refuses the other during a period of fertility then that person has committed a mortal sin. Hays uses either false logic here - or demonstrates ignorance of what the Catholic Church really teaches on the matter of NFP.
Other comments on this article (at the time of the publication of this article/response):
One of the main proponents of John Paul II's "Theology of the Body", Christopher West, uses this kind of reasoning as well.
He says that some people ask "What's the difference between causing infertility, and just waiting for the woman to be infertile?" His response is "what's the difference between killing grandma, and just waiting for grandma to die?"
The same illogic as above and has already been explained/dismissed.
Most Catholics (1) don't abide by the Church's stance on contraception anyhow. In any rate, (2) there's no substantive difference in intent between contraception using a calendar or with a piece of rubber (or a pill). (3) Doesn't the Church keep reminding us that contraception is "ineffective"? If it is, then there's not a greater likelihood of preventing pregnancy with a condom than with NFP.
Well, yes. And the Spartans didn't practice infanticide, strictly speaking - they just left imperfect babies exposed on the hillside overnight.
The irony is that in other spheres, "Catholic social teaching" is scathing of the "just leave people alone" thrust of Whig Protestant capitalism. Governments, say various Popes, have an affirmative duty to ensure that their subjects have healthcare, food, etc. You can't just ignore them while they starve, like Dives with Lazarus, or the "goats" on Judgment Day. Yet when it comes to methods of contraception, the Vatican has copied Judith Jarvis Thomson's "live and let die" defence of abortion http://en.wikipedia.org/wiki/A_Defense_of_Abortion and moved it a stage earlier in the life-cycle.