There was an interesting conversation after Mass yesterday, and I am curious for your thoughts.  The topic was whether a married couple may choose (assuming both husband and wife choose freely) to completely abstain from the marital act to prevent any further children in the marriage.  To be clear, this is not a questions of NFP, but rather completely abstaining from the marital act, presumably for the rest of their lives, or at least until the wife go though the change of life.  Of course, either party could change their mind, and demand the marital debt, and the other should comply, but assuming this doesn't happen, is there any sin in a married couple deciding they don't want any more children, and completely abstaining?

I can see that in the case of both having low libido.

Yes, either complete abstinence, or periodic continence (NFP) are both lawful. Those who claim otherwise are wrong. Pope Ven. Pius XII said so. With regard to complete abstinence, St. Paul counsels, however, that it not be undertaken without both parties consenting to it. It's best to consult your Confessor also.

Yes, either complete abstinence, or periodic continence (NFP) are both lawful. Those who claim otherwise are wrong. Pope Ven. Pius XII said so. With regard to complete abstinence, St. Paul counsels, however, that it not be undertaken without both parties consenting to it. It's best to consult your Confessor also.

No.  Not in the same category.  NFP, unlike abstinence, entails a subordination of the primary ends of martial relations to the secondary, which Pope Pius XI condemned in Casti Conubii.  Pius XII said lots of things, and he was plain wrong about NFP, just like he was about other matters.

No.  Not in the same category.  NFP, unlike abstinence, entails a subordination of the primary ends of martial relations to the secondary, which Pope Pius XI condemned in Casti Conubii.  Pius XII said lots of things, and he was plain wrong about NFP, just like he was about other matters.

If you recall, one of the V2 innovations that caused a stir among the conservative fathers was the intention to elevate the secondary ends of marital relations to the co-primary.  That has extreme ramifications for moral theology, potentially rendering any physical relations geared toward what were theretofore secondary ends licit.  In any case, the chief problem with NFP that's never been addressed is that, along these lines, Pius XI taught (in an Encylical addressed the the Universal Church, a docuмent of much greater authority that Pius XII's long, rambling, clearly speculative speech to a group of midwives) that relations between husband are wife are illicit if their primary ends (procreation) are subordinated to the secondary.  That's just part and parcel of the definition of primary/secondary ends (otherwise the terms are meaningless).

Of all the proponents of NFP, no one has ever explained how engaging in marital relations while intending to exclude procreation does not subordinate the primary end (procreation) to the secondary end.  If seeking the secondary while attempting to exclude the primary doesn't invert the ends, then there's no such thing as an inversion of ends.

As far as Pius XII, his was the watershed papacy that led directly to V2.

Pius XII:
1) failed to consecrate Russia (which would have prevented V2)
2) opened the door to evolution
3) set up Bugnini to begin his liturgical experimentations (even Roncalli kicked the guy out)
4) permitted some of the first Ecuмenical gatherings
5) appointed nearly every single one of the bishops who would go on to give us the glories of V2 (this is the pope's #1 job, to appoint good bishops, and surely he could have found Traditional- and conservative- leaning priests out there to elevate to the episcopacy, thereby transforming the Church during his lengthy/protracted reign)
6) allowed Fr. Feeney to be persecuted by the heresiarch Cushing, who in turn was left undisciplined, doing massive damage to Church dogma

Fr Fox told us that you DON'T practice NFP, you temporarily abstain. 

NFP: Planning the family out of existence!

Right, and by "temporary" is not meant "during the fertile period only".  There seems to be this underlying premise that everyone has some God-given right to marital relations.  What if your spouse becomes ill or incapacitated or leaves you?  At that point you are required to abstain?  There is no right to martial relations.  Same thing holds to those who are single (even if by no choice of their own).  If a situation arises that's grave enough to abstain, and yet you're willing to take the chance that your NFP scheme fails and the wife conceives?  Let's say the wife's life is at stake (as many have falsely claimed).  So you're willing to risk her life by NFP instead of making absolutely sure by abstaining?  Or maybe you're exaggerating the necessity, eh?

See, when it's natural (i.e. not artificial), they apply the euphemism "family planning" vs. when it's artificial now it's "birth control", two terms that denote the same thing with different connotations ... but the formal intent of both is the same, to be able to enjoy the secondary ends of marital relations while thwarting the primary.

Now, if a couple wanted to abstain by mutual consent even for things like spiritual reasons, I believe that's always been permitted, but the trick is for a confessor to discern whether there's really mutual consent or if one part just persuaded the other to think that thye're consenting.