Okay, here’s where I’ve heard a rebuttal to what you’ve just said. Isn’t having sex on your infertile days ONLY also a lie? I know NFP isn’t supposed to be used like that for life-- or can it be based on the circumstances of the couple?
Well, it can be. It does depend on the circumstances of the couple. Some secular couples use NFP; they usually call it FAM, or Fertility Awareness Method, but it’s the same sympto-thermal method that a lot of Catholics use. They generally use it because they don’t want the woman to have to put a lot of really unhealthy chemicals into her system, and the secondary reasons for using it as birth control vary, of course, as they do with any couple.
A Catholic
can use NFP wrongly, sure. They need to have a grave reason to deliberately postpone the possibility of getting pregnant with another child. NFP is a tool that provides information. So’s a computer. Either can be used wrongly, but that doesn’t mean that you refuse to use computers.
NFP can be used until a woman reaches menopause (essentially, for the fertile life of the wife) in grave situations. I know an older couple who had a child late in years (they also married very late, so this isn’t all that unusual). During the birth, something happened which caused permanent damage to the mother. Her doctors–and she went to several to confirm–all were unanimous: another pregnancy would, barring a supernatural miracle, kill her and the baby. After much discussion together and with a wise priest, the couple decided to abstain until she had gotten far enough into menopause that a doctor could say with certainty that she would never ovulate again. At the time I’m talking about, NFP was not as exact a science as it is now, and they didn’t want to risk her dying. In their case, fortunately, it wasn’t as long a time as it would have been for a younger couple. If this had happened now, then they could have instead used NFP very conservatively (ie, only in Phase 3) in order to avoid.
The key in deciding to use NFP to avoid is that there must be a serious reason for it. It’s been a little while since my marriage prep class, but off the top of my head the categories for using it to avoid include:
Health of the mother, both mental and physical: a doctor or midwife has said to wait for a time for physical health reasons, or the mother has a tendency to a mental illness (genuine depression, PPD, bipolar, etc, etc) which pregnancy could trigger or exacerbate, or having another baby would cause the mother (or, for that matter, father) severe stress because of the responsibilities, etc.
Societal: if the couple is living in, say, China, where having another baby means that the baby will probably be killed anyway via neglect or forced abortion or that the fines are so crushing that the parents won’t be able to provide for their children, then a couple may avoid. Similarly, if one is in the middle of a famine or financial depression or a natural disaster (Fukushima, for example) which would make caring for or providing for another child all but impossible or actually impossible, the couple may choose to avoid.
Eugenic reasons: the parents discover that they both carry genes which make it very likely that a child born to them will be severely ill in some way or other. They may choose to avoid in this situation. Such situations can also be short-term, ie, the wife is on chemotherapy which will cause horrendous birth defects if she becomes pregnant during the chemo regimine.
Economic reasons: the couple can’t afford the expenses associated with another child at that time.
Obviously, I can’t possibly include every rational scenario in this post in which a couple can choose to avoid.
Remember, NFP is a tool that, like every other tool, should be used with prudence. A computer is also a tool. NFP can be used with a contraceptive mentality, and a computer can be used to access internet pornography. In the former case, a couple should regularly examine their reasons for using it. In the latter, the computer should be used for good things and not immoral ones. Simply doing without a computer to avoid the possibility of internet porn isn’t feasible for most people nowadays, and not having a tool that can be used to wisely space children would make things very difficult for a lot of married couples.
The two key points here are a) that NFP is a tool, no more, no less and b) that contraception says “I love you except for your body’s inclination to make more children,” while NFP says (if used properly) “I love you, and I will wait rather than engage in an act of mutual masturbation in the marital embrace.” If the sexual act doesn’t occur, a la NFP, it can’t be a lie since the action itself doesn’t exist. If it occurs with condoms, then the condoms are an interference within the context of the act, rather than not engaging in the act in the first place.
Also, please note that unless there is a grave reason, one spouse cannot refuse the spouse sex without incurring grave sin. NFP has to be a mutual decision; it can never be unilateral, so in that sense it isn’t frustrating the act itself, either. (One spouse can refuse sex to the other for a very short list of grave reasons, but as that isn’t the focus of this discussion I won’t go there.)