UPDATE: I've somewhat changed/nuanced this opinion, upon further consideration, to recognize that contraception and sterilization may ultimately be collapsable into essentially the same intention/sin, even if pre-intercourse methods more easily allow for a second act of the will to change the intent.
This post may not be favored by my more liberal readers, especially in light of recent conversations, like this on Reditus, which are very interesting but which would also seem to scoff at a sexual morality that gets too technical or detailed.
I myself am against the idea of some Inquisition to try to enforce it on everyone, and am of course actually quite suspicious of seeming attempts to create public psychological power for the clergy through an obsession with questions of sexuality that should really be mainly private and between the individuals, God, and perhaps a confessor and other close confidants, rather than the center of some culture war (though the fact that it is such a hot-button topic perhaps points to the inherently social, and thus public, nature of sex?)
Nevertheless, as much as I may think there are unhealthy attitudes towards these things among the fundamentalists in the Church, I am ultimately still orthodox at the end of the day, and so do believe there is an important place for a theology of the body (if not "THE Theology of the Body") and for certain nuts-and-bolts questions to be addressed by moral theology regarding chastity.
Those of you who roll your eyes at such discussions or who reject the very premises they are founded on, feel free to disregard the rest of this post, which is indeed more characteristic of my Catholic Answers days than now. This is probably because (pendulums swinging as they do) I've recently been seeing the limits of "loyal dissent" and being a "renegade" gadfly (not that I'm giving that up!).
But many people do have a need for simply the nitty-gritty apologetics type questions like this to be addressed satisfactorily with clear-cut answers about how to act or what to say to opponents. Too often in the circles I've been reading in lately, people are instead hit with intellectual meta-discussions that end up undermining the role of philosophy and theology in answering any practical questions about leading the good life (usually by concluding with endless doubt about whether we can ever actually determine what the good life concretely should look like). But without concrete conclusions, that approach (stimulating as it may be) can, in the final consideration, lead simply to mental and behavioral laxity and decadence; spirals of thought, point and counterpoint endlessly considered, forming an excuse never to act or spiritually change. Something I've always been concerned about.
Anyways, I got into a theology of the body type discussion with some Catholic friends on the difference between impotence and infertility in Catholic thought; the former being an impediment to marriage and invalidating sex, the latter not. And were discussing the minimum requirements of sex for being moral, and had a thought regarding the application of that to the question of birth control.
It seems to me that "contraception" as currently conceived (no pun intended) may not be a particularly accurate category of sin. I'm not saying all the things that we think of as contraception aren't sinful (they are) but it seems to me (based on TOB at least) that there would be a difference between a method like onanism or the use of a condom, and something like the pill or a vasectomy, based on their "visibility" vs "invisibility."
The perceptible acts (like a condom, withdrawl, etc) from that perspective, are seen to make the sex act not even really valid sex in any natural sense. The withholding of the transmission of the semen by the man, or (in the case of something like a diaphragm) the withholding of receptivity of it by the woman...make the act basically just mutual masturbation. The correct "syntax" of sex just isn't there, which involves, on the phenomenological level, the completion of total self-giving in that act.
However, the valid act doesn't require, for example, the presence of any sperm in the semen. Or for the woman to be fertile, or even have a uterus (a woman after a hysterectomy may still have sex). As with any sacrament, only perceptible differences matter on this level. Sex has to be procreative, but it does not have to be reproductive. It has to be the type of act which (on the perceptible level, at least) could be fertile, which signifies the creation of life...but it does not need to actually produce its fruit except implicitly.
And this makes sense. Just as the Church believes that the Real Presence ceases when the particles become too small to recognize with the senses, so too is the language of the body only determined by what we can actually perceive, in terms of the validity of the sacramental act.
And sex is intrinsically a sacrament, whether of the Christian dispensation or merely a "natural sacrament" as Catholic Encyclopedia explains in its article on marriage:
For a better understanding of the sacramental character of Christian as opposed to non-Christian marriage, we may briefly state the relations of the one to the other, especially as it cannot be denied that every marriage from the beginning has had, and has, the character of something holy and religious, and may therefore be designated as a sacrament in the broader sense of the word. In this connection we cannot pass over the instructive encyclical of Leo XIII. He says: "Marriage has God for its Author, and was from the very beginning a kind of foreshadowing of the Incarnation of the Divine Word; consequently, there abides in it a something holy and religious; not extraneous but innate; not derived from man, but implanted by nature. It was not, therefore, without good reason that our predecessors, Innocent III and Honorius III, affirmed that a certain 'sacrament of marriage' existed ever among the believers and unbelievers."It is the perceptible sacramental symbols which convey the language of morality in this case. So, for example, the man must be able to ejaculate into the woman. This is enough to convey the transmission of fertility on the psychological level (even if the semen is actually infertile if examined microscopically), because science cannot override human nature. The conscious rational knowledge of microscopic things doesn't change the deep subconscious psycho-spiritual understanding of sexuality, which considers (in terms of the questions of self-giving and chastity) the sense-perceptible transmission and receptivity only, not the question of unseen gametes.
Which is why methods like the pill or a vasectomy seem to me to perhaps require another category of sin. Not contraception but, rather, sterilization. In other words, their fault might lie not so much in unchastity, but rather in their nature as a deliberate mutilation of what was otherwise a healthy and working function of the body. On the perceptible level (which TOB sees as what effects the spiritual "symbolism" of sex)...the Pill does nothing more than create the same state that a woman is in most of the month anyway, or that an infertile woman is in always.
This can be a problem in arguments about contraception based on TOB type arguments (which modern man does seem to find more compelling in their non-legalistic personalism) and basically all I've heard Catholics offer is, "Well, doing something deliberately to frustrate fertility changes the act, but no one can be blamed if something happens beyond their control" even though, apparently, deliberately waiting for the natural period of infertility is okay...
Yet, it strikes me, an act is either okay or it's not. Yes, context and intent affect the morality of choices as well, but if we allow for sex during infertility (and even recognize the monthly infertile period as a good and natural thing rather than merely pathological), that doesn't answer why the creation of infertility deliberately is wrong, but waiting for it each month deliberately is not. If the latter can be a chaste act, it implies actual fertility in itself is not essential to valid sex, so what suddenly becomes essentially unchaste about the former? It can't be merely the lack of fertility, as that has already been shown by other allowed examples to not be essential. If sex during the naturally infertile period is considered to be of the same type of act that signifies fertility, then sex on the Pill isn't any different as it merely extends the naturally infertile period through the whole month.
However, if we distinguish between contraception as such, and sterilization, between an act that is basically mutual masturbation, and one that is sex but with a separate question of mutilation of the body...this answers a lot of those questions. It explains why NFP is okay, why infertile couples can have sex, and why a man is not required to reverse a vasectomy, why a woman can take the pill for legitimate medical reasons, why she can have sex after a hysterectomy, etc. Because the creation of infertility does not necessarily make the sex unchaste or take something essential away from it (as fertility is clearly not essential to valid sex). But it is nevertheless still sinful, but for a different reason: namely, it is the mutilation of a healthy and working function of the body for no proportional double-effect medical reason.
So, that is basically my little thought: it might be very helpful in arguments with non-believers on this issue to differentiate between "contraception" which deforms the natural act itself and makes it unchaste, and "sterilization" which (while it may have unchaste motives) has its sin more in the mutilation of the body (hence removing the previously tricky question of undeliberate infertility from the debate).
Assuming my differentiation between "contraception" (condoms, diaphragms, coitus interruptus, etc) and "sterilization" (vasectomy, tube tying, the Pill) is correct and helpful (and I think it is given how it takes all the "but why can an infertile couple...?" questions off the table) then we can distinguish between the method itself and the sex had using it.
So, for example, contraception is only wrong in the context of sex. Putting a condom or a diaphragm on...isn't wrong, in itself. There is nothing intrinsically wrong with putting a rubber sheath over your penis. It only becomes wrong if you actually have sex that way and so it stops the "transmission of the gift" as JPII so eloquently euphemized ejaculation, I believe. This sex then becomes unchaste, basically just masturbation with a piece of rubber that happens to be held between a woman's legs, a with-holding of total self-giving that shatters the natural script of sexuality on a deep subconscious level, and turns the act into a "lie" with the body.
In the case of contraception the "syntax" of the sex act is ruined. Human nature knows on a deep level that valid completion of that type of act means, "I want you to be the parent of my child, which is in itself a lifelong commitment," and that lust may be defined as any desire that takes pleasure as an end in itself, or which posits for it a subjective meaning other than its God-given significance as a motivator for that teleological script. The valid act may be lustful in motive too, of course, even between spouses...but invalid acts are lustful by nature. Like any sacrament, certain essentials are needed for validity, and sex done contraceptively becomes like, well, like baptizing a baby who is wrapped in a rain coat (so the water never touches his skin) or even like pouring the water just on the floor instead of on the baby!
This also makes me think of my controversial post in which I argued that 1) the contraceptive effects of using a condom are the lesser evil in situations where, the couple refusing to abstain entirely, to not use a condom would lead to risk of disease and other material consequences, and 2) in most fornicatory or adulterous situations, the use of contraception doesn't really change anything about the morality of the act, because in most cases the fornicators will already be viewing sex as disconnected from both unitive and procreative purposes; they already don't or can't intend either lifelong commitment nor pregnancy (really the same thing) by it, so at that point actually using a method that at least is effective doesn't make it any worse, in fact I'd hope for society's sake that they do.
That point about fornicators using contraception not usually being any worse still stands. As, to continue with the "sacramental" analysis...such people can be analogized to a priest who withholds sacramental intent and therefore invalidates a sacrament. Well, if the sacrament is thus already invalid by withheld intent...does it really matter at that point if he uses the right or wrong matter or form? In fact, at that point, I would hope that such a priest would also use invalid matter or form just so that no one is duped by his intentionally invalid sacrament. At that point, such things don't make it any worse. Likewise in my argument that fornication usually isn't valid "natural" sex already, prior to any question of whether a condom is used or not, as intent is usually already withheld; at that point, additional factors don't make it any worse since it's invalid already and you can't make something "more invalid"...it's like alive and dead, it either is or it isn't. But I also did admit that "simple fornication" that was still "natural" might be possible in some cases of concubinage or common law marriage which are open to life. In these cases, I suppose, to use the common sacramental terminology, the sex could be said to be merely "valid but illicit."
However, sterilization seems to be the opposite of contraception. With a vasectomy, it's not actually the sex following it that is wrong or unchaste (though there may be an unchaste attitude). That sex is still natural and not, in fact, sinful in itself; men who get vasectomies are not required to have them reversed after confession. The sin in sterilization lies rather with the initial act of mutilation in itself, whether sex follows or not. The sin is in the unnecessary violence against a healthy functioning of the body. The sex that follows the act of sterilization (assuming the essentials are all there and it's within marriage) is not sinful, it's the original act of sterilization itself which is the sin (and a sin of violence/mutilation at that, not unchastity).
Contraceptive methods actually ruin the sex act itself, and are sins against chastity. Sterilizing methods are, on the other hand, wrong in the initial mutilation only, not the subsequent sex acts; they are primarily sins of violence against the body, not unchastity. Though, of course, as even with NFP itself...the motives can still be subjectively unchaste (as opposed to just violent) if the goal of the sterilization is purely to enable sex only for pleasure or the fulfillment of lust. You might assume this to always be the case, but I don't think necessarily. For example, a married couple who already have several children together have already demonstrated the significance that they want to be the parents of each others children and are committed for life. At that point, if they sterilize themselves for, say, economic reasons...I'd argue that, while the act of sterilization is still wrong as a mutilation, they are not necessarily being particularly unchaste or lustful.
What this leads me to wonder is about the gravity of all sterilizing acts. Contraception is clearly considered a mortal sin as sins against chastity are. And most forms of deliberate mutilation that sterilize would seem to be also. Certainly something like tube tying, a vasectomy, an unneeded hysterectomy, etc.
But while sins against chastity don't admit of degrees...I think mutilation can. I think there are mutilations of the body which are minor and so only venially sinful. While most sterilizing mutilations are clearly major and mortally sinful, I do have to wonder about something like the Pill. It's a sterilizing mutilation, yes, but it's reversible, a relatively minor act compared to surgical intervention, it can apparently be justified by other conditions as minor as acne, and it's effects are cumulative (ie, the Pill has to be taken daily). I wonder then if the mutilation has to be considered to reach the level of mortal sin every time the woman takes her daily Pill (even though for most of the month she would be infertile on that day anyway)??
I think it's something the Church could reconsider in light of the contraception/sterilization divide that I've fleshed out here. Certainly, while the abstract moral principles behind the condemnation of contraception are objective doctrine, the subjective casuistic application to various specific methods or situations is subject to evolution and interpretation. Now, likely they would conclude that, due to the sacredness of reproduction, any mutilation (however otherwise minor) that effects fertility is by nature mortally sinful even though it is "sterilization" rather than "contraception". And perhaps rightly so. Still, I think they've been rather sloppy in considering and making these distinctions, and it's led to a lot of confusion and faltering arguments on our side against those who, as I said, invoke infertile couples as an argument for invalid sex being okay, or who don't understand why NFP is okay but the Pill isnt, etc.
I'm not really questioning any of the "what" of doctrine, as you can see, but I think there could be some restructuring of categories and explanations like this to make the "why" a lot more convincing for people. By splitting birth control methods into the contraceptive and the sterilizing, with separate reasons given for why they're wrong (one making the sex invalid by removing one of the essentials, the other merely because it is a mutilation of the body) it takes questions about naturally infertile couples, NFP, legitimate medical procedures that have sterility as a side effect, etc, off the table.
I think it would be very helpful in discussing this with people, apologetics-wise, to make this distinction and to clarify right from the start that fertility/reproduction are not intrinsically necessary for valid sex, as long as the perceptible essentials that symbolize them are there (in other words, as you sometimes hear, it is "that type of act"). Deliberate but "invisible" sterilization can then be explained as wrong too, not because of unchastity, but rather as acts of bodily mutilation.