And because it is something of the philosophical lingua franca in the modern Western Church (as disasterously as it was discarded in the late 20th-century in favor of various zeitgeists). I would not make scholasticism the be-all or end-all of philosophy, but I do think it has the ability to ground in a metaphysical precision what can otherwise become a pseudo-mystical or even purely literary or poetic venture that might wind up far from practical or analytical.
However, I do find this selection from Grisez's The Way of the Lord Jesus (about the virtue of temperance, basically) enlightening when it comes to the question of intelligible good as the basis of morality (and thus holistic human fulfillment and happiness), which I do think is a strong-point in terms of the emphases of the New Natural Law school:
The third mode is this: One should not choose to satisfy an emotional desire except as part of one’s pursuit and/or attainment of an intelligible good other than the satisfaction of the desire itself. Violations occur when a person deliberately chooses to act upon impulse, habit, or fixation on a particular goal. The proposal one adopts in making such a choice appeals by promising some sense of inner harmony through tension-reduction. Thus, one’s reason for acting is the very satisfaction of the emotional desire rather than some intelligible good whose instance has features which arouse the desire. A choice to act on this basis sets aside whatever reason there was for restraint, and the action at least wastes time and energy one might otherwise use for the pursuit of goods in line with upright commitments. In deliberately settling for mere emotional satisfaction, one’s choice is not that of a will toward integral human fulfillment.
A person sometimes is aware that his or her desire, instead of pointing to some reason to choose to satisfy it, offers only its own satisfaction as a reason for choosing. Yet one can be drawn—and perhaps almost driven—to choose, for example, by a quasi-compulsive desire, by habitual routine, or by a particular goal on which one’s heart is fixed. (It sometimes happens that goals which were reasonable at the outset lose their point with the passage of time yet retain their emotional appeal.) This is not the same as the situation in which one spontaneously does reasonable things without having reasoned about them. Nor is it the same as cases in which one acts for an intelligible good and gains emotional satisfaction in its concrete, sensibly pleasant aspects.
Sexual intercourse cannot be a communion of persons if it is little more than the juxtaposition of instruments used by isolated self-conscious subjects to reach individual and incommunicable enjoyable sensations.This idea is reminiscent of this article by Alexander Pruss which I've also found very helpful in defending the Church's beliefs, which specifically demonstrates that intersubjective psycho-emotional "union" in either desire/pleasure or the abstract concept of union itself...cannot be considered a transcendent good in-itself on pain of completely self-enclosed circularity ("The pleasure of what? Of unity. Unity in what? Pleasure. But, the pleasure of what?!? Unity!" etc ad infinitum). To speak of communion in communion or ecstasy in ecstasy...is to avoid the question entirely.
This is useful considering that many people mistakenly believe the Church now identifies a "unitive" end in sex essentially separate from the procreative, and take that as referring to this intersubjective sort of "unity." When really, as the article explains, it refers very objectively to the organic biophysical union (and thus cannot be separated conceptually from the procreative end even if actual reproduction does not always result), not some sort of sentimentalist psycho-emotional intimacy (or illusion of intimacy.)
"Sharing the experience" (however intense) of using each other's bodies (or even, as Sartre would seem to suggest, the abstract notion of the other's very consciousness and desire itself) as, essentially, a drug or masturbatory aid...cannot be considered an intelligible good merely on account of the social nature of that cooperation or sharing if the experience shared is not itself intelligibly good. There can only be true relationship and communion of persons in the Good, and the ends cannot justify the means.
This leads me to the question of hedonism, which I've taken to seeing as essentially about a separation of signifier from signified, of a view of the good which would locate it in its fragments or reflections rather than in that which is reflected. As the Pruss article says:
Pleasure thus has an intentionality in it, a signifying of a good, much like the quale of green signifies a green thing. Pleasure, like any other mental representation, derives its significance from what it represents. The good of pleasure thus derives from it being a representation, a perceiving, of something good. (This also shows that there are cases of pleasure that are not good: these are the non-veridical pleasures, pleasures that are representations of goods that are not real.) At the pain of circularity, the pleasure considered as such, must be notionally distinct from that good. Hence, pleasure should not be an end in itself, since its good is derivative from that good which is represented by it. That good could be an end, but not the pleasure itself. Without the good that the pleasure represents, the pleasure has no truth or goodness in itself but only an illusory semblance of a good.The hedonistic view of life, however, would admit no necessity of a concomitant objective good to subjective enjoyments. This view, so prevalent today, would reduce man to basically just an animal whose last end is to be found in satiating desires, many of them arbitrary or at least now vestigial, enjoying that satiation-of-desire for satiation-of-desire's own sake (and, perhaps, in nursing desires exactly so we can satiate them) until we die, with no particular purpose, conscious experiences being like a shell gutted of meaning. Perhaps there never was a meaning!
The existentialist answer is for us to create one ourselves, though this can only ever be finite, and can never take us outside ourselves as only the Absolute can. But, the vast majority of regular people, under such a regime...just won't care to undertake such an existentialist project. They will be more than happy to plug into the Matrix of unchaste sex or drugs or decadent escapist hedonism generally, having an understanding of the Good (even in those things which are of themselves Reasonable) that is little more than masturbatory and self-enclosed, like they're just rats in a Skinner box.
Someone once pointed out to me once that Orwell predicted a dystopia where people were controlled by force and pain, but Huxley predicted a totalitarianism of meaningless pleasure and apathy; I think it's becoming clear, the latter is indeed much more of a threat .
But then, we live in a world whose standard for morality is basically "why not?" rather than "why?" so it is unsurprising that people give no particular consideration to the intelligibility of goods, or mistakenly identify them in experiences which are ultimately circular and solipsistic, when making judgments. So of course we see people alienate and instrumentalize their own bodies and the bodies of others, not only in the form of unchastity but also in hard drugs (not to mention economic exploitation and consumerism).
Even when more "noble" justifications of the humanistic variety are trumped up, they are something much less than transcendent. Because, as that article also wisely says, "Even if a billion people were to unite in striving for some closed end, say for the pleasure of this billion, the people would be united in loneliness, for even though they would be together, still taken as a whole they would be alone." And without God as transcendent end, that's all even humanity-as-a-whole can ever be in our value: alone together.
When the nature of reality is reduced, in practice, to a relativistic subjectivism, and when morality is reduced in turn to only a minimal "rights" based ethics of justice combined with a base sentimentalism, then it is inevitable that questions of virtue, integral human fulfillment, and the all-important question of transcendent meaning for that venture...will be ignored or else have tortured answers counterfeited by (usually academic) philosophical charlatans, and people will settle for merely fragmentary or apparent goods, rather than for the whole and final Good.