Today, we are going to finish our introduction to nature by applying what we have learned to a moral dilemma. Recall our friend from the first post, who likened using contraception to treating an illness. This is his thought process: “Well, it’s natural to get sick, but we take precautions to prevent illness all the time. Similarly, getting pregnant is a natural process. Why can’t we take precautions to stop this natural process? If contraception is unnatural, then I guess preventing an illness is unnatural, too!” Let’s unpack this.
The first assumption that our friend makes is that getting sick is a natural process. Is this true? Remember our beaver example, which demonstrated that certain things can be natural or unnatural in different respects (i.e. eating potato chips). Well, getting sick is natural insofar as all living things are prone to it. If it has life, it can also fall ill, become infected, die, and decay. But we must consider not only what happens to living things, but also the nature of living things. Just because it happens doesn’t mean it’s natural.
Living things possess an innate principle of motion and rest– they are animate; they move. So, when animation is compromised, take a person in a coma for example, then that compromises the living thing’s very nature. It is not “being what it is” at that moment. You don’t look at a person in a coma and think, “That person is living her best life.” To get sick is, in fact, unnatural for the living thing. We all kind of know that through common sense.
So contrary to our friend’s idea, preventing illness is more natural to the human being, in the way we are talking about, than getting sick. That is because preventing illness is the application of reason (proper to humanity) to a problem (illness). According to St. Thomas Aquinas, there is a law that governs all living things, and its precepts are: do good and avoid evil, preserve one’s life, and preserve the life of one’s species. Violating these precepts would be unnatural. Since illness is a threat to one’s life, it is actually natural for animals (human beings included) to seek out remedies that prevent or reverse illness; to do this is natural insofar as it restores nature to its proper order. So no—Christians aren’t against medicine!
Now, we are going to contrast the above with contraception.
Having sex is an activity which, by its nature, intends the procreation of children. This is evident by biology: the reproductive organs have no function except generation, and they don’t “work” on their own but only with each other (one male, one female). If the sexual organs “do their job” to the peak of their powers—if they fulfill their nature as reproductive organs—a baby is conceived. By contrast, there is no organ in the body that exists in order to nurture disease. Rather, there are all sorts of defense mechanisms in the body to fight disease! So just like it would be unnatural to thwart the functioning of the stomach (say, by inducing vomit), to have sex with the intention of thwarting the natural purpose of the sexual organs is unnatural. When we consider the Natural Law applied to the human person, we must consider how having sex without being open to life affects human dignity and flourishing. (Alas, more for a future post!)
In conclusion, we must not treat the “natural process” as a univocal thing; we must always consider the subject which undergoes the process. It is clear that some processes are natural in one respect, but not in another. To ask whether something is natural or unnatural is really to ask. “Is this good for this thing?” If it prevents the living out of a thing’s nature, it is bad (unnatural). If it helps the thing function and flourish, it is good (natural).
 ST I-II, Q.94, Art. 1 & 2
 We are assuming this for now but stay tuned for another post on the ends of procreation.
About the Author: Bridget Groff is an M.A./Ph.D. student in the School of Philosophy at the Catholic University of America. She currently works part-time at the United States Conference of Catholic Bishops as an intern for the Subcommittee for the Promotion and Defense of Marriage.