Why is Marriage a Natural Institution?
According to the Catechism of the Catholic Church, marriage is “written in the very nature of man and woman as they came from the hand of the Creator” (CCC, 1603).  If this is true; if marriage is written in the nature of the human being, then despite the many variations that the institution has undergone throughout history, “These differences should not cause us to forget its common and permanent characteristics.” Marriage’s basis is not in history, then, but in our God-given human nature. That means that marriage cannot be a purely conventional, political, or social institution, but a natural one. In this post, we are going to examine what it means for something to be a natural institution and why marriage is one.
Recall from our last three posts that the word “nature” is said in different ways.  We can talk about the whole world of nature and all the natural things that make it up. In this sense, we contrast natural things with artificial ones. Or, we can talk about the inherent natures of living things and the behaviors or activities that derive from and fulfill a thing’s nature. When considering whether a behavior or activity is natural, we must always look to the nature of the thing engaging in that activity. Remember our potato-chip eating beaver? With this refresher, we are now going to see how an institution can be natural.
The word institution has two different senses. Sometimes, it means an establishment such as a school or a financial organization. But it also means a practice or custom that has become thoroughly integrated into society. For example, the annual televised reveal of Punxsutawney Phil on Groundhog Day is considered by many to be a “national institution.” If someone were to try to cancel this event, there would be widespread objection. These two senses of “institution” mean that something has been established or put in place, and that we consider it to be important.
Now, both the financial organization and Groundhog Day are what we could call conventional institutions; a human being (or many human beings) started them and put them in place. On the other hand, to call something a natural institution implies that the institution was established or put in place by nature, not people. Now, remember that when considering if a behavior or activity is natural, we must consider the nature of the subject which undergoes the activity. An institution likewise is evaluated according to its subjects. The subject of marriage is, of course, the human being; I argue here that marriage is a practice that is rooted in and also fulfills human nature. This is why we say marriage is a natural institution.
Aristotle explains in his Politics why the impulse to marry is a natural one. Men and women, like all other animals, desire sexual union with one another. This desire goes hand-in-hand with the fact that men and women in partnerships take care of each other and look out for one another. Each bring different strengths to their relationship that make their individual lives better. They help each other to live a good life. Of course, when a man and a woman become one in the sexual union, they have the potential to create new life. To nurture, protect, and educate their offspring is another natural impulse of the male-female relationship. This impulse is, of course, present not only in men and women, but also in most animals to various degrees. So, insofar as human beings are animals, they are inclined to sexual union and inclined to care for their offspring.
At this point one might object: but what do these things have to do with marriage? No other animal declares its love before a priest or a judge! And what about things like marriage licenses, wedding rings, and wedding ceremonies? It seems like people had to make a conscious decision to institute these practices, so they can’t be natural. St. Thomas is helpful in answering this question. He says:
…the begetting of offspring is common to all animals. Yet nature does not incline thereto in the same way in all animals; since there are animals whose offspring are able to seek food immediately after birth, or are sufficiently fed by their mother; and in these there is no tie between male and female…; In man, however, since the child needs the parents’ care for a long time, there is a very great tie between male and female, to which tie even the generic nature inclines…
The institution of marriage arose in men and women in virtue of the complex and long-lasting needs of human children. Human beings are born in an incredible state of vulnerability; They cannot even walk on their own two feet for almost a year. Their demands are intense and constant. It does not take a highly developed intelligence to discern that human children need their parents. Penguin mates do not get married, but neither do their children expect to move back in with them after college. Further, while it is true that people created and instituted certain marriage customs, we might say that these customs are actually just the expression or manifestation of a much more basic and foundational reality: the impulse to marry rooted in human nature. The customs surrounding a wedding are accidental to the essence of marriage. So, while the institution of matrimony and its various customs does not simply arise through nature, it is because of the human being’s rational and free nature that the institution exists.
Can you think of other examples of natural institutions? Stay tuned for our next post on the sacrament of matrimony!
 Catechism of the Catholic Church, no. 1603. Washington, DC: United States Conference of Catholic Bishops–Libreria Editrice Vaticana, 2000.
 Politics I.1.1253a30.
 ST Suppl., 41, Ad.1, Co.
 Children raised in intact married families are more likely to attend college, are physically and emotionally healthier, are less likely to be physically or sexually abused, less likely to use drugs or alcohol and to commit delinquent behaviors, have a decreased risk of divorcing when they get married, are less likely to become pregnant/impregnate someone as a teenager, and are less likely to be raised in poverty. (“Why Marriage Matters: 26 Conclusions from the Social Sciences,” Bradford Wilcox, Institute for American Values, www.americanvalues.org/html/r-wmm.html)
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.