Adapted with permission from First Things.

To understand why the United States has the highest divorce rate in the world, go to some weddings and listen to what the brides and grooms say. In particular, listen to the vows. To a remarkable degree, marriage in America today is exactly what the newlyweds say it is: a loving relationship of undetermined duration created of the couple, by the couple, and for the couple.

Our tendency may be to shrug off the significance of formal marriage vows, viewing them as purely ceremonial, without much impact on the "real" marriage.

Yet believing that the vow is only some words is similar to believing that the marriage certificate is only a piece of paper. Both views are technically true but profoundly false. Either, when believed by the marrying couple, is probably a sign of a marriage off to a bad start. In fact, the marriage vow is deeply connected to the marriage relationship. The vow helps the couple to name and fashion their marriage's innermost meaning. The vow is foundational: the couple's first and most formal effort to define and therefore understand exactly what their marriage is.

Recent research into the determinants of marital success, especially the significance in marriage of what the scholars Scott M. Stanley and Howard J. Markman call "dedication," underscores the central importance of the vow. As much as shared interests, or good communications skills, or even erotic attraction or feelings of true love, it is the content and integrity of the dedicating promise itself--what we say and mean when we say, "I do"--that shapes the nature and destiny of the marriage.

In recent years, two basic innovations have transformed the marriage vow in the United States. Both innovations are particularly widespread in both mainline and evangelical Protestant churches, in which about half of all U.S. marriages occur.

First, as Barbara Dafoe Whitehead points out in "The Divorce Culture", marriage vows today commonly downplay or avoid altogether any pledge of marital permanence. The old vow was "till death do us part" or "so long as we both shall live." Most new vows simply leave the question of marital duration unasked and unanswered, as if the issue were either irrelevant or beyond knowing. Other new vows incorporate hopeful but qualified phrases such as "as long as love lasts."

The second change is more subtle but far more profound. Today, growing numbers of couples--perhaps most couples--compose their own vows. My wife and I did in 1986; most couples we know did. I cannot find any data to verify the dimensions of this trend, but my sense is that, principally excepting Orthodox Jewish and most Catholic weddings, self-composed vows are more the rule than the exception today. One wedding book, by Steven Neel, an ordained minister advises couples, "Your wedding ceremony can be highly distinctive and individualized if you use your imagination to personalize your expression of love and commitment." Consequently, Neel urges couples to "accept the challenge of writing your own vows."

It would be hard to exaggerate the symbolic importance of this shift toward self-composed vows. The old vows were created by society and presented to the couple, signifying the goal of conforming the couple to marriage. The new vows are created by the couple and presented to society, signifying the goal of conforming marriage to the couple. The two approaches reflect strikingly divergent views of marriage and of reality itself.

In one view, the vow is prior to the couple. The vow exists on its own, exerting social and sacred authority that is independent of the couple. In this sense, the vow helps to create the couple. In making the same promise that others before them have made and that others after them will make, the couple vows on their wedding day to become accountable to an ideal of marriage that is outside of them and bigger than they are.

In the other, the couple is prior to the promise. The vow is not an external reality, like gravity or the weather, but instead a subjective projection, deriving its meaning solely from the couple. From this perspective, the couple approaches the vow as a painter approaches a canvas. Rather than the vow creating the couple, the couple creates the vow. With this one procedural change in the making and exchanging of vows, a ceremony of continuity and idealized forms is displaced by a ceremony of creativity and personal expression.

The essence of this change reflects a dramatic shrinking of our idea of marriage. With the new vows, the robust expectation of marital permanence shrinks to a frail, often unstated hope. Marriage as a vital communal institution shrinks to marriage as a frail, often unstated hope. As the idea of marriage gets weaker, so does the reality. In this sense, the new vows are important philosophical authorizations for our divorce culture. They are both minor causes and revealing results of a society in which marriage as an institution is decomposing before our eyes.