"Don't ever take a fence down," wrote the great English essayist and novelist G.K. Chesterton (d. 1936), "until you know the reason it was put up."

It's difficult not to think of that statement while contemplating our society's widespread experimentation with novel definitions of "family" and the wholesale rejection, in many elite and other quarters, of "traditional values."

Sheer antiquity by itself, of course, doesn't prove an attitude or a moral judgment good. We're well rid of slavery, narrow tribalism and open racism, for example, and the cheerful and untroubled zest with which our ancestors often went to war is, happily, unimaginable to most of us today.

But if a value or a social practice has flourished for many centuries, that seems to argue that we should think long and carefully before simply casting it aside. To offer an analogy, while last summer's much-praised novel may soon be completely forgotten, works such as Homer's "Iliad," Dante's "Inferno" and Shakespeare's "King Lear" — works that have spoken to readers for hundreds or even thousands of years — surely merit serious attention. They may require discipline, they may not be as immediately "user-friendly" as the latest spy thriller, but, in the long run, they'll likely provide far richer nourishment to those who've cultivated the ability to enjoy them.

Chesterton, it seems to me, is precisely right to insist that we understand the reason for a rule or a restriction before we abolish it. We may, in the end, judge that the reason no longer holds, or that it's no longer sufficient or was never correct. But if we don't understand it at all, we risk missing something important, something essential. Perhaps even something fatal.

"Tradition may be defined as an extension of the franchise," Chesterton wrote elsewhere. "Tradition means giving votes to the most obscure of all classes, our ancestors. It is the democracy of the dead. Tradition refuses to submit to the small and arrogant oligarchy of those who merely happen to be walking about. All democrats object to men being disqualified by the accident of birth; tradition objects to their being disqualified by the accident of death. Democracy tells us not to neglect a good man's opinion, even if he is our groom; tradition asks us not to neglect a good man's opinion, even if he is our father. I, at any rate, cannot separate the two ideas of democracy and tradition; it seems evident to me that they are the same idea."

Each generation has its blind spots and its silly enthusiasms. We laugh at the funny hairstyles of our ancestors, mock their strange dancing, marvel at their odd ideas; we gasp at the startling obviousness of the ethical and social problems that, it seems, were entirely invisible to them. But a bit of humility is in order here: Generations after ours will, it's absolutely certain, laugh at us, too, and be appalled at our moral obtuseness. In fact, some of us are old enough to realize that it's already happening while we're yet alive.

We should be very cautious about assuming that our particular generation is uniquely wise, uniquely insightful or uniquely good. No prior generation has been. Why imagine that we are?

From which, it seems to me, there's a very practical lesson to be drawn: While we shouldn't slavishly accept values or practices from the past, we should also be cautious and reflective about jettisoning them. The care and nurture of children, for example, is by no means guaranteed to be successful. Children are quite capable of going astray on their own, of course, as even many conscientious parents know all too well. But even slight family dysfunctions can cause additional massive unforeseen consequences over time. It seems probable, in that light, that major societal changes affecting child-rearing will also have a substantial impact on the next generation — and we're probably nowhere near wise enough to be able to predict that impact.

What will be the effect of our contemporary experiments with marriage, with gender roles and with families? How confident are we, how confident can we be, that they'll turn out well? Again, modesty is appropriate here, and a disposition to pay humble attention to the voice of "the democracy of the dead." And, for those disposed to faith, a serious attempt to discern not just our own fleeting and often self-serving preferences, but the will of God.

Daniel C. Peterson is a professor of Islamic studies and Arabic at BYU, where he also serves as editor in chief of the Middle Eastern Texts Initiative and as director of advancement for the Neal A. Maxwell Institute for Religious Scholarship. He is the founder of Mormon