We might also see the gradual relaxation of bars against polygamy. Polygamous families exist even now, more widely than generally believed, in the midst of "normal" society. Writer Ben Merson, after visiting several such families in Utah where polygamy is still regarded as essential by certain Mormon fundamentalists, estimated that there are some 30,000 people living in underground family units of this type in the United States. As sexual attitudes loosen up, as property rights become less important because of rising affluence, the social repression of polygamy may come to be regarded as irrational. This shift may be facilitated by the very mobility that compels men to spend considerable time away from their present homes. The old male fantasy of the Captain's Paradise may become a reality for some, although it is likely that, under such circumstances, the wives left behind will demand extramarital sexual rights. Yesterday's "captain" would hardly consider this possibility. Tomorrow's may feel quite differently about it.

Still another family form is even now springing up in our midst, a novel childrearing unit that I call the "aggregate family" – a family based on relationships between divorced and remarried couples, in which all the children become part of "one big family." Though sociologists have paid little attention as yet to this phenomenon, it is already so prevalent that it formed the basis for a hilarious scene in a recent American movie entitled Divorce American Style. We may expect aggregate families to take on increasing importance in the decades ahead.

Childless marriage, professional parenthood, postretirement childrearing, corporate families, communes, geriatric group marriages, homosexual family units, polygamy – these, then, are a few of the family forms and practices with which innovative minorities will experiment in the decades ahead. Not all of us, however, will be willing to participate in such experimentation. What of the majority?

Minorities experiment; majorities cling to the forms of the past. It is safe to say that large numbers of people will refuse to jettison the conventional idea of marriage or the familiar family forms. They will, no doubt, continue searching for happiness within the orthodox format. Yet, even they will be forced to innovate in the end, for the odds against success may prove overwhelming.

The orthodox format presupposes that two young people will "find" one another and marry. It presupposes that the two will fulfill certain psychological needs in one another, and that the two personalities will develop over the years, more or less in tandem, so that they continue to fulfill each other's needs. It further presupposes that this process will last "until death do us part." These expectations are built deeply into our culture. It is no longer respectable, as it once was, to marry for anything but love. Love has changed from a peripheral concern of the family into its primary justification. Indeed, the pursuit of love through family life has become, for many, the very purpose of life itself.

Love, however, is defined in terms of this notion of shared growth. It is seen as a beautiful mesh of complementary needs, flowing into and out of one another, fulfilling the loved ones, and producing feelings of warmth, tenderness and devotion. Unhappy husbands often complain that they have "left their wives behind" in terms of social, educational or intellectual growth. Partners in successful marriages are said to "grow together."

This "parallel development" theory of love carries endorsement from marriage counsellors, psychologists and sociologists. Thus, says sociologist Nelson Foote, a specialist on the family, the quality of the relationship between husband and wife is dependent upon "the degree of matching in their phases of distinct but comparable development."

If love is a product of shared growth, however, and we are to measure success in marriage by the degree to which matched development actually occurs, it becomes possible to make a strong and ominous prediction about the future.

It is possible to demonstrate that, even in a relatively stagnant society, the mathematical odds are heavily stacked against any couple achieving this ideal of parallel growth. The odds for success positively plummet, however, when the rate of change in society accelerates, as it now is doing. In a fast-moving society, in which many things change, not once, but repeatedly, in which the husband moves up and down a variety of economic and social scales, in which the family is again and again torn loose from home and community, in which individuals move further from their parents, further from the religion of origin, and further from traditional values, it is almost miraculous if two people develop at anything like comparable rates.

If, at the same time, average life expectancy rises from, say, fifty to seventy years, thereby lengthening the term during which this acrobatic feat of matched development is supposed to be maintained, the odds against success become absolutely astronomical. Thus, Nelson Foote writes with wry understatement: "To expect a marriage to last indefinitely under modern conditions is to expect a lot." To ask love to last indefinitely is to expect even more. Transience and novelty are both in league against it.

It is this change in the statistical odds against love that accounts for the high divorce and separation rates in most of the techno-societies. The faster the rate of change and the longer the life span, the worse these odds grow. Something has to crack.

In point of fact, of course, something has already cracked – and it is the old insistence on permanence. Millions of men and women now adopt what appears to them to be a sensible and conservative strategy. Rather than opting for some offbeat variety of the family, they marry conventionally, they attempt to make it "work," and then, when the paths of the partners diverge beyond an acceptable point, they divorce or depart. Most of them go on to search for a new partner whose developmental stage, at that moment, matches their own.

As human relationships grow more transient and modular, the pursuit of love becomes, if anything, more frenzied. But the temporal expectations change. As conventional marriage proves itself less and less capable of delivering on its promise of lifelong love, therefore, we can anticipate open public acceptance of temporary marriages. Instead of wedding "until death us do part," couples will enter into matrimony knowing from the first that the relationship is likely to be short-lived.

They will know, too, that when the paths of husband and wife diverge, when there is too great a discrepancy in developmental stages, they may call it quits – without shock or embarrassment, perhaps even without some of the pain that goes with divorce today. And when the opportunity presents itself, they will marry again ... and again ... and again. Serial marriage – a pattern of successive temporary marriages – is cut to order for the Age of Transience in which all man's relationships, all his ties with the environment, shrink in duration. It is the natural, the inevitable outgrowth of a social order in which automobiles are rented, dolls traded in, and dresses discarded after one-time use. It is the mainstream marriage pattern of tomorrow.

In one sense, serial marriage is already the best kept family secret of the technosocieties. According to Professor Jessie Bernard, a world-prominent family sociologist, "Plural marriage is more extensive in our society today than it is in societies that permit polygamy – the chief difference being that we have institutionalized plural marriage serially or sequentially rather than contemporaneously." Remarriage is already so prevalent a practice that nearly one out of every four bridegrooms in America has been to the altar before. It is so prevalent that one IBM personnel man reports a poignant incident involving a divorced woman, who, in filling out a job application, paused when she came to the question of marital status. She put her pencil in her mouth, pondered for a moment, then wrote: "Unremarried."