14

Population and Resources

RupertB.Vancen/an/an/an/a

Is Theory for Demographers?¹

Population studies hold high prestige in scientific circles. Each decade multitudes of facts, equivalent in cost to a completely equipped battleship, are gathered at public expense and poured into our waiting calculating machines. Among the social sciences demography has developed some of the most advanced techniques. Our analyses are of the greatest practical use and are eagerly awaited by municipalities, planning boards, and administrators. Empirically and technically, population has gone a long way. And this is no icy perfection. Population has its human interest angle and its materials are much sought after by publicists.

Demography, on the whole, is doing very well these days. We have facts, we have the techniques and we are neatly polishing up our concepts. But there is one area where demography is getting rather poverty-stricken and frayed at the edges. In the realm of high theory we have been living off our capital and borrowing from our associates. It seems some time since we have made any investment of our own in basic theory. As demography comes of age it comes to a point of necessity —the necessity of a closer working relationship between its research operations and basic theory. In theory demography remains relatively unstructured. It lacks, shall we say, a binder for its diverse findings. Moreover some findings which have passed for population research among the laity barely reach the level of description. The actual work, it is apparent, was done by the Census Bureau. It is with this in mind that a leading sociologist once told me that the Decennial Census was the worst thing which had happened to sociology in this country.… There is such a thing as an excess diet of raw data. Undigested, it is very bad for the development of the theoretical muscles. I am reminded of a boner from a student who was oversold on objectivity. Trying to answer the question: Is sociology scientific? he wrote:

The facts gathered are of value and even though they may not prove a point, it must be remembered that the object is to gather the material and not to prove the point.

I

There exist today striking differences between demography as a field of knowledge and those disciplines with which it is most closely related. These differences are so great that, for good or ill, they are likely to color the future development of our specialty. The development of theoretical systems at a high level of integration is now apparent in fields which touch on population. In economics, in sociology, in social psychology, in the contribution which psychoanalysis and psychiatry are making to the study of human behavior one has the choice of complex thought systems, sophisticated, rationally articulated, and of the highest importance in the tactics and strategy of science. As the validity of these theories is increasingly subjected to test, hypothesis by hypothesis, assumption by assumption, this body of knowledge assumes increasing importance.

In law there is the Corpus Juris—the body of the law. In population the nearest we have to a body of theory is several population texts written for the undergraduate student—admittedly not a high level at which to perform the operations of synthesis and integration demanded for theory. In two texts today I find the implication that it is not the task of the demographer to develop high level theory.

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Among high level theorists we have Malthus to our fathers. He dates from the early Nineteenth Century and falls among the classical English economists for whom Lord Keynes rendered a superb verdict in one sentence: "The characteristics of the special case assumed by the classical theory happen not to be those of the economic society in which we actually live with the result that its teaching is misleading and disastrous if we attempt to apply it to the facts of experience." Undoubtedly in the beginning Malthus intended to analyze the poverty of nations after the fashion of Adam Smith’s Wealth of Nations. Admittedly the theory now falls far short of explaining poverty in the western world for which it was first written in 1800.

We realize that systematic theory is on the wane. High-level theorists admittedly are lone wolves. In the strategy of science we need one generalissimo of basic theory each generation, whether he is forthcoming or not. Certainly these great theories have not proved cumulative; they are competing and conflicting. After systematic theory what next? The consensus of the future to which we demographers look forward will more likely in Robert Merton’s phrase come out of theories of the middle range—"theories intermediate to the minor working hypotheses evolved in abundance during the day by day routines of research, and the all-inclusive speculations comprising a master conceptual scheme from which it is hoped to derive a very large number of empirically observed uniformities of social behavior." It is no secret to tell you that hopes exist that, when all the hypotheses of the Indianapolis Study are finally fused, population will have a healthy young theory of the middle range.

We can not let this occasion pass without some attention to the development of concepts in social demography. Admittedly fertility, mortality, and migration are not concepts in any true sense; they are simply topics we investigate. Further evidence of theoretical weakness in our field is demography’s failure, in President Conant’s phrase, to use the tactics and strategy adequate to develop new and significant concepts. When we realize, for example, the revolutionary impact of the concept of culture on social science we are tempted to ask to what recent concepts of value can we point? Frankly we have neglected to do the rigorous work required to either establish or disprove some of our seminal ideas. I can think of two concepts now suspended halfway between heaven and earth, the concept of optimum population and the theory of intervening opportunities in migration. Both of these examples remind us that since the establishment of any hypothesis is extremely difficult, the scientist’s first duty is to so frame his hypothesis that it is also capable of disproof. Only in this way can we rid the field, piece by piece, of doubtful lumber which otherwise will remain to clutter it up forever. Neither of these valuable hypotheses, I submit, is capable of disproof as now framed. Intervening opportunities can hardly be defined except as potentially different for each migrant, and no equation with that many unknowns can be solved. Similarly in optimum population many students accept the economic optimum as only one of many optima. This will leave the concept forever stillborn. And in the economic optimum one factor, the standard of living, has approximately all the variables of intervening opportunities. Since it is not capable of disproof, neither can it be proved.

Systematic theory, middle range concepts and hypotheses, we will not build [in] demography until we learn, like the physical scientists, to repeat and repeat. Our smaller studies, those below the middle range, must be focused more and more on specific hypotheses already set up and embodied in these systematic formulations. Like science everywhere, demographic analysis must be made cumulative. Once we get a good hypothesis let us repeat and repeat until we determine whether it stands or falls.

In many of our allied fields alternative theories compete for the support of scientists and we are allowed the hope that research by research these theories of the middle range will either approach the closure characteristic of a complete thought system or else be found invalid and discarded. Aye, there is the rub. When a thought system is invalidated and discarded, a dozen reputations may perish with it. Who wants to take that risk?

II

If there is room in demography for the timid souls, is there also room for the bold and audacious? In science as in poker, we realize we can play it one of two ways. We can play it close to the vest, that is, maximize description and minimize synthesis, or we can play it for maximum gains of human knowledge. In other words, as Roger Nett says, the working scientist can be either a tight system builder or a loose system builder. A tight system has high validity and low generality. A line which twists and turns to touch a hundred points in a distribution is worth no more than the hundred points. A line which touches ten points and comes within hailing distance of 90 is usually worth more than the hundred points; it may give the scientist a curve of distribution or an equation of probability for his colleagues to test in a sequence of 100 analyses. "There exists a known tendency for all thought systems to be vulnerable." Accordingly the closer one sticks to his data, the less vulnerable are his generalizations and ofttimes the less important. A loose thought system sacrifices accuracy for the sake of generalization.

In science when one plays for double or nothing, he runs the risk of evolving a system of high generalizations and low validity. Obviously this represents high vulnerability and we are all cautious enough to dread the results. But we should remember there are two forms of maximum error: The first is a system that misses contact with the known facts at every point of observation. The second is no system at all. This is maximum error, for it equates with total ignorance. As a matter of fact, I am willing to make the claim that he who develops a theory capable of being proved invalid makes a contribution. In statistics the disproof of any hypothesis is accepted as a way station on the road to knowledge. Demographers should become brave enough to so state their hypotheses that they are capable of disproof.

Thus far I have been talking about the demographer as a personality, willing or unwilling to take the risks of his profession. As a collectivity, demography should set about organizing its strategy to support shock troops who take calculated risks for theory. In a manuscript which I have been permitted to read in advance of publication, J. J. Spengler demonstrates the extent to which the study of population remains relatively unstructured as to theory and uncircumscribed as to scope. "A variety of scientists," he writes, "have contributed to the development of what currently passes for population theory and their separate contributions have not yet been transfused into an integrated whole."

There is great need for the development of integrated theory of a high order to serve as a "binder" for demography’s diverse and particularized findings. Such theory should meet three criteria, says Professor Spengler: (1) It must be dynamic rather than static, (2) it must take account of demographic interrelations as between countries and groups within nations, and (3) it requires a multi-science approach.

I am happy to say I believe the framework for one such theory is now emerging. In concise statement, the transition from high-level deaths and births to the new equilibrium at a low level of vital rates furnishes the population dynamics of the last 300 years in the Western world. The line of succession runs from Dr. Walter Willcox whose studies of world population growth opened up this whole field to Dr. Frank Notestein who has done so much to clinch the analysis. This Demographic Revolution unfolds and diffuses in a manner reminiscent of the Industrial Revolution. Different countries reach different stages of this transition in terms of (1) a time sequence in the West and (2) in terms of culture contacts and time stages as regards non-Western countries. Population status, age, and even sex composition, can then be viewed as stages in this long sequence. Our own low crude death rates and low proportions of natural dependents can be seen as a transitional stage in age distribution which may later level off.

The swarming of Europe is seen as due to the demographic gap which emerged as fertility remained high for 100 years and more after deaths took a sharp decline. Differential fertility emerged in the initial stage of the great decline in birth rates. Outside the West no countries now appear to have the demographic slack which new continents and untapped industrial markets once offered Europe. Demographic movements in succeeding countries, however, are to be judged by economic stages and cultural diffusion as well as the resistance to change within each culture. Such an over-all view can give meaning to the many descriptive population studies now made country by country. If this transition proceeds in orderly sequence it will be the function of demographic studies to classify populations by stage and sequence. But since populations and countries vary, demographers have a choice. They can either explain these variations in the scheme or demolish the basic theory by a critical analysis of succeeding population movements.

It is agreed, I take it, that the function of theory is not to give answers to all the questions which may rise; rather it is to see that in the unfolding of science the "right" questions get asked in the "right" context. Such theories of the middle range in Merton’s phrase also serve to set known facts in meaningful context. Demographic fluctuations anywhere can then be tested as short-run movements against the background of this long-run demographic transition. Beginning and ending phases of this great transition, however, will remain unclear: the first because our beginnings run back to inadequate data, the second because closing phases will always remain in the future. An incidental contribution of this scheme is to place the work of Malthus in the perspective of history.

That demography must attend more sharply to its basic theory is indicated in this very field of dynamics. What are long-run and what are short-run phenomena in demography? What is trend and what is a fluctuation? And how long can a fluctuation last before it becomes a trend? Are there reversals in trends?

In fertility analysis it is this problem which caught demographers unprepared. Texts in the hands of our students continued to proclaim decline while the figures showed an amazing upsurge. It is this phenomenon which led Dr. Frank Notestein to the wry comment that to some, demographers now appear as "double distilled false prophets"—prophets who, proven wrong, persist in staying wrong.

Demography can put controversy in its place only as it develops basic theory. Other disciplines have faced this problem and come up with answers based on theoretical models complex enough to encompass alternatives. Techniques in this field can still be used to test broadly stated theoretical systems. Empirical operations without basic theory, no matter how carefully safeguarded, are now proved dangerous. Finally, it is my feeling that these controversies hasten the development of systematic theory.

Such theory—now in process of being filled in—satisfies two of Professor Spengler’s requirements: (1) it is dynamic and (2) it takes account of interrelations between countries and classes. It raises, however, the question of a multi-science approach to theory. Interesting to note, the theory of the demographic transition has been the contribution of population specialists developed largely from the consideration of historic changes in the field of vital rates. It did not come out of the theoretical matrix of either biology, sociology or economics. In certain ways the multi-science orientation of demography has operated to delay the development of population theory. Eclecticism is not conducive to the development of unified theory. Biological explanations of changing vital rates have proved immature and completely inadequate; sociologists have not yet developed an adequate theory of social change; economists have often felt obliged to limit their work to direct economic causation. With a theoretical scheme of its own, comparable to its techniques, population study has been able to attain a certain unity of attack.

But as we heard Professor W. F. Ogburn argue so eloquently before the Population Association last year, population study must make its further advances by establishing interrelations and correlations as yet unknown. The dynamics of population need to be integrated with some basic theory of social change. There is no escaping the complexity of the problem of interrelation which demography faces. Population study must seek in the dynamics of culture, the economy, and changing society itself the primary conditions of its own dynamics. And then population change itself operates as a starter. As new demographic conditions emerge—mature age composition, new family size, increasing and then decreasing class differentials, lowered rates of natural dependents—social scientists have the task of seeing how such factors initiate change in the society and in the economy. Truly the work of analysis and theory has just begun if we accept the task of tracing major change through nations and classes from Occident to Orient.

But I forget myself. This is but one theory of many, and I am not attempting here to write the prescription for our theory. I do believe, however, that the best spring tonic demographers can take is a good stiff dosage of theory, adequately compounded. There is a level of complexity to which all our scientific disciplines must aspire or resign their task—namely the creation of valid and significant theory. There is, I take it, work for all. Let us then be about our business.

¹ From , 1952, 31:9–13. By permission.