WHY DO WE STILL BELIEVE that population growth slows economic development?

For 25 years our institutions have mis- analyzed such world development problems as starving children, illiteracy, pollution, supplies of natural resources and slow growth. The World Bank, the State Department's Aid to International Development (AID), The United Nations Fund for Population Activities (UNFPA) and the environmental organizations have asserted that the cause is population growth -- the population "explosion" or "bomb" or "plague."

But for almost as long, there has been a body of statistical evidence that contradicts this conventional wisdom about the effects of population policy toward less-developed countries.

This error has cost dearly. It has directed our attention away from the factor that we now know is central in a country's economic development, its economic and political system.

Furthermore, misplaced belief that population growth slows economic development has been the basis for inhumane programs of coercion and the denial of personal liberty in one of the most valued choices a family can make -- the number of children that it wishes to bear and raise.

One of the reasons this idea stays in currency is that in an ideologically divided world, the population bogey has been the rare sweet issue everyone could agree upon. I ran into this perverted amity at a discussion of population economics in India last winter attended by many employes of international agencies. In four days, there was not a single mention of the role of the economic system, whether market-directed or state-controlled. And when I suggested that the subject should at least be aired, I was met by silence in the formal meeting, and I was told informally that the issue simply is outside the scope of attention. "It's like talking religion," one said.

Nevertheless, by 1985 we know that unlike religion -- which is a matter of personal preference and not of science -- there is objective evidence that a free enterprise system works better than does a planned economy.

As we shall see, among comparable populations, such as those of North and South Korea, East and West Germany, or China and Taiwan (or China and Hong Kong or Singapore), the part with the enterprise system has obviously produced greater economic well-being.

Moreover, population growth under an enterprise system poses less of a problem in the short run, and brings many more benefits in the long run, than under conditions of government planning of the economy.

There are about a dozen competent statistical studies opposing the population-explosion theorists. They begin in 1967 with an analysis by Nobel laureate economist Simon Kuznets covering the few countries for which data are available over the past century, and analyses by Kuznets and Richard Easterlin of the data covering many countries since World War II.

The basic method is to gather data on each country's rate of population growth and its rate of economic growth, and then to examine whether -- looking at all the data in the sample together -- the countries with high population growth rates have economic growth rates lower than average, and countries with low population growth rates have economic growth rates higher than average.

The studies agree that faster population growth is not associated with slower economic growth. On average, countries whose populations grew faster did not grow slower economically.

Of course, as countries develop economically, the fertility rate tends to fall. But it is economic level that influences the rate of population growth, not the reverse. Costs and benefits of having children change with the shift from rural to urban living along with increases in education and shifts in attitudes -- this being the famous "demographic transition."

The examples of Taiwan, South Korea, Singapore and Hong Kong have already been cited. Countries with high population growth and high economic growth include Thailand, Malaysia, Ecuador, Jordan, Brazil, Mexico, Syria, Panama, Taiwan, South Korea, Singapore and Hong Kong.

Typically, Thailand's populations more than doubled from 20 million to 43 million between 1950 and 1977, around 3 percent growth yearly. And its rate of growth of income per person was around 4 percent over the same years. Of course there are counterbalancing examples of high population growth and low economic growth, such as many countries in Africa, where the political- economic system dominates the economic outcome just as it does in the countries with high economic growth.

In a review commissioned by the International Union for the Scientific Study of Population, Ronald D. Lee summarized: "Dozens of studies, starting with Kuznets', have found no association between the population growth rate and per-capita income growth rate."

Yet not a single one of these studies is cited by the extensive World Bank Report, which has been so widely publicized, or in such literature as the Worldwatch Institute's new book by Lester Brown.

The research-wise reader may wonder whether population density is more important than population growth. But the data show that higher density is associated with better rather than poorer economic results.

Check for yourself: fly over Hong Kong -- just a few decades ago a place seemingly without prospects because of insoluble resource problems -- and you will marvel at the astounding collection of modern high- rise apartments and office buildings. Take a ride on its excellent smooth-flowing highways for an hour, and you will realize that a very dense concentration of human beings -- 40 times the density of China -- does not prevent comfortable existence and exciting economic expansion, as long as the economic system gives individuals the freedom to exercise their talents and to take advantage of opportunities.

The experience of Singapore demonstrates that Hong Kong is not unique. Its population density and its soaring per-person income over $5,000 by 1982 are like Hong Kong's. Two such examples do not prove the case, of course. But these dramatic illustrations are backed by the evidence from the aggregate sample of countries.

Hong Kong is a special thrill for me because I first saw it in 1955 when I went ashore from a U.S. Navy destroyer. At the time I pitied the thousands who slept every night on the sidewalks or on small boats. It then seemed clear to me, as it must have to all, that it would be impossible for Hong Kong to surmount its problems -- huge masses of impoverished people without jobs, total lack of exploitable natural resources, more refugees pouring across the border each day. But upon returning in 1983, I saw bustling crowds of healthy, vital people full of hope and energy. No cause for pity now.

And there is growing agreement with the viewpoint expressed here. Mine is certainly not a lone voice.

For example, P.T. Bauer -- made a lord for his services as economic adviser to Prime Minister Margaret Thatcher and nowadays perhaps the most influential theorist on economic development -- says that rapid population growth "has not inhibited economic progress either in the West or in the contemporary Third World." And a book length review of the subject by the National Academy of Sciences to be released soon reaches a much less negative conclusion about population growth's effects than did its previous report in 1971.

The layman inevitably wonders: How can the persuasive common sense embodied in the Malthusian theory be wrong? To be sure, in the short run an additional person -- baby or immigrant -- inevitably means a lower standard of living for everyone; every parent knows that. More consumers mean less of the fixed available stock of goods to be divided among more people. And more workers laboring with the same fixed current stock of capital means that there will be less output per worker. The latter effect, known as "the law of diminishing returns," is the essence of Malthus's theory.

But if the resources with which people work are not fixed over the period being analyzed, then the Malthusian logic of diminishing returns does not apply. And the plain fact is that, given some time to adjust to shortages, the resource base does not remain fixed. People create more resources of all kinds. When horse-powered transportation became insufficient to meet needs, the railroad and the motor car were developed. When schoolhouses become crowded, we build new schools -- more modern and better than the old ones.

As with man-made production capital, so it is with natural resources. When a shortage of elephant tusks for ivory billiard bills threatened in the last century, and a prize was offered for a substitute, celluloid was invented, followed by the rest of our plastics. The English learned to use coal in industry when trees became scarce in the 16th century. Satellites and fiber-optics derived from sand replace now expensive copper for telephone transmission. And the new resources wind up cheaper than the old ones were. Such has been the entire course of civilization.

Extraordinary as it seems, natural-resource scarcity -- that is, the cost of raw materials, which is the relevant economic measure of scarcity -- has tended to decrease rather than to increase over the entire sweep of history. This trend is at least as reliable as any other trend observed in human history. The prices of all natural resources, measured in the wages necessary to pay for given quantities of them, have been falling as far back as data exist. A pound of copper now costs an American only a twentieth of what it cost in hourly wages two centuries ago, and perhaps a thousandth of what it cost 3,000 years ago.

The most extraordinary part of the resource-creation process is that temporary or expected shortages, whether due to population growth income growth or other causes, tend to leave us even better off than if the shortages had never arisen, because of the continuing benefit of the intellectual and physical capital created to meet the shortage.

For all practical purposes there are no resources until we find them, identify their possible uses and develop ways to obtain and process them. We perform these tasks with increasing skill as technology devleops. Hence, scarcity diminishes.

Besides, the general trend is toward natural resources becoming less and less important with economic development. Extractive industries are only a very small part of a modern economy, say a twenthieth or less, whereas they constitute the lion's share of poor economies. Japan and Hong Kong prosper despite the lack of natural resources, whereas such independence was impossible in earlier centuries.

And though agriculture is thought to be a very important part of the American economy, if all of our agricultural land passed out of our ownership tomorrow, our loss of wealth would only equal about a ninth of one year's gross national product.

There is, however, one crucial natural resource that is becoming more scarce -- human beings. Yes, there are more people on earth now than in the past. But if we measure the scarcity of people the same way we measure the scarcity of economic goods -- by the market price -- then people are indeed becoming more scarce, because the price of labor time has been rising almost everywhere in the world.

Just a few years after Egypt was said to have a labor surplus, agricultural wages in Egypt have soared, for example, and people complain of a labor shortage, because of the demand for workers in the Persian Gulf.

Even the World Bank, for years the leading worrier about population and natural resources, has muted its alarms. "The difficulties caused by rapid population growth are not primarily due to finite natural resources," its 1984 Report states. But no sooner is one fear about population growth scotched, then another takes its place.

The latest bugaboo is the effect of population growth upon education. The World Bank now worries that even if a higher birthrate does not imply fewer natural resources, it does imply less education per person. Once more, it just ain't so.

Studies have shown that societies with relatively high proportions of youths somehow find the resources to educate their children almost or equally as well as do countries at similar income levels with lower birth rates. Outstanding examples of high rates of education in the face of relatively large numbers of children include the Philippines, Costa Rica, Peru, Jordan and Thailand.

Now we come to the matter that the international development institutions consider poor form to mention when discussing economic development: economic and social systems.

Compare China with Singapore. China's coercive population policy, including forced abortions, is often called "pragmatic" because its economic development supposedly requires population control.

Singapore, despite its very high population density, now suffers from a labor shortage, and imports workers. It is even considering incentives for middle-class families to have more children, in contrast to its previous across-the-board antinatality policy. This raises the question whether there are economic grounds for China to even ask, much less compel, people to have only one child.

It is said, however: Hong Kong and Singapore are different because they are city- states. But what does that mean -- that if large hinterlands were attached to those "city-states" they would then be caused to be as poor as China?

Compare countries that have the same culture and history, and had much the same standard of living when they split apart after World War II. The accompanying chart shows centrally-planned communist countries that had and still have less population per square mile than the market-directed non-communist countries. The communist and non-communist countries in each pair also started with much the same birth rates and population growth rates.

The chart makes clear, despite the frequent absence of data for the centrally- planned countries, that the market-directed economies have performed much better economically, no matter how you measure economic progress. Income per person is higher. Wages have grown faster.

Further, indexes such as telephones per person show a much higher level of development. And indicators of individual wealth and personal consumption, such as autos and newsprint, show enormous advantages for the market-directed enterprise economies compared to the centrally-planned, centrally- controlled economies.

Also, birth rates fell at least as early and as fast in the market-directed countries as in the centrally-planned countries.

China's problem is not too many children, but rather a defective political-economic system. With free markets China might soon experience the same sort of labor shortage as Singapore -- which is vastly more densely settled, and has zero natural resources. (And this does not mean a "free" system such as China is talking about now; it is quite unlikely that a truly free market can coexist with a totalitarian political system, because a free economy is too great a political threat.)

Even the most skilled persons require a social and economic framework that rewards hard work and risks, enabling their talents to flower. The key elements of such a framework are economic liberty, respect for property, fair and sensible rules of the market that are enforced equally for all and the personal freedom that is particularly compatible with economic freedom.

What should we do about population policy? These are the key issues: First, should we encourage and aid countries to implement coercive population policies, as we have in the past with China, India, Indonesia and many other places? The answer depends upon one's values, of course. But we should recognize that the scientific evidence about the long-run economic consequences offers no support for such policies.

And what should our vision be? Should we heed the message of the doomsayers of the population control movement? This is a message of limits, decreasing resources, a zero- sum game where one gains wealth at the expense of others, conservation, deterioration, fear, conflict and calling for more governmental intervention in markets and family affairs. Or should our vision be that of those who look optimistically upon people as a resource rather than as a burden?

This is a message of receding limits, increasing resources and possibilities, a process in which wealth is created, consistent with the belief that persons and firms, acting spontaneously in search of their individual welfare, regulated only by rules of a fair game, will produce enough to maintain and increase economic progress and promote liberty.