ROBERT McNAMARA has had four careers: Harvard professor, Ford Motor Company executive, secretary of defense, and president of the World Bank. But as he bounds up the curving staircase to his room at the River Club here, taking the steps two at a time, you might peg him for a fifth career - as athlete. Upstairs, as he turns his attention to the agenda for the 21st century, his mind proves equally athletic. He speaks with the rapid-fire vitality of a thinker seized by the subject and impelled by its urgency. Not surprisingly for a man with his background in defense and development issues, he singles out two central items for his agenda.
The first is the nuclear threat, which is the subject of his new book, ``Blundering into Disaster: Surviving the First Century of the Nuclear Age.''
``After all,'' he says, ``if we can't survive as a civilized world, then there's no time to work on any other subject.''
The other item he describes as ``the population problem - not as a density problem, but rather as an imbalance of population growth rates on the one hand and social and economic rates of advance on the other.''
It is a problem, he says, that is ``going to cause very, very serious economic, social, political, and perhaps even military problems'' for the 21st century.
Ranked below these two ``high leverage'' issues, he says, are three others:
East-West political tensions, which he argues are ``distorting our allocation of economic resources.''
A loss of some of the traditional moral values of American democracy.
The need for new forms of institutions fitted to a changing world.
On this last point, Mr. McNamara does not expect to see the development of a world government. But he notes that ``in 50 to 100 years from now, we [in the United States] will find it's in our interest to transfer from national sovereignty to international institutions certain of the powers that we exercise now as a nation-state.''
``The longer we delay in addressing some of these issues - the East-West tensions, the institutional forms appropriate for an increasingly interdependent world, the return to our national traditions - the greater difficulty we're going to face in the 21st century,'' he concludes.
Turning to his first agenda item, McNamara discounts the argument that the West's nuclear strategy - which he finds seriously flawed - has preserved peace since World War II. ``I think it's extremely dangerous,'' he asserts, ``to carry on our present strategy and our present weapons-development programs, in the direction they're headed, for another 40 years.''
The danger, he says, arises ``because of the environment we're in. We are in a world with 50,000 nuclear warheads - each one, on average, some 30 times the destructive power of that dropped on Hiroshima and Nagasaki.'' What nuclear war plans omit `WAR plans covering their use are in existence - and there is, in effect, a mind-set that would assure their use in the event of confrontation between East and West,'' he explains, condensing arguments he has developed at greater length in his book.
``And yet,'' he adds, ``no plan exists for initiating the use of nuclear weapons without the probable destruction of the civilization in the initiator.''
How dangerous is the threat of such conflict?
``I don't believe that any well-informed, coolly rational military or civilian leader on either side, East or West, would initiate the use of nuclear weapons,'' he says. ``But it has been my experience - and I think it is a widely shared experience - that military and civilian leaders in times of crisis are neither well informed nor coolly rational.''
``And I, for one, am not prepared to accept the risk that these [East-West] political rivalries will not, over a period of decades, upon occasion lead to military confrontation,'' he adds.
What, then, can be done?
``Well, clearly, one should address the basic issue, which is the political rivalry between East and West,'' McNamara says. ``We have become almost paranoiac, as a people, with respect to the Soviet Union. We exaggerate their strengths, we underestimate our own, and we keep ourselves in a continual state of anxiety with respect to them.''
This anxiety, he continues, ``has a lot to do with a movement away from our traditional values.''
For 200 years, he argues, the United States has ``supported freedom and liberty and democracy.'' But over the last 40 years, he says, American governments have backed Nationalist Chinese leader Chiang Kai-shek, the Shah of Iran, Philippine President Ferdinand Marcos, and Nicaraguan President Anastasio Somoza Debayle.
``Support of those regimes,'' he says, is ``not consistent with the social, political, moral values I wish to pass on to my children.''
The problem, he says, has arisen because the citizenry has accepted ``actions inconsistent with our national heritage and national traditions, in order to strengthen our position vis-`a-vis this `communist' threat.''
``It is that, of course, which leads to this tremendous - I consider [it] excessive - expenditure on military weapons,'' he says. ``I think we pay a very, very heavy price for failing to deal more effectively with this East-West tension,'' he adds.
For McNamara, better East-West relations include a stronger Western Europe. ``This should be one of our objectives for the 21st century,'' he says, ``to help and encourage Europe to act in a more unified fashion.
``I think that today the West suffers because to a considerable degree it's fragmented. If we could reduce that fragmentation by assisting and encouraging Europe to unify itself - economically, politically, and certainly in terms of defense - we would be much better off.''
With that, McNamara turns to the second major issue on his agenda: the population problem, brought so sharply to his attention during his years at the World Bank.
While he acknowledges that some areas of the world face severe overcrowding, he says that ``the problem today is not, on a global basis, density of population.'' What he describes as ``the carrying capacity of the world'' - the globe's capacity to support its population - is ``greater than the existing world's population.''
The problem arises instead, he says, from ``the imbalance of population growth rates on the one hand and social and economic advance on the other'' - which ``leads to human misery.''
``In sub-Saharan Africa as a whole,'' he says, ``with the population of something on the order of 350 million people, food production growth rates - on average, per capita - have been negative for 10 years.''
``Now, 10 years ago malnutrition existed,'' he says, ``and if you have had a negative per capita food production rate since that time, then there's less food per capita today than there was 10 years ago.''
``That kind of a situation is bound to have political repercussions - and it has had,'' he says, mentioning attempted coups as well as successive waves of migration. ``And lest one think these migration problems are limited to Africa,'' he notes, ``look at our own problem with Mexico.''
There, he says, the problem arose from very high rates of population growth several decades ago. The result, he says, is ``a rate of increase in their labor force that is one of the highest in the world, roughly 3.2 percent per year.''
``The Mexicans want to live in Mexico,'' McNamara says, ``but the operative word is live. And if they can't live there, they're going to live here,'' especially given the 2,000-mile-long US-Mexican border that, he says, ``cannot be protected no matter how much we expand the Immigration Service.''
``I think we must recognize as a fact that for many purposes we are one market,'' he says, adding that ``we have no choice but to take either their men or their goods.''
In dealing with global population issues, McNamara says he sees two ways forward. One is to help nations reduce their population growth rates. In this regard, he says, better distribution of and education about contraceptives is part of the answer.
But he notes that ``in many parts of East Africa where the population growth rates are 4 percent - which means that the population will double for those countries in 17 years - the average female during her reproductive years will produce eight children.'' And in many cases, he adds, ``the females, when asked, state that they want six or seven children.'' To change `mind-sets' IN such situations, he notes, it's not enough to increase the availability of contraceptives. Instead, he says, ``one must change mind-sets.''
Unless that change is made, McNamara warns, the resulting population growth will produce such serious ``quality-of-life'' problems for Bangladesh, India, and sub-Saharan African countries that their governments will be tempted to take ``drastic action'' to reduce population. The example of China's one-child-per-family policy, he says, suggests that such actions can be imposed only autocratically.
``I will predict that if those nations of East Africa do not find a way to reduce the desired family size of seven or eight down toward two,'' he says, ``they are going to move - without any question by the end of the century, and certainly [by] the early part of the next century - to autocratic, repressive, dictatorial family systems that will restrict in the most brutal ways the size of families.''
In that situation, he says, families may kill children whose presence would otherwise ``place them above the prescribed limits [of] the state.''
In addition to controlling population growth, McNamara says, he sees a second way forward: an increase in the rate of economic development. In the 21st century, he says, the US must contribute more to international economic development as an expression of the nation's traditional ``concern for others'' and ``sense of compassion.''
During the period of the Marshall Plan following World War II, he says, when America's real income per capita was ``less than half of what it is today,'' the nation was giving some 2.5 percent of its gross national product in foreign economic assistance. Today, he says, ``we are spending on the order of [only] 0.21 percent of our GNP'' for such assistance.
``I mention this because I think it shows a loss of sensitivity to our responsibility to others,'' he says. ``It's a lack of compassion. It's a failure to pursue those values I felt we had traditionally respected in our society.'' Answers for developing nations PART of the answer for developing nations, he says, is a direct transfer of resources from the industrial nations. But it is even more important, he says, to ``accelerate our own rate of economic advance - because we are a market for their goods.''
``It [has] become a truism to say that the world is becoming interdependent economically,'' he says, adding that ``our economic welfare depends on the welfare of Brazil, Mexico, India, and China, [while] their welfare depends on ours.''
Finally, what about environmental degradation? McNamara ranks it as a serious problem, related in large part to the imbalance of population growth and economic development.
Despite a lack of certainty about the causes of certain environmental problems, such as acid rain, the destruction of the ozone layer, and the greenhouse effect, he says the developed nations should be ``willing to buy insurance that will help us avoid undesirable, irreversible effects'' by tackling what are thought to be the most likely causes of the problems.
``Later,'' he acknowledges, ``it might prove that those were not the causes. In that case we would have wasted those funds.''
``On the other hand, later it may prove that they were the causes, and we would have substantially reduced the cost'' of battling the problem, he says. ``But if we spent 1 or 2 or 3 percent of GNP to protect us against these uncertain environmental effects,'' he concludes, ``I would suggest to you it's money well spent.''
Next: Marina Whitman, economist, Dec. 23.