As a social scientist, I think it is necessary to score Frank Press, president of the National Academy of Sciences, on his defense of "social scientists as real scientists" {Free for All, July 4}. Social scientists cannot be "real" scientists in the same sense as physical scientists.

Essentially, Press says that both social scientists and natural scientists use the scientific method "as a way of considering problems and viewing the world." "Science," he says, "is not a body of facts and theories." "Scientists observe phenomena, develop hypotheses, conduct experiments, analyze findings and generate knowledge." Press's view of the scientific method is incomplete in ways that are crucial to an understanding of the differences between the physical and the social sciences.

All phenomena in the physical universe are subject to possible empirical observation and verification. To generate scientific knowledge we must be able to observe and measure physical phenomena in controlled situations that are replicable by independent observers. It is a fundamental error to say that such knowledge of the physical universe does not consist of laws, theories, principles and concepts that are empirically verifiable or subject to change when empirical findings add to or contradict them.

To the extent that the laws or theories of physics are valid, they enable scientists to predict the future. The special and general theories of relativity continue to be verified by observers, and they enable scientists to predict, for example, how much energy will be released in an atomic explosion with a given element and how space travel will affect space voyagers. In effect, physical scientists are really dealing with a deterministic universe wherein light always travels at the same speed and water is always the end product of the combining of one atom of hydrogen and two atoms of oxygen. The world of physics as a body of knowledge would collapse if, for example, the speed of light were to vary in unpredictable ways.

Such is not the case in the social sciences. There are many phenomena in the social sciences that are subject to empirical observation and measurement. In politics, votes can be counted; in economics, incomes can be measured; and in sociology the demographic characteristics of the population can be described and measured. These measurements can rarely be made with the same precision as in the physical sciences, but statistical concepts enable us to get a handle on the degree of accuracy or inaccuracy in a given series of measurements.

But the most unbridgeable gap between the physical and social sciences appears in their respective abilities to predict the future. The social sciences have little or no ability to do so simply because they are not dealing with a deterministic environment. Human beings have free will and can choose to repeat their behavior in a given situation, modify it or abandon it. Human beings also have values and goals that give meaning to their lives and influence their behavior. Social scientists are simply unable to cope with goals and values in any scientifically predictable way. Nor can they use scientific method to determine which goals or values are better or worse. These are crucial elements in the social science universe.

None of this makes physical scientists superior to social scientists. But given this unbridgeable gulf between them, Press ought to heed the advice of his "hard" scientists and propose that the academy restrict all future appointments to representatives of the physical and natural sciences, whose laws and theories have predictable outcomes. Certainly the academy ought to get out of the business of sponsoring and funding all social science research that has as its goal policy advice to governmental agencies and the public at large. A continuation of that policy would only continue to debase the coin of the academy, which basically is to stimulate and reward distinguished achievement in the "real" sciences. -- Robert J. Pitchell