It was in 1967 that a little paper called “Conservation Reconsidered” appeared in the American Economic Review, sandwiched between contributions by Peter Diamond on stock markets and Charles Plott on majority voting,

The author was John Krutilla, a research economist (Reed College, Harvard PhD in 1952) working for the Washington think-tank Resources for the Future. From his dry first sentence — “Conservation of natural resources has meant different things to different people” — he fastened attention on a historic shift of perspective that then was taking place.

For more than a century, Krutilla wrote, economists had been preoccupied with the problem of scarcity. He recalled that barely twenty years before, his own organization (which had begun life as a presidential commission on raw material shortages) had examined the rate at which scarce natural resources were consumed during World War II and concluded that the long decline in their prices had ended.

What remained was thought to be a problem of optimal inter-temporal utilization of fixed stocks. The only question was, how fast to burn the coal? To use up the remaining copper?

Yet, Krutilla noted, recent studies had concluded that advances in technology so far had compensated “quite adequately” for depletion. Silicon was beginning to substitute for copper. Some optimists were arguing that there might be essentially no fixed limits to growth.

In which case, the problem was less one of husbanding resources stocks for future use as providing to the present and preserving for the future “the amenities associated with unspoiled natural environments, for which the market fails to make adequate provision.”

The resource that now required conservation, in other words, was nature itself, raw and unrefined, valued not so much for its use (or even its potential future use) as for its very existence.

In writing thus, Krutilla was articulating in the idiom of contemporary economics a series of concerns that what had been on minds at least John Stuart Mill. He translated into professional lingo concerns that had been raised by Aldo Leopold and S.V. Ciriacy-Wantrup, among others, that the knowledge produced from rare species and ecosystems might be worth something some day.

He cited Burton Weisbrod’s idea that there existed a demand for options on wilderness areas, environments and species for which no substitute is available and that would be difficult to replace. (Options, like sovereigns, were in the air in those days!)

He considered the relatively small market for such options that had developed through organizations such as the Nature Conservancy and the World Wildlife Fund. And he enumerated the various arguments why it might be incumbent on government to exercise such options on much larger tracts of land and water on behalf of citizens of future generations who might, through experience, gain more highly-developed tastes for wilderness.

Krutilla, in other words, not only anticipated the trend towards explicitly bringing technical change into the equation that occurred during the 1980s. He recognized that changing tastes eventually would have to be taken into account as well. He was not a master of technique. He could point economists to the direction in which they must go, but could not show them how to get there.

“Conservation Reconsidered” remains a sketch, not a blueprint, of a satisfactory model of sustainable development. Yet “existence value” has become an increasingly familiar if still controversial tool, used to estimate the costs and benefits of government policies and corporate actions.

At Resources for the Future, Krutilla had been joined by Allen Kneese, another Harvard-trained economist, whose specialty was the intricate economics of water use. (Harvard professor Otto Eckstein was a big influence on both.) Together they put environmental and resource economics on the map.

In due course, Kneese brought a young Swedish economist named Karl-Göran Mäler to Resources for the Future to write a textbook, Environmental Economics. Mäler proceeded to translate Krutilla and Kneese’s ideas into the mathematical language in which economists routinely had begun to work. He made some fundamental contributions of his own.

And for 25 years, as director of Stockholm’s Beijer Institute, Mäler has run a series of workshops designed to familiarize economists with the special characteristics of environmental economics and ventilate the issues on its cutting edge.

According to V. Kerry Smith of North Carolina State University, the three men together all but invented the analytic apparatus of the field. They were awarded the first Volvo Environment Prize in1990.

Kneese was 70 when he died in 2001. Krutilla died last month at 81. Like Kneese, he is survived by a vibrant community of environmental economists. Often noted is the impact on popular opinion made by those first photos of the earth from the moon — the blue green planet framed by the lifeless surface and set against the emptiness of space.

Among expert economists, “Conservation Reconsidered” had something of the same effect — a sophisticated challenge to take responsibility for a living world changing faster than anyone could yet guess.

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Another long and interesting life that came to a graceful conclusion last month was that of I. Bernard Cohen. He died at home in Waltham, Mass., at 89. A scholar of the works of Isaac Newton, Cohen joined the faculty of Harvard University in 1942 as an instructor in physics and retired in 1984 as Victor S. Thomas professor of the history of science.

Cohen’s unfortunate distinction was that he was the man who got the tenured job teaching the history if science at Harvard instead of Thomas S. Kuhn. It was Kuhn who, as a teaching assistant to chemist (and Harvard president) James Bryant Conant in the years just after World War II, conceived the project that was published fifteen years later in 1962 as The Structure of Scientific Revolutions.

It is no exaggeration to say that Kuhn transformed the field of the history of science into its modern heft and shape. When in 1948 or thereabouts, he joined the professional society, there were fewer than half a dozen people employed in American universities to teach the subject.

After 1962, the field exploded. The subject became a department in early every major university in the world, often displacing more established traditions.

And because of its contribution to understanding the history of science, technology and society, Structure has assumed an significance far beyond the word it contributed to our everyday language — “paradigm,” meaning the improvised conceptual scheme undergirding the practice of some portion of science in a certain way (“A paradigm is what you use when the theory isn’t there,” Kuhn said much later.)

It seems likely that Structure will turn out to have been one the 20th century’s most important works of social science. Its message, slyly summed up by the editors of Kuhn’s papers — “Shifts happen.” From this insight about the growth of knowledge, much flows.

But tenure wasn’t offered in the 1950s, when Kuhn’s term as a Junior Fellow was ending. Instead Cohen was promoted. For 20 years, the teaching of the history of science at Harvard had been dominated by an imperious Belgian named George Sarton. He died at in 1956. He had tabbed Cohen as his successor.

Kuhn, who had been at Harvard since entering college in 1940, went first to the University of California at Berkeley in 1957, then to Princeton for many years, before returning finally to Cambridge at the Massachusetts Institute of Technology after a divorce. Nor did Harvard make an offer to him then.

Meanwhile, Bernard Cohen pursued a thoroughly respectable career. A  considerate and friendly man, he helped many younger scholars, including Tom Kuhn. He obtained an interview with Albert Einstein just before his death. He began a variorum edition of Newton’s classic work, Principia Mathematica, then produced an English language translation from the Latin of the third edition. In 1984, he published an indifferently-received book on “Revolution in Science.”

All the while Harvard slowly built its own department of the history of science.

It was only in retirement that Cohen’s work reached a level of ironic self-unconsciousness worthy of a patient of Sigmund Freud. He undertook a biography of his Harvard colleague Howard Aiken, surely one of the most unfortunate scientists in the history of that university.

In the 1930s, Aiken was America’s leading computer visionary, consultant to IBM, architect of an early “super-calculator” known as the Mark One that was rolled out by the university amid great hooplas in 1944.

But by then Aiken has dug in his heels against the use of binary numbers, turned his back on the concept of software, built a machine that laboriously calculated everything to 23 places, hogged credit for it, and so alienated IBM’s Tom Watson Senior that he fired, not just Aiken but Harvard. Leadership in computer technology shifted briefly to Philadelphia. And when IBM decided that university research would be required to get it back into the business in a competitive way, it was to MIT that they turned.

Ironically, Cohen’s book betrays no awareness of the momentous developments in real-time computing that took place in those years down the river at MIT — perhaps Aiken himself was unaware of them. Increasingly out of touch with developments in computing, he retired under some pressure from Harvard in 1961 and died in 1973.

All the while, a generation of researchers at MIT had invented “real time” computing. Starting with a flight simulator which could be programmed to approximate the behavior of any sort of airplane, a generation of MIT entrepreneurs (of whom Digital Equipment’s Kenneth Olson was foremost) grew rich reshaping the computer industry with “mini-computers” that offered the possibility of continuous control. Harvard was left with the short-lived bragging rights to with word-processing magnate An Wang and, of course, Bill Gates, who left to start Microsoft before completing his degree.

Today, Harvard has returned to the forefront of computer science. A few years ago it tore down the building it had named for Aiken and built one commemorating Gates’ mother instead.

Its History of Science Department is one of the best in the world today as well. Among its stars is Peter Galison, whose new book, Einstein’s Clock’s and Poincaré’s Maps, is a riveting exercise in extending the Kuhnian tradition, bringing ever closer together internal and external accounts of scientific and technological developments.

Thus is illustrated by Bernard Cohen’s long and happy life a fundamental truth about Harvard. It is famous enough that it attracts many of the brightest kids. It is conservative enough that it routinely sends away the most innovative among them — others include Norbert Weiner in computer science, Paul Samuelson in economics, Noam Chomsky in linguisitics — and promotes polished or reliable or simply loyal junior faculty instead.

And it is rich enough that it can buy back the knowledge that its best students have created elsewhere, by recruiting their students to be its next generation of teachers — thereby preserving its reputation as the World’s Greatest University and continuing as magnet to the talented young. Nobody should wonder that an especially knowing novel of faculty life in the 1940s was titled “We Happy Few.”