The example of the Manhattan Project taught that a disparate group of strong-willed scientists, working together voluntarily, could achieve marvels. This was the model followed by the group of scientific advisers we now know as the Jasons. Originally formed by veterans of the Manhattan Project, the group included such gigantic personalities as Freeman Dyson, Edward Teller, Eugene Wigner, and Hans Bethe, and demonstrated how creative cooperation between scientists and the government could produce astonishing results.

In “The Jasons: The Secret History of Science’s Postwar Elite” (Viking, 304 pages, $27.95),Ann Finkbeiner tells the remarkable story of how this small cadre of brilliant American scientists provided vital technological support to our government over a period of 46 years following the end of World War II. Her fascinating, often moving account of the history of the Jasons (named after the Golden Fleece hero) includes interviews with many current and former members, some of whom preferred to remain anonymous.

Although the existence of the group was never acknowledged openly, it was not the most closely guarded secret, either. Originally created by people close to the physicist John Archibald Wheeler in 1960, the idea behind the Jasons was to provide the Defense Department (actually, the Advanced Research Projects Agency) with practical answers to the many threats posed by the suddenly intensified Cold War. The arrival of Sputnik, which could just as well have been carrying a nuclear warhead, created a critical sense of urgency in the military. They needed creative solutions fast. Jason was created to provide them, just as the Manhattan Project had done during the World War II.

What distinguished this group from all the other science advisers that serve the government is the unique way it was organized. The association is voluntary and collegial, and, most important, it is independent. Members are invited to join not by the government, but by other Jasons. And Jason management worked with the government sponsors to decide what questions they would study, and Jasons themselves would work only on those studies that interested them.

Because all the elite members of the group have distinguished careers elsewhere in universities around the country, they meet during the summer months in La Jolla, Calif., and deal with questions put to them by ARPA and other government agencies. What always made the group feasible is the scientists’ sheer excitement about the prospect of working with a bunch of really smart people on projects that were not simply theoretical but existed in the real world. This was applied technology that these theoretical physicists were working on, and, as Ms. Finkbeiner shows, most of the Jasons believed that their scientific role could exist in both realms, the theoretical and the practical. This remained true for the Jasons even when it led inevitably to difficult moral issues about the possible consequences of their work, much as it had for the Manhattan group earlier.

Motivated by a sense of responsibility for how the country uses the products of science to defend itself, most Jasons accepted this conflict. As Freeman Dyson expressed it, “We are scientists second and human beings first.” “We became politically involved,” he wrote, “because knowledge implies responsibility.” The atomic genie was out of the bottle forever, and many of America’s leading scientists, especially the Jasons, chose engagement, rather than withdrawal to the academy. In addition, Ms. Finkbeiner came to believe that these people were deeply, if indemonstrably, patriotic.

During the so-called Glory Years from 1960 until opposition to the Vietnam War reached critical mass, the Jasons were heavily engaged in many aspects of Cold War gamesmanship. They worked on a number of defense projects ranging from researching energy (laser) beams designed to counter enemy rockets to nuclear bombs exploded in the earth’s atmosphere to create huge clouds of energetic electrons that would fry an enemy missile (which actually worked), to the oddly named ELF project (Extremely Low Frequency), a buried loop antenna 8,500 miles long in Wisconsin that was designed to send signals to American subs around the world to fire their missiles. They were also active in developing the technology to help monitor nuclear explosions, as both sides groped toward a test-ban treaty. These were real projects intended for the real world.

The Vietnam period that followed was another matter altogether. Do we remember Rolling Thunder, the futile effort to interdict the flow of supplies down the Ho Chi Min Trail? Jason authored part of the study showing its failure (later included in the Pentagon Papers) and then helped create the Air-Supported Anti-Infiltration Barrier that was supposed to take its place. Thus was created the electronic battlefield with multiple sensors that has dominated military tactics to this day. By this time, of course, the general public not only had turned against the war but also against the evil Strangelove scientists, who were now considered war criminals. Many Jasons were caught up in this destructive frenzy. As Ms. Finkbeiner puts it, “For the first and almost the only time in Jason’s history, the group became fair and public game,” especially for the ideologues on the left, who were busily dismantling the nation’s colleges and universities at that time.

In 1972, a notorious screed titled “Science Against the People: The Story of Jason” was published. It was contemptible but typical. There was, however, one positive result for Jason that emerged out of this intellectual squalor. When the riots were at their height at Columbia University, a postdoctoral student named William Happer, unconnected to the Jasons, was trapped and barricaded in his lab by the rioters. After three days, Mr. Happer managed to escape. Later, he came to the conclusion that if Jason “collects such slimeball enemies as this, it must be pretty good,” and he subsequently became a valuable member of the group.

The real genius of this strange and amorphous organization is that it is more dedicated to the truth than to any of the other competing imperatives, be they political convictions or the wishes of the sponsors or the politics of the current administration. This is why the Jasons have lasted as long as they have. As independent scientists, Jasons are dedicated to the idea that, as anonymous group member “Professor Y” puts it, “there is truth and there’s right and we can find it.” But, the professor adds, “holding on to that purity and walking with society is difficult.” The tradition of the Jasons is to try to do both; to maintain the purity and clarity of the scientific method in the middle of a dirty and lethal world. It is this effort to balance the two that, for many years, has enabled Jason to provide the government with an honest and independent opinion as free from internal bias as possible. Now, because of this excellent study, we know how vital this effort has been for our survival.

Mr. Pettus last wrote for these pages about human behavior.