To the extent that people know about Josef Mengele, the German doctor dubbed the “Angel of Death” for his grisly experiments on inmates at Auschwitz, he is usually taken to be an aberration. Surely, many assume, there was a silent majority of German doctors, who, if not bold enough to speak out against the ghastly turn medicine had taken under the Nazi regime, were against the race-based science the Nazis preached.

But the chilling and provocative exhibit “Deadly Medicine: Creating the Master Race,” which recently opened at the Museum of Jewish Heritage, offers a powerful corrective to the assumption that the majority of scientists and doctors were immune to the seductions of race-based science.

Even more disconcerting, the exhibit shows that for at least a quarter century before the Nazis took power, in 1933, the science upon which Nazi practices were based — eugenics, a now- discredited field that believed that the human race could be biologically perfected — had widespread support from doctors, lawyers, politicians and journalists throughout the Western world. This was not quack science; it was respected and mainstream.

Roughly half of the states in the U.S. passed laws permitting the sterilization of people with conditions only presumed to be hereditary, a practice upheld by the Supreme Court. And before the Nazis sterilized a single person, or implemented their euthanasia program for anyone considered physically inferior, roughly 16,000 Americans had been sterilized by law.

“Deadly Medicine,” curated by the historian Susan Bachrach and originally debuting at the United States Holocaust Memorial Museum in Washington, D.C., in 2004, begins its story with Darwin. It shows how not long after he argued, in the mid-19th century, that certain traits were passed down through a process of natural selection, doctors, politicians and social theorists alike swooned over the theory’s immense social potential.

Particularly at a time when many Western countries were rapidly colonizing non-Western societies, and experiencing mass immigration at home, social Darwinism and its related scientific field, eugenics, provided a useful theory to justify controversial policies. Then as now, the stamp of science conferred intelligence and objectivity, so it is not surprising to learn that Darwin’s cousin, Sir Francis Galton, was the one who invented the term “eugenics.”

Many have heard of social Darwinism and its popular itineration — “survival of the fittest” — but the exhibit briskly and intelligently fills in some necessary gaps about its lesser-known cousin, eugenics. Eugenicists did not merely believe that certain unfavorable traits would “naturally” be self-selected out of the human population. They enthusiastically encouraged scientists and doctors to be the human race’s self-selectors.

Given the esteem eugenics held, many countries in the early 20th century had little trouble implementing policies supported by their ideas. After all, governments around the world today still defer to scientists to justify certain policies — witness the carbon tax and global warming. And most of the time rightfully so.

What makes this exhibit so effective is that it understands that science itself — in reality, not theory — is deeply enmeshed with culture and politics. And not only in one direction either: that is, the exhibit shows how politicians and intellectuals can exploit science to justify their own aims, but also how scientists themselves are swayed by broader cultural debates.

There is nothing more jarring to see, for instance, than a rotted wooden door with a thin peephole in it taken from a German medical lab. Used in the early 20th century, medical researchers used it to observe traits they thought were hereditary, like violence or vandalism. At a time when cities were becoming vastly overcrowded, and violence and vandalism more common, scientists thought these problems weren’t social problems but biological ones.

German scientists and doctors are hardly the only ones cut down to size in this exhibit; American lawyers and liberal intellectuals get a harsh look, too. In perhaps the most glaring example, the exhibit highlights the 1927 Supreme Court case of Buck v. Bell. The court decided to hear a case brought by an 18-year-old Virginian woman, Carrie Buck, who was forcibly sterilized at a state hospital. Because she was deemed mentally disabled and had given birth to a daughter also deemed disabled, Virginia law required Buck, like all patients with presumed genetic disabilities, to be sterilized — “for the protection and health of the state,” the statute read.

Though the exhibit points out that liberals and Catholics were the most vocally opposed to eugenics-based social policies, Buck v. Bell proves how widespread support for eugenics-based laws had become even among those groups. Oliver Wendell Holmes, a stridently liberal Supreme Court justice, wrote in his majority opinion upholding the Virginia law: “The principle that sustains compulsory vaccination is broad enough to cover cutting the Fallopian tubes,” to which he added, “Three generations of imbeciles are enough.”

Even though “Deadly Medicine” illustrates how widespread support for eugenics had become, it makes it clear that what was happening in Germany was of a vastly different order. To be sure, it was not the Nazis who invented or even privileged eugenics, which Germans called by another name: “racial hygiene.” In the first section on eugenics in Germany, the exhibit highlights the popularity of the science in the Weimar era, the liberal period just before Hitler’s rise.

Weimar officials lavishly funded eugenics research, proposed sterilization policies to weed out “inferiors” and sought tax-credit policies to encourage “valuable” families to reproduce. German eugenicists and politicians alike believed that, economically, these policies made perfect sense — it was straining the severely depressed Germany economy to keep chronically ill people alive, and to do so guaranteed that their “type” would continue to bleed the economy if they were allowed to reproduce.

To think this kind of logic could have merit only in the past, and only in Germany, is to forget that, at present, our current debates over health care reform have taken similar factors into account. Charges of “death panels” may be ridiculous, but the idea that economic factors should be considered in what kind of medicine the government pays for is a linchpin for many reformers.

The exhibit is also unusually effective in demonstrating how once legitimate, if still contested, ideas like eugenics can devolve into outright lunacy when co-opted and perverted by politics. What the Nazis did to eugenics was twofold: first, they wed the idea that certain traits were hereditary to pseudoscientific theories about race. Second, they implemented these new, race-based eugenics theories through policies that sought to eliminate people of non-Aryan races entirely.

This is, of course, where Jews take center stage. The exhibit begins that sordid history with the Nuremberg laws of 1935, which targeted all non-Aryan ethnic minorities, but disproportionately affected Jews. Officially named the “Blood Protection Law,” the Nuremberg statues criminalized marriage between Jews and non-Jews, and quickly made Jews the central target of the Nazis’ race-based policies.

The measures we know well — barring Jews from professions, deportations, establishing ghettos, creating death camps — are all discussed in the exhibit, but they take on new meaning when viewed through the prism of science. Less known, and thus even more enlightening, is to see how certain tactics used against the Jews, and ones that they would become the worst targets of — like gas chambers — were originally used against the physically and mentally disabled.

As the war began in 1939, the Nazis used the fog of war to implement its euthanasia program against the physically and mentally handicapped. Not only did this result in the death of some 200,000 Germans, many of them gassed to death in everyday hospitals — well before Zyklon-B arrived at Auschwitz — it also entailed the mass mobilization of hundreds of doctors, nurses, psychiatrists and pediatricians. One of the most disturbing items on view is a metal crib and a few grainy pictures of disabled children killed in this program, just a handful of the 5,000 children murdered in total.

If we take into account the additional 400,000 Germans that were sterilized beginning in 1933, when the Law for the Prevention of Genetically Diseased Offspring went it effect, it becomes clear that the death camp killings were only the worst of it. And what made all these practices possible were not only the perverse politics of Nazis leaders, but also the vast complicity of an entire scientific establishment.

The exhibit notes that doctors in particular, spurred by pressure or even for mere opportunism (money went to those willing to comply) took up the Nazis’ racial policies with enthusiasm. A traditionally conservative lot to begin with, the exhibit explains that no other profession in Germany had a higher number of Nazi party members, and one suspects that no other professional class played such an active role in putting people to death.

“I think that is why this exhibit is so important,” Susan Bachrach, the exhibit’s curator, told The Jewish Week. “Many people think that this was just a couple of quacks, but I wanted to show where people like Mengele came from.”

“Deadly Medicine: Creating the Master Race” is on view at the Museum of Jewish Heritage—A Living Memorial to the Holocaust, located at 36 Battery Pl., through Jan. 16. A symposium on medical ethics in Nazi Germany, featuring Emory professor Sander Gilman and University of Pennsylvania professor Arthur Caplan, will be held at the museum on Sunday, Nov. 6, at 1 p.m. $10; $7 for seniors and students. Call (646) 437-4202 for more information.