In this blog post, I’d like to explore the relationship between science, technology, and ethics through the life of Fritz Haber—the scientist who developed the ammonia synthesis process that has fed humanity, yet was also deeply involved in the development of chemical weapons.
Have you ever heard of the name Janus? Janus is the Roman god of doors, depicted with two faces—one facing forward and one facing backward. Because of this characteristic, the name is often used to describe people with contrasting personalities. Throughout humanity’s long history, there have been many figures whose lives were marked by the coexistence of light and darkness, good and evil. The scientific community is no exception. In particular, one scientist who won the Nobel Prize in Chemistry is considered one of the figures to whom the nickname “Janus” fits best. His name is Fritz Haber. Haber was a German chemist who won the 1918 Nobel Prize in Chemistry in recognition of his contribution to significantly increasing global food production by developing a method for the large-scale industrial synthesis of ammonia. However, even at the time, his Nobel Prize win sparked fierce controversy. It was clear that the industrial-scale synthesis of ammonia enabled the mass production of chemical fertilizers, making a tremendous contribution to solving humanity’s food problems. Nevertheless, many people opposed his award, and Haber is still referred to today as the “Janus of the scientific community.” So why has he been viewed this way, despite his great achievements?
We can find the answer by examining Haber’s life, for his illustrious achievements were accompanied by both dazzling light and deep darkness. In 1868, Haber was born into a Jewish family in Germany. After graduating from a German gymnasium (a secondary school), he studied organic chemistry at the University of Heidelberg, the University of Berlin, and the Technical University of Charlottenburg. He then began his research in physical chemistry at the Karlsruhe Institute of Technology in 1894 and was eventually appointed as a professor at the same university.
From the late 19th century to the early 20th century, physical chemistry was a nascent discipline rapidly evolving at the intersection of physics and chemistry, based on thermodynamics and electrochemistry. As a leading authority in physical chemistry at the time, Haber contributed significantly to the field’s development. After conducting research at the Karlsruhe Institute of Technology for many years, he successfully developed the so-called Haber-Bosch process. The Haber-Bosch process is a method of synthesizing ammonia from nitrogen and hydrogen in the air using a catalyst under high-temperature and high-pressure conditions. This process is highly regarded in the history of science because it enabled the stable, large-scale production of ammonia. Before the large-scale production of ammonia, methods for increasing agricultural productivity had to rely heavily on land reclamation and crop breeding, both of which had clear limitations. However, with the mass production of chemical fertilizers using ammonia as a raw material, crop yields increased dramatically, and global food production capacity also improved significantly.
One example illustrating these effects was Germany at the time. In the 19th century, Germany’s population grew rapidly alongside industrialization, but food production could not keep pace with the growing population. This situation was not unique to Germany but was a challenge faced by many countries around the world. Some experts believe that without the development of technology for mass-producing ammonia, it would have been extremely difficult to reliably support a global population of the size we have today. In fact, the Haber-Bosch process is recognized as one of the technologies that laid the foundation for modern agriculture, and it continues to serve as a core technology supporting global food production to this day.
Another reason the Haber-Bosch process is so significant is that, as mentioned earlier, it represented a landmark achievement in physical chemistry—a field that was still in its infancy at the time. The synthesis of ammonia itself was already an area of interest for researchers at the German chemical company BASF, including Karl Bosch. Haber, an authority in physical chemistry, joined the effort and used thermodynamic analysis to theoretically demonstrate that ammonia synthesis was feasible; through subsequent research, he identified reaction conditions suitable for actual industrial application. Karl Bosch then developed the process to enable large-scale industrial production, thereby completing the Haber-Bosch process as we know it today. In his early research, Haber discovered that ammonia could be synthesized using high temperatures, high pressure, and an appropriate catalyst, and subsequent research focused on finding more efficient catalysts and process conditions. Eventually, around 1910, Bosch’s engineering expertise combined with BASF’s large-scale facilities to complete an economical process for the mass production of ammonia using iron oxide-based catalysts. As such, Haber’s achievements are regarded as a monumental accomplishment, both in the history of science and in terms of the progress of human society.
However, even as Haber steadily built upon his achievements, a great shadow—World War I—began to loom over his life in 1914. Although Haber was of Jewish descent, he was a chemist with a strong sense of patriotism toward Germany. He devoted his research and knowledge unreservedly to Germany’s victory, and this patriotism ultimately left deep scars on himself, his family, and the countless people who were sacrificed because of his technology.
First, we need to examine the mass production process for ammonia developed by Haber. While this great technology saved countless lives, it also had the opposite effect during the war. Ammonia is widely used as a raw material for chemical fertilizers, but it is also a key ingredient in the production of nitric acid. Nitric acid is essential not only for fertilizers but also for the manufacture of gunpowder and explosives. At the time, Germany was facing significant difficulties securing nitric acid as supplies of saltpeter—which it had imported from abroad at the start of the war—became scarce. However, once ammonia could be produced reliably through the Haber-Bosch process, mass production of nitric acid also became possible, allowing Germany to continue producing ammunition and sustain the war for an extended period.
Furthermore, as a chemist directly involved in the war, Haber spearheaded one of the most inhumane research projects of the conflict. At the Hague Peace Conferences of 1899 and 1907, international discussions took place aimed at restricting the use of inhumane weapons, including asphyxiating poison gases. Nevertheless, Haber and German researchers threw themselves into the development of chemical weapons for the sake of their nation’s victory. The chlorine gas they developed was used on a massive scale during the Battle of Ypres in Belgium in 1915, marking the beginning of modern chemical warfare. This attack resulted in countless casualties and spurred a race among many nations to develop chemical weapons.
Haber’s decision also brought irreversible tragedy to his personal life. His wife, Clara Immerwahr, was a scientist who majored in chemistry and firmly believed that chemistry should be used for the benefit of humanity. She strongly opposed Haber’s involvement in the development of poison gas, but he refused to listen. Ultimately, Clara took her own life in deep despair shortly after poison gas was first used in combat. This incident remains a prime example frequently cited even today when discussing scientists’ social responsibility and research ethics.
In the end, even though Haber devoted everything to his homeland, Germany emerged as a defeated nation in World War I. After the war, Haber experienced deep frustration, but he never abandoned his determination to rebuild Germany through advances in science and technology. However, the situation changed completely in 1933 when Hitler came to power and the Nazi regime began systematic discrimination and persecution of Jews. Although Haber, who was of Jewish descent, could have received special treatment in recognition of his past contributions, he could not condone the Nazis’ anti-Semitic policies and ultimately left Germany. After traveling through countries such as the United Kingdom in search of new research opportunities, he died of a heart attack in a hotel in Basel, Switzerland, in 1934. Although he left a significant mark on human history through his outstanding scientific achievements, his final days were lonelier and more tragic than anyone’s.
Views on Haber’s eventful life are broadly divided into two camps. The first holds that his achievements as the scientist who developed the process for the large-scale synthesis of ammonia should be highly valued. In fact, the Haber-Bosch process laid the foundation for modern agriculture and the chemical industry, and is still regarded today as one of the core technologies underpinning global food production. From this perspective, there is a view that the Nobel Committee’s decision to award him the Nobel Prize in Chemistry in recognition of his scientific achievements alone was fully justified.
On the other hand, another perspective emphasizes that while his research was a technology for the benefit of humanity, it was also used to prolong wars and cause more casualties. The mass production of ammonia not only enabled the production of chemical fertilizers but also ensured a stable supply of nitric acid, which is necessary for the manufacture of explosives; moreover, Haber did not stop there but personally led the development of chemical weapons. The fact that he used his scientific knowledge to facilitate the practical use of weapons of mass destruction continues to draw significant criticism to this day regarding the ethics and social responsibility of scientists.
Ultimately, Haber’s life serves as a prime example demonstrating that science and technology do not belong exclusively to either good or evil, but can lead to entirely different outcomes depending on the choices made by the people and society who use them. While his research saved countless people from starvation and made the development of modern civilization possible, it was also deeply exploited in wars that claimed countless lives. Because the achievements and mistakes of a single individual coexist so starkly, Fritz Haber remains one of the most controversial figures in the history of science to this day.
Should scientists be evaluated solely on the basis of their research achievements, or should the impact of that research on society and the researcher’s ethical responsibilities also be taken into account? Fritz Haber’s life continues to pose this question to us today. Especially in this era, when science and technology are advancing faster than ever before, his life remains an important case study that compels us to reflect deeply once again on the values of science and the responsibilities of researchers.
