"AI helps us to grasp more and more complex facts"

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Joachim Buhmann viewed everything he did during his academic career as a service
Joachim Buhmann viewed everything he did during his academic career as a service to society. (Photograph: ETH Zurich / Leonid Leiva Ariosa)
Since 2003, when Joachim Buhmann became an ETH professor, he has helped shape the explosive development of machine learning. It is not technical progress that worries him, but how society deals with it. Shortly before his retirement, he looks back on his academic career.

Joachim Buhmann, why did you become a scientist?
Buhmann: There is a great answer from Luc Ferry, a French philosopher and former Minister of Education. It’s about the question of why people want to leave something behind after they die. This can be achieved by producing and raising offspring or educating and inspiring others as teachers. According to Ferry, however, the greatest legacy is left by scientists, as they make a lasting contribution to humanity as a whole through the knowledge they gain. Whether I was successful or not is for others to judge, and that may only become clear later. However, I believe that as a scientist I have at least tried to answer important questions and gain new insights, and some of my doctoral students have certainly taken away new knowledge that they have then developed further.

Did you already know at the beginning of your career that you wanted to do research at a university?
Buhmann: It was a kind of ideal, but I was never obsessed with the idea of becoming a professor. After my time as a postdoc in California, I was quite open to the idea of becoming a professor because my children were already older. My wife and I had our children in our 20s, and I became an associate professor at the University of Bonn at the age of 32. I am convinced that luck played a role in my career. Things could certainly have turned out very differently.

Would you have had a plan B?
Buhmann: My plan B would have been to go into a research laboratory or industry. There were already options in the field of machine learning in the 1990s, although not as many as there are today.

Joachim Buhmann was a Professor of Practical Computer Science at the University of Bonn from 1992 to 2003, before he accepted a position at ETH Zurich and became a Full Professor of Computer Science. In his teaching and research, he focused on questions related to pattern recognition and data analysis, which includes areas such as machine learning, statistical learning theory, and applied statistics. Professor Buhmann took on important administrative functions at ETH, including the roles of Vice Rector for Study Programmes (2014-2018) and Head of the Institute for Machine Learning (2014-2023). Since 2017, he has also been a member of the Research Council of the Swiss National Science Foundation.

You first studied physics at the Technical University of Munich and later completed a Ph.D. in theoretical biophysics. How did you get into machine learning?
Buhmann: My doctoral supervisor was a theoretical biophysicist, but my research focused on the memory capacity of "Hopfield networks". These are a special type of artificial neural network. If you study such models, then you are essentially already in the academic territory of computer science. It’s no longer just pure physics because it’s not about inanimate matter, but about information processing. This area was not yet fully established in computer science at that time, but it is clearly part of the subject. Later in my career, I moved to Bonn and continued to work in the field of neural networks as an associate professor of practical computer science.

Why did you come to ETH?
Buhmann: I had no prospects of being promoted in Bonn. At the age of 43, I got the opportunity to become a full professor at ETH Zurich. ETH had, as it does now, an excellent reputation, although the University of Bonn in Germany was also outstanding in mathematics, which was the home of computer science at the time. My wife and I had already built a house in Bonn, but as our children were almost finished with school, it was an obvious choice at that time.

What have you worked on in your research career?
Buhmann: Even before I came to ETH Zurich, I was working on the question of how clustering algorithms assign their data to different groups. The way this allocation works differs from that of classification algorithms. In classification algorithms, data is usually annotated manually by a human, and the algorithms are then trained with these annotations. For example, you want to automatically classify images of dogs and cats into two groups and use a training dataset to specify that an image should either be classified in the "dog" group or the "cat" group.

With clustering algorithms, there are no such labels, so there is no predefined "dog" or "cat" class. Nevertheless, the algorithm is supposed to eventually assign a label to every object. I wanted to find out how the algorithms carry out the clustering when there is no quality measure that they can use as a guide.

What is the purpose of such algorithms?
Buhmann: I applied this theory to various biological and medical projects. The approach of the clustering algorithms reflects the situation of a doctor who is tasked with predicting the probability of survival of a patient based on an X-ray image and other sources of information.

How has your field of research at ETH Zurich changed over the last 20 years?
Buhmann: I had not foreseen that my field of research would develop so dramatically in the last 15 years. These are incredibly exciting times. The current rise of artificial intelligence affects all disciplines of science and is comparable to the introduction of quantum mechanics in physics. When I joined the Department of Computer Science, hardly anyone was interested in machine learning. Things are different nowadays. There is now an Institute for Machine Learning with 11 professors.

Do you view these developments in the field of artificial intelligence with concern or enthusiasm?
Buhmann: I’m not worried about the scientific development itself. My concern, if any, is that society may not sufficiently understand or anticipate the consequences of these scientific advances. Artificial intelligence is a technology that improves human thinking by enormously expanding the limits of the human capacity to store facts and grasp complexity. This is because the human brain tends to ignore details and focus on the big picture, i.e. to abstract. Enabling society to learn how to use these systems in an ethically correct way is an important educational task. New procedures need to be developed to ensure transparency, responsibility and fairness in the use of these programs.

At ETH Zurich, you were both a researcher and a lecturer and took on some administrative roles. How do you look back on your time as Vice Rector?
Buhmann: You are confronted with questions that are at the interface between the preconceived set of rules and an empathetic, ethically correct assessment of individual cases. The decisions you make can result in significant restrictions on someone’s life options. For example, you must decide whether a student should be expelled from their programme. This must be grounded on a very good reason rather than the randomness of any given processes. The role of Vice Rector was certainly a challenge, but I think I was able to contribute reasonable solutions.

What have you learned during your time as Vice Rector?
Buhmann: First and foremost, I became a scientist to do research. However, in addition to producing new knowledge, as a university lecturer I also have the responsibility to pass on existing knowledge. During my time as Vice Rector, I learned that the university’s priority is always teaching, and that research comes second. However, as the quality of research is easier to measure, it is often given more importance than teaching. Students at universities should first and foremost be trained to become intelligent problem solvers who can make reasonable decisions even in conditions of great uncertainty - regardless of whether they go on to work in industry or stay in academia.

You are retiring in July. Do you have any concrete plans?
Buhmann: My family is relatively large. We are expecting our eighth grandchild soon. I’m sure I’ll have a few tasks ahead of me. Professionally, I haven’t prepared myself for a direct follow-up job and I’m not actively looking for one. However, I would like to maintain my contacts with the institute and try to make myself useful as an emeritus professor. I also think that I will continue to do research, but probably less than now. I would also like to contribute my time and expertise to public relations work to support society in this digital transition.

in full on the website of the Department of Computer Science.

Professor Joachim Buhmann will deliver his farewell lecture this Thursday, 30 May in the ETH main bulding.

Lernst du noch oder nutzt du schon KI?
Time: 17:15
Location: Zürich Zentrum HG F30
Language: German

The lecture will be live-streamed from the AudiMax.