An Interview with Carl Friedrich von Weizsäcker

Rafael Capurro

Published in Mark Burgin and Gordana Dodig-Crnkovic (Eds.). Theoretical Information Studies - Information in the World, Vol. 11. New Jersey: World Scientific 2020, 177-185.
See also:
The Structure of the World, Unity of Nature and the Problem of Time  (Rafael Capurro and Mark Burgin).  In:  Mark Burgin and Gordana Dodig-Crnkovic (Eds.). Theoretical Information Studies - Information in the World. Vol. 11  New Jersey: World Scientific, 2020, 139-176.

Burgin Dodig


In 1982 I had the privilege of meeting Carl Friedrich von Weizsäcker (1912-2007) at his private home near Munich. While working at the Center for Nuclear Energy Documentation located in the premises of the Karlsruhe Nuclear Research Center (1980-1985), I asked a small group of engineers and physicists interested in natural philosophy to discuss von Weizsäcker’s works. After a while we wanted to meet him personally. He invited us to visit him and I took some notes of the conversation that were published in Spanish in the Uruguayan weekly newspaper Opinar whose Founder and Director was Enrique Tarigo (1927-2002), Professor of Procedural Law at Uruguay State University (Capurro 1982). Tarigo became Vice President of Uruguay under President Julio María Sanguinetti between 1985 and 1989, which was the first democratic government after the military intervention of 1973-1985. In the introduction to this interview Enrique Tarigo wrote:

From Germany:  Rafael Capurro interviews von Weizsäcker.

Carl Friedrich von Weizsäcker is one of the great names in 20th century thinking. His life was dedicated to this: thinking. A disciple and friend of Werner Heisenberg, his original interest was in physics. In the thirties he developed Quantum Theory together with Niels Bohr. This was the start of a deep controversy about some presuppositions of Einstein's thinking that still persists. But physics was not the only passion of this man. His yearning for deeper thinking took him to philosophy and particularly to the study of two thinkers, namely Plato and Kant. Religious thinking was also among his fields of interest. But his life was not only dedicated to thinking. The danger arising from nuclear weapons led him some years ago to setting up the Max Planck Institute for the Study of the Scientific-Technical World.
Today, aged 70, von Weizsäcker has retired from teaching but continues working with a group of scientists devoted to what remains his main research interest, namely Quantum Theory. What follows are the responses of a multifaceted and profound man given to the critical questions of our correspondent Rafael Capurro. Ideas and men come across a privileged mind. (Tarigo 1982, p. 20)

I. Physics and Philosophy  

Question. What is the contribution of philosophical thinking to modern physics and to science in general? Isn't it superfluous? Is it not enough to simply do science?

Answer. The fundamental concepts of physics (matter, space, time, energy, etc.) originate in the philosophical tradition. I became aware very early on that physicists often do not know what they are talking about. I decided to do research on the origin of such concepts. This took me first to Kant. But in order to understand Kant it is necessary to have read Descartes who takes us to the Platonic and Aristotelian medieval traditions. Plato and Aristotle can be considered as the originators of such concepts, that is to say, they gave them an original and crucial shape. My first philosophical steps in Kant were under the guidance of my friend Georg Picht with whom I read without understanding much of it, to say the truth, the first twenty pages of the Critique of Pure Reason.

Q. How would you see the relation between philosophical thinking and a physicist’s everyday research?

A. In this point I think that the distinction made by the American philosopher and historian of science, Thomas S. Kuhn, in his book The Structure of Scientific Revolutions (Kuhn 1962) might be helpful. Kuhn distinguishes between "normal" and "revolutionary science." Progress in science is achieved, according to Kuhn, not by accumulating knowledge but is based on leaps or "revolutions" when a traditional "paradigm" used so far to explain phenomena is questioned and replaced by another one. This is the case of, for instance, the revolution brought about by the Copernican paradigm as opposed to the Ptolemaic one. During a period of "normal science" scientific progress aims at looking for solutions to a "puzzle" within a given paradigm. During such periods, philosophy has no direct influence on scientific research, and can even be deleterious, in contrast to a "revolutionary" period when a scientist can get an opportunity to question given presuppositions thanks to radical philosophical thinking. This is what we see in the case of Einstein influenced by Ernst Mach who himself criticized Newton. Einstein did not believe in the Newtonian paradigm, although it worked.

Q. According to what you say, philosophical thinking has the quality of incessantly questioning.

A. This quality originates in Greece. Philosophy is a Greek experiment. Only analogically can we speak of Hindu "philosophy" with regard to, for instance, the Vedas. Philosophy is per se so beautiful that, similarly to other activities, it does not need a why.

II. The Path of Natural Science

Q. How do you see the questions raised by so-called alternative movements such as the ecological movement?

A. Ecology, in my understanding, is a branch of modern biology and cannot be understood without it. Ecologists criticize some devastating applications of modern biology. But such applications, I believe, are not a necessary consequence. A non-destructive path can be found also within the frame of modern natural science. Our technology is not at its end. The path of natural science is consistent and true although we cannot predict the next steps of evolution based on it. It was not possible, for instance, to predict the existence of the main religions before they arose or to predict Homer before the rise of epic poetry.

Q. But nevertheless, during the Renaissance...

A. Yes, there was a start, for instance, with Leonardo da Vinci’s first attempts to predict. But the limits of such attempts are obvious.

Q. How would you see the relation, for instance, between the path of natural science with other experiences of reality such as poetry or painting?

A. Such paths, well understood, are not opposed to natural science but they address different ways of relating ourselves to reality that do not have the structure of empirical-rational science. Our perception of beauty concerns the connections of a whole that natural science does not deal with and that, in a certain way, cannot observe. Natural science is of recent origin. Humans as hunters, farmers, poets, etc. have a long history. From an historical point of view, the description of reality provided by natural science was not and is not the only one.

III. The Path of Meditation

Q. How in this context do you see the concept of meditation as a path of knowledge?

R. Meditation is an experience that arises originally in different religious traditions. Today it is fashionable to speak about it. This is why I only dare deal with your question with some shyness. On the other hand, it is something that I do not feel competent to teach. In order to come near to this phenomenon, the question, 'what is?', is not very helpful. It is better to ask 'how do you do it?' But in this case, as well as in other fields, one only sees what one previously knows.

Q. Can you give a simple  example of 'how do you do it?'

A. You view a flower, for instance. You view it. You remain a little bit longer. You close your eyes and continue viewing the flower. You think that you and the flower are alone in the world. It is a process of retreat. Imagine what this experience can mean if you do not do it just once but every day and if, instead of a flower, you experience yourself. Learning to see the things themselves is what religions have talked about. They are older than natural science. Its relation with them is not clear so far.

Q. In your writings you mention the relativity of religious traditions. 

A. Relativity in the sense of their interconnection. Think about the Jesuit priest Ennomiya Lasalle, for instance, whom I know personally. He is also a ZEN monk. Religious experience is sometimes the same but interpretations vary.

Q. And in the case of Christianity? 

A. We have a high level of rationality due particularly to the influence of Greek philosophy, in contrast to Buddhism, for instance. The question about 'salvation as such' has always had an historical answer. It is different in each case. The encounter among the religions is, without doubt, the most important event of our age. If natural science could become a partner in this dialogue on a parity basis, perhaps, after some world catastrophes, a new phase of consciousness could arise.

IV. The Unification of Modern Physics

Q. In your writings and particularly in The Unity of Nature (Weizsäcker 1971) you point to different paths that could lead to the unity of modern physics.

A. The present physical theory, valid in all fields and tested millions of times, is Quantum Theory. What it basically deals with can be summarized on a single page. The project is to formulate the conditions of possibility of the quantum phenomenon. To provide the foundations for this theory is something to which I have pointed in the book you mentioned and also the one on which I am working at present.

Q. How do you see Einstein's position with regard to Quantum Theory?

A. For Einstein it was difficult to accept the fundamental probabilistic character of this theory. He looked for hidden parameters that would explain in a deterministic way all physical phenomena. It was Heisenberg who, proceeding from the indeterminacy principle, radically questioned the world or, as we previously said, the paradigm of classical physics. In quantum physics we think with the category of probability which is nothing other than the quantification of what is possible, and what is possible is one of the dimensions of the structure of time, the dimension of the future. A thinking of the possible is given only in relation to a factical past from a concrete present. Modern physics is based on this three-dimensional structure of time without which, as Heidegger says, we could not even formulate or understand the second principle of thermodynamics.

Q. How do you see modern currents in the philosophy of science?

A. I already mentioned Thomas Kuhn. But if we go back a little more we will remember Rudolf Carnap and his criticism of apriorism: science must be empirical. But, what does 'empirical' mean? Carnap defines it a priori. Karl Popper remarked that the path of induction is wrong. The truth of our theories and general propositions cannot be achieved through generalization of singular experiments. Science proceeds through propositions that prima facie do not look well-founded. But, on the other hand, in my view, Popper's thinking is oriented towards classical physics. This is the reason why I think that it is insufficient. Kuhn, by comparison, is more empirical by relying on the history of scientific revolutions. Scientific revolutions are, accordingly, paradigms that have not yet been falsified.

Q. The introduction of the temporal scheme would be one of these revolutions.

A. From a philosophical perspective it was Heidegger who asked profoundly, again and again, about the phenomenon of temporality.

V. Physics and Temporality

Q. How are quantum physics and the experience of thinking addressed by Heidegger related to the phenomenon of temporality?

A. The closeness of the issues is, without doubt, greater with regard to Heidegger than to the philosophy of science, without implying a total equivalence with Heidegger's thinking. Philosophy of science moves further and further from the real problems. This reminds me of Ernst Mach  ― we talked about him before ― who denied the existence of atoms and relativity.

Q. Heidegger says that science does not think.

A. Which must be understood in the sense that normal science ― in Thomas Kuhn's terminology ― does not think, that is to say, it does not question its own paradigm. In contrast to Edmund Husserl, I believe that the basic shape of a phenomenon is not something unchangeable but takes place in time and can change according to experience. In Plato's terminology, I would say that our challenge is about thinking the "idea" of time. We cannot escape three-dimensional time. I remember an anecdote about Einstein asking Carnap and Popper 'what is time?' without receiving an acceptable answer. Einstein tried to eliminate time. Shortly before he died, when somebody told him that a friend died a few weeks ago, he answered that "a few weeks ago" is an illusion. For a physicist, as a believer, the difference between past, present and future is an illusion. I think, quite the contrary, that the introduction of  three-dimensional time,  that was made explicit by Heidegger, can bring about a new revolution in physics that would also resonate in philosophy. Already in Plato and Aristotle we find the key concept of kinesis, that is to say, movement and change. Chronos, literally translated as time, is already for Plato a derivative representation of aion, a term that I would like to leave untranslated. It implies the temporal structure and refers, for instance, to a person’s lifetime.

Q. Physics and philosophy meet here, in the question concerning time,...

A. as if Magellan and Vasco da Gama, starting from different points and in opposite directions, would meet during circumnavigation.



Translating this conversation – originally in German, then published in Spanish –, thirty five years later is an amazing experience, not only because my thinking and, of course, my life have changed, but particularly because the world has changed with regard to what we are used to calling the digital revolution, a paradigmatic change in the sense addressed by Thomas Kuhn and von Weizsäcker, having impact not only on science and philosophy but also on everyday life. Nobody could have predicted at the time the invention of the internet, although it was not far away. As with other paradigm changes, it has the tendency to overestimate itself and even to believe that this is eventually the final true paradigm change bringing us – whom? – the foundation and the tools needed to better understand nature and ourselves.

As in the case of physics, both classical and the quantum, it is important not to forget, as von Weizsäcker remarks at the beginning of this interview, the roots of digital technology not only in Modernity but also in Greek philosophy. Von Weizsäcker himself mentions these roots with respect to one key concept of our age, namely, information. He remarks that information, as distinct from matter and consciousness, is a third foundational category whose roots are the "Platonic eidos" and the "Aristotelian form" "dressed up in a way that a human being in the 20th century might learn about them." (Weizsäcker 1971a, 51).

This remark sent me on a long journey of research on the concept of information whose first result was my PhD on the etymology and history of ideas of the concept of information (Capurro 1978). Von Weizsäcker mentions philosophy as being a Greek invention. This is true. But it is not less true that this invention became widespread in the Hellenistic age as well as in the Arabic world, with the translation of Greek philosophers and, through them, later on into Latin in the Middle Ages. Philosophy is originally intercultural, that is to say, it disseminates and hybridizes through the ages. If we want to understand who we are in the digital age, that is to say, how we understand nature and ourselves from a digital perspective, and what are the theoretical and practical gains and losses from such an enterprise, we must think about how foundational philosophical categories such as time, matter, information, etc. are "dressed up" – "eingekleidet" writes von Weizsäcker – in our time also in different languages and contexts (Capurro, Eldred, Nagel 2013).

Von Weizsäcker addresses particularly the issue of three-dimensional time – as distinct from the pervading concept of time as a succession of 'nows' – being one of the main discoveries made by Heidegger and essential not only for understanding Quantum Theory but also for understanding nature beyond the cast of Modernity (Eldred 2014, 2015). He also points to the potential impact of this discovery in philosophy, an impact that remains still unthought, having also high relevance in the field of information ethics (Nakada, Capurro 2013). It needs no further evidence to become aware of the impact of digital technology in the lives of most people with different kinds of dependency on the time regime instantiated by digital technology that regulate and even rule life, thus becoming what is being called onlife. The gains and losses of onlife concern not only surveillance issues by different private and public agents, but also a loss of freedom that we could get back by going offlife not only in everyday life but also in experiences of meditation as addressed by von Weizsäcker in order to distance oneself from the obsessions of the digital age. What is particularly relevant for future research in natural philosophy is to think about how the present one-dimensional time regime grounded in digital technology affects the way we understand nature and ourselves, the gains and losses thereof, and the possibility of a revolutionary cast based on three-dimensional time as addressed by von Weizsäcker thirty five years ago.


Capurro, Rafael (1978). Information. Ein Beitrag zur etymologischen und ideengeschichtlichen Begründung des Informationsbegriffs. Munich: Saur.

Capurro, Rafael (1982). La deuda de la ciencia natural. Opinar, Dec. 30, p. 20.

Capurro, Rafael; Eldred, Michael; Nagel, Daniel (2013). Digital Whoness: Identity, Privacy and Freedom in the Cyberworld. Berlin: de Gruyter.

Eldred, Michael (2014). Being Time Space: Heidegger's Casting of World.

Eldred, Michael (2015).  A Question of Time. An Alternative Cast of Mind. North Charleston: CreateSpace.

Kuhn, Thomas S. (1962). The Structure of Scientific Revolutions. Chicago: The University of Chicago Press.

Nakada, Makoto; Capurro, Rafael (2013). 'An Intercultural Dialogue on Roboethics,' in Makoto Nakada and Rafael Capurro (eds.): The Quest for Information Ethics and Roboethics in East and West. Research report on trends in information ethics and roboethics in Japan and the West. Research Group on the Information Society (ReGIS), Tsukuba (Japan) and International Center for Information Ethics (ICIE) (Karlsruhe, Germany) (eds.), March 31, 2013, pp. 13-22. ISSN 2187-6061.

Tarigo, Enrique (1982). Introducción. Opinar, Dec. 30, p. 20.

Weizsäcker, Carl Friedrich von (1971). Die Einheit der Natur. Munich: Hanser (Engl. The Unity of Nature. New York 1980).

Weizsäcker, Carl Friedrich von (1971a). Sprache als Information. In ibid.: Die Einheit der Natur. Munich: Hanser.

Last update: August 24, 2018


Copyright © 2018 by Rafael Capurro, all rights reserved. This text may be used and shared in accordance with the fair-use provisions of U.S. and international copyright law, and it may be archived and redistributed in electronic form, provided that the author is notified and no fee is charged for access. Archiving, redistribution, or republication of this text on other terms, in any medium, requires the consent of the author.


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