What are the limits of science

Beyond the limits of the natural sciences

Views of a physicist

I recently got stuck in a traffic jam while driving a car. As usual in such situations, I turned on the radio. Then I heard a program about the “Limits of Science” being presented. My anger over the traffic jam quickly gave way and curiosity set in: What will be said there now? Are there the usual complaints that the scientific worldview has become too dominant, but that only a world reduced to measurable sizes is perceived and taken seriously? Is “something” going to be lost again? Is there again talk of the fact that there are other “realities”. And do you feel sorry for the scientists afterwards because they live in an emotionally barren world and can only see sound waves of different frequencies in the sounds of the 9th Symphony?
Well, I am exaggerating a little in disclosing some of my experiences in such discussions in this way. The explanations that followed were in no way so undifferentiated. Although the line of thought meandered back and forth, there was indeed much talk of reality, sometimes of its interpretation, sometimes of its diversity, in particular that none of the different manifestations is “true” (whatever that means ) and the whole thing culminated in the fact that the author of the show believed he had to break a lance for the importance of interpersonal relationships and human feelings. They are just as real as scientific phenomena, but would be described as subjective and thus “devalued”.

But the author of the program aptly described some important specifics of the scientific method, such as viewing the world as a counterpart. His remarks on phenomenology and the insight he derived from it into the impossibility of a comprehensive interpretation of the world also seemed to me to indicate that, although he is a theologian, he is not striving for a so-called ultimate justification.

But afterwards I was at a loss. Was he just claiming that in reality there are also feelings and interpersonal relationships, and that these can never become the object of scientific study? And did he complain that art, literature and music no longer enjoy the appreciation they deserve, even being treated as a “subjective residual”? The first would be trivial, the second simply not true - you only need to look at the daily feature section of a newspaper.

Even after looking into the manuscript, I didn't really realize what the author was really getting at. Somehow he had a great discomfort, like someone who didn't feel properly valued. He spoke, for example, of the fact that the arts represent an independent interpretation of reality, but because of their subjectivity it is not of inferior rank. Neither is “the so-called objective what is actually real, nor [..] the subjective just a secondary interpretation”. So he was constantly putting things in an order that could not be compared and thought he had to contradict the advocates of a naturalistic view, because they believed they had a framework for a comprehensive worldview and looked around "in reality" like a landowner, who travels to his lands, which he can by and large survey and cultivate with his tools. It seems to me that the author is not correctly interpreting the naturalists' way of thinking.

Evolution to increasingly complex systems

It is not the idea of ​​a uniform conceptual world for all phenomena in this world that makes a naturalist. He simply visualizes the becoming of all things, as we understand it today through the knowledge of natural science. In the course of evolution, increasingly complex systems with new properties and phenomena have emerged. It began with the physical evolution during the early universe, when atoms and molecules were formed, continued through chemical and biological evolution, and we humans are now equipped with a brain with which we compose symphonies and reliable knowledge about the world can create. The systems of nature have become more and more complex, in this way life came into being and with it those abilities that we call spiritual, with which we practice art and science, express our feelings and with which we are self-conscious.

All sciences are constructions of the human mind, but of different types. On the one hand, they can in turn refer to constructions of human mind, as the name “humanities” describes aptly. But they can also refer to something completely different, namely to things and phenomena in nature, whereby we want to understand everything here by nature except our intellectual constructions, then one simply does “natural sciences”. From this point of view, mathematics and theoretical computer science are humanities as well as the history of physics or the theory of science. (The fact that the structures that are constructed and analyzed in mathematics can for the most part be found in nature is no reason to count mathematics as natural science. This fit between nature and our intellectual constructions arises from this that otherwise we would not have developed that far as a species.)

Different worlds of terms

Now the variety in the phenomena of nature and in the constructions of the human mind is so great that a wide variety of areas have formed, each with a specific area of ​​phenomena. Physics, chemistry and biology are interested in systems in nature of different complexity, music and literary studies for different arts, psychology, sociology, economics and law for the coexistence of people. We should not speak of “different realities”, but of different layers of reality, even better of different areas of phenomena that the corresponding sciences seek to structure. For this they have developed their own terms and special methods and of course it does not occur to any scientist to want to describe “whole reality” with the terms of his field. It would not occur to a sane person to use the conceptual apparatus of physics to describe feelings, even if some words such as “impulse” are used in both areas.

Linking the terms of different layers, emergence

If the conceptualizations in the layers are so differently complex, if all have their own justification and constantly prove their appropriateness more or less successfully, then the question arises as to whether concepts from a more complex layer of laws and concepts can be " lower ”, less complex layer can be derived or explained. A naturalistic view only emerges when one has discovered such relationships between the objects and concepts of the individual layers and has understood the phenomenon of emergence: A multitude of objects in nature can, through their interaction with one another, form systems that have new properties and sometimes unexpected behavior demonstrate. And a scientist knows that these new properties and the new behavior are precisely the result of the interplay of the constituents. In physics, the lowest, that is, the least complex science, this is possible in many cases. I have explained this in detail in my blog posts “Emergence” and “Emergent Phenomena”. All of our terms and phenomena in our everyday world that relate to material things are recognized as emergent, and our mental activities and our consciousness are also viewed by brain researchers as emergent phenomena, although this can only be viewed as a hypothesis for the time being, because one really has not yet understood how the interaction of neurons creates our sense of consciousness.

On the other hand, we have fully understood how thermodynamic terms such as temperature and pressure arise in a gas if it is understood as a set of individual atoms or molecules. If one were to say in this revelation of the relationships between two layers that a gas is “nothing more than a set of molecules”, one would not have grasped the essential point: It is the interaction of the constituents that lead to the phenomena of the overall system “gas " to lead. The formula “that is nothing else than…” is not, as so often claimed, a “naturalistic narrowing”, as the author of the show puts it, but just a way of speaking about a kind of “silent post” on the way emerged from natural science and does not take into account the essential point, the interplay of the constituents. In football it is also the teamwork that defines a team, with a melody it is not the set of tones but at least their order and with a group of people it is precisely the interpersonal relationships that determine the character of the group.

Many explanations in the natural sciences are precisely of the type in which “top-down” relationships are established. The motive behind it is always the belief in the unity of nature. Of course this is a metaphysical assumption, but it is a hypothesis that has so far proven itself brilliantly and which has already led to a reliable, uniform worldview for the lower classes. Nobody is surprised if he understands the concept of emergence correctly and does not fall into the “nothing but…” trap. Much could be said about the relationships between chemical and physical, biological and chemical, mental and physiological terms and phenomena, but that would be a story of its own.

Objectivity and subjectivity

Findings in the natural sciences are described as objective and reliable. In fact, there is no serious physicist who today doubts the validity of the theories of relativity or of quantum mechanics for large areas of phenomena. Short-term aberrations such as the “German Physics” movement only confirm that the laws of physics must be regarded as universally valid, regardless of all ideologies. Should aliens ever really visit our earth, they will probably know the same laws, albeit in a completely different form. The reliability of the findings is shown most clearly in the fact that they can be used in technical devices.

There is also objective and reliable knowledge in the humanities, e.g. in relation to events that have taken place in history. I can often not be in doubt about my own feelings either. But it is the relationships between such facts that make a science, and this is where the big difference comes about. We accept that “Faust” is different in every performance and can be reinterpreted for every time, or that there are contemporary ideals for the performance of symphonies and operas. If you try to create ever greater connections and go into the field of philosophies and religions, you will find that there are at least as many philosophical approaches as there are philosophers and an almost unmanageable number of religions. Even today we can no longer imagine a human life without this diversity and individual freedom in thinking.

If one assumes that “creating knowledge” means something like “setting or formulating relationships”, then the sciences that deal with the constructions of the human mind and those that analyze the phenomena of nature do not differ at all . The only advantage in the natural sciences is that these relationships can be quantified and checked. This is simply due to the object of the research, and this ultimately results in the possibility of objectivity and reliability. Recognizing this possibility of quantitative formulation and verification and demonstrating it using the example of free fall, that was the achievement of Galileo, and he saw very clearly that he had discovered a “new science” here, which natural philosophy on the Would replace duration.


What about the devaluation of the “subjective” that the author is talking about. Finally, when he comes back to “interpersonal experiences, aesthetic impressions of the visual arts or music”, and “spontaneous experiences of meaning” and “intuitions of fundamental moral values”, he complains that we call them “subjective and in banish the inner being of the individual ”. He sees this as "an unfounded metaphysical assumption that at the same time devalues ​​the phenomena."

Whenever one speaks of a value, one must always ask oneself for “what” then “something” is supposed to represent a value. For a single person, a “spontaneous experience of meaning” can be of great value and a great support for his future life. For others, an associated meaning is just one of many, and everyone will have their own subjective experiences, impressions and intuitions. We should grant every subject the right to be able to follow his “spontaneous experiences of meaning”, but we should not raise any of these experiences to the rank of objective knowledge and claim that everyone must see this meaning “with correct use of their reason”. This contradicts my “intuition of a moral behavior”.


Josef Honerkamp was professor for theoretical physics for more than 30 years, first at the University of Bonn, then for many years at the University of Freiburg. He has worked in the fields of quantum field theory, statistical mechanics and stochastic dynamic systems and is the author of several text and non-fiction books. After his retirement in 2006, he would like to devote himself even more to interdisciplinary discussions. He is particularly interested in the respective self-image of a science, its methods as well as its basic starting points and questions and can report on the views a physicist comes to in view of the development of his subject. Overall, he sees himself today as a physicist and "really free writer".