Is Quantum Mechanics a Science? Here’s What Karl Popper Thinks

Why did philosopher Karl Popper believe that quantum mechanics should be revised?

Aug 11, 2023By Viktoriya Sus, MA Philosophy
quantum mechanics science karl popper


Karl Popper was the most influential 20th-century philosopher of science. Central to much of his work were questions relating to quantum mechanics. One might be curious as to how a philosopher could insert himself into discussions strictly related to scientific research. And yet Popper’s engaging arguments regarding quantum mechanics quickly become apparent when one delves deeper into his critical writings.


In particular, Popper was concerned with how one might falsify quantum mechanics, as he argued that any proper scientific theory should be falsifiable.


Who Was Karl Popper?

karl popper photo
Photo of Karl Popper, c.1980, via Flickr.


Karl Raimund Popper is considered one of the greatest philosophers of science of the 20th century. He was also a major social and political philosopher who declared himself to be a “critical rationalist,” a staunch opponent of all forms of skepticism, conventionalism, and relativism in science. Karl Popper was a staunch defender of the “Open Society” and an implacable critic of totalitarianism in all its forms.


He argued that the only way for science to make progress was by objective testability, refuting his opponents’ views. He is known especially for his criticism of the logical positivism movement and for his famous book The Logic of Scientific Discovery (1935). Popper argued that scientific theories can never be proven to be true but can instead only ever be tentatively and hypothetically accepted as an approximation of the truth.


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Since Karl Popper lived in the 20th century, his philosophical and logical-methodological concepts embodied a whole range of concepts, ideas, problems, and requirements that were relevant at this time in history. In this sense, Karl Popper, as a scientist and philosopher, is a “brainchild” of his era. He not only forms the style of thinking of his time and embodies it in his future programs, but he himself is under some influence of the latter.


His works, including his later works on quantum mechanics, were highly influential in the realm of scientific philosophy. Popper is remembered as one of the champions of science and reason against the superstitious and authoritarian tendencies of the 20th century. Popper engaged in debates with many other philosophers of science, including Niels Bohr and Albert Einstein, and his views often challenged the accepted scientific conventions of his time.


Why Did Karl Popper Become Interested in the Problems of Quantum Mechanics?

false mirror magritte
The False Mirror by René Magritte, 1929, via MoMA.


Karl Popper’s engagement with the problems of quantum mechanics stems from his interest in the philosophy of science. He was a firm believer in the scientific method and saw it as the best way to make progress in understanding the universe. Furthermore, he believed that science should be falsifiable and testable and that theories should always be subject to criticism.


Due to the nature of quantum mechanics, with its probabilistic and uncertain equations, Popper felt that it was not amenable to the scientific method and, therefore, could not be truly studied or understood. He argued that it was impossible to make predictions using quantum mechanics and that it must be reinterpreted to render it testable.


Besides, Popper was also critical of the Copenhagen interpretation, which stated that physical laws could only be applied to observed phenomena. In his opinion, it was too reliant on human interpretation and prevented a truly scientific explanation of the universe.


So, Popper proposed an alternative interpretation that would render quantum mechanics observational, testable, and falsifiable. These views put him at odds with many of his contemporaries, but they were highly influential in the field of scientific philosophy.


Advances in Physics and the Crisis of Understanding

isaac newton hannah
Master Isaac Newton in His Garden at Woolsthorpe, in the Autumn of 1665 by Robert Hannah, early 1850s, via ArtUK.


Physical science is of great importance not only for the philosophical style of thinking, the basis of which is an expanding knowledge of the world around us, of which we are a part. The importance of physics lies in the fact that it periodically gives rise to reviewing and improving the system of our views and concepts as a tool of knowledge. Within the framework of each epoch, such areas of knowledge that determined the style of philosophical thinking of past epochs remain essential for science as a whole.


The classical mechanics of Newton-Maxwell, for example, still retain their fundamental importance for the whole of natural science, but it no longer determines the way of thinking of the modern era.


As in most sciences, there is also a crisis of understanding in physics. It is associated with the appearance of new questions and problems in mathematics, physics, and other sciences.


The crisis of understanding, according to Popper, arose in physics along with the Copenhagen interpretation, or, more precisely, from the point of view of Bohr and Heisenberg on the status of quantum mechanics.


In his opinion, quantum mechanics should be interpreted as the last revolution in physics, since the inherent boundaries of knowledge were reached in it.


solvay conference
The Fifth Solvay International Conference on Electrons and Photons by Benjamin Couprie, 1927, via ETH Library.


Popper believed that quantum mechanics should not be considered a finished theory but rather an interim one that must be understood and developed further. He argued that it should be interpreted as an open system and subject to criticism, which will then help solve many of this field’s mysteries.


Linking the crisis of understanding in physics with the Copenhagen interpretation of quantum mechanics, Popper points to the reasons underlying this crisis – the penetration of subjectivism into physics and the belief that quantum theory contains complete and final truth.


Popper believes that the only way out of this crisis is to replace the Copenhagen interpretation with a new, more objective view that allows us to form testable hypotheses and then test and verify or falsify them.


Quantum Theory and the Schism in Physics

abstract speed sound balla
Abstract Speed + Sound by Giacomo Balla, 1913, via Guggenheim.


The book Quantum Theory and the Schism in Physics (1982) occupies a special place in Popper’s creative heritage. Popper always showed interest in quantum mechanics, not as an outside observer but as an active participant. He was constructively intruding into theoretical physics, offering thought experiments and interpretational models.


Popper, in his interpretation of quantum mechanics, is a stark opponent of the Copenhagen approach formulated by Niels Bohr, Werner Heisenberg, Wolfgang Pauli, and also partly by Max Born and Paul Dirac. This approach means that the quantum world is essentially unpredictable, but nevertheless, there are certain restrictions on its behavior.


In this regard, his position is similar to the position of such major modern physicists who contributed to the development of quantum mechanics, such as Albert Einstein and Erwin Schrödinger.


einstein photo
Photo of Albert Einstein in 1947 by Orren Jack Turner, via Library of Congress.


One of the problems that essentially determined the development of the philosophy of science at the beginning of the 20th century was called the problem of demarcation (this term was introduced by Karl Popper). This problem is about defining the boundaries between science and non-science.


At the time, Popper was not interested in the question “when is a theory true?” nor in the question “when is a theory acceptable?” Popper posed a different problem for himself – he wanted to distinguish between science and pseudoscience, knowing full well that science is often wrong and that pseudoscience can accidentally stumble upon the truth.


The most common answer to this question was that science differs from pseudoscience or from “metaphysics” in its reliance on facts in its empirical method. Popper, however, disagreed with this view. Instead, he argued that relying on empirical facts was not enough to distinguish science from pseudoscience.


Popper argued that science should be based on falsifiable hypotheses and that pseudoscience is based on unfalsifiable hypotheses. By this criterion, Popper believed that quantum mechanics was a pseudoscience because it relied on fundamentally uncontrolled and uncontrollable interactions.


How Should Quantum Mechanics Go Forward According to Popper?

circles kandinsky
Several Circles by Vasily Kandinsky, 1926, via Guggenheim.


For Popper, the aim of quantum mechanics should be to find an open system that can be tested and potentially falsified. He believed that if this system is not found, then quantum mechanics would remain a pseudoscience.


Popper’s interpretation of quantum mechanics is open and based on the idea of probability, not determinism. He suggests that instead of finding an answer to a single “right” question, we should accept that there are multiple possible answers, each with its own probability.


As a central aspect of his philosophy, Popper strongly opposed any form of anti-realism and subsequently Heisenberg’s uncertainty principle. He argued that quantum mechanics should not be used as a basis for anti-realism.


In Popper’s interpretation of quantum mechanics, it is important to note that a predetermined physical law does not determine the probability of an event occurring. Still, instead, it is determined by our own ideas and assumptions.


Popper believes that quantum mechanics should be used as a tool to create falsifiable and hypotheses, which can then be tested and verified. It would move quantum mechanics away from the Copenhagen interpretation, which Popper has criticized for being too subjective.


By proposing an objective view of quantum mechanics that allows us to form testable hypotheses, Popper has opened the door for a new interpretation of quantum mechanics that considers falsifiability’s importance. In this sense, Popper’s work on quantum mechanics has greatly contributed to the development of science.

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By Viktoriya SusMA PhilosophyViktoriya is a writer from L’viv, Ukraine. She has knowledge about the main thinkers. In her free time, she loves to read books on philosophy and analyze whether ancient philosophical thought is relevant today. Besides writing, she loves traveling, learning new languages, and visiting museums.