My introduction to the legendary physicist Max Planck was decades ago during my undergraduate studies in thermodynamics. Through his work across the late 19th and early 20th centuries, Planck deduced a universal constant ‘h’ for the distribution of energy emitted from a blackbody. What came to be known as Planck’s constant forever changed scientific perceptions of the natural world. His work was a foundational precursor to modern quantum theory and marked the “end of the mechanical age in science, and the opening of a new era.”
Today, in my study of science and religion, I am discovering that what made Planck such a great physicist was also his understanding of philosophy. In his 1932 book, Where is Science Going?, Planck laments the crisis of history that he observed overwhelming every branch of “spiritual and material civilization” and corrupting“the general attitude towards fundamental values in personal and social life.” Some people saw this change as positive progress while others believed it marked the end of civilization. This skepticism, Planck notes, first took root in religious fields—eroding the moral systems of society—and evenly burrowed its way into the sciences such that, “There is scarcely a scientific axiom that is not nowadays denied by somebody. And at the same time almost any nonsensical theory that may be put forward in the name of science would be almost sure to find believers and disciples somewhere or other.”
More than 70 years later, Planck’s lament rings familiar as many wonder, as he did then, if “there is any rock of truth left on which we can take our stand and feel sure that it is unassailable and that it will hold firm against the storm of skepticism raging around it” Every generation has its share dystopian acolytes, yet Planck’s concern seems keenly prophetic in depicting the state of the modern mind.
Planck’s chief concern in science was the trend among respectable institutions to reject the principle of causality which was, prior to his time, universally accepted and a foundational assumption for research. Specifically, Planck opposed scientific positivism which denied the reality of the outside world. Planck shared common ground with positivists in seeing the individual’s sense-perception of the outside world as the starting point for all scientific knowledge . Einstien in his intoruction to the book summarizes this idea well:
Thus the supreme task of the physicist is the discovery of the most general elementary laws from which the world-picture can be deduced logically. But there is no logical way to the discovery of these elemental laws. There is only the way of intuition, which is helped by a feeling for the order lying behind the appearance and this Einfuehlung is developed by experience.
Recognizing this shared epistemolgical starting point, but the positivist was not willing to go any further. Planck rightly saw the danger in the positivist’s rejection of a reality outside one’s own personal experience. The following is the example he used to illustrate the dilemma:
Our daily habits of speech make it rather difficult for us to observe the strict positivist rule. In ordinary life when we speak of an outer object—a table, for instance—we mean something that is different from the table as actually observed by physical science. We can see the table and we can touch it and we can try its firmness by leaning on it and its hardness and if we give it a thump with our knuckles we shall feel a hurt. In the light of positivist science the table is nothing more than a complex of these sensory perceptions and we have merely got into the habit of associating them with the word table. Remove these sensory perceptions and absolutely nothing remains. In the positivist theory we must entirely ignore everything beyond what is registered by the senses and therefore we are impregnable in this clearly defined realm. For the positivist, to ask what a table in reality is has no meaning whatsoever; and this is so with our other physical concepts.
The ultimate danger of positivism was its denial of scientific realism and of any objective reality outside experience. If this is true, Planck argues, then the entire scientific revolution is rendered meaningless because both Ptolemy’s earth-centered universe and Copernicus’ heliocentrism are equally valid. “They are merely two different ways of making a mental construction out of sensory reactions to some outer phenomena; but they have no more right to be looked upon as scientifically significant than the mental construction which the mystic or poet may make out of his sensory impressions when face to face with nature.” Thus, the positivist is left with no way to meaningfully observe nature and must consequently reject any esthetic or ethical standard.
The positivist philosophy is impotent to make sense of everyday experiences. For example, when a stick is placed into a glass half filled with water, what do we observe? The length submerged appears bent. But is any trained observer tricked by their eyes into thinking the stick is truly bent? No. They recognize the law of refraction is at work and the appearance of a bent stick is a deception of the eye. Experience then is falsifiable. Reality exists outside experience if we only have a way to determine that reality. However, the positivist is not so lucky. “The positivist will not allow us to conclude anything. We have a sensory impression of the part of the stick that is in water and a contiguous sensory impression of the part that is in air; but we have no right to say anything about the stick itself.”
Planck’s illustration reminds me of the old scientific riddle, “If a tree falls in the forest and no one is there to hear it, does it make a sound?” As a trained acoustician, my first response is to answer “the tree does make a noise, but does not make a sound.” But this is a purely materialistic interpretation of this question. A noise is the production of energy waves when the tree strikes the ground, but only becomes sound if there is someone to hear it. But there is a deeper metaphysical truth exposed by this question I had not considered prior to reading Planck. The question really asks, “does anything exist outside of observational experience?” “Can the sound exist for me, but not for you?” How a person answers this question exposes them as either a scientific positivist or scientific realist. In denying any external reality, the positivist has no way to discern any truth outside of personal sense experience. Even more destructive, the positivist is left in isolation with no way to share in the experience of others.
When we come from the animal world to the world of human beings we find the positivist scientists making a clear distinction between one’s own impressions and the impressions of others. One’s own impressions are the sole reality and they are realities only for oneself… But, in the strict positivist view, we have no reliable knowledge whatsoever of other people’s impressions. Because they are not a direct sensory perception, they do not furnish a basis for the certainty of our knowledge.
Positivist logic has continued to creep its way into the foundation of Western culture and today we can observe the deleterious consequence in our isolationist—even narcissistic—ethics as predicted by Planck. The everyday positivist of our time concludes:
- If I can feel only my pain, then only my pain exists.
- If I self-identify as female, then no one can deny my feeling because there is no biological reality to constrain me.
- If I feel like aborting my baby, then the feelings of others do not exist in my reality and any choice I make is justified.
- If I am offended by your actions, your feelings or intentions do not matter because only my feelings can determine my truth.
- If my heart tells me something is good, then there is no external reality to contradict my feelings or tell me my actions are bad.
- If a man is not a woman, then he cannot speak to a “woman’s issue” because he cannot “know” her experience.
Positivism leaves us stranded on our own island of reality; impotent to exchange ideas or speak to the experience of others because there is no common reality outside of us to govern that exchange. Given this challenge, how then must we respond? Planck makes the choice for scientists clear:
So we are faced with the alternative of either renouncing the idea of a comprehensive science, which will hardly be agreed to even by the most extreme positivist, or to admit a compromise and allow the experiences of others to enter into the groundwork of scientific knowledge. But we should thereby, strictly speaking, give up our original standpoint, namely, that only primary data constituted a reliable basis of scientific truth.
So then, if we accept all sense perception as absolute we cannot deny the validity of any scientific experiment. To every researcher, their own experience is truth and theoretical physics is excluded from knowledge. If science rests solely on the foundation of isolated experience, then the dependability of science is lost. But, if we choose to accept the reports of others as knowledge (scientific data) we break the chain of logic in scientific positivism.
Now, having poisoned the roots of scientific positivism, Planck moves into the realm of the metaphysical. If sense-perception is a starting point, but not the end of science, we must have a way to determine the validity of experience outside our own. That is, we must accept a scientific realism that exists outside of individual perceptions, feelings, and emotions. The two pillars of realism he outlines are: “(1) There is a real outer world which exists independently of our act of knowing) and, (2) The real outer world is not directly knowable.”
On the surface, these two statements appear in contradiction. But together they make the case that scientific knowledge is only partial and corrigible and it must interact with other disciplines, such as philosophy and theology, to make any sense of the real world. Every new scientific discovery only unveils a new realm to be discovered. The goal of science is unobtainable as it can never reach the metaphysical.
How will you determine the truth that exists outside you own experience?
That is the question Planck evokes in the mind of the reader. For me, the answer lies in the warranted true belief in the external reality of God who speaks to us through his word: the Christian Bible, the Holy Spirit, the living Christ and the manifest church. In humility, I accept scientific realism and through my faith seek to find a way to engage with others and learn from their experiences. To that end, I leave you with this poem by Planck.
“Was Du gefflueckt, was ich gefflueckt
Das wollen wir verbinden
Und weil sich eins zum andern schickt
Den schoensten Kranz draus winden.”
 Max Planck, Where is science going?, trans. James Vincent Murphy, First ed. (New York: W.W. Norton & Company, 1932), 17.
 Ibid., 64.
 Ibid., 65.
 Ibid., 66.
 Ibid., 10.
 Ibid., 69.
 Ibid., 71.
 Ibid., 73.
 Ibid., 74.
 Ibid., 76.
 Ibid., 77.
 Ibid., 36.