Nathan Gardels is the editor-in-chief of Noema Magazine. He is also the co-founder of and a senior adviser to the Berggruen Institute.
The insight of quantum physics is that the discoveries of classical science did not so much reveal “objective truths” of the world as co-constitute them through our subjective perception of the object of inquiry. This led to the further insight that all phenomena do not exist in and of themselves but are constituted by their relations to something else. Unforetold possibilities emerge out of that relationality in the constant flux of contingent circumstance.
Since human participation in the construction of reality is perspectival, there are necessarily blind spots beyond that perception. Thus, there can be no “complete objectivity” just as there is no comprehensive closed system, the course of which is predetermined.
In his new book, “On the Equality of All Things: Physics and Philosophy,” the celebrated theoretical physicist Carlo Rovelli offers some tantalizing passages on how the ideas of Niels Bohr, a leading pioneer of quantum science, were likely influenced by a most unlikely source: the Christian existentialist philosopher Søren Kierkegaard.
Bohr could not have grown up in his native Denmark without being exposed to the ideas of that country’s most famous thinker. And, as Rovelli quips, “physicists rarely invent anything without first getting permission from a philosopher.”
The dominant cultural paradigm of Kierkegaard’s time, from the early to mid-19th century, was the Hegelian system, “where everything finds its place in a rational universal conception of reality.” Yet, Kierkegaard felt intuitively that “something essential was missing” from this grand framework of the spirit of history unfolding from above and beyond.
Rovelli recounts the doubts the Danish philosopher cast on the abstract notion of an objective order as an encompassing whole, the laws of which humans could only endeavor to decipher.
As Kierkegaard saw it, “the system of Hegel, or all the objective truths of Christianity, are irrelevant to our individual choice, which is the central issue, the only true issue,” writes Rovelli. Standing at the crossroads between salvation and eternal damnation in the Christian eschatology, Kierkegaard argued that the choice of believing in God or not was of “infinite importance for each one of us.”
“In this way,” Rovelli continues, “Kierkegaard reverses the Hegelian perspective: what matters most is individual truth. Then he makes a fundamental observation which seems to me to anticipate Heidegger: the Hegelian system is described from the outside. What distinguishes it from the abstract description of something that is not real? What links it to reality? The answer is that it is our individual perspective that shows it to us as real, since we, as parts of it, are ourselves real.
“This way of thinking puts the individual perspective at the center, even if every individual perspective is only partial. This is the inescapable existential situation in which we find ourselves. Kierkegaard’s conclusion is extreme — ‘truth is subjectivity’ — thus overturning the widespread idea that arriving at truth requires our subjectivity to be set aside.”
In other words, since faith is experienced subjectively, the truth of Christianity for Kierkegaard lies in the personal commitment to that experience. Objective uncertainty over whether God exists or not can only be resolved through the act of a “leap of faith.” By taking this leap that embraces “the most passionate inwardness of truth,” the believer is a constitutive participant in the relational construction of the existence of God. (This is also the theme of an earlier essay in Noema titled, “The Birth Of God In The Soul.”)
How does this relate to quantum physics?
“The truth of a physical process is subjective,” Rovelli explains from the quantum perspective. “It lies in the observer. Kierkegaard, like Bohr, intuits that the heart of reality lies in subjectivity, and in the plurality of subjectivities …. the ‘subjectivity’ I am speaking of has nothing to do with the eternal salvation of Christianity, nor even with us humans in general. It is instead the central idea that truth is intrinsically perspectival. ‘Relative’ is thus a better word than ‘subjective’ here, since ‘subjective’ is usually reserved for human or animal perspectives. But the thread from the tormented Danish philosopher is nevertheless there.”
“As ‘co-creators of the fabric of reality,’ the world ahead of us is not predetermined but shaped by the choices we make.”
Our world is a “mirroring of perspectives,” Rovelli concludes. “Objectivity without a subject is an abstract construct, of little relevance — it is the illusion of a science now belonging to the past.”
The Nobel poet Czeslaw Milosz once put that realization this way: “The theory of quanta … restores the mind to the role of co-creator of the fabric of reality. This favors a shift from belittling man as an insignificant speck in the immensity of galaxies to regarding him again as a main actor in the universal drama.” In short, we are fundamental to the reality we observe.
As “co-creators of the fabric of reality,” the world ahead of us is not predetermined but shaped by the choices we make. Yet those choices must be made in the absence of full knowledge of the world; in the uncertainty of an undetermined future that can’t be known. Their true meaning will only emerge after events occur.
As Rovelli points out, this is the quantum reality as well: We don’t know in advance what reality will emerge from the plurality of relational influences that converge to constitute the next moment.
Kierkegaard pithily summed up this existential condition of humanity, which also conveys the insights of quantum science: “Life can only be understood backwards, but it must be lived forwards.”
