By the turn of the seventeenth century, early modern Europe had laid out the groundwork for calculus, deciphered the basic principles of electromagnetism, engineered the telescope and microscope, and devised mathematical laws for the motion of physical bodies. The Scientific Revolution that marked the century ushered in profound advancements among the prevailing intelligentsia and broader society, but it also overshadowed a tragic divide that was beginning to emerge within natural philosophy – the then-prevailing study of the physical world.
Before Bacon’s advocacy of the scientific method and Galileo’s advent of observational astronomy, inquiries on the inner workings of the universe were predicated on logic and reasoning. Then came Newton’s 1687 synthesis of the physical world expounded in his Principia Mathematica, which brought about a mathematical understanding of nature that was empirical, rigorous, and self-consistent. It popularized a robust method for dealing with metaphysical questions—such as on space, time, and motion—that estranged many in the philosophical community, who were both satisfied with a qualitative analysis and alienated by the technicality of Newton’s approach. The successes of Boyle, Gauss, Helmholtz, Kelvin, and Maxwell—among others—only deepened this divide. By the nineteenth century, physics began to take shape as a distinctive discipline with an already sizeable literature. In fact, it had grown so large in scope that it became impractical to learn enough physics (which already included mechanics, thermodynamics, acoustics, electromagnetism, and optics) and canonical philosophy to contribute to both disciplines.
The current attitude in physics could hardly be more opposed to philosophy, at least on the surface. In his book Against Philosophy, Stephen Weinberg, widely regarded as one of the greatest physicists of the last generation, argued that philosophy is more damaging to physics today than it is helpful. Neil deGrasse Tyson publicly remarked that physics “rendered [philosophy] essentially obsolete”, while Stephen Hawking famously quipped that “philosophy is dead.” The common trope among the physics community today is to “shut up and calculate.” Who could blame them? It was this emphasis on computation and calculation that led to the enormous successes of solid state physics, particle colliders, nuclear and atomic physics, and the Standard Model – our closest rendition yet of a “theory of everything”.
Yet it was also substantive philosophical reasoning that led Einstein towards his Theory of Relativity and which paved way towards Quantum Mechanics. Einstein frequently proclaimed his debt to philosophy, writing, “[a] knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is—in my opinion—the mark of distinction between a mere artisan or specialist and a real seeker after truth.” Philosophy affords a series of skills that training in physics seldom imparts directly: the dissection of conceptual ambiguities, a lucidity towards hidden assumptions, an ability to devise radically novel perspectives, and a proficiency for putting together and pulling apart robust qualitative arguments.
Perhaps the most striking irony lies not with the provenance of modern physics nor with its apparent neglect of philosophical doctrine, but with its current mode of practice. Theoretical physics, the branch of physics responsible for creating frameworks that describe and explain the universe, is rife in philosophical reflection and logical reasoning. This is hardly surprising too. Such a great deal of nature lies outside the scope of our current observational domain—from the enigmatic interiors of black holes or the earliest moments of the big bang to the microscopic structure of spacetime—that a theorist is left with little choice but to ponder on how the universe should work, if at least the universe was a logical place. The problem is that our sense of logic is subjective, depending not only on our personal experiences but also on our evolutionary upbringing: biology occurs at a certain scale in the universe, and the laws of nature take a shape at that scale that is not the same as the shape it takes at more fundamental scales. This leaves it to be (almost) anyone’s guess which theory is the right one to describe the parts of the universe that we cannot yet observe.
In the absence of empirical data, philosophical synthesis has stealthily crept into the margins of most theorists’ work. It may be that a degree of philosophical training is exactly what theoretical physics needs then, not because philosophy alone will pave the path towards the theories of the future but because it will provide theorists with the tools and skills that they will need to elucidate nature in the dark.
Sarah W. Hirschfield 