Buchwald, Jed

historian and philosopher of science, Caltech; former research assistant to Thomas Kuhn

Jed Buchwald: Isaac Newton and the Philosophy of Science

Lex Fridman Podcast · Aug 27, 2021

• Jed Buchwald
• Isaac Newton biography
• Thomas Kuhn and paradigm shifts
• history of optics
• wave theory versus particle theory of light
• Newton-Leibniz calculus dispute
• Newton and alchemy
• Newton's religious beliefs
• scientific realism
• history of the scientific method
• Robert Hooke rivalry

Core ideas

Buchwald, drawing on decades of direct engagement with Thomas Kuhn (whose research assistant he was), pushes back on the clean version of Kuhn's "paradigm shift" model of scientific revolutions. Using his own historical work on the 19th-century triumph of the wave theory of light over Newton's particle theory, he argues the standard Kuhnian story — that an old paradigm collapses because it cannot explain some anomaly — doesn't hold up: Newton's particle account of light could, after the fact, accommodate the same diffraction phenomena the wave theory explained. What actually mattered was that the mathematics of wave optics let researchers like Augustin Fresnel generate genuinely new experimental phenomena and devices (via polarization) that the older framework could only retrofit, never originate — so scientific frameworks are displaced less by explanatory failure than by their comparative fertility for producing novel work. He extends this to a broader claim that the history of science is not cleanly divisible into "lone genius" and "collective/gradual" narratives: transformative shifts typically involve one or a few central figures, but those figures work within, and are enabled by, a wider context of mathematical tools, instruments, and social practice that would likely have produced similar developments (via different people, like Huygens) even absent any single individual.

He situates Newton's originality carefully. Newton was already a highly skilled but disengaged mathematician when a suggestion from his rival Robert Hooke (later a source of bitter priority disputes) supplied the key technical device — treating motion as unfolding through infinitesimal time increments — that let him mathematize forces acting at a distance, an idea previously dismissed by mechanical philosophers who required direct contact between interacting bodies. Buchwald recounts Newton's prism experiments (showing white light is composed of distinct, unequally refrangible rays, contra the prevailing view that prisms merely "tinted" light) as an example of ingenious manipulative experimentation — Newton exploited the very impossibility of precise instrumental calibration by hand-tuning the prism to a special angle where image movement is slowest, letting imprecise manipulation still yield an exact result. He also credits Newton and contemporaries like Huygens with the shift, traceable to Descartes, from believing sensory qualities (color, sound, warmth) exist "out there" in nature to understanding them as artifacts of the perceiving mind — a conceptual break Buchwald calls comparable in magnitude to Einstein's insights, since it reoriented science toward distrust of raw sensation in favor of instrumentally mediated investigation.

On calculus, Buchwald describes Newton's route through generalizing the binomial theorem to expansions involving continuous change, arriving at reciprocal procedures for finding areas under curves and tangents to them; he covers the parallel, contested case of Leibniz's independent (or, per a disputed reading of manuscripts uncovered by historian Domenico Bertoloni Meli, possibly reverse-engineered) development of calculus notation, and situates the resulting priority dispute within a period when scientific credit and professional norms were still being established, contrasting it with less personality-driven episodes (though he also narrates a case of scientific rivalry functioning productively: Arago's resentment of Biot indirectly launched Fresnel's career in wave optics). He characterizes Newton as a solitary, self-contained, sometimes vindictive man — citing his ruthless pursuit of counterfeiters as Master of the Mint and his lifelong resentment of the stepfather who took his mother away — and traces some of Newton's scientific productivity, including the "year of wonders" 1666, partly to enforced isolation from Cambridge during plague closures, though Buchwald is careful to note Newton had already made substantial progress before going home and likely would have continued regardless.

On method and evidence, Buchwald explains that Newton's era lacked modern statistical concepts like averaging repeated measurements (only formalized via the central limit theorem in the mid-to-late 1700s); scientists like Huygens, who took many measurements, would nonetheless publish only the single value they felt most confident in, rather than an average — a norm Buchwald contrasts with, and cautions against over-trusting, our own contemporary reliance on statistical aggregation. On alchemy, he reframes it as neither pure mysticism nor proto-chemistry but a serious manipulative practice ("chrysopoeia") aimed at transmuting materials, through which practitioners (including Newton, who spent more time on alchemical work in the late 1670s than on anything else) developed real techniques for producing chemical amalgams, even if encoded in symbolic, esoteric language. On Newton's religion, Buchwald describes him as a deeply devout but heterodox believer — an anti-Trinitarian who held Christ was empowered but not divine, believed miracles had ceased since antiquity, and accepted a roughly 6,000-year-old biblical chronology for creation — and argues Newton's confidence that nature's laws could be rationally discovered stemmed directly from his belief in a non-arbitrary, rule-following creator.

Buchwald is explicitly skeptical of naive scientific realism, describing himself as doubting that instruments and mathematics ever grant unmediated access to "the depths of reality," and uses an extended analogy (a dragonfly's radically different perceptual construction of the same scene, or a PDF being merely a construct of light rather than "real paper") to argue scientific knowledge is inevitably filtered through the instruments and perceptual/mathematical structures used to probe it. He is a self-described materialist about consciousness — rejecting that inanimate objects like a bottle of water are conscious, while declining to claim confident insight into what organizational structure of matter produces subjective experience, and suggesting neuroscience may eventually correlate brain activity with experience without necessarily explaining first-person perception itself. Looking toward physics's future, he doubts the field will continue relying on ever-larger particle accelerators indefinitely, expects attention to shift toward unresolved higher-level phenomena (chemistry, complex systems), and voices mild skepticism (contra Steven Weinberg) that a completed "theory of everything" would constitute full understanding of reality's deepest workings, given his broader doubts about whether mediated, instrument-based science can ever get "beneath" appearances at all. He closes by speculating that a time-displaced younger Newton could, with gradual exposure to intervening technology and ideas, eventually grasp Einsteinian relativity, but that the conceptual distance between Newtonian and Einsteinian physics reflects an enormous, multi-century accumulation of mathematical, experimental, and technological development rather than a single leap.

Excerpts