Pierre-Louis Moreau de Maupertuis

Life and Scientific Career

Pierre-Louis Moreau de Maupertuis (1698–1759) was a French mathematician, physicist, and natural philosopher whose work bridged Newtonian mechanics, experimental science, and speculative metaphysics during the Enlightenment. Born into a prosperous merchant and corsair family in Saint-Malo, he initially trained for a military career but soon turned to mathematics and the natural sciences in Paris.

In Paris, Maupertuis joined the Académie des Sciences (as a correspondent in 1723 and full member in 1727) and became an influential advocate of Newtonian physics in a predominantly Cartesian French intellectual milieu. He wrote expository works that helped introduce and defend Newton’s theory of gravitation in France, arguing against Cartesian vortex theory and championing the empirical and mathematical virtues of Newton’s system.

Maupertuis gained international prominence through his role in the celebrated French geodesic expeditions organized to determine the exact shape of the Earth, a high-stakes test between Newtonian and Cartesian cosmologies. In 1736–1737 he led the Lapland expedition to measure a degree of meridian near the polar circle, while another team traveled to Peru. The Lapland measurements supported Newton’s prediction that the Earth is an oblate spheroid (flattened at the poles), undermining rival Cartesian models and strengthening the Newtonian synthesis. Maupertuis reported these results in La figure de la Terre (1738), which framed the outcome as a decisive victory for Newtonian physics.

In 1740 Maupertuis accepted an invitation from Frederick II (Frederick the Great) of Prussia, who admired him as a leading Newtonian. In 1745 he became president of the Berlin Academy of Sciences (Académie Royale des Sciences et Belles-Lettres), where he promoted mathematical and experimental work and entered into often contentious interactions with other intellectuals, including Voltaire. A notorious controversy over alleged plagiarism and mathematical errors in a problem concerning geodesy—known as the Königsberg longitude dispute—helped sour his relations with some contemporaries and damaged his reputation late in life.

Suffering from ill health, Maupertuis left Berlin for Basel, where he spent his final years in relative isolation and died in 1759. Despite personal and intellectual conflicts, his work exerted lasting influence on physics, the philosophy of nature, and early biological thought.

Principle of Least Action and Natural Philosophy

Maupertuis’s most famous contribution is his formulation of an early, general version of the principle of least action, articulated in a series of memoirs in the 1740s, notably Accord de différentes lois de la nature qui avaient jusqu’ici paru incompatibles (1744) and related writings. He proposed that in all physical changes, nature acts in such a way that a certain quantity—action—is minimized (or more generally, rendered “least” or “extremal”).

For Maupertuis, action was defined mathematically (in modern terms, akin to an integral of mass × velocity × distance), but it also carried a philosophical significance. He presented two intertwined claims:

1. Scientific-unificatory claim: diverse laws of mechanics and optics (such as the laws of refraction or the trajectories of bodies under forces) could be understood as consequences of a single, overarching principle of economy. This move anticipated later variational principles in physics and the Euler–Lagrange formalism, although these were systematized by others after him, especially Leonhard Euler and Joseph-Louis Lagrange.

2. Metaphysical-teleological claim: the very fact that natural processes follow a path of least action expressed a kind of finality or purpose in nature. Maupertuis interpreted the principle as evidence of a wise, ordering intelligence—a divine architect—who organized the universe according to the most “economical” plan. Thus, the principle functioned both as a physical postulate and as a natural-theological argument.

This dual status provoked debate. Supporters in the 18th century regarded the principle as an elegant unifying idea that harmonized mathematical physics with a theistic worldview and provided a powerful tool for deriving known laws. Critics raised several concerns:

• Some mathematicians, including d’Alembert, questioned whether Maupertuis’s formulations were precise and general enough, or whether they merely restated known laws in a more obscure form.
• Philosophers skeptical of natural theology saw the invocation of divine economy as speculative and unnecessary, preferring to treat the principle (if accepted at all) as a purely mathematical device.

Later reformulations of the principle of least action in analytical mechanics largely stripped away Maupertuis’s stronger teleological overtones, but his work remains an important historical step in the development of variational approaches and in discussions about the metaphysical interpretation of physical laws.

Biology, Heredity, and Metaphysical Views

Beyond mechanics and astronomy, Maupertuis made notable forays into what would now be called biology and genetics, seeking law-like regularities in living nature similar to those he found in physics. In texts such as Vénus physique (1745) and memoirs on human and animal reproduction, he advanced speculative but pioneering ideas about heredity.

Observing traits passed through families, including cases of polydactyly (extra fingers or toes) in a particular lineage, Maupertuis argued that:

• Both parents contribute “particles” or “germs” that determine offspring characteristics.
• Inherited traits, including anomalies, can persist over multiple generations.
• Some changes in traits appear to arise spontaneously and then be transmitted, suggesting a mechanism of variation and inheritance.

These reflections led him to challenge preformationism (the idea that organisms pre-exist in miniature form within reproductive cells) and to lean toward an epigenetic view, according to which the embryo develops progressively through the interaction of elements provided by both parents. Although lacking modern genetics and embryology, his discussion is often cited as an early attempt to formulate a hereditary mechanism and to recognize the significance of familial lineages in biological traits.

Maupertuis occasionally framed these biological views in quasi-evolutionary terms, speculating that repeated variations and selection-like processes could shape species over long periods. However, he did not work out a systematic evolution theory comparable to later 19th‑century accounts; instead, his remarks were exploratory, operating at the boundary between empirical observation and speculative natural philosophy.

Metaphysically, Maupertuis was influenced by, yet critical of, Leibnizian ideas. He engaged with concepts such as monads, pre-established harmony, and the principle of sufficient reason, often modifying them in light of Newtonian physics and his own least-action philosophy. In some writings he suggested that ultimate constituents of reality might be simple, immaterial entities with both physical and mental aspects, attempting to reconcile mechanical description with phenomena of consciousness and finality.

Contemporaries and historians have differed in their assessments of Maupertuis’s metaphysical system:

• Sympathetic interpreters emphasize his effort to integrate advances in mechanics and biology with a coherent picture of a lawful, ordered, and purposive cosmos.
• Critical commentators underline the speculative character of his metaphysics and the ambiguities in his attempt to blend Newtonian and Leibnizian themes.

Despite these debates, Maupertuis is widely recognized as a representative Enlightenment figure who sought to extend the methods of mathematics and experiment into broader philosophical territory, connecting precise physical law, theological reflection, and nascent biological theory in a single, if sometimes unstable, intellectual project.