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Maupertuis and Experimental Philosophy

A guest post by Marco Storni.

Marco Storni writes …

Was Maupertuis an experimental philosopher? In a recent post on this blog, Peter Anstey pointed out the many ambiguities one encounters when one raises such a question. The perplexity concerns in particular the seemingly contradictory nature of Maupertuis’ contributions to the Berlin Academy: a forward-looking Newtonian in the 1730s, after he takes over the presidency of the Prussian Academy of Sciences in 1746, Maupertuis’ writings deal with stricto sensu scientific topics no more. Although an Experimental Philosophy and a Mathematics class existed in the Berlin Academy, “Maupertuis didn’t publish a single article in the Experimental Philosophy memoirs […] nor did he publish anything in the Mathematics section” (Anstey, The Ambiguous Status of Maupertuis), but only in the memoirs for Speculative Philosophy. This remark can be further generalized for, after 1746, also Maupertuis’ non-academic writings also deal with non-scientific subjects, including theodicy, the origin of language, and ethics. How can we explain such a change of perspective?

To answer these questions, it is necessary to understand what Maupertuis actually means by “experimental philosophy” and “speculative philosophy”. A key text is the academic address Des devoirs de l’académicien (1750), where Maupertuis discusses one by one the nature and the tasks of the Berlin Academy classes. Whereas experimental philosophy, Maupertuis says, studies natural bodies with all their sensible properties, and mathematics deals with bodies “deprived of the large majority of those properties” (Les œuvres de Maupertuis (ed. 1768), 3, p. 293), speculative philosophy is rather concerned with all the objects that have no sensible properties. In this sense,

The Supreme Being, the human soul, and everything relating the mind are the object of this science. The nature of bodies too, as they are represented in our perceptions, even if they are something else than these very perceptions, falls within its scope (Ibid., p. 293-294).

Speculative philosophy is thus concerned with all the areas experimental philosophy and mathematics do not cover. In fact, speculative philosophy studies the very same objects experimental philosophy and mathematics are concerned with (e.g., natural bodies), but from a different perspective (in the case of natural bodies, from the perspective of the experience of such bodies). Therefore, in Maupertuis’ view, speculative philosophy and experimental philosophy are not necessarily opposed but rather complementary. This is well displayed in his studies on the principle of least action, first formulated as a physical principle (in the academic paper Accord de différentes lois de la nature qui avaient jusqu’ici paru incompatibles, 1744), and then given a metaphysical interpretation (in the Essai de cosmologie, 1750).

Maupertuis says something more on the relationship between “speculative philosophy” and “experimental philosophy” in another text of the 1750s, namely the Lettre sur le progrès des sciences (1752). Here, Maupertuis introduces the notion of “metaphysical experience” that turns out to be interesting for our present concern. If physical experiences have to do with bodies—and in the first half of his career Maupertuis focused on physical experiences—metaphysical experiences deal with the spiritual world. Would it not be possible, Maupertuis asks himself, to operate on the soul by means of physiological modifications on the brain? Likewise, would it not be possible to find out how languages are formed by isolating some children and seeing how they manage to communicate? However quaint all this might seem, it nonetheless indicates that speculative philosophy is for Maupertuis essentially intertwined with experimental philosophy. Ultimately, a large part of Maupertuis’ activity in Berlin might be described as the attempt to construct an “experimental metaphysics”.

On my analysis, Maupertuis’ status as an experimental philosopher turns out to be less ambiguous than it might prima facie seem. In fact, according to Maupertuis, “over so many centuries […] our metaphysical knowledge has made no progress” (Les œuvres de Maupertuis, 2, p. 430) precisely because the method of speculative philosophy was too abstract and arbitrary. Grounding metaphysics on experiences, as he argues, might actually help to stimulate such progress: and this is the objective Maupertuis strives for in his works of speculative philosophy. On the whole, therefore, I incline to read Maupertuis’ mature position as the attempt to reform speculative philosophy out of an experimental approach. I would nonetheless be glad to hear other thoughts on Maupertuis’ experimentalism.

The ambiguous status of Maupertuis

Peter Anstey writes…

Pierre-Louis Moreau de Maupertuis (1698–1759) was one of the leading and most celebrated French natural philosophers of the eighteenth century. A competent mathematician who studied with Johann I Bernoulli, a foreign member of the Royal Society, a member of the Parisian Académie royale des Sciences and, from 1746, the perpetual President of the Berlin Académie des sciences et belles lettres, Maupertuis was one of the premier savants of his age. But, was Maupertuis an experimental philosopher?

There is no doubt that his greatest achievement was the Lapland expedition to determine the length of a degree of longitude near the North Pole and to settle once and for all the debate over the shape of the Earth. Maupertuis’ observations, in spite of challenges from the astronomer Cassini, proved decisive and the Newtonian theory that the Earth is an oblate spheroid, bulging at the Equator, was finally accepted. The expedition involved all the elements of experimental natural philosophy: instruments, teamwork, careful observations, measurement, analysis, experimental reports, etc.

The expedition took place from May 1736 to August 1737, just at the time when experimental philosophy was being enthusiastically embraced in France through the influence of Nollet, Voltaire and others. On the expedition Maupertuis was accompanied by the young Pierre Charles Le Monnier, who five years later dedicated his translation of Roger Cotes’ lectures on experimental philosophy to him. It is entitled Leçons de physique expérimentale (Paris, 1742) and in the dedicatory epistle Le Monnier says of Maupertuis, ‘no one can ignore how many discoveries you have enriched natural philosophy with’.

It is tempting, therefore, to regard Maupertuis as having vindicated Newtonian experimental philosophy over and above the speculative Cartesians and to see him as a beacon for the new methodology that gives priority to experiment and observation over premature theorizing. Who would better qualify to be a leading experimental philosopher in France? However tempting this may be, we should resist it, for, as J. B. Shank intimates (The Newton Wars, Chicago, p. 429), Maupertuis seems never to have expressed any enthusiasm about experimental philosophy. Moreover, from the 1740s his intellectual trajectory seems to take him in the opposite direction.

No doubt one of the motivations for Frederick the Great to invite Maupertuis to Berlin to head up the revivified Academy there in 1746 was to secure the services of a leading and mathematically competent experimental philosopher whose Lapland expedition was now a cause célèbre throughout Europe. The new structure of the Académie, as we have noted before on this blog, consisted of four classes: Experimental Philosophy, Speculative Philosophy, Mathematics and Belles-lettres. Each member of the Academy, apart from the President, belonged to one of these classes, and the bulk of the work of the Academy was published in one of the four sections of the Memoirs that matched the classes.

Surprisingly, a careful survey of Maupertuis’ contributions to the main publication of the Berlin Academy, the Histoire de l’académie royale des sciences et belles lettres reveals that, in spite of his scientific achievements, Maupertuis didn’t publish a single article in the Experimental Philosophy memoirs. Nor did he publish anything in the Mathematics section. His account of his famous Principle of Least Action, entitled ‘The laws of motion and of rest deduced from a metaphysical principle’, appears in the 1748 memoirs for speculative philosophy. Likewise, his ‘The different ways by which men have expressed their ideas’ and his ‘Philosophical examination of the proof of the existence of God’ also appeared in the Speculative Philosophy section in 1756 and 1758 respectively. His ‘On the manner of writing and reading the lives of great men’ appeared in Belles-lettres in 1757. Moreover, there appears to be no evidence that he ever performed an experiment after arriving in Berlin in 1746.

An adequate explanation of this ambiguous status of Maupertuis vis-à-vis experimental philosophy is likely to be complicated. It would have to reach back to some of his earliest papers in natural philosophy, such as ‘On the laws of attraction’ published in 1735, for this includes a metaphysical section on God and the inverse square law (Histoire de l’académie royale des sciences, 1735, pp. 343–62). It would also have to explore the influence of Leibniz and Wolff on both Maupertuis and others in the Berlin Academy, such as its secretary Samuel Formey. For example, the influence of Leibniz and Wolff may account for the absence of any tension between experimental and speculative philosophy in the Berlin Academy. Clearly the case of Maupertuis requires further reflection. We are very keen to hear from anyone who has thoughts on these matters.


The ESD and the Berlin Académie

Peter Anstey writes …

One good indicator of the wide dissemination of experimental philosophy in the early modern period is the extent to which it manifested itself in the institutions of the time.

The first chair in experimental philosophy was the Plumian Chair in Experimental Philosophy and Astronomy that was established at the University of Cambridge in 1707. The first incumbent of the Chair was Roger Cotes who went on to edit the second edition of Newton’s Principia. We have also mentioned Abbé Nollet before on this blog and the fact that he was appointed Professor Royale de physique expérimentale at the Collège de Navarre in Paris in 1753.

It is of great interest, therefore, to note that the important restructuring of the Académie Royale des Sciences at Belles Lettres in Berlin in the 1740s also reflected the central place that was now accorded to experimental philosophy in Europe.


Pierre Louis Moreau de Maupertuis (Public Domain)

King Frederick II of Prussia sought to reinvigorate the institution by appointing the prominent French savant Pierre-Louis Moreau de Maupertuis as President of the Académie in 1746 and restructuring it into four classes. In the ‘Rules of the Academy’ from 1746, which are the official position of the Académie, the nature of these four classes is spelt out as follows:

The Academy will continue as it is, divided into four classes

  1. The class of Experimental Philosophy, including chemistry, anatomy, botany and all sciences that are founded on experiment.
  2. The class of Mathematics, including geometry, algebra, mechanics, astronomy and all the sciences which have as their object the abstract and numbers
  3. The class of Speculative Philosophy which will apply to logic, metaphysics and morals
  4. The class of literature will include antiquities, history and languages.

(Histoire de l’Académie Royale des Sciences et Belles Lettres, 1748, pp. 3–4)

There are a number of striking features of these classes. First, note that Experimental Philosophy is here grouped with Speculative Philosophy. It is clear that a form of experimental-speculative distinction is part and parcel of the Academicians’ conception of natural philosophy.

Second note that anatomy and botany are included in Experimental Philosophy. This is striking because it is closer to the manner in which experimental philosophy in Britain in the seventeenth century was understood in so far as it encompasses disciplines that were often regarded as part of natural history. In the mid-eighteenth century in France, by contrast, Nollet regarded physique expérimentale and natural history as distinct disciplines.

We note also that astronomy and mechanics, two sciences in which Maupertuis excelled, are grouped under Mathematics. This is in spite of the fact that they required observation and experiment. Indeed, Maupertuis’s fame rested in large part on his Lapland expedition of 1736 on which he was able to establish experimentally that the Earth is an oblate spheroid. Yet this had implications for both mechanics and astronomy.

Furthermore, it is worth highlighting that morals is considered to be a speculative science. This provides an interesting contrast to the situation in mid-eighteenth-century Scotland where there was a concerted attempt, as David Hume put it ‘to introduce the experimental method of reasoning into moral subjects’.

We can obtain a clearer sense of just what each class encompassed by examining the Histoire de l’Académie two years later. Here is how experimental philosophy is described:

Experimental Philosophy includes all natural history, all knowledge for which one has need of eyes, of hands, and of all the senses. It considers the bodies of the universe covered with all their sensible properties. It compares these properties linking them together and deducing one from another. This science is all founded on experiment. Without it reason is always in danger of falsehoods and losing itself in systems that it denies. However, experiment also has need of reason; it saves the natural philosopher time and pains; it makes him grasp all at once certain relations that deliver him of several useless operations; and it permits him to turn all his focus towards those phenomena that are decisive. (Histoire de l’Académie, 1750, p. 118)

By contrast speculative philosophy is that which ‘considers those objects that don’t have any properties of bodies. The supreme being, the human mind, and all that which belongs to the mind is the object of this science. The nature of bodies themselves, as represented by our perceptions, even if they are things other than these perceptions, they are in its remit’ (Histoire de l’Académie, 1750, p. 120).

Interestingly, speculative philosophy here is not a method that begins with hypotheses and principles and constructs natural philosophical systems. Rather it includes subject matter that is beyond the scope of natural philosophy, what we would call metaphysics. Of course, metaphysics had long been associated with speculative philosophy. Newton’s railing against metaphysics is a case in point. However, for Newton the hypothetical or speculative philosophers allowed metaphysics to intrude into their natural philosophical reasoning. Here, by contrast, speculative philosophy is clearly demarcated from the study of material bodies.

Is this indicative of a shift towards regarding speculative philosophy as pertaining to metaphysics rather than to natural philosophy in mid-eighteenth-century Europe? I would be keen to know of parallel definitions of speculative philosophy.