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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.

 

3 thoughts on “The ambiguous status of Maupertuis

  1. Thank you for the interesting discussion of the ambiguities that Maupertuis’ thought presents.

    I am pretty much convinced that, in order to make sense of his ambiguous status, we have to keep separate Maupertuis’ Parisian period (1723-1745) and the years he then spent in Berlin (1745-1758). The first part of his career can of course be labelled as ‘Newtonian’, although the peculiar way in which Maupertuis was a Newtonian would require a separate discussion. The turning point of his career is—to my eyes—the formulation of the Principle of Least Action (PLA), first elaborated in 1744, and then famously given a theological interpretation in the Essai de Cosmologie (1750). Why do I say the ‘turning point’? Because, with the formulation of the PLA, Maupertuis is convinced to have attained a deeper level of generality and a further insight in God’s design than Newton with his law of universal attraction. As Maupertuis himself writes in Letter XII (1752): “Nous avons fait voir que toutes les lois du mouvement étaient fondées sur le principe de la moindre quantité d’action: Newton a démontré que tous les corps célestes se meuvent par une attraction vers le soleil: et M. Euler a trouvé que si des corps se meuvent par une force qui les attire continuellement vers un centre, ils emploient dans leurs routes la moindre quantité d’action qu’il soit possible. Peut-on refuser ici son admiration? Peut-on n’être pas frappé de l’accord de ces différentes lois? Si l’on ne voit point que l’attraction elle-même dépende du principe de la moindre quantité d’action, ses effets du moins lui sont soumis: elle fait mouvoir les corps comme il faut qu’ils se meuvent pour obéir à cette loi universelle de la nature’ (Œuvres, vol. II, pp. 288-289). For this reason, after 1745, Maupertuis is ready to elaborate a ‘philosophical system’ of his own, less dependent on Newton’s theories; and this he does taking up several Leibnizian suggestions as well.

    A last word on Mauperuis’ experimentalism after 1746. In fact, if we just consider the contributions he published in the Mémoires, we find no proof of his commitment to experimental philosophy. However, the academic papers are not everything Maupertuis published after 1746. If we look at his Letters (1752), for instance, we find interesting discussions of experiences he carried out. I refer in particular to his experiences on the heredity of characters made on the Ruhe family of Berlin, whose members were affected by polydactyly. These experiences Maupertuis describes in letter XIV ‘On the Generation of Animals’ (Œuvres, vol. II, pp. 299-314).

  2. Thanks for your insightful comments Marco. What are the Leibnizian suggestions that you claim Maupertuis took up?

  3. Hopefully, my comment will appear this time (a shortened version without links).

    To solve this problem you probably need a cup of coffee with Leibniz’s monads floating inside instead of sugar (cf. Maupertuis, Lettre VIII, Œuvres, vol. II, p. 262-263 ). I am not sure if there were enough of monads in my coffee but I can risk an answer from a linguist’s point of view (however limited it may be).
    A suitable point of departure is Lettre XIV mentioned in the previous post. In the case of polydactyly observational data were waiting to be collected and interpreted in terms of probability calculus. So, strictly speaking, Maupertuis didn’t conduct an experiment on humans (but he did verify his conclusions on dogs – chiens d’Islande).
    But what to do if no data are available? Here lies the core of the problem. For conceptualizing experiments Maupertuis needed theory/paradigm based on reliable primordial ideas (on paradigms, see: D. Papineau, “The vis viva controversy: Do meanings matter?,” Studies in History and Philosophy of Science Part A 8 (2):111-142 (1977)). These, however, were distorted due to external influence and required reconstruction. (cf. “Sur l’origine des langues et la signification des mots” in: Les oeuvres de Mr. de Maupertuis [Dresde: Chez George Conrad Walther, 1752], p. 356).
    The only way out of the impasse seemed to be an impossible experiment à la Psammetichus. Typically enough, Maupertuis classifies it as ‘metaphysical’ since it concerns human minds and not physical bodies (Maupertuis, Lettre sur le progrès des sciences, 1752, p. 112.).
    The most striking is that one group of two or three infants kept in isolation wouldn’t be enough for Maupertuis. He thought it necessary to compare groups of children of different nationalities to find out if birth as a sort of apriori education influenced primordial ideas (Maupertuis, Lettre sur le progrès des sciences, 1752, p. 118 ff.)
    This uncertainty about the character of original deep semantic structures is likely to be crucial in understanding how Maupertuis conceived the language/languages of physics and consequently the role of experiments.
    Let’s begin with some details concerning ideas muddled at the later stages of mental development.
    There is little doubt that Maupertuis occupied an extreme position on the spectrum of possible interpretations of the Aristotelian triad: things-words-concepts. He was inclined to the language-dependent diversity of concepts: different nations could form different and even incommensurable ideas. (“Sur l’origine des langues et la signification des mots” in: Les oeuvres de Mr. de Maupertuis, p. 356.)
    At the opposite pole were of course universal concepts, i.e. the same for all people.
    A linguistic position as such is too basic to tip the scales either in favour of experimental philosophy or against it.
    With this reservation in mind, it is worth analysing how contrasting views on semantic deep structures affected the definitions of the fundamental concepts of eighteenth-century physics, e.g. that of substance.
    Maupertuis’s linguistic position clearly contributes to undermining a universal concept of substance:

    Dans Arbre, ils [les philosophes] ont crû que la partie de cette perception qu’on appelle étendue et qu’on trouve aussi dans Cheval, Lyon, etc. pouvoit être prise pour cette Substance, et les autres parties comme couleur, figure etc. qui différent dans Arbre, dans Cheval, dans Lyon ; ne devoient être regardées que comme des Modes. Mais je voudrois bien qu’on examinât, si en cas que tous les objêts du monde fussent verds, on n’auroit pas eu la même raison de prendre la Verdeur pour substance. Si l’on dit qu’on peut depouiller l’Arbre de sa Verdeur et qu’on ne le peut pas de son Etendue. Je répons que cela vient de ce que dans le langage établi, on est convenu d’apeller Arbre ce qui a une certaine figure independamment de sa verdeur. Mais si la langue avoit un mot tout différent pour exprimer un Arbre sans verdeur et sans feuilles, et que le mot Arbre fut nécessairement attaché à la verdeur, il ne seroit pas plus possible d’en retrancher la verdeur que l’étendue. (Maupertuis, “Sur l’origine des langues et la signification des mots,” p. 361-362)

    Port-Royal’s influence leads to quite different results. E.g. the definition of substance in Institutions Physiques by Emilie du Châtelet is not prone to vacillating (noteworthy, Maupertuis was one of her tutors):

    …et l’on peut définir la Substance, ce qui conserve des déterminations essentielles et des attributs constans, pendant que les modes y varient et se succèdent ; (Émilie du Châtelet, Institutions Physiques [Amsterdam: de la Compagnie, 1742], p. 77.)

    The passage above bears the marks of both Port-Royal and Leibniz.
    (cf. Du Châtelet, “La Grammaire raisonnée. Chapters 6, 7 and 8,” in Wade, Studies on Voltaire (New York: Russell & Russell, 1967), p. 209.)

    The Leibnizian concept of universal language was sharply criticized by Maupertuis. The following quote from Dissertation sur les differents moyens dont les hommes se sont servis pour exprimer leurs idees (1756) goes deeply into his reasons for this by dealing explicitly with the incommensurability of the languages of physics:

    XL — En effet, comment pourrait-on se flatter de faire convenir tous les hommes sur le rang et la valeur des idées, tandis qu’ils diffèrent si étrangement sur cela, que les uns regardent comme aussi anciennes que notre âme, des idées que les autres prétendent qu’elle n’acquiert que par les sens et l’expérience ? que les uns regardent comme fondamentale, et comme une des premières de toutes : l’idée de l’espace et du vide, que les autres soutiennent qu’il est impossible d’avoir ? Si sur ce principe du rang et de la valeur des idées Descartes ou Mallebranche eussent formé une écriture universelle, jamais Newton ni Locke n’eussent su lire.

    As stated above, Maupertuis’s arguments against the universality of deep semantic structures don’t subvert the idea of experimental philosophy. We could easily imagine perfect French experimental philosophy built on the scaffolding of superior French language (l’éclat de la langue française). (“Harangue prononcée par Mr. de Maupertuis, dans l’Académie Françoise,” in: Les oeuvres de Mr. de Maupertuis, p. 275.)

    However, without metaphysical experiment on infants Maupertuis wasn’t able to prove that French was in fact a better tool for the theorization of observational data and therefore he was left with uncertainty as to relationship between perception and physical objects.

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