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Early Modern Experimental Philosophy
A project of the Early Modern Thought Research Theme at the University of Otago

The Experimental-Speculative debate in early modern Spain 3

Juan Gomez writes…

It has been a while since my previous post, so I will begin by recapping my series on early modern Spain up to the point where we left off. This series focuses on an interesting debate between scholastics and novatores in Spain at the beginning of the eighteenth century, a debate which revolves around natural philosophy and methodology. The origins of the debate can be found in a book by Gabriel Alvarez de Toledo, Historia de la Iglesia y del Mundo (History of the Church and the World), where he tries to give an account of the book of Genesis which is consistent with the theory of atomism. This attempt to combine elements of the scholastic tradition with the new science was seen as a threat from the scholastic camp, which set out to criticize the book. Fransisco Palanco took advantage of this opportunity to go beyond a criticism of Alvarez’ book and set out to attack the novatores and the new science. The novatores quickly replied to Palanco, Juan de Najera and Diego Mateo Zapata responding with an attack on Aristotelianism and the scholastic ways. This exchange was the topic of our previous post, but it was not the end of the debate.

In 1717, a year after de Najera and Zapata’s comments, the response from the scholastic camp appeared. Juan Martin de Lessaca, a doctor from Toledo who was loyal to Aristotelianism, published Formas ilustradas a la luz de la razón (Forms enlightened through the light of reason [redundant as it is]). Lessaca claims that his book is a vindication of Aristotelianism in response to Najera and Zapata. The book consists of two parts: first a response to Zapata’s review, and then a response to Najera’s text. Lessaca begins his criticism by confirming a claim already made by Palanco, namely, that the novatores were guilty of heresy, based on their appeal to the new science.

Aside from the justification of the connection between heresy and new science, Lessaca offers a picture of the new philosophy that can shed some light on the way the scholastics viewed the doctrines of the novatores:

The Atomists claim that their Philosophy is the best, since it is founded on experience itself, and what the senses perceive; and so they call their Philosophy experimental, and sensible. Such is the Chemical Course, so highly praised by the Author of the Review [Zapata] who says: And so Chemistry being a demonstrative science, accepts as a foundation only what is palpable, and demonstrative. It is truly of great advantage to have such sensible principles which can be ascertained with more reason. The elevated imaginations of other Philosophers, who hold on to their Physical principles by lifting their spirits to the level of great ideas, but never prove anything demonstratively. This being so, it is why it is called Experimental Philosophy…

Here we have a clear contrast between the two movements: the scholastics found their research on ideas and the use of reason alone, while the novatores focus on experimental observation and the perception of the senses. Lessaca uses the distinction to point out that the novatores can be referred to as being “crude”, given that the senses are cruder than reason. Lessaca refers to those maxims held by the novatores to show the baseness of their methodology.

Lessaca continues to criticize the novatores‘ emphasis on experience. He accepts that they might have an adequate knowledge of the human body, thanks to their attention to sensible experience, but they cannot rely on the latter “to discern those parts that cannot be seen, or touched, or accessed through sensible experience, and of this kind is all of the internal part of man, all that concerns spirits, their movement, nutrition, augmentation, etc”. The strategy here is not to attack the novatores on grounds of the faults of their method, but rather to point out that their method falls short when it comes to the knowledge of what cannot be experienced through the senses.

Lessaca’s comments are of great interest to us because they give us specific arguments against the methodology of experimental philosophy. Beyond the charges of heresy, Lessaca does point out that experimental philosophy, though not completely useless, is too limited; the emphasis on experience and observation entails, from Lessaca’s viewpoint, that experimental philosophers were not capable of studying anything that went beyond the senses. And with this he flips the situation around: if experience and observation are our guides, then whatever we say about anything which escapes these guides becomes mere conjecture.

In our research we have found many instances of the way experimental philosophers criticize and oppose speculative philosophers and their methodology. But examples from the other side of the ESD divide attacking experimental philosophy are scarce. This is where Lessaca’s work stands out, giving us some insight into the arguments adopted and promoted by speculative philosophers to defend their movement within the ESD.

Emilie du Châtelet and Experimental Philosophy II

A second guest post by Hanna Szabelska.

Hanna Szabelska writes …

As I indicated in my previous post, the fatal destiny (fatalité), about which Voltaire complained in a letter to Jean-Jacques d’Ortous de Mairan [1], made Madame du Châtelet’s mind more and more prone to the allure of Leibniz’s metaphysics, in particular his concept of vis viva.

For example, the comparison of fire to living force notwithstanding, the first edition of her essay on heat shows the traces of the influence of de Mairan’s Dissertation sur l’estimation et la mesure des forces motrices des corps. One possible reason for this inconsistency being that de Mairan distanced himself from metaphysics and concentrated on pure laws of motion [2][3]. In the version submitted for the Academy’s prize competition, du Châtelet added a note criticising Leibniz and praising de Mairan as an advocate of the Cartesian measure of force (mv). Afterwards the Marquise desperately fought for permission to remove it before publication. She argued that this insipid compliment (fadeur) had resulted from her ignorance and was not related to the main theme. But she was unsuccessful [4].

The Leibnizian measure – mv² – was incorporated only in the second version together with a remarkable passage that unravels a complex interplay between the experimental and the speculative approach in du Châtelet. Having discussed the hypothesis that the Sun is a solid body containing fire and emanating it to the Earth, she concludes:

But this emanation of light is subject to far greater difficulties, and seems impossible to be assumed despite the modern observations that apparently speak in its favour: certain observations are enough to destroy a superstition when they seem contrary to it, but they are not enough to establish it and physical and metaphysical difficulties undermining the [hypothesis of] emanation of light seem so insuperable that without them being removed there are no observations that can induce one to assume it. But this is not the place to discuss them. [5]

The moral of this digression is that observational data are not enough to establish a hypothesis if there are strong metaphysical objections against it. This is the assumption, although not always articulated, that remains at the core of du Châtelet’s rhetorical vein in the heat of debates, e.g. her discussion with de Mairan about one of Jacob Hermann’s experiments and the measure of force. Remarkably, the exchange with de Mairan was published not only together with the Institutions physiques (1742), the second edition of du Châtelet’s manual of physics, but also with the revised version of her essay on fire.

The experiment in question is as follows [6]:

Let the ball A move with the velocity 2 on a horizontal plane and collide with another ball B=3A, being at rest. The ball A will give the velocity 1 to the ball B and move backwards with the velocity 1.  Afterwards, let the ball A with the velocity 1 collide with another body at rest C=A. The ball A will also give to the ball C the velocity 1 and as a result of the second collision, it will come to halt. All this can be easily derived from the very well known rules of the motion of elastic bodies. [7]

To disprove du Châtelet, de Mairan adds scalar magnitudes (m|v|), and then he goes on to directed ones, i.e. applies the measure he accepted. [8]

His calculation could be interpreted as a correct addition of momenta [9], but du Châtelet does not consider it either as an alternative of force measure or a different concept. Here comes into play her rhetorical impetus:

To tell the truth, it is remarkable with what ease this small bar you put in front of the formula for the force of the body A rid you of this 8 of force that even your own calculation gave you after collision instead of 4 that you had expected from it; but, tell me, I beg you, you certainly do not think that this sign minus and this subtraction would take away some part of force from the bodies A and B, and that the effects exercised by these bodies on any obstacles would be diminished by it. I also doubt that you would like to either experience it or find yourself in the path of a body that would bounce back affected by this minus sign with 500 or 1000 of force. [10]

One may think that du Châtelet did not understand the concept of directed magnitudes but was this really the case? After all, she was a very attentive reader of Willem Jacob ‘s Gravesande, who analyses the paradoxical cases of bodies moving in the opposite directions and compares the effectiveness of Leibnizian force measure with the Cartesian one.

This is the description of ‘s Gravesande’s experiment, somewhat simplified by du Châtelet: [11]

‘s Gravesande devised an experiment that wonderfully confirms this theory. He fastened a ball of clay in Mariotte’s Machine and he made it collide successively with a copper ball, whose mass was three and velocity one, and with another ball of the same metal, whose velocity was three and mass one, and it happened that the impression made by ball one, whose velocity was three, was always much greater than that made by ball three with the velocity of 1, which testifies to the inequality of the forces. But when these two balls with the same velocities as before collided at the same time with the clay ball freely suspended from a thread, the clay ball was not shaken and the two copper balls stayed at rest and equally sunk in the clay and after measurement these equal impressions were found to be much greater than the impression that ball three with the velocity of one had made, having hit only the fastened clay ball and less than that which had been made by ball 1 with the velocity three. For ball 3 consumed its force to make an impression on clay, and its impression having been augmented by the effort of ball one that pressed the clay ball against ball three, reduced the impression of this ball one. Therefore, soft bodies that collide with velocities in inverse proportion to their masses, stay at rest after the collision, because they consume all their forces to mutually impress their parts. For it is not simple rest that holds these parts together, but a real force, and in order to flatten a body and drive into its parts, this force, named coherence or cohesion, must be overcome, and nothing but the force used to drive into these parts is consumed in the collision. [12]

For both ‘s Gravesande and du Châtelet force is a positive magnitude [13]. Besides, she obviously agrees with ‘s Gravesande that opposite forces do not destroy each other in a direct manner but their interaction is much more complicated: in the collision of two bodies whose forces are opposite there are two actions and two reactions. [14]

But there is one crucial difference between them: ‘s Gravesande, a Newtonian converted to the Leibnizian force measure by his experiments, was particularly sensitive to difficulties involved in theorizing observational data. For him, the concept of force is vague and leaves room for alternative measurements:

If the word ‘force’ is given a different meaning, if this different meaning is said to be more natural, I do not object: all I wanted to claim is that this what I have called ‘force’ must be measured by the product of mass and velocity squared. In order to claim that it is possible to assume a different measure of force as considered under a different aspect it is necessary to explain all the experiments conducted with respect to force and collision. This is what we do on our part; and I assure you that this has not been done yet by those who have adopted the contrary opinion. [15]

Not so Madame du Châtelet. The Marquise’s irony towards de Mairan, sardonic despite her capacity to grasp counterarguments, tempts one to suppose that it is one of the aforementioned difficultés métaphysiques that underlies it. Should the Cartesian force be posited as a metaphysical principle of the Universe, the Universe could potentially be left with a metaphysically embarrassing zero value (like in the case of two moving bodies whose momenta are equal but opposite: p and –p). In this respect, velocity squared in the vis viva formula guarantees its superiority.

What follows from this is that the relationship between the speculative and the experimental in du Châtelet’s arguments is far from being straightforward. On the one hand, rigorous conceptualization of experiments like that of Boerhaave can serve to build up metaphysical principles, e.g. weightless fire as one of the springs of the Creator. On the other, there is sometimes hidden metaphysical bias in interpreting experiments as the example of Hermann’s balls proves. This complex mix is certainly incommensurable with mathematized classical mechanics as taught today. The question that imposes itself here is: are we really able to pin down the slippery Proteus of experimentalism with a Leibnizian tinge?


  1. MLXXXIV – A M. de Mairan, à Bruxelles, le 1er avril 1741, in Oeuvres complètes de Voltaire, ed. Ch. Lahure, vol. 25 [Paris: Librairie de L. Hachette, 1861], p. 522.
  2. de Mairan, Dissertation sur l’estimation et la mesure des forces motrices des corps, Nouvelle édition, ed. Deidier [Paris, 1741], pp. 7-8.
  3. Mary Terrall, “Vis viva Revisited,” History of Science 42 (2004): 189-209.
  4. cf. Letter 148. To Pierre Louis Moreau de Maupertuis, Les lettres de la Marquise du Châtelet, ed. Theodore Besterman [Genève: Institut et Musée Voltaire, 1958], vol. 1, pp. 266-267; the errata allowed by the Academy contains nothing but a stylistic improvement; note a factual mistake in Du Châtelet, Selected Philosophical and Scientific Writings, ed. Judith P. Zinsser [Chicago: University of Chicago Press, 2009], p. 77, note 54  and p. 110, note 10: “In the errata that she was allowed to submit, she changed a reference to Dortous de Mairan’s formula for force to that of Bernoulli. She had been reading Bernoulli and Leibniz on the nature of collisions and had changed her mind.”
  5. Dissertation, p. 128.
  6. du Châtelet describes it on page 459 ff. of the Institutions physiques.
  7. Jakob Hermann, “De mensura virium corporum,” Commentarii Academiae Scientiarum Imperialis Petropolitanae 1 (1726, published 1728): 14.
  8. de Mairan, “Lettre sur la question des forces vives,” in du Châtelet, Institutions Physiques, p. 487 ff.
  9. cf. Leibniz’s “Essay de Dynamique sur les loix du mouvement,” unpublished at the time, in Leibnizens Mathematische Schriften, ed. Carl Immanuel Gerhardt, Bd. 6 [Halle: H. W. Schmidt, 1860], p. 215.
  10. Institutions physiques, p. 529.
  11. cf. Boudri’s interesting interpretation. However, ‘s Gravesande mentions this experiment in Essai d’une nouvelle théorie du choc des corps and not in Nouvelles expériences, as Boudri claims. Christiaan Boudri, What Was Mechanical about Mechanics: The Concept of Force between Metaphysics and Mechanics from Newton to Lagrange, trans. Sen McGlinn [Dordrecht: Kluwer Academic Publishers, 2002], p. 108.
  12. Institutions physiques, pp. 466-467. For this passage, I consulted the translation by I. Bour and J. P. Zinsser; Du Châtelet, Selected Philosophical…, pp. 196-197. There are, however, small inaccuracies. E.g. “He took a firm ball of clay and, using Mariotte’s Machine…” See ‘s Gravesande’s description on p. 236: “…une pièce de bois bien affermie par des vis, dans laquelle il y avoit de chaque côté une cavité en demi-sphère, qui servoit à affermir une boule de terre glaise…” ‘s Gravesande, “Essai d’une nouvelle théorie du choc des corps,” in Oeuvres philosophiques et mathématiques, ed. J. N. S. Allamand [Amsterdam: Rey, 1774], Première Partie, pp. 235-236.
  13. cf. ‘s Gravesande, Essai d’une nouvelle théorie du choc, p. 219, definition II and du Châtelet’s malicious remark that de Mairan would not like to be hit by a body moving with a considerable force either from the left or from the right side.
  14. cf. the combination of the loss of velocity and indentation in  ‘s Gravesande’s experiment discussed above.
  15. “Nouvelles expériences,” in Oeuvres philosophiques et mathématiques, Première Partie, p. 284.


Emilie du Châtelet and experimental philosophy I

A guest post by Hanna Szabelska.

Hanna Szabelska writes …

Gabrielle Émilie le Tonnelier de Breteuil, la Marquise du Châtelet (1706–1749), ambitious femme savante and Voltaire’s muse had an unusual penchant for physics and mathematics, which pushed her towards conducting and discussing experiments.

By way of an example, to show that heat and light, as opposed to rarefaction – the distinctive property of fire – are nothing but its modes that do not necessarily accompany each other, she made use of the phenomenon of bioluminescence while imitating René-Antoine Ferchault de Réaumur’s experiment:

Dails [pholads] and glowworms are luminous without giving off any heat, and water does not extinguish their light. M. Réaumur even reports that water, far from extinguishing it, revives the light of dails [pholads]. I have verified this on glowworms, I have plunged some in very cold water, and their light was not affected. [1][2]

Since she held Newton’s experimental precision in the Opticks in high esteem, to the point that she acquired knowledge to do experiments about different degrees of heating among primitive colours on her own [3], du Châtelet had reservations about Charles du Fay’s attempt to reduce the seven primitive colours to three.[4]

The following passages are characteristic of her reliance on experiments. Letter 152. To Pierre Louis Moreau de Maupertuis [about the first of December 1738]

I know the Optics by Mr Newton nearly by heart and I must confess that I did not think it possible to call into question his experiments on refrangibility.


A tremendous series of experiments [une furieuse suite d’expériences] is necessary to undermine the truth that Mr Newton seems to have felt with all his senses. However, since I have not seen du Fay’s experiments I suspend my judgement… [5]


However, as much as she was fascinated by the potential of experimental philosophy, du Châtelet had an acute awareness of her own limitations and those of available apparatus. For example, she ventures the generalization that the tactile sensations of various colours differed analogically from the visual ones but admits her inability to conduct a decisive experiment and confides this task to the judges of her essay on fire [6].

Moreover, one can detect irony in her remarks about a defective camera obscura designed for optical experiments. In a letter to Algarotti she complains that:

The abbé Nollet has sent me my camera obscura, more obscure than ever; he claims that you have found it very clear in Paris: the sun of Cirey must be, therefore, unfavourable to it. [7]

Imperfect instruments could distort the results of experiments but so could an experimenter’s understanding of them if, like Locke or Leibniz, one takes the camera obscura as a metaphor of both visual perception and ideas based on it. Such epistemological doubts were also preying on du Châtelet’s mind, giving her natural philosophy a metaphysical depth. Thus, having enumerated some great names of experimental philosophy, she comes to the conclusion that:

It seems that a truth that so many competent natural philosophers have not been able to discover is not to be known by humanity. With regard to first principles, only conjectures and probabilities are within our reach. [8]

Interestingly, for Voltaire, this amalgam of the experimental and the speculative, imbued with the venustas muliebris of style, as Cicero would put it, was just the Marquise’s way of life, expression of her complex personality, philosophical to the backbone, but not easy to deal with.

The Marquise’s experimental inclination, under the spell of Leibnizian speculative philosophy, gave rise to sophisticated arguments, that often elude the language of modern physics. The devil is, as usual, in the details so let’s analyse some of them.

One of the most instructive stories is du Châtelet’s disagreement with Voltaire on the nature of fire, in particular on the question of its weight. While assisting with his experiments (cf. Peter Anstey’s post), she came to different conclusions and started working on her own essay in secret.

Voltaire evidently tried hard to interpret his results through the lens of a Newtonian experimentalist: to show that fire has weight and is subject to the force of gravity. Therefore, he downplays Herman Boerhaave’s reservations concerning the acquisition of weight by heated bodies [9] and opts for Peter van Musschenbroek‘s interpretation [10][11].

I visited an iron forge to do an experiment [exprès] and whilst I was there I had all the scales replaced. The [new] iron scales were fitted with iron chains instead of ropes. After that I had both the heated and the cooled metal within the range of one pound to two thousand pounds weighed. As I never found the smallest difference in their weights I reasoned as follows: the surface of these enormous masses of heated iron had been enlarged due to their dilation, therefore they must have had less specific gravity. So I can conclude – even from the fact that their weight stays the same irrespective of whether they are hot or cool – that fire had  penetrated the masses of iron adding precisely as much weight as dilation made them lose, and consequently, fire has real weight. [12]

To save his Newtonian face, Voltaire jumps to hypotheses in a rather non-Newtonian manner:

However, although no experiment to date seems to have shown beyond any doubt the gravity and impenetrability of fire, it is apparently impossible not to assume them. [13]

Despite his efforts, Voltaire’s conclusion remains caught in a limbo between mere hypothesis and a proposition deduced from phenomena and generalized by induction.

Of course, Newton would not have been himself had not his rejection of hypotheses been nuanced [14] but even so the leap in Voltaire’s reasoning seems a hidden thorn in his Newtonian flesh.

The conceptualization of Boerhaave’s experiment offered by du Châtelet is, on the contrary, more consistent with the data than that of her companion [15]. But on the other hand, it opens the way for establishing fire as one of the grand metaphysical principles of the Universe:

…but claiming that fire has weight is to destroy its nature, in a word, to take away its most essential property, that by which it is one of the mainsprings of the Creator. [16]


The action of fire, whether it is concealed from us or perceptible, can be compared to force vive [living force] and force morte [dead force]; but just as the force of bodies is perceptively stopped without being destroyed, so fire conserves in this state of apparent inaction the force by which it opposes the cohesion of the particles of bodies. And the perpetual combat of this effort of fire and of the resistance bodies offer to it, produces almost all the phenomena of nature. [17]

The passages above are to be found in both versions of du Châtelet’s essay on fire: the original  (1739, reprinted in 1752 by the Academy) and the revised one from 1744 (published by the Marquise’s own assumption by Prault, fils). However, it is worth noting that her conceptual framework became more consistently Leibnizian with time. It is this development that I will discuss in my next post.


  1. Trans. Isabelle Bour and Judith P. Zinsser; Du Châtelet, Selected Philosophical and Scientific Writings, ed. J. P. Zinsser, Chicago: University of Chicago Press, 2009, p. 64.
  2. Dail is an obsolete French term for pholade, pholas dactylus. (Du Châtelet, Dissertation sur la nature et la propagation du feu, Paris: Chez Prault, Fils,1744, p. 4.)
  3. Dissertation, p. 69.
  4. du Fay, Observations physiques sur le meslange de quelques couleurs dans la teinture, Histoire de l’Académie royale des sciences … avec les mémoires de mathématique & de physique,” 1737, p. 267.
  5. Les lettres de la Marquise du Châtelet, ed. Theodore Besterman [Genève: Institut et Musée Voltaire, 1958], vol. 1, pp. 273–274.
  6. Dissertation, pp. 70–71.
  7. Letter 63. To Francesco Algarotti, in Cirey, the 20th [of April 1736], Les lettres de la Marquise du Châtelet, vol. 1, p. 112.
  8. Trans. I. Bour and J. P. Zinsser; Du Châtelet, Selected Philosophical…, p. 71.; Dissertation, p. 17.
  9. Hermannus Boerhaave, “De artis theoria,” in: Elementa chemiae, Tomus primus, editio altera [Parisiis: Apud Guillelmum Cavelier, 1733], p. 193 ff.
  10. Petrus van Musschenbroek, Elementa physicæ conscripta in usus academicos, editio prima Veneta [Venetiis: Apud Joannem Baptistam Recurti, 1745], p. 323 ff.
  11. cf. Bernard Joly, “Voltaire chimiste: l’influence des théories de Boerhaave sur sa doctrine du feu,” Revue du Nord 77, No 312 (1995): 817–843.
  12. Voltaire, “Essai sur la nature du feu et sur sa propagation,” in Recueil des pièces qui ont remporté le prix de l’Académie royale des Sciences en 1738, par M. Rouillé de Meslay [Paris: de l’Imprimerie Royale, 1739], p. 176.
  13. Voltaire, “Essai sur la nature du feu,” Recueil, p. 180.
  14. cf. e.g. William L. Harper, Isaac Newton’s Scientific Method: Turning Data into Evidence about Gravity and Cosmology (Oxford: Oxford University Press, 2011), p. 44.
  15. Dissertation, p. 24, 33 ff.
  16. Trans. I. Bour and J. P. Zinsser; Du Châtelet, Selected Philosophical…, p. 80; Dissertation, p. 40.
  17. Trans. I. Bour and J. P. Zinsser; Du Châtelet, Selected Philosophical…, pp. 84–85; Dissertation, p. 52.


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.

How general was Newton’s experimental philosophy?

Kirsten Walsh writes…

Newton is often taken to have spawned two important, but different, sciences: an experimental science exemplified in the Opticks, and a mathematical science exemplified in the PrincipiaI. Bernard Cohen and George Smith, for example, write:

There is, perhaps, no greater tribute to the genius of Isaac Newton than that he could thus engender two related but rather different traditions of doing science.

Like many commentators, they emphasise the differences between the austere, formal mathematism of Newton’s so-called ‘rational mechanics’ and the complex and sophisticated experimentalism of his work on light and colour.  And so, the two works are typically taken to exemplify very different methodologies.

In contrast, on this blog, I have emphasised the common features, rather than the differences—presenting a more integrated account of Newton’s methodology.  For example, I have argued that his claim, that the Principia is a work of experimental philosophy, is something we should take seriously.  And so the mathematico-experimental method is a feature of both the Opticks and the Principia.  Moreover, I have argued that Newton’s mathematico-experimental method can be broadly characterised by an epistemic triad: a three-way epistemic division between theories, hypotheses and queries.  The epistemic triad drives Newton’s optical work and his rational mechanics in a trajectory from experiment to certainty, using mathematical reasoning.

While the Opticks and the Principia represent two fields to which Newton made important contributions, these impressive tomes do not signify the entirety of his research output—nor even the bulk.  During his lifetime, Newton produced vast quantities of written work on chymistry, theology and Church history, as well as mathematics.  Over several posts, I plan to explore some of this less well-known work in order to learn more about Newton’s methodology.  In particular, I want to see what kinds of methodological continuity, if any, there are between his many projects.

This may seem like a fool’s errand.  Indeed, these lesser-known parts of Newton’s research have a poor reputation.  One idea, floated by Jean-Baptiste Biot in his 1829 biography, was that Newton’s intellectual life divided naturally in two: prior to his mental breakdown in 1692, Newton’s life was sane, rational and scientific, but afterwards was mad, irrational and religious.  And so Newton’s alchemical and theological manuscripts are often dismissed as the half-baked musings of an old man.  In more recent times, however, commentators such as Betty Jo Teeter Dobbs, William R. Newman, Rob Iliffe and Sarah Dry (to name just a few!) have aimed to redress this situation.  They have demonstrated that Newton’s alchemical and theological pursuits were as much a part of his intellectual life as the optics, rational mechanics and mathematics, for which he is famous.  So, firstly, if there was any kind of cleavage, it was not along disciplinary lines, and secondly, these intellectual pursuits should be counted as serious scholarship—not simply to be swept under the proverbial rug.

So what sorts of continuities should we expect to find?  In the remainder of this post, I’ll offer a few preliminary suggestions.

One striking feature of Newton’s published scientific work is how methodologically reflective it was.  Perhaps we should expect similar reflections in his manuscripts on chymistry, theology or Church history.  Indeed, a cursory look at the collection shows that Newton approached chymistry, theology and Church history with the same persistence and vigour that we find in his other work.  Moreover, we can recognise several of the same methodological and foundational concerns.  For example, Newton’s interest in the restoration of an ancient tradition of knowledge that has been lost or corrupted, and the view that reason, hard work and disciplined empirical research are always preferable to speculation.

Another feature of Newton’s work that I have discussed on this blog is what I call his ‘rhetorical style’: Newton borrowed familiar terms and bent them to his own needs.  He is, moreover, best characterised as a methodological omnivore—he read widely on different methodologies and approaches, and selected from among them the best tools for the job.  We might expect to find the same thing in his chymistry and theology.  Again, my preliminary reading offers some support.  Newton appears to have been interested in all aspects of chymistry—a heavily experimental discipline, often with a pragmatic eye to profit, as much about developing chemical technologies and pharmaceuticals as it is about turning base metals into gold.  However, while Newton worked on the typical alchemist’s project of deciphering ancient myths, he doesn’t seem to have drunk the Kool-Aid.  He appears to have been much more concerned with linking his chymical research to his more mainstream science—for example, his matter theory.  In short, in these manuscripts, we can recognise the same desire to penetrate appearances and arrive at the fundamental truths of nature that we find in his physics.

Following on from this, we might also expect to find a concern for unification: the idea that Newton’s many topics of investigation are in fact part of a larger project.  For example, in Query 31 of the Opticks, Newton argues for both ontological and methodological unification.  Again, looking briefly at some of his alchemical manuscripts, we see a similar preoccupation.  Newton’s discussions of the ‘vegetative spirit’, for example, offer insight into the ways in which the various strands of his scholarly endeavours, including chymistry and theology, were united under one grand scheme.

When understanding the development of Newton’s thought, I often find it helpful to distinguish between Public-Newton and Private-Newton.  I have argued that there are important methodological differences between the work that Newton published (and hence, was willing to assert and defend) and the work he kept private.  While the former conforms, in some sense, to the experimental philosophy, the latter is typically much more speculative.  The distinction is particularly useful when considering Newton’s optical work, where we find stark differences between draft material and the final published version.  But I suspect it won’t be so useful once we turn to his chymistry, theology and Church history, where many of Newton’s unpublished manuscripts were in circulation—some only among his closest circle of like-minded friends, and others, much more widely.  And yet, this raises one final issue.  Newton’s efforts to pass off his published work as experimental philosophy may well have been politically motivated: by describing his work as ‘experimental philosophy’, he was signalling his commitment as much to the Royal Society as to observation- and experiment-based theorising.  His chymical, theological and Church history manuscripts were circulated much more privately—and presumably the same political motivations did not apply.  When working outside the jurisdiction of the Royal Society, did Newton conform to the experimental philosophy?

I’d love to hear your thoughts on this!

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.


Call for Abstracts: Conceptions of Experience in the German Enlightenment between Wolff and Kant

Call for Abstracts: Conceptions of Experience in the German Enlightenment between Wolff and Kant

University of Leuven, February 24-25, 2017

Submission deadline: October 15, 2016

Confirmed keynote Speakers
Christian Leduc (Montréal)
Arnaud Pelletier (Brussels)
Anne-Lise Rey (Lille)
Udo Thiel (Graz)

Organized by Karin de Boer (University of Leuven) and Tinca Prunea-Bretonnet (University of Bucharest)

The purpose of this conference is to analyze the various conceptions of experience at play in eighteenth-century German philosophy between Leibniz’s death in 1716 and Kant’s Critique of Pure Reason. During this period, the classical Aristotelian definition of experience as cognition of singulars – to some extent still present in Wolff – became confronted with the Baconian and Newtonian accounts of empirical knowledge. In the decades before the mid-century, the views of Locke and Hume, as well as French sensualism and materialism, complicated the prevailing German perspective on experience even more: the notion of empirical or ‘historical’ knowledge became linked to experiment and observation, investigations into perception and sensation took center stage, and ‘inner experience’ grew into a widely discussed topic.

The Berlin Academy, through the prize-essay contests it organized and the writings of its members, importantly contributed to the dissemination of Newtonianism and empiricism. Yet while most philosophers acknowledged the fundamental role of experience, they tried to accomodate the modern notions of experience to a view of cognition and science influenced by Wolffian metaphysics. The question as to the contribution of foundational metaphysical principles and empirical data to scientific knowledge was much discussed, as was the relationship between inner and outer experience, experience and thought, experience and judgment, experience and facts, experience and perception, experience and experiment, and perception and apperception.

Challenging the historiographical opposition between empiricism and rationalism, the conference aims to explore the often ambivalent or fluid conceptions of experience at work in these debates, as well their influence on disciplines such as psychology and aesthetics. Whereas all contributions relevant to these topics are welcome, we are particularly interested in contributions on the conceptions of experience elaborated by members of the Berlin Academy and by participants in the contests initiated by this institution.

The conference aims at stimulating fruitful exchanges between established scholars, junior researchers, and PhD students. Presentation time will be 25 minutes + 20 minutes for discussion.

Abstracts (of no more than 500 words) should be sent in MSWord as attachment to

Abstracts should be prepared for double-blind review by removing any identification details. The author’s name, paper title, institutional position and affiliation, as well as contact information, should be included in the body of the e-mail.

Notification of acceptance by November 15, 2016.


The Experimental-Speculative debate in early modern Spain 2

Juan Gomez writes…

Following up on my previous post, we will examine today the second part of the  Alvarez-Palanco-Zapata-Lessaca-Najera controversy. Last time, we introduced the issue by examining Gabriel Alvarez de Toledo’s attempt to stand at the crossroads of the experimental/speculative divide. We saw that he gave an account of the creation of the world which he claimed was consistent with both the story told in Genesis and the theory of atomism. However, some scholastic thinkers viewed Alvarez’s account as a threat, and decided to criticize him. In today’s post we will look at Fransisco Palanco’s attack on the new science and a reply from the novatores side by Juan de Nájera.

Fransisco Palanco published in 1714 his Dialogus physico-theologicus contra Philosophiae Novatores, sive thomista contra atomistas as a reaction to Alvarez’s texts. Palanco was perhaps the most vocal of the scholastic thinkers who opposed the novatores and the new science, but his attacks were easily dismissed by the novatores themselves. In fact, even some well-known priests from Palanco’s same order (Emmanuel Maignan and Jean Saguens) criticized the Dialogus physico-theologicus. To begin with, the title of the text suggests that it proposes a defense of Thomism from atomism, but it turns out the text is actually an attack on Descartes and the Cartesian system. Even this description of the text is somewhat inaccurate, since the criticisms made are against a few Cartesians (Antoine Le Grand, Theodore Graanen, and François Bayle) and not Descartes himself. Palanco had missed his target: Cartesianism is not the same as atomism, as the novatores would soon point out. But the most criticized aspect was the fact that Palanco takes the discussion out of its scientific framework, focusing solely on the religious and theological aspect.

In spite of all the flaws of Palanco’s text, the book did manage to get the attention of the novatores and it set the stage for a proper scientific debate between scholastics and novatores.

In 1716 Juan de Nájera, under the pseudonym Alejandro de Avendaño, published Diálogos philosophicos en defensa del atomismo as a response to Palanco. Nájera constructs a dialogue between an atomist and a scholastic (Palanco), where he shows the supremacy of atomism and reinforces the maxims we saw in Alvarez’s Historia de la Iglesia: corpuscles as the primitive matter for compounds, material forms, the distinction between substance and accident, among other topics.

Besides Nájera’s response, the book contains a review by Diego Mateo Zapata where he defends the new science and the novatores, explaining that atomism is different from cartesianism, rejecting Aristotelianism, and reinforcing the importance of experimental physics for our investigation of the natural world. Zapata’s review stands out as valuable, since it gives us some very clear statements of the way in which the novatores stand as Spain’s promoters of experimental philosophy.

Zapata first clarifies: “I am not Cartesian, but rather Maignanist,” stating that he adheres to the atomism of Maignan. Despite this claim, he goes on to defend Descartes, making an exaggerated emphasis on the latter’s religious devotion and faith. Aside from this defense of Descartes, the main thrust of the review is to defend the new science. Zapata gives us the following statement which summarizes his viewpoint:

Oh poor, miserable, weary Physics, or Natural Philosophy, how unattended and disregarded you are, on accounts of not being understood! Everyone dares you, abuses you, and disfigures you wanting to dress you with a Metaphysical varnish. Your truth, real nature and properties are obscured so they can’t be found, nor can the immense variety of your legitimate, sensible, natural Phenomena be explained.

Following this, Zapata claims that the cause for this neglect lays in upholding Aristotelianism. He comments that the scholastics follow Aristotelianism blindly, to the point where “the eyes are not believed so the belief in Aristotle is not lost.” This rejection of Aristotelianism and the complaint of the way the scholastics carry out their natural philosophy places the Spanish novatores clearly on the experimental side of the ESD, strengthening the claim that the ESD can be useful for our interpretation of the history of philosophy in Spain.

As for the controversy at hand, Palanco’s arguments are not strong enough and even a bit sidetracked, leaving us without much to work with in order to understand the scholastic viewpoint on the matter and if such views line up with the speculative side of the ESD. However, in my next post we will have the opportunity to examine a text by a scholastic which does shed some light on the matter: Juan Martin de Lessaca’s Formas ilustradas a la luz de la razón, a response to Zapata and Nájera.


Locke and the Newtonian Achievement

Kirsten Walsh writes…

In the Principia, Newton claimed to be doing experimental philosophy.  Over my last three posts, I’ve wondered whether we can interpret his so-called ‘experimental philosophy’ as Baconian.  In the first two posts, I identified methodological similarities between Bacon and Newton: first, the use of crucial instances; second, the use of Baconian induction.  In each case, I concluded that, without some sort of textual evidence clearly tying Newton’s method to Bacon’s, such similarities don’t demonstrate influence.  In my third post, I tried a different approach: I considered Mary Domski’s claim that Newton’s Principia should be considered Baconian because members of the Royal Society recognised, and responded to, it as part of the Baconian tradition.  While Domski’s argument was fruitful in helping us better to understand what’s at stake in discussions of influence, I raised several concerns with her narrative.  In this post, I shall address those concerns in more detail.

Let’s focus on Domski’s account of how Locke reacted to Newton’s Principia.  Domski argues that Locke regarded Newton’s mathematical inference as the speculative step in the Baconian program.  That is, building on a solid foundation of observation and experiment, Newton was employing mathematics to reveal forces and causes.  In short, Domski suggests that we read Locke’s Newton as a ‘speculative naturalist’ who employed mathematics in his search for natural causes.  Last time, I expressed two concerns with this account.  Firstly, ‘speculative naturalist’ looks like a contradiction in terms (I have discussed the concept of ‘speculative experimental science’ here), and surely neither Locke nor Newton would have been comfortable with the label.  Secondly, there’s a difference between being part of the experimental tradition founded by Bacon, and being Baconian.  Domski’s discussion of the reception of the Principia establishes the former, but not necessarily the latter.

We can get more traction on both of these concerns by considering Peter Anstey’s account of how the Principia influenced Locke.  Anstey argues that Newton’s achievement forced Locke to revise his views on the role of principles in natural philosophy.  In the Essay, Locke offers a theory of demonstration—the process by which one can reason from principles to certain truths via the agreement and disagreement of ideas.  In the first edition, Locke argued that this method of reasoning was only possible in mathematics and moral philosophy, where one could reason from certain principles.  Due to limitations of human intellect, such knowledge was not possible in natural philosophy.  Instead, one needed to follow the Baconian method of natural history which provided, at best, probable truths.  However, Anstey shows us that, by the late 1690s, Locke had revised his account of natural philosophy to admit demonstration from ‘principles that matter of fact justifie’ (that is, principles that were discovered by observation and experiment).

I now draw your attention to two features of this account.  Firstly, Newton’s scientific achievement—his theory of universal gravitation—as opposed to his successful development of a new natural philosophical method per se forced Locke to revise his position on demonstration from principles.  (A while ago, Currie and I noted that this situation is to be expected, if we take the ESD seriously.)  This feature should make us suspicious of Domski’s claim that Newton’s Principia was taken to exemplify the speculative stage of Baconian natural philosophy.  Locke did not see Newton’s achievement as a system of speculative hypotheses, but as genuinely empirical knowledge, demonstrated from principles that are justified by observation and experiment.  Newton had not constructed a Baconian natural history, but nor had he constructed a speculative system.  Rather, Locke recognised Newton’s achievement as something akin to a mathematical result—one which his epistemological story had better accommodate.  This forced him to extend his theory of demonstration to natural philosophy.  And so, by the late 1690s, we find passages like the following:

“in all sorts of reasoning, every single argument should be managed as a mathematical demonstration; the connection and dependence of ideas should be followed, till the mind is brought to the source on which it bottoms, and observes the coherence all along” (Of the Conduct of the Understanding).

Secondly, Anstey emphasises that Locke didn’t regard Newton’s mathematico-experimental method as Baconian, but only as consistent with his, Locke’s, theory of demonstration.  (Anstey also claims that Locke never fully integrated the revisions required to his view of natural philosophy in the Essay.)  On this blog, we have suggested that, in the 18th century, a more mathematical experimental natural philosophy displaced the natural historical approach.  And Anstey has offered a sustained argument for this position here.  He argues that the break was not clean cut, but in the end in Britain mathematical experimental philosophy trumped experimental natural history.  That this break was not clean cut helps to explain why experimental moral philosophers, such as Turnbull, thought they were pursuing both a Baconian and a Newtonian project, and were quite comfortable with this.

Notice that I’ve shifted from the vexed question of the extent to which Bacon influenced Newton, to a perhaps more fruitful line of enquiry: how Newton influenced Locke and others.  This is no non sequitur.  The members of the Royal Society strove to understand Newton in their terms—namely, in terms of Baconianism and the experimental philosophy.  Here, it seems that two conclusions confront us.  Firstly, we (again) find that Newton was taken as legitimately developing experimental philosophy by emphasising both the role of experimentally-established principles of natural philosophy and the capacity of mathematics to carry those principles forward.  These aspects are, at best, underemphasised in Bacon and certainly missing from the Baconian experimental philosophy adopted by many members of the Royal Society.  Secondly, we see that Newton’s influence on Locke was due, at least in part, to his scientific achievements.  Newton did not argue directly with Locke’s epistemology or method, nor did Locke take Newton’s methodology as a replacement for his own.  Rather, Locke took Newton’s scientific success as an example of demonstration from ‘principles that matter of fact justifie’.  This, in turn, necessitated modifications of his own account.

A response to Anstey’s ‘Experimental Philosophy before the Restoration’

A guest post by Mordechai Feingold.

Mordechai Feingold writes …

I thank Peter Anstey for drawing attention to my ‘“Experimental Philosophy”: Invention and Rebirth of a Seventeenth-Century Concept’, and for giving me the opportunity to correct certain misunderstandings of my argument.

Anstey begins: ‘Feingold has done us a real service by trawling through the Hartlib Papers and uncovering every use of the term “experimental philosophy” in them.’ The unsuspecting reader of the blog may conclude that the paper is devoted in its entirety to such minute study; in fact, only a third is given over to the Hartlib papers. More serious, however, is Anstey’s insinuation that on the basis of such a survey I conclude: ‘there was no such thing as experimental philosophy before 1660’. I make no such claim. As both the title and the content of my article make abundantly clear, I argue explicitly that it was the concept of ‘experimental philosophy’, not the practices that would be identified later under such term, that was absent before the Restoration.

Anstey pivots to my claim that when John Aubrey, John Wallis, and Anthony Wood described, two decades and more after the events, the activities carried out at Oxford during the 1650s, they anachronistically projected the term ‘experimental philosophy’ onto such activities—thereby leading historians to assume that the term had been in use already back then. Anstey disagrees. ‘As early as 1659 in his Seraphic Love’, he writes, ‘Boyle had been described by the anonymous author … of the Advertisement to the ‘Philosophicall Readers’ as a lover of ‘Experimentall Philosophy’. I was aware of this reference. However, since the first edition of Seraphic Love was published in late September 1659, and since it is not at all clear whether the anonymous second advertisement was actually included in the initial printing of the book, I considered the following statement sufficient to denote Boyle’s centrality to the revamping of the concept: ‘By early 1660 Boyle added “experimental philosophy” to his rhetorical repertoire, thereby becoming intimately involved in refitting the meaning of the phrase’. I documented the statement by citing the very expressions from New Experiments Physico-Mechanical, Touching the Air that Anstey cites against my interpretation. In particular, Anstey claims, the context in which Boyle referred to John Wilkins as the ‘Great and Learned Promoter of Experimental Philosophy’ is ‘entirely experimental’—thereby implying that I denied the existence of experimental activity before 1660. Anstey further contends that ‘Boyle could hardly have been anachronistic here, for this was written before 1660 about the very recent past, and yet his comments square almost exactly with those of Wallis, Aubrey and Wood’. I don’t see the problem here. The reference to Wilkins was obviously added to the discussion of the twentieth experiment when Boyle prepared the manuscript for press in early 1660. Thus, the inclusion of the term coheres perfectly with the other references to ‘experimental philosophy’ in the book.

Ultimately, whether Boyle started using the term in late 1659 or in early 1660 is of no great matter. What is important, and this is the point I insist on, is that Boyle and other members of the Royal Society—with the notable exception of William Petty whom I discuss at some length in my article—had previously used terms other than ‘experimental philosophy’ to describe their scientific activities. And in view of my pronounced aim to probe the changing fortunes of a concept, I’m puzzled by Anstey’s characterization of my undertaking as a denial of the historical relations furnished by Aubrey, Wallis, Wood, and Boyle concerning the existence of a flourishing experimental activity at Oxford during the 1650s. My intent was to show why it was only around 1660 that Boyle and his Royal Society colleagues decide to appropriate the term ‘experimental philosophy’ to describe their activities, thereby imbuing it with a fixed conceptual and polemical meaning. Given Anstey’s divergent understanding of the meaning and fortunes of ‘experimental philosophy’, it is understandable why he is reluctant to accept my argument or my periodization. This divergence notwithstanding, however, ultimately Anstey and I share much more in common than we disagree.