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

Locke’s earliest use of the term ‘experimentall naturall philosophy’

Peter Anstey writes…

It is well known that the leading English philosopher John Locke (1632–1704) had much exposure to the writings and practice of experimental philosophers within his ambit from the early 1660s. For example, Locke was involved in some of Boyle’s natural historical projects and read most of Boyle’s writings as they came off the press. Likewise, he read Henry Power’s Experimental Philosophy which appeared in 1664.

It is hardly surprising then that Locke’s early medical essays, ‘Anatomia’ (1668) and ‘De arte medica’ (1669) contain many of the leading methodological ideas of the English experimental philosophers, not least the decrying of hypotheses and the endorsement of natural history. Nevertheless, Locke seems not to have used the term ‘experimental philosophy’ in any of his medical writings from the 1660s nor in the early drafts of the Essay dating from c. 1671.

The earliest use of the term in his own writings that I have found appears in a journal entry from 8 February 1677 written while Locke visited Montpelier during his long sojourn in France. The entry has various marginal headings indicating the subject. It opens with the heading ‘Understanding’ followed by ‘Knowledg its extent & measure’, ‘End of Knowledg’ and then simply ‘Knowledg’. Here is what Locke says:

we need no other knowledge for the attainment of those ends [being happy in this world and the next] but of the history and observation of the effects and operations of natural bodies within our power, and of our duties in the management of our own actions as far as they depend on our wills, i.e. as far also as they are in our power. One of those is the proper enjoyment of our bodies and the highest perfection of that, and the other our souls, and to attain both those we are fitted with faculties both of body and soul. Whilst then we have abilities to improve our knowledge in experimentall naturall philosophy, whilst we want not principles whereon to establish moral rules, nor light … to distinguish good from bad actions, … we have no reason to complain if we meet with difficulties in other things. (Cited from Locke: Political Essays, ed. M. Goldie, Cambridge, 1997, p. 264, with modifications)

The sentiments of this passage certainly appear in the published Essay. And, in fact, there are verbal parallels between the whole entry and Essay IV, chapter 3, called ‘Of the extent of human knowledge’. The subjects broadly overlap and so does some of the terminology. For example, Locke uses terms such as ‘canton’ (which only appears once in the Essay) and ‘abyss’ in both passages in similar ways.

So what are we to make of this early appearance of the term ‘experimentall naturall philosophy’? Well first, it is worth pointing out that it is accompanied in the entry with other comments that suggest that Locke was thinking about our knowledge of nature from the perspective of experimental philosophy. We note in the above extract the reference to ‘history and observation’ of the ‘effects and operations of natural bodies within our power’. It is almost certain that Locke has natural history in mind here. This is because Locke claims earlier in the entry that we need only trouble ourselves with ‘the history of nature and an enquiry into the qualities of the things in this mansion of the universe’. Likewise, we find Locke expressing the standard warning against hypotheses:

They might well spare themselves the trouble of looking any further, they need not concern or perplex themselves about the original, frame or constitution of the universe, drawing this great machine into systems of their own contrivance and building hypotheses obscure, perplexed, and of no other use but to raise disputes and continue wrangling. (Locke: Political Essays, p. 262)

There is, therefore, no doubt that Locke has imbibed the methodology of the experimental philosophers and that this is informing his musings on the nature and extent of human knowledge in the winter of 1677.

A second point is just how naturally Locke deploys the term. Its first appearance in Locke is as an obiter dicta: Locke seems to use the term quite naturally with no special focus or emphasis. If the evidence of Locke’s early medical essays is not enough, it is clear that by the time of his travels in France Locke had come to conceive of the acquisition of knowledge of nature in the terms of the new experimental natural philosophy.

Is this Locke’s earliest use of the term? I would be most grateful to any reader who could direct me to an earlier usage.

Review of the rationalism-empiricism distinction in Latin America

Juan Gomez writes…

In this post I want to take a break from sharing my research on the ESD in early modern Spain. I want to talk about the current application of the rationalism-empiricism distinction (RED) by philosophers in Latin America.

A few days ago, Sociedad de Filosofia Aplicada (Society for Applied Philosophy), an organization in Spain, posted on their Facebook page a link to a blog written by a philosopher in Mexico. The blog entry is titled “Racionalismo y empirismo: el realismo.” I had to check out the post, and what I found led me to do a bit of research on the current use of the RED distinction in the Spanish-speaking world. In this post I want to focus on two examples to illustrate both the dangers of the RED and the benefits of adopting the experimental-speculative distinction (ESD).

In Spanish speaking countries, we are taught in philosophy classes in high school and university that the rationalism-empiricism debate frames the history of philosophy in the seventeenth and eighteenth centuries and that such debate was brought to an end by Kant. This assumption leads us to think of rationalism and empiricism as two opposing philosophical schools or movements. This is where the RED starts giving us problems. The author of the blog mentioned above has two posts on rationalism and empiricism: “Racionalismo y empirismo: el realismo” and “Apunte critico: la metafísica dentro del empirismo.” In the former, the author presents rationalism and empiricism as two opposing philosophical theories, although his description of them reflects that they are two opposing epistemological viewpoints. As we have already mentioned in this blog, the fact that the RED is an epistemological distinction means that it is not at all appropriate when it comes to our interpretation of the breadth history of philosophy of that period. This same problem arises in the author’s other post, where he presents empiricism as a whole movement which pretends to “eliminate metaphysics.” There are two issues here: the author uses the term empiricism to refer to logical positivism and the verification principle, and he takes empiricism as more than an epistemological theory. Regarding the first issue, we can see that the use of the term ’empiricism’ itself is unclear, given that it is used to describe both the Vienna Circle and eighteenth-century empiricists; at best, this would lead us to distinguish different kinds of empiricism which, as we have already mentioned elsewhere in this blog, is troublesome. The second issue reiterates the problem of adopting the RED as much more than an epistemological distinction. The author runs into trouble when trying to describe Hume’s thought: “Hume admits, to a certain degree, the value of reason…” Labeling Hume as an empiricist and then claiming that he admits the value of reason raises doubts regarding the usefulness and accuracy of the label.

For a second example I want to refer to a blog entry by a Brazilian philosopher. On the blog for, she has an entry titled “Sobre o Empirismo e o Racionalismo de John Locke.” She acknowledges the difficulty of labeling a philosopher under either rationalism or empiricism, and then sets out to explain how John Locke cannot be labelled under any of these terms. She explains that Locke in some sense has a foothold in each of the so-called philosophical schools: “Locke’s starting point is an empirical method while at the same time he is committed to a rationalist project…” “This is how Locke’s philosophy encompasses, admirably and sui generis, not rationalism as opposed to empiricism, but rather a rationality which follows a rigid, reasonable, and novel empiricist method.” The author here acknowledges the issues that arise when considering the work of Locke under the RED framework, but her thought can be finessed by switching to the ESD framework. The apparent ambiguity of Locke’s work —sitting between rationalism and empiricism— vanishes when his thought is viewed under the ESD lens. Locke can be more comfortably labelled an experimental philosopher, providing us with a more accurate description of his work and a clearer insight into his thought.

The two examples mentioned here just serve the purpose of illustrating the current situation when doing early modern philosophy with the RED framework. Though there has been some talk among Spanish-speaking philosophical circles of the suitability of the RED, most philosophers in the region still take the rationalist–empiricist distinction for granted and work within such framework, unaware of the issues (like in the first example) or the advantages (like in the second example) of an alternative framework. Historians of philosophy in the region can enhance their work and understanding of early modern philosophy by adopting the ESD framework. The switch is a difficult but very rewarding one, one that needs to take place across the whole curriculum in the region; from introductory classes in high school, to advanced research projects in universities.

Vegetative and mechanical processes in Newton’s Chymistry

Kirsten Walsh writes…

In my last post, I started thinking about the lesser-known aspects of Newton’s work—his chymistry, theology and Church history—in order to learn more about his methodology.  In particular, I wondered what kinds of methodological continuity, if any, there are across his many projects.  In this post, I’ll focus on a tract, now referred to as ‘Of Natures obvious laws and processes in vegetation’, from Newton’s alchemical corpus.  Newton probably wrote this piece in 1672—the year that he wrote his ‘New Theory of Light and Colour’.  The piece represents Newton’s attempt to give a synopsis of his early alchemical reading and to come up with, essentially, a ‘theory of everything’.

There is a great deal to interest us in this tract, including an early mechanical-æthereal theory of gravity and a discussion of the nature of God.  But here, I’ll focus on one idea: Newton’s distinction between mechanical processes and vegetative processes.  Where ‘vegetation’ is the generative process through which animals, plants and minerals grow, putrefy and regenerate themselves, ‘mechanical’ processes involve adding, subtracting and rearranging parts (described as “a gross mechanical transposition of parts” (5r)).  Newton considers these processes to be exhaustive: “Natures actions are either vegetable or purely mechanical” (5r).

Newton’s discussion of this idea highlights several methodological continuities.  I’ll discuss two of them here.

The first concerns the way Newton infers physical processes from observed phenomenal patterns.  Drawing comparisons across the ‘three kingdoms of nature’—animal, vegetable and mineral—Newton notes that some metals grow, putrefy and regenerate within the Earth, much in the way that trees grow out of the earth, suggesting that some metals and minerals ‘vegetate’.  In contrast, some salts and minerals appear to generate by the simple combining and arranging of parts.  And so Newton proposes that there are two distinct processes at work in nature: vegetative and mechanical.  The postulated distinction in turn guides further exploration of natural phenomena, enabling him to unify some patterns of generation and to differentiate others.  The phenomena he explores go well beyond the initial cluster of metals and salts, eventually including organic life, heat and flame, and gravitation.  And these phenomena, in turn, offer further clues about nature’s hidden processes.  In short, observed phenomena illuminate underlying processes, which, in turn, guide further exploration of phenomena.

We see Newton engaging in similar inferential patterns in both the Principia and the Opticks.  In the Principia, from the observed Keplerian orbits of the planets, Newton infers the inverse-square centripetal force.  The inverse-square force, in turn, guides Newton’s exploration of other celestial phenomena, allowing him to calculate the motions of comets, the shapes of planets, and also to correct for perturbations of orbits.  Similarly, in the Opticks, from the phenomena of the unequal refraction of light, Newton infers the heterogeneity of white light.  The heterogeneity of white light, in turn, guides Newton’s exploration and theorising of other optical phenomena, including the colours of thin plates, thick plates and coloured fringes.  In other words, this inferential feedback loop between phenomena and processes appears to be a standard feature of Newton’s methodology.  In Query 31 of his Opticks, Newton describes this in terms of the joint methods of ‘analysis’ and ‘composition’.  ‘Of Natures obvious laws’ might be considered an early manifestation of this method.

A second feature worth considering is the way Newton operationalised the concept of vegetation in order to develop a quantitative test for such processes.  The term ‘vegetative’ was familiar to those concerned with the study of life and vitalism, and Newton was happy to speculate on the nature of this process:

The principles of her vegetable actions are noe other than the seeds or seminal vessels of things those are her onely agents, her fire, her soule, her life (5r).

But such a qualitative description of the process wasn’t very helpful for establishing which phenomena were generated by which processes.  Especially since, as he noted, some natural phenomenon might appear to have been generated through vegetative processes, but in fact be produced mechanically.  The way to distinguish between the two kinds of effects was to analyse them—i.e. break the entity down into its parts—and then try to put it back together again.  If the recomposition was successful, then this indicated mechanical processes, if it wasn’t, then vegetative processes were operative.  And so the methods of resolution and composition, or analysis and synthesis, provided him with a way of testing for vegetative processes.  And thus ‘vegetation’ was effectively operationalised: the concept was defined through the operations which tested for it.

We see Newton engaging in a similar practice in his study of interference phenomena.  His hypothesis on the nature of light postulated a hypothetical cause for the observed pattern of coloured rings: an æthereal ‘pulse’.  Operationalising the concept of a pulse gave Newton a unit of measurement and, eventually, a way of formalising and abstracting the explanation.  I have argued that Newton’s hypotheses played sophisticated supporting roles in his optical investigations.  The role performed by the hypothesis of vegetation in this alchemical tract, and the way Newton links it to observation and experiment, looks similarly rich and sophisticated.

This feature helps me to say something more specific about, what I have termed, Newton’s ‘rhetorical style’.  As I have noticed in previous posts, Newton took familiar terms and stretched them to fit his methodology.  It is well-known that he did this with physical concepts such as ‘force’ and ‘mass’, and I have shown, on this blog, that he did this with methodological concepts such as ‘query’, ‘hypothesis’ and ‘principle’.  Bill Newman has demonstrated that Newton also borrowed the concepts of ‘analysis’, ‘synthesis’ and ‘redintegration’ from chymistry and adapted them to his optical work—massaging them to fit his own needs.  But Newton’s use of ‘vegetation’ highlights a particular feature of his rhetorical style: Newton took common terms with imprecise, qualitative meanings and defined them in terms of methods which measure, quantify or detect certain processes.  And so what was really innovative in this case wasn’t that Newton used analysis and synthesis to investigate salts and metals, but rather, that he defined mechanical and vegetative processes in terms of that kind of intervention.  In other words, Newton’s rhetorical style involved operationalising concepts—turning them into tools of measurement.

I closed my last post by pointing out that 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.  Newton’s chymical papers were circulated much more privately and so, presumably, the same political motivations didn’t apply.  Moreover, Newton did not describe himself as an ‘experimental philosopher’ in his published work until 1713.  So it is not surprising that we find no explicit mention of experimental philosophy or the methods of the Royal Society in this tract, which predates that explicit declaration by at least 40 years.  However, the two features I’ve identified highlight Newton’s commitment to observation- and experiment-based theorising.  That this commitment is evident, absent of any political pressure, suggests that it was genuine.

Call for Papers: Causa sive ratio: causality and reason in modernity between metaphysics, epistemology and science

Call for Papers: Causa sive ratio: causality and reason in modernity between metaphysics, epistemology and science

14-16 November 2017, Università degli Studi di Milano

Submission deadline: 15 June 2017

Confirmed keynote Speakers
Jeffrey Mcdonough (Harvard U.)
Katherine Brading (Duke U.),
Angela Breitenbach (Cambridge U.)
Walter Ott (U. of Virginia)
Ansgar Lyssy (LMU München)
Hylarie Kochiras (IAS Bologna)
Andrea Sangiacomo (U. Groningen)

Organizers : Tzuchien Tho, Stefano Di Bella

The very advent of modernity in philosophy could be interpreted through the lens of the fundamental redefinition of causality in the ontological, epistemological and logical separation of cause from reason. From the rejection of formal and final causes in the generation of Descartes and Gassendi, the debates on these questions in the period of Hobbes, Spinoza and Leibniz, to the phenomenalization of causation in Hume and its subsequent idealization in Kant’s Critique of Pure Reason, we can see the definitive conceptual separation between logical implication, epistemic explanation and physical causation. It is this historical conceptual transformation and its present consequences that is the object of this conference.

What does this separation between cause and reason mean for the role of rationality, the property of intelligibility and the ontology of grounding in the development of metaphysics and the foundations of science in the 17th and 18th century? How do the emergent concepts of the general laws of nature and universally conserved physical magnitudes harmonize the rationality of nature and the uniqueness of causes in a new cosmology? What becomes the status of the self-caused? How does the early modern rejection of formal and final causes return, in other guises, and transform the semantic content of physical theories? How does the identity or distinction of reason and cause continue to inform contemporary philosophy?

The aim of this conference is to explore the distinction (and relation) of cause and reason from a historical examination of early modern philosophy and science while engaging with the contemporary debates surrounding grounding, causation and scientific explanation. Aside from paper presentations by invited and selected speakers, short reading groups of primary source texts (relevant to the presentations) will be led by conference organizers and invited speakers.

We invite papers addressing these problems of reason and cause based on historical studies and contemporary problems. We are particularly interested in papers that are able to connect 17th and 18th century thinkers with contemporary issues in metaphysics and philosophy of science. However, papers focusing on these issues contextually based in the 17th and 18th century are also enthusiastically welcomed.

Presentations are planned to be 45 minutes, leaving 15-20 minutes for discussion.

Please submit an abstract of 500 words, including the title of the presentation, to easychair. The abstract should be prepared for blind review. We welcome Ph.D. students and postdoctoral scholars as well as more established colleagues.

Notification of acceptance by 30 June 2017

For more information, see the conference website.

Please direct any futher questions to Tzuchien Tho.


Martin Martin, experimental philosophy and Baconian natural history

Peter Anstey writes…

Sometimes we can appreciate the impact of a new way of thinking or a new movement by examining the views and writings of those on the periphery or of minor, lesser-known figures. Such is the case with the Scotsman Martin Martin. His A Description of the Western Islands of Scotland published in 1703 is written as a Baconian natural history, and in its short preface Martin very self-consciously situates his work as a contribution to experimental philosophy.

It is well known that the book gained some renown in the eighteenth century for its discussion of the phenomenon of second sight –– a discussion that is literally matter of fact and which accords with the methodology of experimental philosophy in so far as he refrains from entertaining any speculations concerning causes of this phenomenon.

The book also gained some notoriety from the fact that Boswell and Johnson used it as a kind of travel guide for their tour of the western Scottish isles in 1773. Yet it is Martin’s brief but poignant methodological comments that are of interest to students of early modern experimental philosophy.

Martin views his book as something of a supplement to the leading histories of Scotland, especially that of George Buchanan, whose History of Scotland (Rerum Scoticarum historia, Edinburgh) appeared back in 1582. Martin tells us:

since his [Buchanan’s] time, there’s a great Change in the Humour of the World, and by consequence in the way of Writing. Natural and Experimental Philosophy has been much improv’d since his days, and therefore Descriptions of Countries without the Natural History of ’em, are now justly reckon’d to be defective. (sig. a4r)

This comment signals Martin’s understanding of the place of natural history in the methodology of experimental philosophy and the requirement that histories of countries have a natural historical component. He goes on to list some of the topics that he covers in order to render his account of the western isles of Scotland such a natural history:

the Nature of the Climate and Soil, of the Produce of the Places by Sea and Land, and of the Remarkable Cures perform’d by the Natives meerly by the use of Simples, and that in such variety as I hope will make amends for what Defects may be found in my Stile and way of Writing. (sig. a5v)

These topics or heads or articles of inquiry are typical of this genre of natural history, and much of the actual content of the book covers Robert Boyle’s desiderata for the natural history of a country set out as early as 1666 (‘General Heads for a Natural History of a Country, Great or Small’) in the Philosophical Transactions (vol. 1, pp. 86–9) and republished in 1692.

Martin mentions experimental philosophy a second time:

Humane Industry has of late advanc’d useful and experimental Philosophy very much, Women and illiterate Persons have in some measure contributed to it by the discovery of some useful Cures. (sig. a5v–a6r)

Now, from a 21st century perspective the comment on women and the illiterate might seem condescending, nevertheless, Martin’s is making the very Baconian point that not just the learned, but everyone can contribute to the project of the history of nature. He then goes on to stress the importance of observation:

the Field of Nature is large, and much of it wants still to be cultivated by an ingenious and discreet application; and the Curious by their Observations might daily make further advances in the History of Nature. (sig. a6r)

It is worth noting that the inspiration for his natural history derived from some within the Royal Society itself, probably including Hans Sloane. For, we are told in the Preface to his earlier A Late Voyage to St. Kilda, London, 1698 (dedicated to the then President of the Royal Society, Charles Montagu), that he had had the

honour of Conversing with some of the Royal Society, who raised his natural Curiosity to survey the Isles of Scotland more exactly than any other; in prosecution of which design he as already brought along with him several curious Productions of Nature, both rare and beautiful in their kind (sig. A4v)

It might be thought, therefore, that Martin’s text is one of many such natural histories from the early eighteenth century; however, I have argued elsewhere that from the 1690s this approach to experimental philosophy actually began to decline. Not only had the program of experimental natural history not delivered much by way of new natural philosophy, but also a rival mathematical form of experimental philosophy was emerging in the wake of Newton’s Principia (1687). If this thesis concerning the decline of Baconian natural history is correct, Martin’s work should be viewed as one of the final installments of an approach to experimental philosophy that was soon to be superseded, even if it never completely disappeared.

Moreover, Martin seems to have had few like-minded natural historians around him in Scotland. Andrew Fletcher of Saltoun, Scotland wrote to John Locke in October 1701 and had the letter hand delivered by Martin. Fletcher recommends him to Locke and, after mentioning Martin’s materials for his natural history of ‘westerne isles of Scotland’ says,

Their is so little encouragement for such a man herre, that if he can meete with any in England, he thincks of staying their or going further abroad (Correspondence of John Locke, Oxford, vol. 7, p. 471)

I would be most interested in hearing from readers about other examples of Baconian natural histories in Britain in the early years of the eighteenth century that might complement that of Martin Martin and round out my own understanding of this very fascinating manifestation of experimental natural philosophy.

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!