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


HOPOS 2016 Call for Submissions


June 22-25, 2016, Minneapolis, Minnesota, USA


Keynote Speakers

Karine Chemla (REHSEIS, CNRS, and Université Paris Diderot)
Thomas Uebel (University of Manchester)


The International Society for the History of Philosophy of Science will hold its eleventh international congress in Minneapolis, on June 22-25, 2016. The Society hereby requests proposals for papers and for symposia to be presented at the meeting. HOPOS is devoted to promoting research on the history of the philosophy of science. We construe this subject broadly, to include topics in the history of related disciplines and in all historical periods, studied through diverse methodologies. In order to encourage scholarly exchange across the temporal reach of HOPOS, the program committee especially encourages submissions that take up philosophical themes that cross time periods. If you have inquiries about the conference or about the submission process, please write to Maarten van Dyck: maarten.vandyck [at]


To submit a proposal for a paper or symposium, please visit the conference website:

Baconian Induction in the Principia

Kirsten Walsh writes…

Recently, I have been looking for clear cases of Baconianism in the Principia. In my last post, I offered Newton’s ‘moon test’ as an example of a Baconian crucial instance, ending with a concern about establishing influence between Bacon and Newton. Newton used his calculations of the accelerations of falling bodies to provide a crucial instance which allowed him to choose between two competing explanations. However, one might argue that this was simply a good approach to empirical support, and not uniquely Baconian. In this post, I’ll consider another possible Baconianism: Steffen Ducheyne’s argument that Newton’s argument for universal gravitation resembles Baconian induction.

Let’s begin with Baconian induction (this account is based on Ducheyne’s 2005 paper). Briefly, Bacon’s method of ampliative inference involved two broad stages. The first was a process of piecemeal generalisation. That is, in contrast to simple enumerative induction, shifting from the particular to the general in a single step, Bacon recommended moving from particulars to general conclusions via partial or mediate generalisations. Ducheyne refers to this process as ‘inductive gradualism’. The second stage was a process of testing and adjustment. That is, having reached a general conclusion, Bacon recommended deducing and testing its consequences, adjusting it accordingly.

Ducheyne argues that, in the Principia, Newton’s argument for universal gravitation proceeded according to Baconian induction. In the first stage, Newton’s argument proceeded step-by-step from the motion of the moon with respect to the Earth, the motions of the moons of Jupiter and Saturn with respect to Jupiter and Saturn, and the motions of the planets with respect to the Sun, to the forces producing those motions. He inferred that the planets and moons maintain their motions by an inverse square centripetal force, and concluded that this force is gravity—i.e. the force that causes an apple to fall to the ground. And, in a series of further steps (still part of the first stage), Newton established that, as the Sun exerts a gravitational pull on each of the planets, so the planets exert a gravitational pull on the Sun. Similarly, the moons exert a gravitational pull on their planets. And finally, the planets and moons exert a gravitational pull on each other. He concluded that every body attracts every other body with a force that is proportional to its mass and diminishes with the square of the distance between them: universal gravitation. Moving to the second stage, Newton took his most general conclusion—that gravity is universal—and examined its consequences. He demonstrated that the irregular motion of the Moon, the tides and the motion of comets can be deduced from his theory of universal gravitation.

Ducheyne notes that Newton didn’t attribute this method of inference to Bacon. Instead, he labelled the two stages ‘analysis’ and ‘synthesis’ respectively, and attributed them to the Ancients. However, Ducheyne argues that we should recognise this approach as Baconian in spirit and inspiration.

This strikes me as a plausible account, and it illuminates some interesting features of Newton’s approach. For one thing, it helps us to make sense of ‘Rule 4’:

In experimental philosophy, propositions gathered from phenomena by induction should be considered either exactly or very nearly true notwithstanding any contrary hypotheses, until yet other phenomena make such propositions either more exact or liable to exceptions.

Newton’s claim that, in the absence of counter-instances, we should take propositions inferred via induction to be true seems naïve when interpreted in terms of simple enumerative induction. However, given Newton’s ‘inductive gradualism’, Rule 4 looks less epistemically reckless.

Moreover, commentators have often been tempted to interpret this rule as an expression of the hypothetico-deductive method, in which the epistemic status of Newton’s theory is sensitive to new evidence. Previously, I have argued that, when we consider how this rule is employed, we find that it’s not the epistemic status of the theory, but its scope, that should be updated. Ducheyne’s Baconian interpretation supports this position—and perhaps offers some precedent for it.

Ducheyne’s suggestion also encourages us to re-interpret other aspects of Newton’s argument for universal gravitation in a Baconian light. Consider, for example, the ‘phenomena’. Previously, I have noted that these are not simple observations but observed regularities, generalised by reference to theory. They provide the explananda for Newton’s theory. In Baconian terms, we might regard the phenomena as the results of a process of experientia literata—they represent the ‘experimental facts’ to be explained. This, I think, ought to be grist for Ducheyne’s mill.

Interpreting Newton’s argument for universal gravity in terms of Baconian induction brings the experimental aspects of the Principia into sharper focus. These aspects have often been overlooked for two broad reasons. The first is that the mathematical aspects of the Principia have distracted people from the empirical focus of book 3. I plan to examine this point in more detail in my next post. The second is that the Baconian method of natural history has largely been reduced to a caricature, which has made it difficult to recognise it when it’s being used. Dana Jalobeanu and others have challenged the idea that a completed Baconian natural history is basically a large storehouse of facts. Bacon’s Latin natural histories are complex reports containing, not only observations, but also descriptions of experiments, advice and observations on the method of experimentation, provisional explanations, questions, and epistemological discussions. We don’t find such detailed observation reports in the Principia, but we do find some of the features of Baconian natural histories.

So, Ducheyne’s interpretation of Newton’s argument for universal gravitation in terms of Bacon’s gradualist inductive method proves both fruitful and insightful. However, recall that, in my last post, I worried that the resemblance of Newton’s methodology to Bacon’s isn’t enough to establish that Newton was influenced by Bacon’s methodology. If Bacon was just describing a good, general, epistemic method, couldn’t Newton have simply come up with it himself? He was, after all, an exceptional scientist who gave careful thought to his own methodology. Is Ducheyne’s discussion sufficient to establish influence? What do you think?

“Secta Empírica y Dogmáticos Racionales”: medicine and the ESD in early modern Spain II

Juan Gomez writes…

I have been discussing the reception and development of experimental philosophy in early modern Spain in a number of posts in our blog. In my previous entry, I introduced a 1711 text by Marcelino Boix which presents an interesting sketch of the relationship between natural philosophy and medicine. In particular, we saw that Boix sets out to defend empiric doctors from the attacks of rational dogmatists. However, I did not examine in detail Boix’s conception of empiric doctors. It is to Boix’s description of the empiric sect that I want to turn to now.

Boix establishes his definition of the empiric sect by placing it in relation to what he calls “the three main sects of natural philosophy”: sceptics, academics, and rational dogmatists. While all three sects are driven by the search for truth, they differ in the accounts of their results:

Rational dogmatists brag that they have found the truth, in contrast to the Sceptics, which have not been able to find it, in spite of the fact that they have never lost hope of finding it…The Academics have completely despaired in finding it. While Rational dogmatists insist on giving an answer to every question in nature, Academics and Sceptics suspend their judgment.

Boix wants the reader to think that out of the three sects, the Academic one is the best. This is made evident in his description of the way the three sects have made an impact on the history of medicine. Boix comments that medicine up to the eighteenth century was founded on the rational dogmatist philosophy, which has Aristotle and Chrysippus as its leading figures, since “they were the first who taught Dogmatists and Scholastics to talk loud when it comes to the search for truth.”

The academics are discarded quickly, since they have given up in the search for the truth. The sceptics are considered in a more favorable light, since they are the foundation for the empiric doctors, who Boix sides with. He mentions that the Sceptics had Pyrrho for their guide, who “acquired the knowledge, solely through the light of nature, that Philosophy and Medicine were not learnt through disputes and useless questions.”  Boix starts his defense of the empiric sect and finds support in the work of Robert Boyle. He quotes a passage from Boyle’s Certain Physiological Essays in order to show that the way rational dogmatists conduct their research does not yield results:

If a physician be asked, why rhubarb does commonly cure looseness, he will probably tell you as a reason, that rhubarb is available in such diseases, because it hath both a laxative virtue, whereby it evacuates choler, and such other bad humours as are wont, in such cases, to be the peccant matter; and an astringent quality, whereby it afterwards arrests the flux. But if you further ask him the reason, why rhubarb purges, and why it purges choler more than any other humour; it is ten to one he will not be able to give you a satisfactory answer.

Boix uses the quote to prove a point: that the rational dogmatists (focusing their accounts on occult and secondary qualities) cannot explain why rhubarb purges choler more than any other humour. He comments that not even Robert Boyle, “the Prince of philosophy in our time”, can explain why rhubarb purges choler more than any other humour. The point is that those partial to the empiric sect know when to abstain from giving an answer, unlike the rational dogmatists who make up their explanations.

This brings Boix to ask an interesting question to his sketch: If none of the sects can give us answers, what is the difference between them? Boix reiterates his suggestion that while rational dogmatists claim to know certain truths, without proof, sceptics focus on the plausibility of their explanations based on experience:

If, like Valles says, a doctrine is more probable than another, because it has better foundations both ab extrinseco and ab intrinseco, then in Philosophy the Sceptics will make it more probable than the Rational dogmatists, the latter make doctrines plausible based on the authority of many, which is ab extrinseco, and on reason, which is ab intrinseco. But the Sceptics laugh at all this, since with experience they prove both reason and authority wrong. The same can be said of the Empiric doctors, given that, despising useless questions they search for experience, because they know that it will bring them closer to the truth (even though they lose hope in ascertaining it), and in this way Sceptics and Empirics make their doctrine more plausible than the Rational dogmatists do: since opposed to experience there can be no disputes, especially when it is accompanied by reason.

Boix’s description of the distinction between rational dogmatists and sceptics/empiric doctors closely resembles the speculative-experimental divide: rational dogmatists, just like speculative philosophers, turn to authority, syllogisms, and occult qualities to ground their doctrines; sceptics/empiric doctors rely solely on experience in their search for truth, just like experimental philosophers. Boix’s references to Boyle and Sydenham also suggest that his empiric doctors are committed to the same methodology the experimental physicians promoted. In this sense, Boix’s work can help us decipher the way in which Spanish philosophers received and interpreted experimental philosophy, giving way to the philosophy of the Novatores, a group that would shape the development of early modern Spanish philosophy.

Leibniz’s early reflections on natural history and experiment

Peter Anstey writes…

G. W. Leibniz visited England in late October 1676. While there he renewed his acquaintance with Henry Oldenburg, Secretary of the Royal Society, and showed him his calculating device. After a week’s visit he boarded a ship bound for the Continent on 29 October, but for various reasons the ship was delayed and he used his time while moored in the Thames to write a dialogue about the nature of motion.

This dialogue, recently translated in full for the first time, has a very interesting preamble about natural philosophical methodology. This preamble may well have been stimulated by his recent visit to London, for it mentions some of the leading ideas of the new experimental philosophy that was practised there and promoted by many Fellows of the Royal Society of which Leibniz was a foreign member.

The dialogue is between Pacidius, aka Leibniz, Gallantius, Theophilus and Charinus. Pacidius opens with a comment about the danger of looking for causes when one does natural history. (I am quoting from the translation of Richard Arthur, G.W. Leibniz: The Labyrinth of the Continuum: Writings on the Continuum Problem, 1672–1686, New Haven: Yale University Press, 2002.) We take it up from Gallantius’ reply:

GALLANTIUS: I have certainly often wished that observations of nature, especially histories of diseases, could be presented to us unadorned and free from opinions, as are those of Hippocrates, and not accommodated to the opinions of Aristotle or Galen or somebody more recent. For we will only be able to revive philosophy when we have solid foundations for it. (p. 133)

Gallantius focuses on natural histories of disease, but his point applies more generally to the project of Baconian natural history (described here) which, as Oldenburg repeatedly claimed, was to provide solid foundations for natural philosophy. Theophilus replies:

THEOPHILUS: I do not doubt that the royal road is through experiments, but unless it is levelled out by reasoning we will make slow progress, and will still be stuck at the beginning after many generations. (p. 133)

Theophilus here raises the issue of the relation between the gleanings from observation and experiments, which is the focus of natural history, and the need to theorise in order to get an understanding of nature. The comment about being ‘stuck at the beginning after many generations’ is prescient because, as we have pointed out before on this blog, one of the reasons that the Baconian program of natural history faltered in the late seventeenth century was because it had delivered so little in the way of stimulus to new natural philosophy. Robert Hooke was sensitive to this very point in his ‘Discourse of Earthquakes’:

tho’ the things so collected [by our natural historians] may of themselves seem but like a rude heap of unpolish’d and unshap’d Materials, yet for the most part they are so qualified as that they may be fit for the beginning, at least of a solid, firm and lasting Structure of Philosophy. (Posthumous Works, London, 1705, p. 329)

Theophilus continues:

… I am amazed at how many excellent observations we have …, at how many elegant experiments the chemists have performed, at what an abundance of things the botanists or anatomists have provided, which philosophers have not made use of, nor deduced from them whatever can be deduced.

PACIDIUS: But there does not yet exist a technique in natural philosophy for deducing whatever can be deduced from the data, as is done according to a definite order in Arithmetic and Geometry. … Once people have learnt to do this in natural philosophy … they will perhaps be surprised that many things were unknown to them for so long––which should not be put down to the laziness of the true method, which alone sheds light. (pp. 133/135)

Here Leibniz reveals that he was aware of the significant progress of the new experimental philosophy as applied in disciplines, such as chemistry, anatomy and botany, and at the same time the lack of progress in using this for developing a philosophy of nature. He puts it down to the lack of a method that is analogous to that in mathematics. The same lack of progress had been noticed by other critics of the new experimental philosophy, particularly the English wits, but rather than viewing this as a methodological deficiency they simply mocked the new natural philosophers in works such as Thomas Shadwell’s play The Virtuoso which appeared in 1676, the very same year as Leibniz’s visit.

Charinus, who speaks next in the dialogue, uses Pacidius’ observations as a segue into a discussion of the nature of motion, and so the methodological reflections tail off at this point. However, the little we do have gives us a fascinating window onto Leibniz’s views of the state and prospects of the new experimental philosophy with its emphasis on natural history in the mid-1670s.

CFP: Bucharest Colloquium in Early Modern Science

A colloquium at the Institute for Research in the Humanities, University of Bucharest & The Center for the Logic, History and Philosophy of Science, Faculty of Philosophy, University of Bucharest:


CFP: Bucharest Colloquium in Early Modern Science

6th-7th November 2015


Invited speakers:

Daniel Garber (Princeton University)
Paul Lodge (University of Oxford)
Arianna Borrelli (Technical University, Berlin)


We invite papers by established and young scholars (including doctoral students) on any aspects of early modern philosophy/early modern science. Abstracts no longer than 500 words, to be sent to Doina-Cristina Rusu ( ) by September 10. Authors will be notified by September 15.



Dana Jalobeanu ( and Doina-Cristina Rusu ( ).


More details:




Crucial Instances in the Principia

Kirsten Walsh writes…

In the General Scholium, which concluded later editions of Principia, Newton described the work as ‘experimental philosophy’:

In this experimental philosophy, propositions are deduced from phenomena and are made general by induction. The impenetrability, mobility, and impetus of bodies, and the laws of motion and the law of gravity have been found by this method.

On this blog, I have argued that we should take this statement at face value. In support, I have emphasised similarities between Newton’s work in optics and mechanics. For example, I have considered the kind of evidence provided in each work, arguing that both the Principia’s ‘phenomena’ and the Opticks’s ‘experiments’ are idealisations based on observation, and that they perform the same function: isolating explananda. I have also emphasised Newton’s preoccupation in the Principia with establishing his principles empirically. Finally, I have suggested that this concern with experimental philosophy, in combination with his use of mathematics, made Newton’s method unique.

In my last blog post, I wondered if we should regard Newton’s methodology as an extension of the Baconian experimental method, or as something more unique. I have written many blog posts discussing the Baconian aspects of Newton’s optical work (for example, here, here and here), but the Baconian aspects of the Principia are less well-established. I can identify at least three possible candidates for Baconianism in the Principia. The first, suggested by Daniel Schwartz in recent conversation, is that book 3 contains what might be interpreted as Baconian ‘crucial instances’. The second, discussed by Steffen Ducheyne, is that Newton’s argument for universal gravitation resembles Bacon’s method of induction. The third, discussed by Mary Domski, is that the mathematical method employed in the Principia should be viewed as part of the seventeenth-century Baconian tradition. In this post, I’ll focus on Schwartz’s suggestion—the possibility there is a crucial instance in book 3 of the Principia—I’ll address the rest in future posts.

To begin, what is a ‘crucial instance’? For Bacon, crucial instances (instantiae crucis) were a subset of ‘instances with special powers’ (ISPs). When constructing a Baconian natural history, ISPs were experiments, procedures, and instruments that were held to be particularly informative or illuminative of aspects of the inquiry. These served a variety of purposes. Some functioned as ‘core experiments’, introduced at the very beginning of a natural history, and serving as the basis for further experiments. Others played a role later in the process. This included experiments that were supposed to be especially representative of a certain class of experiments, tools and experimental procedures that provided interesting investigative shortcuts, and model examples that came close to providing theoretical generalisations.

Crucial instances are part of a subset of ISPs that were supposed to aid the intellect by “warning against false forms or causes”. When two possible explanations seemed equally good, then the crucial instance was employed to decide between them. To this end, it performed two functions: the negative function was to eliminate all possible explanations except the correct one; the positive function was to affirm the correct explanation.

According to Claudia Dumitru, Bacon’s crucial instances have a clear structure:

  1. Specify the explanandum;
  2. Consider the competing explanations (these are assumed to exhaust the possibilities);
  3. Derive a consequence from one explanation that is incompatible with the other explanation(s);
  4. Test that consequence.

Are there any arguments in the Principia that look like crucial instances? I think there’s at least one: Newton’s famous ‘Moon test’. Let’s have a look at it.

In proposition 4 book 3, Newton used his Moon test to establish that “The moon gravitates toward the earth and by the force of gravity is always drawn back from rectilinear motion and kept in its orbit”. Here, Newton argued that the inverse-square centripetal force, keeping the moon in orbit around the Earth, is the same force that, say, makes an apple fall to the ground, namely, gravity. I think we can tease out the features of a Baconian crucial instance from Newton’s reasoning here.

Firstly, there is an explanandum: what kind of force keeps the Moon in its orbit and prevents it from flying off into space? Secondly, two possible explanations are provided: the force is either (a) the same force that that acts on terrestrial objects, namely, gravity; or (b) a different force. Thirdly, we have a consequence of (a) that is incompatible with (b): if the moon were deprived of rectilinear motion, and allowed to fall towards Earth, it would begin falling at the rate of 15 1/12 Paris feet in the space of one minute, accelerating so that at the Earth’s surface it would fall 15 1/12 Paris feet in a second. Finally, we see a test of that consequence: the calculations based on the size and motion of the Moon, and its distance from the Earth. The results are taken to support (a) and refute (b).

I have three concluding remarks to make.

Firstly, interpreting the Moon test as a crucial instance involves ‘rational reconstruction’. In the text, Newton starts by calculating the rate at which the Moon would fall, and shows that this supports proposition 4. But I think my reading of this as a crucial instance is supported by Newton’s concluding remarks:

For if gravity were different from this force, then bodies making for the earth by both forces acting together would descend twice as fast, and in the space of one second would by falling describe 301/6 Paris feet, entirely contrary to experience.

Here, Newton described the Moon test as a crucial instance: he used an observation to choose between two competing explanations of the explanandum.

Secondly, when looking for crucial instances in the Principia, it might be tempting to start with the phenomena, listed at the beginning of book 3. Elsewhere, I have argued that these resemble Newton’s experiments in the Opticks, which function as instances with special powers. But the label ‘crucial instance’ describes the function, not the content, of an empirical claim. And so, to see if they provide crucial instances, we need to consider how the phenomena are used. In fact, I think they do provide crucial instances for Newton’s rejection of Cartesian vortex theory in favour of universal gravitation, found at the end of book 2. But again, this requires rational reconstruction.

Finally, there is the issue of historical influence. I have shown that Newton employed the Moon test to decide between two competing explanations, and that this argument resembles one of Bacon’s crucial instances. However, one might think that this was simply a good approach to empirical support, and that Newton was using his common-sense. So perhaps we shouldn’t take this to indicate (direct or indirect) influence. And so I have a question for our readers: was this style of reasoning uniquely Baconian?


Master-class: Isaac Newton’s Philosophical Projects

A master-class at the Institute for Research in the Humanities, University of Bucharest:


Isaac Newton’s Philosophical Projects

6th-11th October 2015


The purpose of this master-class is to discuss and to set in context some of Newton’s philosophical, scientific and theological projects. It aims to address a number of well-known (and difficult) questions in a new context, by setting them comparatively against the natural philosophical and theological background of early modern thought. By bringing together a group of experts on various aspects of Newton’s thought with experts on Descartes, Bacon and Leibniz, the master-class facilitates interdisciplinary and cross-disciplinary perspectives

The activities of the master-class will consist of lectures, reading groups and seminars, as well as more informal activities (tutorials, and discussions). The master-class will be set within the interdisciplinary environment of the Institute of Research in the Humanities, University of Bucharest. It aims to bring together 15 students (post-docs and graduate students) coming from different fields and willing to spend 5 days working together within the premises of the Institute, and under the supervision of leading experts.


Invited speakers:

Rob Illiffe (Sussex), Niccolo Guicciardini (Bergamo), Andrew Janiak (Duke University)



Dana Jalobeanu, Kirsten Walsh


To participate:

There is no participation cost, but there are limited places available.  In order to apply for the master-class send a CV and a letter of intention to Dana Jalobeanu ( by August 15, 2015. The final list of participants will be announced on the web-site of the institute by August 30, 2015. If you want to present a short paper in the master-class, please send an extended abstract (no longer than 800 words).


More details:





The ESD and the Berlin Académie

Peter Anstey writes …

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

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

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


Pierre Louis Moreau de Maupertuis (Public Domain)

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

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

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

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

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

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

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

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

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

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

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

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

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



“Secta Empírica y Dogmáticos Racionales”: medicine and the ESD in early modern Spain

A couple of months ago Peter Anstey directed me to a book by Miguel Marcelino Boix, a Spanish doctor and professor of surgery at the Universidad de Alcalá. The book, a defense and commentary on the first aphorism of Hippocrates, was published in 1711 and it contains some references to the experimental philosophy of the time. But what really caught my eye was the use Boix makes of the terms rationalism (racionalismo) and empiricism in medicine, and the connection of the latter term to experimental philosophy. In this and a couple of future posts I want to present Boix’s text and hopefully shed some light on the connection between experimental philosophy and empiricism (and the ESD) in early modern Spain.

Vita brevis, ars longa, occasio praeceps, experimentum periculosum, iudicium difficile.

This is Hippocrates’ first aphorism, the focus of Boix’s text. The Spanish doctor gives his analysis of the five phrases of the aphorism while criticizing various other interpretations of them. It is during his account of the fourth phrase, experimentum periculosum, that Boix contrasts the two sects, rational dogmatists (dogmáticos racionales) and empirics (empíricos), and begins to connect the latter with experimental philosophy.

Boix begins by offering his interpretation of the phrase, explaining that it says that doctors “never apply any medicine to the human body with absolute certainty that the desired effect will result.” In this sense, the phrase serves as warning to doctors, both rational and empiric, to be mindful of the limits of our knowledge and experience regarding medicine. However, Boix comments, some rational dogmatists have taken the phrase to mean that “experience is dangerous and false if it is not accompanied by reason.” This interpretation is used by rational dogmatists to attack the empirics, given that they follow experience blindly without any reference to reason. But Boix believes that this description of the empiric doctors, which is popular among people, is flawed. It is this mistaken account of the empirics that leads him to explain the differences between the two sects.

Given that the rational dogmatists attack the empirics for detaching reason from experience, Boix begins by examining the reasons the former give in their accounts.

They (rational dogmatists) say that their Medicine and Philosophy is founded on the four Elements, and the four humours; look at these four columns, these four strong pillars. And so they say, that knowing that there is heat, cold, wet and dry; blood, yellow bile, phlegm and black bile, they know all the effects they want, and that solely with the knowledge of these two quartets they have enough to defeat even the toughest questions contained in Natural philosophy and all of medicine. To this they add, that they are extremely happy, that Galen and Aristotle,their Princes, one in Medicine, the other in Philosophy, knew all they could, because neither to them or their disciples, has a problem been put forward, whether Physical or Medical, that they have not been able to solve solely by knowing that there are four qualities, and four humours.

By contrast, the popular opinion of the empirics is that they focus solely on experience and never give reasons for it; they “are those tricksters or scoundrels that come from Foreign Nations with half a dozen remedies, wanting to cure all kinds of diseases with them.” But this is a false depiction of the empiric sect. In order to explain what the empiric doctors are really about, Boix refers to the main sects in natural philosophy: sceptics, academics, and rational dogmatists. But we will get into that in my next post. I want to stop here to talk about the popular concept of the empiric doctors and the connection with experimental philosophy.

As Alberto Vanzo pointed out in a previous post, “experimental physicians” saw themselves as opponents of “empirical physicians.” But the text by Boix brings in a new scenario for our consideration. It seems that in Spain, rather than seeing themselves as opponents of the empirical physicians, experimental physicians felt that were indeed part of the empiric sect and opposed the rational dogmatists. However, the position of the Spanish doctors is not different from that of the physicians described by Alberto in his post. When doctors like John Gregory and Friederich Hoffman described themselves as opponents of the empirical physicians, they had in mind the popular concept of empiric that Boix points out in his text. The Spanish doctors, just like their Scottish and German counterparts, saw themselves as opponents of that specific kind of physician. The difference lies in the fact that Spanish physicians believed that the true empirical physicians were far from the popular depiction of empirics. In fact, the way they described the true empirical doctors is very similar to that of Gregory and Hoffman regarding experimental physicians. It is this description of the empiric sect that we will turn to in my next post.



Huygens and Newton

Kirsten Walsh writes…

In a previous post, I noted that, unlike other members of the Royal Society, Newton saw a role for mathematical reasoning in experimental philosophy. In many ways, it was this mathematical approach that distinguished his methodology from the Baconian experimental philosophy, adopted by Boyle and Hooke.  Given this distinctive mathematical bent, one might be tempted to suggest that Newton’s approach has far more in common with that of mathematicians such as Huygens, than with experimental philosophers such as Boyle and Hooke. (Indeed, Eric Schliesser argues for this position here.) In today’s post, I’ll examine this claim. First I’ll look at Huygens’ and Newton’s mechanics, then I’ll broaden the scope to consider their optical work as well.

Let’s begin by comparing Huygens’ Horologium Oscillatorium (or, the Pendulum Clock) with Newton’s Principia. The Horologium and the Principia are generally regarded as two of the three most important seventeenth-century works on mechanics (the third being Galileo’s Two New Sciences). We know that Newton read, and very much approved of, Huygens’ Horologium well before he began work on his Principia. So it is an obvious source of inspiration and influence for Newton’s work. Moreover, there are important similarities between them. Most obviously, they share fundamental assumptions and content, including axioms regarding motion, analyses of pendulum motion and theories of curves. Furthermore, each work, to some extent, re-derives Galileo’s work on mechanics. But the similarity runs deeper. Firstly, both works display a marked preference for classical-geometrical inference strategies. For one thing, they both exploit the axiomatic structure of geometry as a model of logical rigour. And for another, they employ geometrical diagrams to demonstrate propositions. Secondly, both works draw on experiment (for example, pendulum experiments) to establish the explananda.

Another similarity between the two works is that both authors remain agnostic with regard to the mechanism or cause of gravity. Newton’s (in)famous phrase, Hypotheses non fingo, is a declaration of this. And in part II of the Horologium, Huygens’ second hypothesis begins, “By the action of gravity, whatever its sources…” (my emphasis). On the face of it, this is a feature that unites them. But, despite appearances, it is at this point that they come apart.

After its publication, Huygens criticised the Principia for appearing to support action at a distance. Huygens was committed to the mechanical philosophy and, as far as he was concerned, Newton’s account of gravity couldn’t be given a mechanical explanation. Newton was not swayed. The fact that his account seemed to support an unsavoury metaphysical commitment did not deter him from appreciating its empirical success. In the preface to book 3 of the Principia, Newton wrote that he was wary of its inclusion, since

“…those who have not sufficiently grasped the principles set down here will certainly not perceive the force of the conclusions, nor will they lay aside the preconceptions to which they have become accustomed over many years…” (my emphasis).

Huygens did exactly what Newton was afraid of: he allowed his mechanical preconceptions to prevent him from appreciating “the force of the conclusions”.*  As far as Newton was concerned, “it is enough that gravity really exists and acts according to the laws that we have set forth”. (And in the final paragraph of the Principia we see that Newton hoped to conceive of gravity as a spirit or vapour—he had not given up on the possibility of a local-action explanation. However, he wasn’t willing to sacrifice the rigour of his account in order to provide one.)

And so, one difference between Newton and Huygens lies in their commitment to mechanical philosophy. Where, for Huygens, the ability to give mechanical explanations—appealing to the shape, size, motion and texture of corporeal bodies—is a requirement of natural philosophy, Newton sees this as a needless restriction. Although Huygens’ commitment to the mechanical philosophy aligns him closely with Boyle and other early members of the Royal Society, the mechanical philosophy and the experimental philosophy were distinct. Arguably, Newton’s decoupling of experimental and mechanistic philosophy is one thing that sets him apart from both the early Royal Society and Huygens.

Another difference between Newton and Huygens is revealed when we broaden the scope to consider their optical work as well. Newton, following Isaac Barrow, thought that there was a place for mathematical reasoning in optics and natural philosophy more generally. In mathematics, one can reason deductively from axioms to propositions, without epistemic loss. So too, Newton thought, one can reason in natural philosophy. And so, by starting with experimentally established axioms (or laws), one could reason deductively to propositions, without epistemic loss. In this way, Newton conceived of a ‘science of optics’, grounded in experiment and observation, and inferred via mathematical reasoning. In contrast, Huygens thought that optics required a very different approach than mechanics. Where, in mechanics, it was possible to reason mathematically, without epistemic loss; Huygens thought that the hypothetico-deductive method was more appropriate for optics.

In brief, Newton took his theoretical claims in optics to be certain, as they were (1) mathematically derived from axioms, which were (2) established by careful experiment. Huygens, like the early Royal Society, held that certainty is out of our reach, so the best we can hope to achieve is a high degree of probability. Here we see one way in which Newton diverges from the Baconian experimental philosophy. He distanced himself from the probabilism of the Baconian experimental philosophers—and Huygens.

Here we have seen that there are indeed striking similarities between Huygens’ Horologium and Newton’s Principia. But, if we want to understand their methodological outlooks, we may learn more by considering the differences. The points of disagreement between Huygens and Newton allows us to identify two very different methodological approaches. Huygens was undoubtedly a strong influence on Newton. As were Descartes, Barrow and Hooke—not to mention his early reading of Aristotelian textbooks, his later interest in Pappus, and the many contemporary works of logic and natural philosophy! Despite these influences, or perhaps because of them, the methodology ultimately developed and exemplified by Newton was utterly original. In a nutshell, he saw mathematical deductive inference as compatible with the observations and experiments of Baconian natural history.  In combining these, he forged a new method of experimental philosophy, which eventually superseded Baconian experimental philosophy.

And so, what was Newton’s relationship with the mathematicians? Well, Newton actively engaged with their methodological approaches, and took a lot from them. Just as he did with the experimental philosophers of the early Royal Society.  How distinctive was Newton’s approach?  Mary Domski has argued that the methodology of the Principia should be viewed as a natural extension of the Baconian experimental philosophy – and that this was recognised by Locke.  In my next post, I’ll examine this idea and try to nail down just what was original about Newton’s methodology.


* Incidentally, here I offer a different reading of this passage to the one offered by Eric Schliesser. Where Schliesser argues that Newton was rejecting “a whole package of practices that are (implicitly) captured by the ESD”, I argue that Newton was rejecting the mechanical philosophy. (On the historiography of the mechanical philosophy, including some thoughts on the relationship between the experimental philosophy and the mechanical philosophy, see Peter Anstey’s recent essay review.  He has also posted on the topic here and here.)