The French Philosophe Voltaire played an important role in the transmission of experimental natural philosophy to France in the 1730s. That Voltaire regarded the emergence of experimental philosophy as a pivotal moment in history is seen in his history of TheAge of Louis XIV (1751). In the Introduction to this work he speaks of the Italians of the Renaissance being ‘in possession of everything that was beautiful, excepting music, which was then in but a rude state, and experimental philosophy, which was everywhere unknown’.
The decisive moment came in the early seventeenth century in the writings of Francis Bacon. For, in his Letters Concerning the English Nation (Oxford, 1994) that appeared in English and French in 1734, Voltaire credits Bacon with being the first experimental philosopher:
He is the Father of experimental philosophy … no one, before the Lord Bacon, was acquainted with experimental Philosophy, nor with the several physical Experiments which have been made since his Time. (pp. 51–2)
But did Voltaire himself take up experimental philosophy or was he merely a herald and conduit for this movement to the French reading public?
Two works suggest that Voltaire fully embraced the new experimental philosophy that he had encountered in England in the 1720s. The first is his Treatise on Metaphysics that he wrote in 1734, the year in which his Letters appeared but which was published posthumously. This work bears the marks of someone who had imbibed the methodological position of the new experimental philosophy both in its rejection of speculative philosophy and hypotheses and the priority it gives to observation and experiment. For example, he says:
It is clear that one should not make hypotheses. We ought not to say ‘Let us begin by inventing some principles with which we will try to explain everything’, but we ought to say, ‘Make an exact analysis of things and then we will try with great diffidence whether they are related to certain principles’.
He goes on to claim ‘when we can help ourselves with neither the compass of mathematics, nor the torch of experiment and natural philosophy, it is certain that we are not able to do anything’ (ibid., p. 301).
The second work is his ‘Essay on the nature of fire and its propagation’, an essay he submitted for the Académie des sciences prize in 1738. As things turned out Leonhard Euler’s essay won the prize, but Voltaire’s submission and that of Madame du Châtelet were published alongside Euler’s winning essay in the Recueil des pieces qui ont remporté le prix de l’Académie royale des sciences in 1739. This is Voltaire’s only serious foray into experimental natural philosophy.
In the Part One of the essay, the part that addresses the nature of heat, he uses the experiments of others to argue for an Aristotelian theory of heat as an element. In doing so he cites the experimental work of Boyle, Newton and Boerhaave. However, in the second article of Part Two of the essay, on the subject of how fire acts on other bodies, Voltaire relates a whole series of experiments that he had performed himself. This is with a view to establishing certain laws by which fire acts, the second of which purported laws is an inverse square law analogous to Newton’s law of gravitational attraction! (p. 201) At one point he tells us:
the comparative degrees of heat of fluids of minerals and of vegetables can, I believe, be known with the aid of a single thermometer constructed on the principles of Mr de Réaumur.
There is only one precaution to take, and this is that the spirit of wine should not boil in the thermometer. To achieve this I plunged only up to half of the ball of the thermometer in the boiling liquors. (p. 207)
Much more could be said about this fascinating essay, but the key point of interest here is that it is a demonstration of Voltaire’s commitment to and practice of experimental natural philosophy.
He may never have experimented again, yet he continued to refer to experimental philosophy, alluding to his essay on heat in his Metaphysics of Newton (La métaphysique de Neuton, Amsterdam, 1740, p. 49) and, most famously, referring to experimental philosophy in his literary works, including Candide (1759) and Micromégas (1752).
A one-day conference at New York University on February 20, 2016
Contemporary work in experimental philosophy investigates the relationship between empirical methods and philosophical questions. However, there is a rich history of thinking through the general issues surrounding armchair and experimental approaches to philosophy; for instance, such projects can be found in 19th century philosophy, early modern philosophy, and classical Chinese philosophy.
To explore these topics and philosophical questions at the intersection of experimental philosophy and history of philosophy, we will host a one-day conference. The conference will be held at New York University on February 20th, from 10:00 AM to 6:15 PM. The conference features six presentations, each with a paired commentary. Further information can be found here. Please direct any questions to: firstname.lastname@example.org.
Peter Anstey (The University of Sydney)
discussion by Stephen Darwall (Yale University)
Scott Edgar (Saint Mary’s University)
discussion by John Richardson (New York University)
Alex Klein (California State University)
discussion by Henry Cowles (Yale University)
Hagop Sarkissian (Baruch College, CUNY)
discussion by Stephen Angle (Wesleyan University)
Kathryn Tabb (Columbia University)
discussion by Don Garrett (New York University)
Alberto Vanzo (University of Warwick)
discussion by Alison McIntyre (Wellesley College)
An Interdisciplinary Master class on the Nature and Status of Principles in Western Thought
15–18 March 2016
Eligibility: Graduate students and post-doctoral researchers Maximum attendance: 15 (selected by application) Organisers: Dr Dana Jalobeanu (Director, IRH-UB) and Prof Peter Anstey (Sydney University) Invited speakers: Dr Vincenzo de Risi (Max Planck Institute, Berlin) and Dr Aza Goudriaan (Vrije Universiteit, Amsterdam)
The purpose of this interdisciplinary master class is to examine the nature and status of principles across a variety of disciplinary domains and a variety of historical periods. The concept of principles is almost ubiquitous in Western thought: it is used in philosophy, natural philosophy, ethics, art, mathematics, politics and theology. One only needs to cite some of the canonical works of early modern philosophy, natural philosophy or art to appreciate the centrality of the notion: for example, Descartes’ Principia philosophiae (1644), Newton’s Principia (1687) and Taylor’s New Principles of Linear Perspective (1719). Yet to date there are few if any systematic treatments of the subject. This master class will address the following questions in relation to classical, Hellenistic, Renaissance and early modern thought:
Which disciplines appealed to principles?
What sorts of principles did they deploy?
How does one get epistemic access to these principles?
And what roles did principles play in the period and discipline under scrutiny?
How does the use of principles vary across disciplines and across historical periods?
Is the principles concept stable or subject to change?
Is there a typology of principles?
What is the relation between principles, axioms, hypotheses and laws?
The master class will include 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 up to fifteen post-docs and postgraduate students from different fields and willing to spend four days working together within the premises of the Institute, and under the supervision of experts in the field. The master class will also benefit from logistical support of CELFIS (Center for the Logic, History and Philosophy of Science), Faculty of Philosophy. Each student attending the master class will have the opportunity to give a twenty-minute presentation on the final day. Student contributions are voluntary.
How to apply
In order to apply for the master class send a CV (maximum 2 pages) and a short letter of intention to Dr Mihnea Dobre (email@example.com) by 30 January 2016. The final list of participants will be announced on the website of the institute by 5 February 2016.
As readers of this blog know, I have been exploring the application of the ESD framework for interpreting the history of philosophy and science in early modern Spain. Throughout the past 18 months or so I have been sharing my research and thought on the experimental/speculative divide in Spain, the application of the experimental method in medicine and natural philosophy by the Novatores, and the attacks on the “new philosophy” by Spanish scholastic thinkers. It is time to take stock on the ESD in early modern Spain, and I want to begin by focusing on one particular issue in this post.
One of the purported advantages of applying the ESD framework is that, unlike the terms “rationalist” and “empiricist,” the terms “experimental” and “speculative” were in fact the terms used by early modern philosophers. However, as is evident in a number of my posts, it seems that in early modern Spain the rationalist/empiricist distinction is used by the players in the debate. Could this perhaps mean that the ESD framework is not that appropriate for the Spanish context? I don’t believe this is the case. Let’s start by examining the use of the empiric/rationalist distinction I have referred to in previous posts.
Almost all of the figures involved in the intellectual debates in early modern Spain were either within or had some connection to the medical context. It is in this context where we see the terms “empirico” (empiric) and “racional” (rational) in use. The terms appear opposed to each other, where the empiric doctors are those that focus on experience and observation and the rational doctors those who follow the teachings of Galen and Aristotle. This being the case, we could perhaps claim that the ESD has no clear advantage over the RED framework. In fact, we could even think that the RED is better, since the figures involved in the debate were using “empirico” and “racional.”
It is important here to remember that the frameworks have two dimensions: a historical and a historiographic one. In the Spanish case, the presumed advantage of the RED would hold at the historical level, but it is yet to be seen if this carries over to the historiographical level.
However, even at the historical level the RED framework’s advantage is doubtful. As we have explained, there is a very important difference between the two frameworks: while the ESD highlights a methodological distinction, the RED highlights an epistemic one. As we examined in my last post, while Boix uses “empirico” and “racional”, he uses those terms to refer to a methodological distinction, not an epistemic one. So the use of the terms by Boix does not line up with the way they appear within the RED framework.
In fact, the fact that the way Boix uses the terms differs from the RED way actually points to the advantages of the ESD at the historiographical level. Even if the figures within the debate were not using “experimental” and “speculative”, the fact that the ESD focuses on a methodological distinction makes it a more appropriate framework for our interpretation of the period.
There is another consideration that can shed light on our present discussion. As I mentioned earlier, the empiric/rational distinction is rooted in the medical context. In other contexts, as in astrology and natural philosophy, the debate is not phrased in those terms. The Novatores, guided by the work of Benito Feijoo, phrase the methodological distinction in terms of the systemic/experimental divide, where “the former explain nature according to some system; the latter discover it through the way of experience.”
So it seems that, in spite of the empiric/rationalist distinction that appears within the medical context in early modern Spain, the ESD is still a more appropriate framework for our interpretation of the intellectual development in the Iberian Peninsula. This being said, there is still a lot of work to do in order to give a fuller account of the use of “empiric” and “rational” by early modern Spanish figures and their relation to the experimental/speculative divide.
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] ugent.be.
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?
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.
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)
… 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.
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
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 (firstname.lastname@example.org ) by September 10. Authors will be notified by September 15.
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:
Specify the explanandum;
Consider the competing explanations (these are assumed to exhaust the possibilities);
Derive a consequence from one explanation that is incompatible with the other explanation(s);
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?