Newton’s ‘Phenomena’
Kirsten Walsh writes…
On this blog, I have often argued that Newton’s Principia should be characterised as a work of experimental philosophy (for example, here, here and here). To support this argument, I have tended to emphasise similarities between Newton’s work in optics and mechanics. Recently, however, I have noted that some aspects of Newton’s methodology varied according to context. For example, in the Opticks, Newton employed ‘experiments’, but in the Principia, he employed ‘phenomena’. Given that experimental philosophy emphasises observation- and experiment-based knowledge, it is important for my project that I understand Newton’s use of phenomena, and its relationship to observation. In this post, I’ll discuss the phenomena in Principia, and in my next, I’ll discuss the relationship between phenomena and experiments in more detail.
Firstly, let’s consider the origin of the phenomena of Principia. In the first edition of Principia (1687), book 3 contained nine hypotheses. But in the second edition (1713), Newton re-structured book 3 so that it contained only two hypotheses. Five of the old hypotheses were re-labelled ‘phenomena’, and he added one more (phenomenon 2), to bring the total to six:
Phenomenon 1: The circumjovial planets, by radii drawn to the centre of Jupiter, describe areas proportional to the times, and their periodic times – the fixed stars being at rest – are as the 3/2 powers of their distances from that centre.
Phenomenon 2: The circumsaturnian planets, by radii drawn to the centre of Saturn, describe areas proportional to the times, and their periodic times – the fixed stars being at rest – are as the 3/2 powers of their distances from that centre.
Phenomenon 3: The orbits of the five primary planets – Mercury, Venus, Mars, Jupiter, and Saturn – encircle the sun.
Phenomenon 4: The periodic times of the five primary planets and of either the sun about the earth or the earth about the sun – the fixed stars being at rest – are as the 3/2 powers of their mean distances from the sun.
Phenomenon 5: The primary planets, by radii drawn to the earth, describe areas in no way proportional to the times but, by radii drawn to the sun, traverse areas proportional to the times.
Phenomenon 6: The moon, by a radius drawn to the centre of the earth, describes areas proportional to the times.
There are several things to notice about these phenomena. Firstly, they are distinct from data, in that they describe general patterns of motion, rather than measurements of the positions of planetary bodies at particular times. So, while the phenomena are detected and supported by astronomical observations, they are not observed or perceived directly.
Secondly, they are distinct from noumena (or the nature or essence of things), in that they are facts inferred from the observable, measurable properties of the world. They describe the motions, sizes and locations of bodies, but not the substance or causes of these properties of bodies.
Thirdly, they describe relative motions of bodies. That is, in each case, the orbit is described around a fixed point. For example, phenomenon 1 describes the motions of the satellites of Jupiter around Jupiter, which is taken as a stationary body for the purposes of this proposition. In phenomena 4 and 5, the motion of Jupiter is described around the sun, which is taken as stationary.
Fourthly, these phenomena do not prioritise the observer. Rather, each motion is described from the ideal standpoint of the centre of the relevant system: the satellites of Jupiter and Saturn are described from the standpoints of Jupiter and Saturn respectively, the primary planets are described from the standpoint of the sun, and the moon is described from the standpoint of the Earth. And because Newton doesn’t prioritise the observer, effects such the phases and retrograde motions of the planets are not phenomena but only evidence of phenomena.
The re-labelling of these propositions as ‘phenomena’ is somewhat puzzling. The term ‘phenomenon’ has a variety of uses, such as:*
- A particular (kind of) fact, occurrence, or change, which is perceived or observed, the cause or explanation of which is in question;
- An immediate object of sensation or perception (often as distinguished from a real thing or substance); or
- An exceptional or unaccountable thing, fact or occurrence.
But, as we’ve seen, Newton’s ‘phenomena’ don’t properly fit any of these definitions. Can any reader shed light on what Newton really meant by the term?
* Definitions (a) and (c) feature in both C18th and C21st dictionaries, but in the C21st, definition (b) has become more prominent, particularly in philosophy.
UPDATE: I have written a follow-up post.
Borrowed Terms and Innovative Concepts in Newton’s Natural Philosophy
Kirsten Walsh writes…
In my last two posts, I have discussed my alterations to the 20 theses of our project. In this post, I’ll continue to discuss thesis 8.
In 2011, I claimed that:
- 8. The development of Newton’s method from 1672 to 1687 appears to display a shift in emphasis from experiment to mathematics.
But at the start of this year, I replaced this thesis with a new thesis 8:
- 8. In his early work, Newton’s use of the terms ‘hypothesis’ and ‘query’ are Baconian. However, as Newton’s distinctive methodology develops, these terms take on different meanings.
In my last post, I told you that I decided to remove my original thesis 8 because the methodological differences between Newton’s early papers and Principia aren’t as great as I initially thought. This isn’t to say that I now think that the methodology of the 1672 paper is precisely the same as the methodology displayed in Principia. Rather, I don’t think my original thesis 8 captures what is important about these differences.
In today’s post, I’ll tell you about my new thesis 8.
On this blog, we have argued that the early members of the Royal Society adopted the new experimental philosophy in a Baconian form. Newton initially encountered the experimental philosophy in the early- to mid-1660s through his reading of Boyle, Hooke and the Philosophical Transactions. While he never adopted the Baconian method of natural history, other features of his early methodology resemble the Baconian approach. For example, in Newton’s 1672 paper and the debate that followed, his use of experiment and queries, and his anti-hypothetical stance, were recognised and accepted by the Baconian experimental philosophers. Moreover, his 1675 paper, in which he explored his hypothesis of the nature of light, was recognised by his contemporaries as an acceptable use of a hypothesis.
In Newton’s later work, however, hypotheses and queries look quite different.
Firstly, consider Newton’s Opticks. When the Opticks was published in 1704, it contained no hypotheses, and the introduction explicitly stated that:
- “My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments.”
Book III ended with a series of queries, which provided directions for further research, in the style of Baconian queries. E.g.:
- “Query 2. Do not the Rays which differ in Refrangibility differ also in Flexibility…?”
However, in the 1706 and 1718 editions, Newton introduced new queries, which explore the nature of light. E.g.:
- “Qu. 29. Are not the Rays of Light very small Bodies emitted from shining Substances?”
Like the earlier queries, these ones set out a new research program. But they are much more speculative than was acceptable according to the Baconian method.
Now consider Newton’s Principia. There are hypotheses in every edition of Principia, but they look nothing like Newton’s 1675 hypothesis. In particular, they do not explore the nature of things. For example:
- “Hypothesis 1. The centre of the system of the world is at rest.”
I have argued that the hypotheses in Principia provide a specific supportive role to theories. These propositions are temporarily assumed in order to draw out the observational consequences of Newton’s theory of gravitation. They are simplifying assumptions; not assumptions about the nature of gravity.
Previously, I have argued that Newton’s methodology should be seen as a three-way epistemic distinction between theories, hypotheses and queries. I call this an ‘epistemic triad’. I claim that Newton took these, already familiar, terms and massaged them to fit his own three-way epistemic distinction. It is important to recognise, therefore, that the triad is a three-way epistemic division, rather than the juxtaposition of three terms of reference. The terms ‘theory’, ‘hypothesis’ and ‘query’ are simply labels for these epistemic categories.
In fact, this is a feature of many of Newton’s innovative concepts. He borrowed familiar terms and massaged them to fit his own needs. I have shown that he did this with his key methodological terms: ‘theory’, ‘hypothesis’ and ‘query’. Steffen Ducheyne has argued that Newton did this in other aspects of his methodology, such as his dual-methods of analysis and synthesis. This suggests that Newton’s labeling and naming of things was very much post hoc. It seems that, when discussing Newton’s methodology, we should emphasize divisions and functions over definitions.
Newton on Experiment and Mathematics
Kirsten Walsh writes…
In my last post, I discussed our 20 revised theses and why I altered thesis 5. In this post, I’ll discuss why I replaced thesis 8.
In 2011, I claimed that:
- 8. The development of Newton’s method from 1672 to 1687 appears to display a shift in emphasis from experiment to mathematics.
But at the start of this year, I replaced this thesis with a new thesis 8:
- 8. In his early work, Newton’s use of the terms ‘hypothesis’ and ‘query’ are Baconian. However, as Newton’s distinctive methodology develops, these terms take on different meanings.
Since my new thesis is a replacement of the original thesis, rather than a modification, two explanations are required. So in today’s post, I’ll tell you why I decided to remove my original thesis 8, and in my next post, I’ll tell you about my new thesis 8.
I originally included thesis 8 because there are some obvious differences in the styles of Newton’s early work on optics and his Principia. In Newton’s first paper on optics (1672), there is a strong emphasis on experiment. Experiment drives his research and guides his rejection of various possible explanations of the phenomena under consideration. Ultimately, he presents an Experimentum Crucis as proof for the certainty of his proposition that white light is heterogeneous. In contrast, the Principia (1687) displays a strong emphasis on mathematics. The full title of the work, the Author’s Preface to the Reader, and the fact that Book I opens with 11 lemmas outlining the mathematical framework of the work are just a few features that make it clear that Principia is primarily a mathematical treatise.
I now think that my original thesis 8 is misleading.
Firstly, as I have emphasised on this blog, Newton’s early work had a mathematical style that made it unique among his contemporaries. While they recognised him as an experimental philosopher, his claims of obtaining certainty via geometrical proofs set him apart from the Baconian-experimental philosophers. Moreover, his methodological statements show evidence of a tension between experiment and mathematical certainty. For example, he says that the science of colours,
- “depend[s] as well on Physicall Principles as on Mathematicall Demonstrations: And the absolute certainty of a Science cannot exceed the certainty of its Principles. Now the evidence by wch I asserted the Propositions of colours is in the next words expressed to be from Experiments & so but Physicall: Whence the Propositions themselves can be esteemed no more then Physicall Principles of a Science.”
Secondly, Newton continued to identify as an experimental philosopher until the end of his life. For example, in the General Scholium at the end of Principia, he says:
- “and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy.”
This resembles Newton’s earlier emphasis on grounding propositions on empirical evidence, rather than on speculative conjectures.
Thirdly, in Principia, Newton appears to be negotiating a similar tension between experiment and mathematical certainty that we saw in his early work. For example, in the Scholium to the Laws of Motion he asserts the certainty of his Laws, while at the same time, acknowledging their experimental basis:
- “The principles I have set forth are accepted by mathematicians and confirmed by experiments of many kinds.”
And:
- “By these examples [i.e. the experiments mentioned above] I wished only to show the wide range and the certainty of the third law of motion.”
From these three points, we can see that the methodological differences between Newton’s early papers and Principia aren’t as great as they first appear. But I did not remove my original thesis 8 because I think that the methodology of the 1672 paper is precisely the same as the methodology displayed in Principia. Rather, I don’t think my original thesis 8 captures what is important about these differences.
As I have explained here, my project is to distinguish between those features of Newton’s methodology that changed, and those that stayed the same. Some aspects of Newton’s methodology developed over time. For example, he came to value geometrical synthesis over algebraic analysis. Other aspects of his methodology varied according to context. For example, in Opticks, he employs ‘experiments’ and ‘observations’, but in Principia, he employs ‘phenomena’. But this triumvirate of methodological ideas – experiment, mathematics and certainty – should be considered an enduring feature of Newton’s methodology.
Teaching Experimental Philosophy III: the case of Francis Hauksbee the Elder
Peter Anstey writes …
In two previous posts I examined an early teacher of experimental philosophy, John Theophilus Desaguliers and a later one, George Adams. In this post I turn to a third teacher of experimental philosophy, Francis Hauksbee the Elder (1660–1713). (He was called ‘the Elder’ to differentiate him from his nephew of the same name who also taught experimental philosophy.) Hauksbee was one of the two most important first-generation pedagogues. (We will examine the other, John Keill, in my next post.)
He was a gifted instrument maker who not only developed a new much improved design of Robert Boyle’s air-pump, but also conducted a series of very important new experiments using this instrument. Many of these were published in the Philosophical Transactions. As a result of his proficiency with experimental apparatus he became a kind of de facto curator of experiments at the Royal Society in c. 1704 after Robert Hooke’s death. In addition he seconded James Hodgson FRS to carry out public lectures on experimental philosophy in London while he acted as the demonstrator.
By 1709 he himself was lecturing on experimental philosophy and continued this until his death in 1713. In 1709 he published a compilation volume of his air-pump experiments entitled Physico-Mechanical Experiments … touching Light and Electricity. This volume, in many ways, mimicked Boyle’s ground-breaking New Experiments Physico-mechanical touching the Spring of the Air (1660). (Even the titles are similar.) Hauksbee clearly saw himself as working in a tradition of experimental natural philosophy that extended back to Boyle.
The work gives us an interesting insight into how he viewed natural philosophy. He begins by telling us that:
The Learned World is now almost generally convinc’d, that instead of amusing themselves with Vain Hypotheses, which seem to differ little from Romances, there’s no other way of Improving Natural Philosophy, but by Demonstrations and Conclusions founded upon Experiments judiciously and accurately made. (Preface)
By now our readers should recognize the standard tropes of the experimental philosopher: the decrying of hypotheses; the likening of them to romances; the appeal to the necessity of experiment for the improving of natural philosophy.
Hauksbee goes on in the Preface to mention ‘The Honourable and most Excellent Mr. Boyle’ and ‘the … Incomparable Sir Isaac Newton’ implying that he himself is engaged in the same natural philosophical project. It is interesting to note, however, that there is no mention of the method of natural history as practised and promoted by Boyle in the Preface or in Hauksbee’s work. Hauksbee’s experimental practice was a natural extension of Boyle’s work, but at the same time methodologically discontinuous with it.
Hauksbee was also much quicker than Boyle to draw natural philosophical conclusions from his experiments. He did not, however, apply mathematics to his discoveries and he was later criticized by Desaguliers in his Course of Experimental Philosophy (1734) in so far as his experiments
were only shewn and explain’d as so many curious Phaenomena, and not made Use of as Mediums to prove a Series of philosophical Propositions in a mathematical Order, they laid no such Foundation for true Philosophy. (vol. 1, Preface)
Hauksbee may not have had developed views on the methodology of natural philosophy or much aptitude in mathematics, but he was a gifted experimenter and a keen promoter of experimental philosophy.
Newton and the ESD
Kirsten Walsh writes…
We rang in 2013 by reconsidering our set of 20 core theses on the emergence and fate of early modern experimental philosophy. While our general theses regarding the distinction between experimental and speculative philosophy (ESD) were unchanged, I altered several of the specific claims about Newton’s methodology. In this post, I’ll focus on thesis 5 and why I changed it.
In 2011, I claimed that:
5. The ESD is operative in Newton’s early optical papers.
By ‘operative’, I mean that Newton appears to frame his methodology in terms of the ESD and aligns himself with the experimental philosophers of the Royal Society. While Newton’s methodology differed from his contemporaries in important ways (for example, unlike his contemporaries, Newton emphasised quasi-mathematical reasoning), it nevertheless reflects some of the key ideas and preferences of the Royal Society. Previously, I have discussed Newton’s early anti-hypothetical stance and Newton’s early use of queries as evidence of this his preference for the experimental philosophy of the Royal Society.
I now have enough evidence to broaden the scope of thesis 5. The ESD is operative in all of Newton’s scientific work; not just his early work:
5. The ESD is operative in Newton’s work, from his early work on optics in the 1670s to the final editions of Opticks and Principia published in the 1720s.
Let’s start with Newton’s Opticks. This book is widely recognised as a work of experimental philosophy. Newton’s experimental focus is made explicit by the opening sentence (which appears in every edition):
- “My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments…”
Moreover, the presence of queries and the absence of hypotheses reflect the epistemic commitments of the experimental philosophy.
Commentators often notice that, in later editions of Opticks, Newton’s queries become increasingly speculative. This suggests that, despite his use of ESD-jargon, Newton was not following the experimental philosophy after all. In response to this kind of objection, I have argued that these later queries perform a role that is distinct to that of hypotheses, and that this role is consistent with Newton’s methodology. Moreover, the general features of Newton’s methodology reflect his commitment to experimental philosophy in opposition to speculative philosophy. In short, the ESD is operative in every edition of the Opticks.
Now consider Newton’s Principia. This book is often seen as less a work of experimental philosophy and more a work of mathematics. However, I have argued that the methodological passages in the first edition of Principia, though sparse, make it clear that experiment is an important theme of this work. Moreover, in the ‘General Scholium’, which was introduced in the 2nd edition in 1713, Newton makes his commitment to the experimental philosophy explicit.
Commentators often notice that Newton’s use of hypotheses in Principia, and their changing roles between the three editions, suggest that his methodology changes over time. However, I have argued that, in all three editions, Newton’s use of hypotheses is consistent with his experimental method. Moreover, the late introduction of Rule 4 in 1726 demonstrates that this commitment to experimental philosophy, in opposition to speculative philosophy, is long-lasting. In short, the ESD is operative in every edition of the Principia.
To summarise, the notions of experiment, queries and a decrying of speculative hypotheses that are enduring themes in Newton’s work, from the 1670s to his death in 1727, support my broader thesis 5. Commentators often see Newton’s use of these notions as rhetorical and argue that he failed to follow his own methodology. However, I argue that Newton’s methodology is internally consistent. Moreover, these methodological statements are more than ‘mere’ rhetoric. Rather, to some extent they track his epistemic and ontological commitments.
Do you think my argument is convincing? I’d love to hear what you think about my conclusion.
Did Newton Adopt Hypothetico-Deductivism?
Kirsten Walsh writes…
In 1718, Newton published the second edition of Opticks. Query 23 was renamed Query 31, and in this query Newton expanded on his method of analysis. He wrote:
- “If no Exception occur from Phænomena, the Conclusion may be pronounced generally. But if at any time afterwards any Exception shall occur from Experiments, it may then begin to be pronounced with such Exceptions as occur.”
At first glance, this passage suggests that Newton adopted the hypothetico-deductive method, in that the epistemic status of a theory is sensitive to new evidence. However, if we consider how Newton put this methodology into practice, in Principia book III, we will get a different reading of this passage.
In the 3rd edition of Principia, Newton introduced a 4th rule of philosophising:
- “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.”
The similarities between this rule and the earlier passage from Query 31 are striking: that new evidence can make a proposition “either more exact or liable to exceptions” is similar to pronouncing the conclusion either “more generally” or “with such Exceptions as occur”. So looking at how this rule was employed should tell us a lot about how to interpret the earlier passage.
In Principia, Newton only explicitly employed rule 4 once: in proposition 5 book III. In this proposition, Newton made his argument for universal gravitation by generalising step-by-step from the motions of the planets around the sun, and the satellites of Saturn and Jupiter around their respective centres, to the forces producing those motions. Newton introduced three corollaries, the third of which states that “all planets gravitate towards one another”.
In the scholium following this corollary, Newton said:
- “Hitherto we have called ‘centripetal’ that force by which celestial bodies are kept in their orbits. It is now established that this force is gravity, and therefore we shall call it gravity from now on. For the cause of the centripetal force by which the moon is kept in its orbit ought to be extended to all the planets, by rules 1, 2, and 4.”
Rules 1 and 2 tell us not to postulate more causes than necessary, and that we should assume that effects of the same kind have causes of the same kind. In this context, rule 4 tells us that, if exceptions to universal gravitation occur, then instead of reducing our credence in the theory, we should reduce the scope of the theory: it is still true, but true of less instances. De-generalising a theory doesn’t reduce its certainty; rather, it reduces the scope of the theory while maintaining its certainty. So according to rule 4:
- In the absence of exceptions, we should take gravity to be universal.
- If exceptions to universal gravitation are found, we should infer that the domain of gravity is limited (i.e. not universal).
- We should not allow our assumptions about matter theory (e.g. the improbability of action at a distance) to have any influence on our epistemic attitude towards universal gravitation.
Instead of reading rule 4 and the passage from Query 31 as accounts of hypothetico-deductivism, we should read them as accounts of what I Bernard Cohen called the ‘Newtonian Style’: a way of modelling the world in a series of increasingly complex and increasingly accurate idealisations (i.e. approximations that would hold exactly in certain specifiable circumstances).
On this blog, I have often discussed Newton’s aim of certainty and his corresponding claims to have achieved this aim. Newton’s youthful aim of certainty places him in a position that is quite isolated from his contemporaries. Most of the experimental philosophers of the Royal Society thought it epistemically irresponsible to make such bold claims. Instead, they had more modest aims: obtaining highly probable theories. Rule 4, and the passage from Query 31, suggest that Newton eventually adopted a version of the hypothetico-deductivism preferred by his contemporaries. I have argued, however, that this is a misleading way of reading these passages. Newton uses rule 4, not to update the epistemic warrant of the theory, but its scope.
Robert Saint Clair
Peter Anstey writes…
It is not uncommon for very minor contributors to early modern thought to go unnoticed, but every now and then they turn out to be worth investigating. One such person is Robert Saint Clair. A Google search will not turn up much on Saint Clair, and yet he was a servant of Robert Boyle and a signatory to and named in Boyle’s will. He promised twice to supply the philosopher John Locke with some of Boyle’s mysterious ‘red earth’ after his master’s death, and a letter from Saint Clair to Robert Hooke was published in the Philosophical Transactions of the Royal Society (vol. 20, 1698, pp. 378–81).
What makes Saint Clair interesting for our purposes is his book entitled The Abyssinian Philosophy Confuted which appeared in 1697. For in that book, which contains his own translation of Bernardino Ramazzini’s treatise on the waters of Modena, Saint Clair attacks Thomas Burnet’s highly speculative theory of the formation of the earth. I quote from the epistle to the reader:
I shall not care for the displeasure of these men of Ephesus [Burnet and others], whose trade it is to make Shrines to this their Diana of Hypothetical Philosophy, I mean who in their Closets make Systems of the World, prescribe Laws of Nature, without ever consulting her by Observation and Experience, who (to use the Noble Lord Verulams words) like the Spider … spin a curious Cob-web out of their Brains … (sig. a4)
The rhetoric of experimental philosophy could hardly be more obvious. Burnet and the other ‘world-makers’ are criticized for being adherents of ‘Hypothetical Philosophy’, for making ‘Systems of the World’, and for not consulting nature by ‘Observation and Experience’. He also praises Ramazzini’s work for being ‘the most admirable piece of Natural History’ (sig. a2). Saint Clair rounds off this passage with a reference to Bacon’s famous aphorism (about which we have commented before) from the New Organon comparing the spider, the ant and the bee to current day natural philosophers (I. 95).
What can we glean from Saint Clair’s critique here? First, it provides yet another piece evidence of the ubiquity of the ESD in late seventeenth-century England: the terms of reference by which Saint Clair evaluated Burnet were clearly those of experimental versus speculative philosophy.
Second, it is worth noting the term ‘Hypothetical Philosophy’. This expression was clearly ‘in the air’ in the late 1690s in England. For instance, it is found in John Sergeant’s Solid Philosophy Asserted which was also published in 1697. Indeed, it is the very term that Newton used in a draft of his letter of 28 March 1713 to Roger Cotes to describe Leibniz and Descartes years later. Clearly the term was in use as a pejorative before Newton’s attack on Leibniz.
Saint Clair has been almost invisible to early modern scholarship on English natural philosophy and yet his case is a nice example of the value of inquiring into the plethora of minor figures surrounding those canonical thinkers who still capture most of our attention. I would be grateful for suggestions as to names of others whom I might explore.
Incidentally, Saint Clair obviously thought that John Locke might be interested in his book, for we know from Locke’s Journal that he sent him a copy.
Electricity: A Speculative Newtonian Experimental Science?
Kirsten Walsh writes…
In his book, Franklin and Newton, I. Bernard Cohen described Franklin’s work on electricity as an example of “Speculative Newtonian Experimental Science”. The central thesis of our project is that the most common and the most important distinction in early modern philosophy is that between Experimental and Speculative Philosophy. So ‘speculative experimental science’ sounds like a contradiction in terms. Today, I’ll consider whether this label is appropriate.
Cohen describes electricity as a Newtonian science that only took off after Newton’s death. While Newton was fascinated with electrical phenomena, he, like his contemporaries, didn’t really understand it. However, his discussions of electricity, especially the queries of the Opticks, provided a useful starting point for Franklin’s electrical research. So we can see why Cohen wants to call Franklin’s electrical research a ‘Newtonian science’.
Newton’s discussions of electrical phenomena are always found in speculative contexts, but they usually have an experimental tone. For example, Newton first mentioned electrical phenomena in 1675 in his paper on his ‘hypothesis of light’ – which is explicitly a speculative paper. He specified six hypotheses concerning light and colour. Hypothesis 1 states that “there is an æthereall Medium much of the same constitution with air, but far rarer, subtiler & more strongly Elastic”. In the discussion, he suggested that everything is made of æther. To support this suggestion, he described an experiment involving glass and little pieces of paper. Using friction, he created static electricity in the glass, and caused the paper to dance around. He concluded that: “At least the electric effluvia seem to instruct us, that there is something of an æthereall Nature condens’d in bodies.”
Moreover, at various times, Newton speculated that electricity could provide an explanation for gravity. Again, he discussed this idea in explicitly speculative contexts, and drew on experiments performed by Francis Hauksbee to support his speculations. For example, in query 31 of the Opticks he asked:
- Have not the small Particles of Bodies certain Powers, Virtues, or Forces, by which they act at a distance, not only upon the Rays of Light for reflecting, refracting, and inflecting them, but also upon one another for producing a great Part of the Phænomena of Nature?
He argued that we have observational and experimental evidence that bodies attract one another by gravity, magnetism and electricity: “and these Instances shew the Tenor and Course of Nature, and make it not improbable but that there may be more attractive Powers than these.”
Despite all this speculating, Newton displayed epistemic caution:
- For we must learn from the Phænomena of Nature what Bodies attract one another, and what are the Laws and Properties of the Attraction, before we enquire the Cause by which the Attraction is perform’d. The Attractions of Gravity, Magnetism, and Electricity, reach to very sensible distances, and so have been observed by vulgar Eyes, and there may be others which reach to so small distances as hitherto escape Observation; and perhaps electrical Attraction may reach to such small distances, even without being excited by Friction.
The final paragraph of the General Scholium of the Principia echoes these ideas:
- A few things could now be added concerning a certain very subtle spirit pervading gross bodies and lying hidden in them; by its force and actions, the particles of bodies attract one another at very small distances and cohere when they become contiguous; and electrical bodies act at greater distances, repelling as well as attracting neighbouring corpuscles… [However,] there is not a sufficient number of experiments to determine and demonstrate accurately the laws governing the actions of this spirit.
From these passages, it’s easy to see why Cohen calls Newton’s electicity ‘speculative experimental science’: Newton’s discussions of electricity are speculative in tone, and yet they can be considered experimental, since they draw on experimental and observational evidence. However, there is a sense in which this label isn’t appropriate. I have previously argued that this kind of speculation has a role within Newton’s experimental philosophy. The epistemic caution displayed by Newton suggests that he is indeed following his methodology and that these discussions of electrical phenomena are taking place within his experimental philosophy. So Newton’s electrical work shouldn’t be taken as an example of ‘speculative philosophy’. Taken in this sense, the label ‘speculative experimental’ is indeed an oxymoron.
Laura Bassi: An Eighteenth-Century Newtonian
Kirsten Walsh writes…
Laura Bassi (1711-1778) had a remarkable career. In eighteenth-century Italy, it was rare, but not unheard of, for a woman from a wealthy family to receive a higher education, a doctorate, or even a lectureship. But what made Bassi unique was how she used her positions at the University of Bologna and the Academy of Science (which would ordinarily have been symbolic) to contribute to the scientific community of Europe.
Thony Christie over at The Renaissance Mathematicus recently wrote a very good post about Bassi’s life and career, so I will not go into those details here. Instead, today I’m interested in Bassi as an eighteenth-century Newtonian and experimental physicist.
Over the course of her career (roughly 1732 to 1778), Bassi presented papers on mathematics, pneumatics, fluid dynamics, mechanics, optics and electricity. Most of these papers have been lost, but the few surviving papers display Bassi’s talent for mathematics and her commitment to the Newtonian method (as exemplified by Principia). For example, in her paper on differential calculus (“De problemate quodam mechanico”, 1757), Bassi dealt with the problem of how to determine the motion of the centre of mass of two or more bodies moving along any curved paths in a plane. In this paper, she followed the Newtonian method of avoiding metaphysical and empirical assumptions about the nature of matter.
From the 1740s onwards, Bassi and her husband Giuseppe Veratti became very interested in electrical phenomena. Here, we can identify two different Newtonian themes. Firstly, their research appears to have been heavily influenced by the later queries of the Opticks, which attempt to link phenomena such as light, heat, electricity and magnetism with biological phenomena such as muscle movement, growth of plants and phosphorescent fish. Secondly, they supported Franklin’s electrical-fluid theory, which had been systematised in a Newtonian framework by Beccaria.
In the late 1740s, Bassi began teaching privately. Bassi and Veratti had a well-equipped physics laboratory in their home, including an electricity machine. This made it possible for Bassi to teach experimental physics in their home. At the University, the philosophical curriculum was essentially scholastic, and at the Institute of Sciences, the courses on experimental physics had a physiological focus (which reflected the interests of the Bolognese scholars, most of whom had medical degrees). Bassi’s knowledge-base, which by then included advanced mathematics, mechanics, optics, and electricity, made her uniquely qualified to teach a course on Newtonian philosophy and Franklinian electricity. In a letter to Scarselli in 1755 she mentioned the popularity of her classes: “The classes have gathered such momentum that they are now attended by people of considerable education, including foreigners, rather than by youths”.
From this brief survey of Bassi’s work, she appears to have adopted many facets of Newtonianism: she accepted and built on Newton’s rational mechanics, but also followed the leads left by Newton in his optical queries. Indeed, in her own time, Bassi was a well-known Newtonian. Algarotti mentioned her several times (although not by name) in his Sir Isaac Newton’s Philosophy explain’d for the use of the Ladies and explicitly presented her as a Newtonian in ‘Non la lesboa’ – his contribution to the book of poems published in honour of Bassi’s graduation. Also, in 1744 Voltaire implicitly compared Bassi with Newton when he wrote:
- Most Honoured Lady: I would like to visit Bologna so that I might say to my fellow citizens that I have seen Signora Bassi, but, deprived of this honour, I trust that I may with justice cast at your feet this philosophical homage in reverence to the glory of her century and sex. As there is no Bassi in London I should more happily enter your Academy of Bologna than the English one, even though it may have produced a Newton.
But what can we say about Bassi’s ‘experimental physics’? The subject-matter was certainly Newtonian, but what about the methodology? On this blog, we have argued that, from the 1690s onwards, the experimental philosophy was approached in a way that emulated Newton’s mathematical-experimental method. Bassi certainly had the expertise to follow the Newtonian method, which raises the question: Should Bassi’s experimental physics be seen as another facet of her Newtonianism, or should we regard it as a more general interest in the experimental method?
Unfortunately, I haven’t been able to find the evidence to answer this question. I’m not even sure if Bassi engaged in any kind of methodological reflection. Does anyone know how I might find out?
The origins of ‘solar system’
Peter Anstey writes…
The Cartesian vortex theory of planetary motions came under serious suspicion in England in the early 1680s. To be sure, many still spoke of ‘our vortex’ well into the 1680s and ’90s, such as Robert Boyle in his Notion of Nature of 1686 (Works, eds. Hunter and Davis, London, 1999–2000, 10, p. 508), but by the early 1690s the new Newtonian cosmology was coming to be widely accepted and many in England thought that the vortex theory had been disproved. By that time the vortex theory of planetary motions had come to be seen as the archetypal form of speculative natural philosophy. What was required then was a new descriptor for that cosmological structure in which the earth is located. And a new term was soon deployed, namely, ‘solar system’.
Some have claimed that it was John Locke who coined the term ‘solar system’. In fact, the OED lists Locke’s Elements of Natural Philosophy, which it dates at c.1704, as the earliest occurrence. However, the term first appears in his writings in Some Thoughts concerning Education of 1693 where speaking of Newton’s ‘admirable Book’ about ‘this our Planetary World’, he says,
his Book will deserve to be read, and give no small light and pleasure to those, who willing to understand the Motions, Properties, and Operations of the great Masses of Matter, in this our Solar System, will but carefully mind his Conclusions… (Clarendon edition, 1989, p. 249)
Interestingly, a quick word search of EEBO reveals that the term was also used by Richard Bentley in his seventh Boyle lecture of 7 November 1692, but published in 1693 in a volume that Locke owned (Folly & Unreasonableness of Atheism, London). Bentley uses the term in an argument for the existence of God on the basis of the claim that the fixed stars all have the power of gravity. It is God who prevents the whole system from collapsing into a common centre:
here’s an innumerable multitude of Fixt Starrs or Suns; all of which are demonstrated (and supposed also by our Adversaries) to have Mutual Attraction: or if they have not; even Not to have it is an equal Proof of a Divine Being, that hath so arbitrarily indued Matter with a Power of Gravity not essential to it, and hath confined its action to the Matter of its own Solar System: I say, all the Fixt Starrs have a principle of mutual Gravitation; and yet they are neither revolved about a common Center, nor have any Transverse Impulse nor any thing else to restrain them from approaching toward each other, as their Gravitating Powers incite them. Now what Natural Cause can overcome Nature it self? What is it that holds and keeps them in fixed Stations and Intervals against an incessant and inherent Tendency to desert them? (p. 37, underlining added)
There is no evidence, however, that Bentley was using the term as an alternative to ‘our vortex’. In a letter to Newton of 18 February 1693 he speaks unabashedly of matter that ‘is found in our Suns Vortex’.
Who published the word first? Bentley’s seventh Boyle lecture was not published separately, but appeared in the 1693 volume, the last lecture of which was not given its imprimatur until 30 May that year. Locke’s book was advertised in the London Gazette #2886 for 6–10 July. I have not been able to establish exactly when Bentley’s volume appeared, but it’s not mentioned in the London Gazette before #2886.
Whatever the case, it is most likely that the term was already ‘in the air’ and history shows that it was soon widely used and, of course, it is a commonplace today.
(N.B. This post also appears on the Early Modern at Otago blog.)
