Kirsten Walsh writes…
Lately, I’ve been thinking about Newton’s work on the tides. In the Principia Book 3, Newton identified the physical cause of the tides as a combination of forces: the Moon and Sun exert gravitational pulls on the waters of the ocean which, together, cause the sea levels to rise and fall in regular patterns. This theory of the tides has been described as one of the major achievements of Newtonian natural philosophy. Most commentators have focussed on the fact that Newton extended his theory of universal gravitation to offer a physical cause for the tides—effectively reducing the problem of tides to a mathematical problem, the solution of which, in turn, provided ways to establish various physical features of the Moon, and set the study of tides on a new path. But in this post, I want to focus on the considerable amount of empirical evidence concerning tidal phenomena that underwrites this work.
Let’s begin with the fact that, while Newton’s empirical evidence of tidal patterns came from areas such as the eastern section of the Atlantic Ocean, the South Atlantic Sea, and the Chilean and Peruvian shores of the Pacific Ocean, Newton never left England. So where did these observational records come from?
Newton’s data was the result of a collective effort on a massive scale, largely coordinated by the Royal Society. For example, one of the earliest issues of the Philosophical Transactions published ‘Directions for sea-men bound for far voyages, drawn up by Master Rook, late geometry professour of Gresham Colledge’ (1665: 140-143). Mariners were instructed “to keep an exact Diary [of their observations], delivering at their return a fair Copy thereof to the Lord High Admiral of England, his Royal Highness the Duke of York, and another to Trinity-house to be perused by the R. Society”. With respect to the tides, they were asked:
“To remark carefully the Ebbings and Flowings of the Sea, in as many places as they can, together with all the Accidents, Ordinary and Extraordinary, of the Tides; as, their precise time of Ebbing and Flowing in Rivers, at Promontories or Capes; which way their Current runs, what Perpendicular distance there is between the highest Tide and lowest Ebb, during the Spring-Tides and Neap-Tides; what day of the Moons age, and what times of the year, the highest and lowest Tides fall out: And all other considerable Accidents, they can observe in the Tides, cheifly neer Ports, and about Ilands, as in St. Helena’s Iland, and the three Rivers there, at the Bermodas &c.”
This is just one of many such articles published in the early Philosophical Transactions that articulated lists of queries concerning sea travel, on which mariners, sailors and merchants were asked to report. In its first 20 years, the journal published scores of lists of queries relating to the tides, and many more reports responding to such queries. This was Baconian experimental philosophy at its best. The Royal Society used its influence and wide-ranging networks to construct a Baconian natural history of tides: using the method of queries, they gathered observational data on tides from all corners of the globe which was then collated and ordered into tables.
Newton’s engagement with these observational records is revelatory of his attitudes and practices relating to Baconian experimental philosophy. Firstly, especially in his later years, Newton was regarded as openly hostile towards natural histories. However, here we see Newton explicitly and approvingly engaging with natural histories. For example, in his discussion of proposition 24, he drew on observations by Samuel Colepresse and Samuel Sturmy, published in the Philosophical Transactions in 1668, explicitly offered in response to queries put forward to John Wallis and Robert Boyle in 1665:
“Thus it has been found by experience that in winter, morning tides exceed evening tides and that in summer, evening tides exceed morning tides, at Plymouth by a height of about one foot, and at Bristol by a height of fifteen inches, according to the observations of Colepress and Sturmy” (Newton, 1999: 838).
I have argued previously that Newton was more receptive to natural histories than is usually thought. The case of the tides offers additional support for my argument. Newton’s notes and correspondence show that, from as early as 1665, he was heavily engaged in the project of generating a natural history of the tides, although he never contributed data. And eventually, he was able to use these empirical records to theorise about the cause of the tides. This suggests that Newton didn’t object to using natural histories as the basis for theorising. Rather, he objected to treating natural histories as the end goal of the investigation.
Secondly, I have previously discussed the fact that Newton seldomly reported ‘raw data’. The evidence he provided for Phenomenon 1, for example, included calculated average distances, checked against the distances predicted by the theory. Newton’s empirical evidence on the tides, as reported in the Principia, was similarly manipulated and adjusted with reference to his theory. Commentators have largely either condemned or ignored this ‘fudge factor’, but such adjustments are ubiquitous in Newton’s work, suggesting that they were a key aspect of his practice. Newton recognised that ‘raw data’ had limited use: to be useful, data needed to be analysed and interpreted. In short, it needed to be turned into evidence. The Baconians appear to have recognised this: queries guide the collection of data, which is then ordered into tables in order to reveal patterns in the data. As this case makes clear, however, Newton’s theory-mediated manipulation of the data went beyond basic ordering, drawing on causal assumptions to reveal phenomena from the data.
Thirdly, this case emphasises Newton’s science as embedded in rich social, cultural and economic networks. The construction of this natural history of tides was an organised group effort. That Newton had access to data collected from all over the world was the result of hard work from natural philosophers, merchants, mariners and priests who participated in the accumulation, ordering and dissemination of this data. Further, the capacities of that data to be collected itself followed the increasingly global trade networks reaching to and from Europe. Newton’s work on the tides was the very opposite of a solitary effort.
On this blog, we have noted in passing, but not explored in depth, the crucial roles played by travellers’ reports and information networks in Baconian experimental philosophy. Newton’s study of the tides is revelatory of the attitudes and practices of early modern experimental philosophers with respect to such networks. I shall discuss these in my next post.
Peter Anstey writes…
Sometimes we can appreciate the impact of a new way of thinking or a new movement by examining the views and writings of those on the periphery or of minor, lesser-known figures. Such is the case with the Scotsman Martin Martin. His A Description of the Western Islands of Scotland published in 1703 is written as a Baconian natural history, and in its short preface Martin very self-consciously situates his work as a contribution to experimental philosophy.
It is well known that the book gained some renown in the eighteenth century for its discussion of the phenomenon of second sight –– a discussion that is literally matter of fact and which accords with the methodology of experimental philosophy in so far as he refrains from entertaining any speculations concerning causes of this phenomenon.
The book also gained some notoriety from the fact that Boswell and Johnson used it as a kind of travel guide for their tour of the western Scottish isles in 1773. Yet it is Martin’s brief but poignant methodological comments that are of interest to students of early modern experimental philosophy.
Martin views his book as something of a supplement to the leading histories of Scotland, especially that of George Buchanan, whose History of Scotland (Rerum Scoticarum historia, Edinburgh) appeared back in 1582. Martin tells us:
since his [Buchanan’s] time, there’s a great Change in the Humour of the World, and by consequence in the way of Writing. Natural and Experimental Philosophy has been much improv’d since his days, and therefore Descriptions of Countries without the Natural History of ’em, are now justly reckon’d to be defective. (sig. a4r)
This comment signals Martin’s understanding of the place of natural history in the methodology of experimental philosophy and the requirement that histories of countries have a natural historical component. He goes on to list some of the topics that he covers in order to render his account of the western isles of Scotland such a natural history:
the Nature of the Climate and Soil, of the Produce of the Places by Sea and Land, and of the Remarkable Cures perform’d by the Natives meerly by the use of Simples, and that in such variety as I hope will make amends for what Defects may be found in my Stile and way of Writing. (sig. a5v)
These topics or heads or articles of inquiry are typical of this genre of natural history, and much of the actual content of the book covers Robert Boyle’s desiderata for the natural history of a country set out as early as 1666 (‘General Heads for a Natural History of a Country, Great or Small’) in the Philosophical Transactions (vol. 1, pp. 86–9) and republished in 1692.
Martin mentions experimental philosophy a second time:
Humane Industry has of late advanc’d useful and experimental Philosophy very much, Women and illiterate Persons have in some measure contributed to it by the discovery of some useful Cures. (sig. a5v–a6r)
Now, from a 21st century perspective the comment on women and the illiterate might seem condescending, nevertheless, Martin’s is making the very Baconian point that not just the learned, but everyone can contribute to the project of the history of nature. He then goes on to stress the importance of observation:
the Field of Nature is large, and much of it wants still to be cultivated by an ingenious and discreet application; and the Curious by their Observations might daily make further advances in the History of Nature. (sig. a6r)
It is worth noting that the inspiration for his natural history derived from some within the Royal Society itself, probably including Hans Sloane. For, we are told in the Preface to his earlier A Late Voyage to St. Kilda, London, 1698 (dedicated to the then President of the Royal Society, Charles Montagu), that he had had the
honour of Conversing with some of the Royal Society, who raised his natural Curiosity to survey the Isles of Scotland more exactly than any other; in prosecution of which design he as already brought along with him several curious Productions of Nature, both rare and beautiful in their kind (sig. A4v)
It might be thought, therefore, that Martin’s text is one of many such natural histories from the early eighteenth century; however, I have argued elsewhere that from the 1690s this approach to experimental philosophy actually began to decline. Not only had the program of experimental natural history not delivered much by way of new natural philosophy, but also a rival mathematical form of experimental philosophy was emerging in the wake of Newton’s Principia (1687). If this thesis concerning the decline of Baconian natural history is correct, Martin’s work should be viewed as one of the final installments of an approach to experimental philosophy that was soon to be superseded, even if it never completely disappeared.
Moreover, Martin seems to have had few like-minded natural historians around him in Scotland. Andrew Fletcher of Saltoun, Scotland wrote to John Locke in October 1701 and had the letter hand delivered by Martin. Fletcher recommends him to Locke and, after mentioning Martin’s materials for his natural history of ‘westerne isles of Scotland’ says,
Their is so little encouragement for such a man herre, that if he can meete with any in England, he thincks of staying their or going further abroad (Correspondence of John Locke, Oxford, vol. 7, p. 471)
I would be most interested in hearing from readers about other examples of Baconian natural histories in Britain in the early years of the eighteenth century that might complement that of Martin Martin and round out my own understanding of this very fascinating manifestation of experimental natural philosophy.
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?
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)
… 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.
Kirsten Walsh writes…
In a recent post, I considered Newton’s use of observation and experiment in the Opticks. I suggested that there is a functional (rather than semantic) difference between Newton’s ‘experiments’ and ‘observations’. Although both observations and experiments were reports of observations involving intervention on target systems and manipulation of independent variables, experiments offered individual, and crucial, support for particular propositions, whereas observations only supported propositions collectively.
At the end of the post, I suggested that, if we view them as complex, open ended series’ of experiments, the observations of books 2 and 3 look a lot like what Bacon called ‘experientia literata’, the method by which natural histories were supposed to be generated. In this post, I’ll discuss this suggestion in more detail, following Dana Jalobeanu’s recent work on Bacon’s Latin natural histories and the art of ‘experientia literata’.
The ‘Latin natural histories’ were Bacon’s works of natural history, as opposed to his works about natural history. A notable feature of Bacon’s Latin natural histories is that they were produced from relatively few ‘core experiments’. By varying these core experiments, Bacon generated new cases, observations and facts. The method by which this generation occurs is called the art of ‘experientia literata’. Experientia literata (often referred to as ‘learned experience’) was a late addition to Bacon’s program, developed in De Augmentis scientiarum (1623). It is a tool or technique for guiding the intellect. By following this method, discoveries will be made, not by chance, but by moving from one experiment to the next in a guided, systematic way.
The following features were typical of the experientia literata:
- The series of observations was built around a few core experiments;
- New observations were generated by the systematic variation of experimental parameters;
- The variation could continue indefinitely, so the observation sequence was open-ended;
- The experimental process itself could reveal things about the phenomena, beyond what was revealed by a collection of facts;
- The trajectory of the experimental series was towards increasingly general facts about the phenomena; and
- The results of the observations were collated and presented as tables. These constituted the ‘experimental facts’ to be explained.
Now let’s turn to Newton’s observations. For the sake of brevity, my discussion will focus on the observations in book 2 part I of the Opticks, but most of these features are also found in the observations of book 2 part IV, and in book 3 part I.
The Opticks book 2 concerned the phenomenon now known as ‘Newton’s Rings’: the coloured rings produced by a thin film of air or water compressed between two glasses. Part I consisted of twenty-four observations. Observation 1 was relatively simple: Newton pressed together two prisms, and noticed that, at the point where the two prisms touched, there was a transparent spot. The next couple of observations were variations on that first one: Newton rotated the prisms and noticed that coloured rings became visible when the incident rays hit the prisms at a particular angle. Newton progressed, step-by-step, from prisms to convex lenses, and then to bubbles and thin plates of glass. He varied the amount, colour and angle of the incident light, and the angle of observation. The result was a detailed, but open ended, survey of the phenomena. Part II consisted of tables that contained the results of part I. These constituted the experimental facts to be explained in propositions in part III. In part IV, Newton described a new set of observations, which built on the discussions of propositions from part III.
When we consider Newton’s observations alongside Bacon’s experientia literata, we notice some common features.
Firstly, the series of observations was built around the core experiment involving pressing together two prisms to observe the rings that appeared.
Secondly, new observations were generated by the variation of experimental parameters: i.e. new observations were generated, first by varying the obliquity of the incident rays, then by varying the glass instruments, then by varying the colour of the incident light, and so on.
Thirdly, the sequence of observations was open-ended. Newton could have extended the sequence by varying the medium, or some other experimental parameter. Moreover, at the end of the sequence, Newton noted further variations to be carried out by others, which might yield new or more precise observations.
Fourthly, the experimental process itself revealed things about the phenomenon, beyond what was revealed by a collection of facts. For example, in observation 1, Newton noticed that increasing the pressure on the two prisms produced a transparent spot. The process of varying the pressure, and hence the thickness of the film of air between the two prisms, suggested to Newton a way of learning more about the phenomenon of thin plates. He realised he could quantify the phenomenon by introducing regularly curved object glasses, which would make the variation in thickness regular, and hence, calculable.
Fifthly, the trajectory of the experimental series was towards increasingly general facts about the phenomenon. Newton began by simply counting the number of rings and describing the sequence of colours under specific experimental parameters. But eventually he showed that the number of rings and their colours was a function of the thickness and density of the film. Thus, he was able to give a much broader account of the phenomenon.
Finally, these general results were collated and presented as tables in part II. Thus, the tables in part II constituted the facts to be explained by propositions in part III.
Many commentators have emphasised the ways that Newton deviated from Baconian method. However, when viewed in this light, book 2 of the Opticks provides a striking example of conformity to the Baconian method of natural history: Newton led the reader from observations in part I, to tables of facts in part II, to propositions in part III. Moreover, it ended with a further series of observations in part IV, emphasising the open-endedness of the art of experientia literata.
In contrast to the observations in book 2, Newton’s experiments in book 1 look like Bacon’s ‘instances of special power’, which are particularly illuminating cases introduced to provide support for specific propositions. I’ll discuss this next time. For now, I’d like to hear what our readers think of my Baconian interpretation of Newton’s observations.
Kirsten Walsh writes…
In my last post, my analysis of the phenomena in Principia revealed a continuity in Newton’s methodology. I said:
- In the Opticks, Newton isolated his explanatory targets by making observations under controlled, experimental conditions. In Principia, Newton isolated his explanatory targets mathematically: from astronomical data, he calculated the motions of bodies with respect to a central focus. Viewed in this way, Newton’s phenomena and experiments are different ways of achieving the same thing: isolating explananda.
In this post, I’ll have a closer look at Newton’s method of isolating explananda in the Opticks. It looks like Newton made a distinction between experiment and observation: book 1, contained ‘experiments’, but books 2 and 3, contained ‘observations’. I’ll argue that the distinction in operation here was not the standard one, which turns on level of intervention.
In current philosophy of science, the distinction between experiment and observation concerns the level of intervention involved. In scientific investigation, intervention has two related functions: isolating a target system, and creating novel scenarios. On this view, experiment involves intervention on a target system, and manipulation of independent variables. In contrast, the term ‘observation’ is usually applied to any empirical investigation that does not involve intervention or manipulation. This distinction is fuzzy at best: usually level of intervention is seen as a continuum, with observation nearer to one end and experiment nearer to the other.
If Newton was working with this sort of distinction, then we should find that the experiments in book 1 involve a higher level of intervention than the observations in books 2 and 3. That is, in contrast to the experiments in book 1, the observations should involve fewer prisms, lenses, isolated light rays, and artificially created scenarios. However, this is not what we find. Instead we find that, in every book of the Opticks, Newton employed instruments to create novel scenarios that allowed him to isolate and identify certain properties of light. It is difficult to quantify the level of intervention involved, but it seems safe to conclude that Newton’s use of the terms ‘observation’ and ‘experiment’ doesn’t reflect this distinction.
To understand what kind of distinction Newton was making, we need to look at the experiments and observations more closely. In Opticks book 1, Newton employed a method of ‘proof by experiments’ to support his propositions. Each experiment was designed to reveal a specific property of light. Consider for example, proposition 1, part I: Lights which differ in Colour, differ also in Degrees of Refrangibility. Newton provided two experiments to support this proposition. These experiments involved the use of prisms, lenses, candles, and red and blue coloured paper. From these experiments, Newton concluded that blue light refracts to a greater degree than red light, and hence that blue light is more refrangible than red light.
In the scholium that followed, Newton pointed out that the red and blue light in these experiments was not strictly homogeneous. Rather, both colours were, to some extent, heterogeneous mixtures of different colours. So it’s not the case, when conducting these experiments, that all the blue light was more refrangible than all the red light. And yet, these experiments demonstrate a general effect. This highlights the fact that, in book 1, Newton was describing ideal experiments in which the target system had been perfectly isolated.
Book 2 concerned the phenomenon now known as ‘Newton’s Rings’: the coloured rings produced by a thin film of air or water compressed between two glasses. It had a different structure to book 1: Newton listed twenty-four observations in part I, then compiled the results in part II, explained them in propositions in part III, and described a new set of observations in part IV. The observations in parts I and IV explored the phenomena of coloured rings in a sequence of increasingly sophisticated experiments.
Consider, for example, the observations in part I. Observation 1 was relatively simple: Newton pressed together two prisms, and noticed that, at the point where the two prisms touched, there was a transparent spot. The next couple of observations were variations on that first one: Newton rotated the prisms and noticed that coloured rings became visible when the incident rays hit the prisms at a particular angle. But Newton steadily progressed, step-by-step, from prisms to convex lenses, and then to bubbles and thin plates of glass. He varied the amount, colour and angle of the incident light, and the angle of observation. The result was a detailed, but open ended, survey of the phenomena.
I have argued that Newton’s experiments and observations cannot be differentiated on the basis of intervention, but there are two other differences worth noting. Firstly, whereas the experiments described in book 1 were ideal experiments, involving perfectly isolated explanatory targets, the observations in books 2 and 3 were not ideal. Rather, through a complex sequence of observations, as the level of sophistication increased, the explanatory target was increasingly well isolated. When viewed in this way, the phenomena of Principia seem to have more in common with the experiments of book 1 than the observations of books 2 and 3.
Secondly, the experiments of book 1 were employed to support particular propositions, and so, individually, they were held to be particularly relevant and informative. In contrast, the observations of books 2 and 3 were only collectively relevant and informative. Moreover, the sequence of observations was open ended: there were always more variations one could try.
What are we to make of these differences between observation and experiment in the Opticks? I have previously argued that, while Newton never constructed Baconian natural histories, his work contained other features of the Baconian experimental philosophy, such as experiments, queries and an anti-hypothetical stance. However, in viewing them as complex, open ended series’ of experiments, I now suggest that the observations of books 2 and 3 look a lot like what Bacon called experientia literata, the method by which natural histories are generated. I’ll discuss this in my next post, but in the mean time, I’d like to hear what our readers think.
Alberto Vanzo writes…
A while ago, I wrote a post on the late seventeenth-century Italian natural philosopher, Geminiano Montanari. I argued that his stints of speculative reasoning were, after all, compatible with his allegiance to the experimental philosophy. In this post, I will focus on another aspect of Montanari’s experimentalism that appears to clash with his natural-philosophical practice: his view that, before even attempting to explain natural phenomena, we should compile a universal natural history.
The problem: disagreements and errors in natural philosophy
Montanari sees the compilation of a universal natural history as way of overcoming disagreements among philosophers. Having noted the many competing views on what “the first principles of natural things” may be, Montanari explains that this variety is due to the excessive self-confidence of “nearly all great minds”. Instead of jumping to first principles,
- It was necessary to start philosophy from particular things, examining the whole of nature one piece after another, and to amass a rich capital of experiences so as to prepare the historical matter on whose basis one should later speculate about the reasons [of those experiences].
The solution: building a universal natural history
We can avoid errors and reach agreement on the principles of things by following Francis Bacon’s suggestion of building a natural history including “all experiences and other certain information that one could get from faithful sources”.
How much information should be gathered before we can discover the first principles of natural things?
- [I]n order to find what the true, first and most universal principles of all things may be, it is not sufficient to make an induction from few terms, but it is necessary first to cognize all natural effects, so that one can later find a common reason which satisfies all experiences. But who can already boast to possess such an universal information?
Montanari’s answer is: nobody. It is still too early to make an induction from the observation of everything to its first cause. We must postpone the task of explaining the whole of nature and focus our strengths on the task of compiling natural histories.
Did Montanari do what he says?
He certainly collected many experiments and observations on manifold phenomena, from the capillary behaviour of liquids to the comets and celestial bodies. But he did not refrain from developing explanations of those phenomena, even though he was aware that his experiences were limited and many phenomena had not yet been observed. It is tempting to conclude that Montanari did not do what he says, that his allegiance to the Baconian view that a comprehensive data collection must precede natural-philosophical explanations was merely verbal, and that he was merely paying lip-service to the Baconian fashion of the time.
I do not think that this is the case. Montanari claims that completing a universal natural history is necessary to establish the “true, first and most universal principles of all things”. However, he does not claim that completing a universal natural history is necessary to explain specific natural phenomena, nor does he think that we must first establish the first principles of all things in order to explain specific phenomena. On the contrary, Montanari thinks that, upon completing a universal natural history, we will have to to advance piecemeal toward the first principles, by formulating explanations of specific phenomena and proceeding to increasingly higher levels of generality.
Montanari’s two-part discussions of specific phenomena follow, on a small scale, his favoured Baconian method that for establishing first principles. Regardless of whether he is discussing the capillary action, the behaviour of hot spheres of glass in water, or the position of a comet, Montanari starts by providing a natural history of the phenomenon at hand in the form of a list of observations and experiments. He then proceeds from the “historical matter” to its “reasons”, that is, he provides natural-philosophical explanations of the phenomena.
These explanations are fallible. Natural histories are inescapably incomplete and it is always possible that future experiments or observations invalidate his explanations. However, Montanari holds that it is possible to “deduce” explanations “with physico-mathematical evidence” from a suitable, even if limited, natural-historical basis. What warrants his explanations is the fact that they “explain all the other effects we have observed.”
In conclusion, Montanari does not violate his claim that we should build a universal natural history before identifying the very first principles of the whole nature. The magnitude of the task suggests that this may be only a regulative ideal and may even warrant a certain scepticism on whether we will ever be able to discover the first principles. However, discovering these principles is not necessary to do science for Montanari. What drives Montanari’s natural philosophy is the fact that he allows for fallible natural-philosophical explanations which are based on small-scale, necessarily incomplete, subject-specific natural histories.
Peter Anstey writes…
There were many types of Baconianism in the eighteenth century and many philosophers and natural philosophers traced their lineage from Bacon or regarded Bacon as the progenitor of views that they espoused. And yet most of these self-proclaimed ‘Baconians’ held views that Bacon himself would hardly recognize or they adhered to what, at best, could be described as a truncated form of Baconianism. A nice example is George Adams Jr whose views on the method of reasoning in natural philosophy in his Lectures on Natural and Experimental Philosophy (1794) (discussed previously on this blog) amount to little more than a summary of the first book of Bacon’s Novum organum (1620).
What would it take then for someone to be a true Baconian? Of course, the question itself is problematic because there is no principled way of determining the necessary and sufficient conditions that would settle the issue. But let us run with the question nonetheless.
Given the prominence of Bacon’s method of natural history in his conception of how we are to acquire knowledge of nature – that is, given the quality and quantity of writings that he devoted to natural history and the efforts he expended in assembling his own exemplar histories in the last years of his life – I suggest that to be a true Baconian one must (at least) be an advocate of the Baconian method of natural history. If this is right, then as far as I am aware, the last true Baconian was the French philosophe Denis Diderot (1713–1784).
Diderot’s ‘Prospectus’ for the Encyclopédie, was first published in 1750 and then appended in a modified form to the ‘Preliminary Discourse’ of the first volume of the Encyclopédie itself in 1751. It presents an overtly Baconian scheme of the sciences set within a tripartite faculty psychology à la Bacon, but more importantly, it shows a clear understanding and acceptance of the structure and content of Bacon’s account of the overall project of natural history. Drawing heavily on Bacon’s De augmentis scientiarum he tells us that:
The history of uniform nature is divided, following its principal objects, into: celestial history or history of the stars, of their movements, sensible appearances, etc., without explaining their cause by systems, hypotheses, etc. (It is a matter here only of pure phenomena.) Into meteorological history such as winds, rains, tempests, thunder, aurora borealis, etc. Into the history of the earth and the sea, or of mountains, rivers, streams, currents, tides, sands, soils, forests, islands, configurations of the earth, continents, etc. Into history of minerals, into history of vegetables, into history of animals. Whence results a history of the elements, of the apparent nature, sensible effects, movements, etc., of fire, air, earth, and water. (Preliminary Discourse, Chicago, 1995, 147)
(Regular readers of this blog will note the decrying of systems and hypotheses as hallmarks of a commitment to the experimental philosophy.)
Yet Diderot does not merely reproduce the structure and content of Bacon’s method of natural history, he also appreciated the heuristic structure of these histories and the fact that they needed to be subject to what Bacon called interpretatio naturae, the interpretation of nature. For, in 1754 Diderot published a work entitled On the Interpretation of Nature which, as many scholars have recognized, is very Baconian in character. It is, in effect, Diderot’s own version of Book Two of Bacon’s Novum organum. To be sure it lacks any extended discussion of Baconian induction and prerogative instances, but it is written in aphoristic form and contains many Baconian themes including advice on experimenting, the use of queries and conjectures and concrete natural philosophical examples. Surely on this evidence Diderot must qualify as a true Baconian. Was he the last?
Peter Anstey writes…
John Locke’s commitment to the experimental philosophy was extraordinary. In the 1690s, arguably the busiest decade of his life, Locke continued to make daily detailed records of the prevailing weather conditions at Oates, the house of Francis Masham where he resided from 1691.
Each day he would enter the day of the month, the hour, the temperature, barometric pressure, humidity, wind direction and speed, and the overall weather conditions. Sometimes he recorded three or four sets of data within a single day. Of course, Locke was not the only one in England who was collecting such data. He was merely a small part in a larger loosely connected project that aimed to construct a natural history of the air. The inspiration here was his mentor Robert Boyle whose A General History of the Air Locke had seen through the press in 1692 after Boyle’s death. Indeed Locke included a set of his own weather records from the 1660s in that work and perhaps it was the self-confessed incomplete nature of Boyle’s history that spurred Locke on to resume his weather charts in December 1691 (the very month in which Boyle died). The incompleteness of Boyle’s history is also the explanation of the fact that Locke had his own copy of the work interleaved and began to add new observations on the air.
One particularly interesting set of records is that for the month of September 1694. Here are the readings for the 4th of that month:
Day Hour Temp Barom Hygrom Wind Weather
|4||∙9||5o—||15.||2436||WS 3||covered, a shower at 21|
|24||1 ∙ 7||29∙10.||2233||very fair|
The small dot to the left of the hour indicates that the first reading was made around 9.45am. There was no standard of temperature in Locke’s day, so he provides a relative reading of 5 marks above the zero mark, which was set at temperate rather then freezing. The morning wind from the WSW was evidently quite strong: Locke’s scale is from 0 to 4. And he was up late recording that there was a rain shower at 9pm and taking another set of readings at midnight. (It is interesting to note too that he used a 24-hour clock and records made at midnight are not uncommon.)
After this entry, Locke makes the following observation:
SWALLOWS. No Swallow or Martins this day plying about the house or Moat as they used to be but every now & then 3 or 4 or more appeared & after 2 or 3 turns were gone again out of sight they generally flew very high and seemed to be passengers & to take their course southward as far as I could observe whether they were plying about the house yesterday or not I did not observe.
Then on the 19th of the month he reflects back on the swallows:
SWALLOWS The observation made 4° Sept will need some further experiments to confirm it. It being hard to take notice of their flight so as to be sure they doe not return again. But this I am certain that after that day neither SWALLOWS nor Martins were so many nor so busy as before. But yet some of them though not so frequent were to be seen till the 19th & then I went to London.
Notice the talk of the need for further experiments. Here, within a project for the systematic collection of data for a Baconian natural history, a project that involves the daily use of newly invented meteorological instruments, Locke makes a further observation and conceives of it in terms of the application of the experimental method.
So thorough are Locke’s records that, by his own admission, ‘there seldom happen’d any Rain, Snow, or other remarkable change, which I did not set down’. And what was it all for? He told Hans Sloane that with enough meteorological data ‘many things relating to the Air, Winds, Health, Fruitfulness, &c. might by a sagacious man be collected from them, and several Rules and Observations concerning the extent of Winds and Rains, &c. be in time establish’d to the great advantage of Mankind.’
Alberto Vanzo writes…
I have been wondering recently when German thinkers ceased considering physics as a part of philosophy and whether this may be related to the demise of experimental philosophy in late eighteenth-century Germany. I think that this may have well been the case. My hypothesis is that experimental philosophy declined as the result of the influence of Kantian and post-Kantian idealism and that the distinction between physics and philosophy gained foot in the 1830s and the 1840s as a reaction to post-Kantian idealism. In this post, I would like to expand on this suggestion and ask you for comments and pointers for further research.
As is well-known, physics was generally regarded as a part of philosophy in the early modern age. This is true for most early modern German writers, including several German experimental philosophers who, in the 1770s and 1780s, attempted to develop their systems on the basis of experiments and observations and eschewed hypotheses and a priori speculations. They held that the whole of philosophy relied on the same method as physics.
In the last two decades of the eighteenth century, Kantian and post-Kantian philosophies came to dominate the philosophical scene and eclipsed the German tradition of experimental philosophy. Kant vindicated a metaphysics based on a priori reasonings rather than observations and experiments. Kant held that we can discover some features of the natural world a priori. He distinguished this a priori, metaphysical study of nature from empirical, experimental physics, which he regarded as a part of philosophy too. However, at the end of the Critique of Pure Reason he introduced a narrow notion of philosophy that includes only a priori disciplines and excludes empirical physics from the domain of philosophy:
- Thus the metaphysics of nature as well as morals, but above all the preparatory (propaedeutic) critique of reason that dares to fly with its own wings, alone constitute that which we can call philosophy in a genuine sense. (A850/B878)
Early-day Kantians agreed with Kant that experimental physics was part of philosophy in the broad sense, but not of philosophy in the narrow sense. However, many of their pronouncements imply that physics (tacitly identified with experimental physics) is not part of philosophy (tacitly identified with Kant’s narrow notion of philosophy). For instance, the Kantian Johann Gottlieb Buhle wrote that, when seventeenth-century writers used the expression “Cartesian philosophy”, they were often thinking “about his physics and cosmogony rather than about his philosophy in the proper sense”. With statements like this, Kant and his disciplines promoted a division of labour between the a priori inquiries of philosophers and the a posteriori research of physicists.
Did German authors start distinguishing between physics and philosophy once the Neo-Kantians started spreading Kant’s outlook in the 1860s, as Richard Rorty claimed? I believe that several German authors started distinguishing physics from philosophy much earlier, in the 1830s or 1840s. One of the most important events in the German intellectual scene between Kant’s death in 1804 and the 1840s was the rise and decline of post-Kantian idealism. Post-Kantian idealists like Schelling and Hegel pursued an approach to the study of nature that was heavily influenced by their own philosophical speculations (Schelling, for instance, founded a Journal for Speculative Physics). I believe that the tendency to distinguish physics from philosophy spread as a reaction to the attitude of post-Kantian idealists towards physics. The entry “Physik” published in the Brockhaus Conversations-Lexicon in 1833, two years after Hegel’s death, states:
- philosophy, at least in Germany, has again attempted to gain influence on physics. However, after all attempts to found physics from this side [i.e. on philosophy] proved unfruitful, only very few physicists, and actually not the most thorough ones, still believe that they could replace the secure footing that mathematics made possible to give [to physics] with the still very shaky concepts of philosophy. Hence, even if the so-called dynamical conception of physics that is related to this philosophical point of view still survives in some speculations, nevertheless we must admit that now only the mechanical point of view is influential and valid in real-life physics [im Leben der Physik].
Although suggestive, this single quote is hardly sufficient to prove my hypothesis that German authors started distinguishing physics from philosophy as a reaction to the post-Kantian idealistic tendencies that had in turn eclipsed experimental philosophy. Do you think that this view is persuasive? Also, when did physics stop being regarded as a part of philosophy in Great Britain and France? I would be grateful for any comments and suggestions.