Oldenburg and Newton on ‘Experimental Philosophy’
Kirsten Walsh writes…
During the debate following the publication of Newton’s first paper, Newton provided a set of eight queries, in an attempt to steer the debate towards a satisfactory conclusion. When Henry Oldenburg, Secretary of the Royal Society and Editor of the Philosophical Transactions, published Newton’s queries, he added the following introduction:
- A Serie’s of Quere’s propounded by Mr. Isaac Newton, to be determin’d by Experiments, positively and directly concluding his new Theory of Light and Colours; and here recommended to the Industry of the Lovers of Experimental Philosophy, as they were generously imparted to the Publisher in a Letter of the said Mr. Newtons of July 8. 1672.
However, Newton didn’t describe his own work as ‘experimental philosophy’ until 1713, when he added the General Scholium to the Principia. He wrote:
- … and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this experimental philosophy, propositions are deduced from the phenomena and are made general by induction.
In 1672, would Newton have been comfortable with Oldenburg’s label ‘experimental philosopher’? Or did he consciously avoid the label, as Alan Shapiro suggests, in order to distance himself from the methodology of the early Royal Society?
Oldenburg on ‘Experimental Philosophy’
Henry Oldenburg (1619-1677)
To begin, what did Oldenburg mean by ‘experimental philosophy’? Let’s look at his prefaces to each issue of the Philosophical Transactions.
Firstly, Oldenburg was talking about the Baconian experimental philosophy. In the 1672 Preface, Oldenburg chose to adopt Bacon’s term, ‘Operative Philosophy’, which he used interchangeably with the term ‘Experimental Philosophy’. And he wrote:
- But, when our renowned Lord Bacon had demonstrated the Methods for a perfect Restauration of all parts of Real knowledge … The success became on a sudden stupendious, and Effective philosophy began to sparkle, and even to flow into beams of bright-shining Light, all over the World.
Moreover, in 1671, Oldenburg advocated Abraham Cowley’s Baconian-vision for the Royal Society. In his book, Proposition for the Advancement of Experimental Philosophy, Cowley proposed that the Royal Society appoint professors who were:
- bound to study and teach all sorts of Natural, Experimental Philosophy, to consist of the Mathematicks, Mechanicks, Medicine, Anatomy, Chymistry, the History of Animals, Plants …. and briefly all things contained in the Catalogue of Natural Histories annexed to My Lord Bacon’s Organon.
(Incidentally, in a previous post on this blog, Peter Anstey has identified this as the first English book to use the term ‘experimental philosophy’ in its title.)
Secondly, Oldenburg had in mind an experimental philosophy that emphasised the construction of natural histories. For example, in 1669, Oldenburg wrote:
- …we then made an Attempt of laying some Foundation for the Improvement of real Philosophy, and for the spreading of Useful knowledge; in publishing Advices and Directions for the writing of an Experimental Natural History…
Thirdly, Oldenburg had in mind an experimental philosophy that attempted to recover ancient knowledge. For example, in 1671, responding to critics of the experimental philosophy, Oldenburg wrote:
- they call it contemptuously the New Philosophy; when as yet perhaps themselves are not ignorant, that ‘tis so old as to have been the Discipline in Paradise; and from the First of Mankind … to have been practised and countenanced by the Best of Men…
Moreover:
- … we may not lay aside the other expedient, which is so helpful to explicate the Old Wonders of Art, and Old Histories of Nature; namely, To inquire diligently The things that are; What Rarities of Nature, and what Inventions of Men are now extant in any parts of the World.
To summarise, Oldenburg had in mind an experimental philosophy that:
- Followed Bacon’s method;
- Constructed natural histories; and
- Investigated ancient knowledge.
Newton on ‘Experimental Philosophy’
Isaac Newton (1642-1727)
Would Newton have approved of this way of describing his work?
Certainly Newton would have approved of being broadly aligned with the experimentalist philosophers, as opposed to the speculative philosophers. In his ‘Queries Paper’, he wrote:
- … the Theory … was evinced to me … not by deducing it only from a confutation of contrary suppositions, but by deriving it from Experiments concluding positively and directly.
And in the first paper, he wrote: “And I shall not mingle conjectures with certainties”.
While Newton didn’t construct natural histories, he may have approved of the Baconian overtones of the label. For, as I’ve discussed previously, Newton’s 1672 queries resemble Baconian queries.
Newton may even have approved of the suggestion that his method had ties to the Ancients. For example, as early as 1686, in his Preface to Principia, Newton emphasised the influence of the Ancients:
- Since the Ancients (according to Pappus) considered mechanics to be of the greatest importance in the investigation of nature and science and since the moderns – rejecting substantial forms and occult qualities – have undertaken to reduce the phenomena of nature of mathematical laws, it has seemed best in this treatise to concentrate on mathematics as it relates to natural philosophy.
So, I think Newton would have approved of Oldenburg’s label, even though later on, when he came to describe his own experimental philosophy, the emphasis was quite different. For example, in Query 31 of the Opticks, Newton wrote:
- This Analysis consists in making Experiments and Observations, and in drawing general Conclusions from them by Induction, and admitting of no Objections against the Conclusions, but such as are taken from Experiments, or other certain Truths. For Hypotheses are not to be regarded in experimental Philosophy.
The Experimental Role of Hypotheses in Newton’s Principia
Kirsten Walsh writes…
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. All but one of the old hypotheses were simply re-labelled. Those that specified explanatory constraints were called ‘Rules of Reasoning’, those that were simply unsupported generalisations were called ‘Phenomena’, and only the assumptions about nature were called ‘Hypotheses’.
| 1st edition | 2nd edition |
| Hypothesis 1 | Rule 1 |
| Hypothesis 2 | Rule 2 |
| Hypothesis 3 | Replaced by Rule 3 |
| Hypothesis 4 | Hypothesis 1 |
| Hypothesis 5 | Phenomenon 1 |
| Hypothesis 6 | Phenomenon 3 |
| Hypothesis 7 | Phenomenon 4 |
| Hypothesis 8 | Phenomenon 5 |
| Hypothesis 9 | Phenomenon 6 |
| Lemma 3 | Hypothesis 2 |
Table: Book 3 changes from 1st to 2nd editions.
These changes seem to indicate that Newton’s attitude to hypotheses changed dramatically between 1687 and 1713 – probably in response to Leibnizian criticisms and Cotes’ editorial comments.
On this blog, I have given you many reasons to suppose that, as early as 1672, Newton was working with a clear epistemic distinction between theories and hypotheses. More recently, I have argued that in fact, Newton was working with a three-way epistemic distinction between theories, which are certain and experimentally confirmed, hypotheses, which are uncertain and speculative, and queries, which are not certain, but provide the proper means to establish the certainty of theories. I call this division Newton’s ‘epistemic triad’. I argued that hypotheses perform a distinctive and vital supporting role to theories and queries, and that this role is an enduring feature of Newton’s methodology.
Today I’ll compare the roles of hypotheses and rules of reasoning in book 3, and argue that Newton’s attitude to hypotheses c.1713 was a refinement of his attitude c.1687, but not a dramatic change.
To begin, consider hypothesis 1 (2nd edition): “The centre of the system of the world is at rest.”
Upon introducing this hypothesis, Newton explained that:
- “No one doubts this, although some argue that the earth, others that the sun, is at rest in the centre of the system. Let us see what follows from this hypothesis.”
This is a simplifying assumption. From this hypothesis, in conjunction with Corollary 4 of the Laws of Motion,
- “The common centre of gravity of two or more bodies does not change its state whether of motion or of rest as a result of the actions of the bodies upon one another; and therefore the common centre of gravity of all bodies acting upon one another (excluding external actions and impediments) either is at rest or moves uniformly straight forward”,
Newton derived Proposition 11: “The common centre of gravity of the earth, the sun, and all the planets is at rest.”
This enabled him to calculate the motions of the planets – that is, to deduce the observational consequences of his theory. I consider this to be the chief role of hypotheses, and it is experimental.
Now compare this with how Newton uses his rules of reasoning.
Rule 1 states: “No more causes of natural things should be admitted than are both true and sufficient to explain their phenomena.”
And Rule 2 states: “Therefore, the causes assigned to natural effects of the same kind must be, so far as possible, the same.”
In his discussion of Proposition 4, Newton explained:
- “And therefore that force by which the moon is kept in its orbit, in descending from the moon’s orbit to the surface of the earth, comes out equal to the force of gravity here on earth, and so (by rules 1 and 2) is that very force which we generally call gravity.”
These rules didn’t help Newton to deduce the observational consequences of his theory in the same way as his hypothesis 1. They provide an important supporting role for his theory, but it is not an experimental role.
To the second edition, Newton also added the General Scholium, in which he (in)famously declared “hypotheses non fingo”. Recently I argued that, in this passage, Newton was not railing against hypotheses in general, but rather, against the use of ‘causal hypotheses’ to illustrate more abstract theories. Given that the first edition did not contain any causal hypotheses, I consider this addition to indicate Newton’s increasing conviction in his method, rather than any dramatic change.
So finally, to summarise the developments between the first and second editions of Principia:
In the first edition:
- Hypotheses are temporarily assumed, untestable propositions that provide a supportive role; and
- There are no causal hypotheses.
In the second edition:
- Hypotheses are temporarily assumed, untestable propositions that provide a supportive experimental role;
- Other temporarily assumed, untestable propositions are given other labels to distinguish them from hypotheses; and
- Emphatically, there are no causal hypotheses.
I see these changes as developments of Newton’s epistemic triad, rather than dramatic methodological changes.
Experimental Philosophy in Spain Part II
Juan Gomez writes…
In my previous post I reviewed some texts from Spanish authors in the 17th century to show that, contrary to common opinion, intellectuals in the Iberian Peninsula were in fact acquainted with the progress and achievements of the new experimental philosophy. They did not just know of it, but actually advocated its application and called for the rejection of the old method of the scholastics. In this post I will conclude this overview of the ESD in Spain by looking at the work of the Novatores in the eighteenth century.
The texts we examined in my last post were both written by physicians. In the eighteenth century medicine remained as the forum for the promotion of experimental philosophy. The first author I will examine is Doctor Martín Martínez. He was a physician and professor of anatomy in Madrid, and royal physican to Phillip V. Besides a number of medical writings, in 1730 he published Filosofía Escéptica which consisted in a dialogue between an Aristotlian, a Cartesian, a Gassendist, and a Sceptic. In the preliminaries to this book he tells us that
- The spirit of this book is to give to the Curious Romantics an idea of the most famous philosophies that today run through Europe, relegating that Aristotle just for theological studies.
Even in the 1730’s books in Spain still included a statement of approval made by a priest or friar that confirmed that there was nothing in the book to be censured. The censorship for Filosofía Escéptica was written by Friar Agustín Sanchez and in it we find a statement in the spirit of experimental philosophy. Speaking of the account Martínez gives of the Aristotelian, Cartesian, and Gassendist positions he tells us that the Doctor
- Is determined not to follow any of them, but is inclined towards what he judges more plausible; he does not believe in what experience cannot confirm, based on the fact that words cannot reach the truth of physical and material things, nor their natures and properties; what experience cannot testify, and persuade, cannot be known by words.
Martínez begins his dialogue by giving a brief history of philosophy in Spain, blaming the Arabians for the introduction of Aristotelian philosophy,
- From which that contentious and vociferous philosophy we call Scholastic, as opposed to Experimental, has been derived.
A few lines later Martínez comments that he shares the same opinion held by Bacon:
- The most judicious Verulam also held, that of all the philosophies that have been invented, and received, so many were but fables, and Comical Scenes, each of them making the world to their liking, amassing the Elements to the measure of their palate, and arbitrarily establishing hypotheses as difficult to believe, as they are to prove.
In the case of Martín Martínez we can see the experimental philosophy and the rejection of mere speculation clearly represented. But to show that this was not an isolated case I turn now to another doctor, Andrés Piquer. Out of all the Novatores that practices medicine, Piquer was the one that published most on other topics. He published a book on logic, one on moral philosophy, and one on physics. This last one was published in 1745 under the title Física Moderna Racional, y Experimental (Modern Physics, Rational and Experimental). Piquer begins this book by giving some preliminaries about the state and history of physics and the method to follow. In his historical account he tells us that
- Physics was wrongly cultivated for many centuries, until Francis Bacon Lord Verulam, Great Chancellor of England, towards the end of the sixteenth century, started to renew it, freeing it form the superfluity of reasoning, and manifesting, that the true way to advance in it is through the path of experience.
Speaking about the proper method Piquer sets up a distinction that illustrates the presence of the ESD (in some form) in Spain:
- Modern physicists, are either Systematic, or Experimental. The former explain nature according to some system; the latter discover it through the way of experience. The Systematic form in the imagination some idea, or drawing of the principal parts of the World, of its connections, and mutual correspondence; and holding such idea, that sometimes is strictly willed, as a principle, and foundation of their Philosophy, try to explain everything that occurs in the universe according to it. This has been done by Descartes, and Newton. The Experimental work to collect many experiments, combine them, and use them as the basis of their reasonings. This is how Robert Boyle, Boerhaave, and many other philosophers of these times treat physics.
One of the interesting features of this passage is that Piquer groups Descartes and Newton together under systematic philosophers! However, I don’t have the space or time to discuss this very interesting issue in this post, but Piquer’s distinction between systematic and experimental is something worth looking into. For now, I believe I have provided some very interesting passages from early modern Spanish authors that show that they were acquainted with experimental philosophy and opposed and rejected mere speculation.
N.B. The English translation of the quotes presented here is mine
Shapiro and Newton on Experimental Philosophy
Kirsten Walsh writes…
In a recent post, I discussed Alan Shapiro’s paper, ‘Newton’s “Experimental Philosophy”‘, where he argues that
- the apparent continuity between Newton’s usage [of the term ‘experimental philosophy’] and that of the early Royal Society is, however, largely an illusion.
I examined his claim that ‘experimental philosophy’ was used as a synonym for ‘mechanical philosophy’ by the early Royal Society, whereas for Newton, the two terms had different meanings.
Today I’ll address another argument Shapiro makes in that paper.
Shapiro claims that Newton’s adoption of the experimental philosophy occurred quite late – while preparing the 2nd edition of Principia, published in 1713. To support this claim, Shapiro argues that, in the 1713 edition of Principia, Newton uses the term ‘experimental philosophy’ for the first time in public. Moreover, the methodology Newton describes in this context is very different to the methodology he describes in his early optical papers. Shapiro writes:
- At this time [1675] for Newton confirmation is by mathematical demonstration and secondarily – only if you think it is worth the bother – by experiment. He clearly believed that a mathematical deductive approach would lead to great certainty and that experiment could provide the requisite certain foundations for such a science, but until the eighteenth century he did not assign experiment a primary place in his methodology.
If Newton’s ‘experimental philosophy’ is a late development, then this provides additional support for Shapiro’s claim that Newton’s experimental philosophy is not continuous with the methodology of his predecessors, the early members of the Royal Society.
In this post, I’ll argue that (1) experiment is a prominent theme in Newton’s methodological statements between 1672 and 1713, and (2) Newton’s methodology has features that suggest the influence of the early Royal Society.
1. Experiment is a prominent theme between 1672 and 1713
There is a strong experimental theme in Newton’s early optical papers (1672-1675). For example, he says:
- the proper Method for inquiring after the properties of things is to deduce them from Experiments.
And:
- I drew up a series of such Experiments on designe to reduce the Theory of colours to Propositions & prove each Proposition from one or more of those Experiments by the assistance of common notions set down in the form of Definitions & Axioms in imitation of the Method by which Mathematicians are wont to prove their doctrines.
And:
- Now the evidence by which 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.
In the opening paragraph of De Gravitatione (date of composition unknown), Newton says:
- in order, moreover, that … the certainty of its principles perhaps be confirmed, I shall not be reluctant to illustrate the propositions abundantly from experiments as well…
In the 1st edition of Principia (1686), Newton says:
- The principles I have set forth are accepted by mathematicians and confirmed by experiments of many kinds.
And in the 1st edition of Opticks (1704), Newton says:
- 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…
Experiment doesn’t seem secondary to me!
2. Newton’s methodology suggests the influence of the early Royal Society
As we have said before, the Royal Society adopted the experimental philosophy in a Baconian form – according to the Baconian method of natural history. There is good evidence that Newton was familiar with the work of the Royal Society by the time he wrote his first optical paper in 1672: his notebooks show that he took notes from many issues of the Philosophical Transactions and he took careful notes on Boyle’s work. Newton never adopted the Baconian method of natural history. However, other features of Newton’s methodology suggest the influence of the early Royal Society. For example, he made use of queries, he adopted the familiar distinction between theory and hypothesis, he was concerned with experiments, and he rejected speculation and speculative systems.
Shapiro notices that Newton rejected speculative systems, but fails to recognise that Newton wasn’t the first member of the Royal Society to take this stance. On this blog we have provided ample evidence that the early members of the Royal Society railed against speculation. Newton’s anti-speculation and anti-hypothetical stance, while extreme, was still inside the spectrum of acceptable experimental positions. Consider this passage from Hooke’s Micrographa, addressed to the Royal Society:
- The Rules YOU have prescrib’d YOUR selves in YOUR Philosophical Progress do seem the best that have ever yet been practis’d. And particularly that of avoiding Dogmatizing, and the espousal of any Hypothesis not sufficiently grounded and confirm’d by Experiments. This way seems the most excellent, and may preserve both Philosophy and Natural History from its former Corruptions.
Whether or not Newton explicitly identified himself as such, we have good reason to think that Newton’s first optical paper in 1672 was written by an experimental philosopher.
Workshop in Ghent: “Matter and Nature in Early Modern Philosophy”
Thursday, June 7, 2012
Blandijnberg 2, Ghent, room 2.16
13:45-15:00 Marleen Rozemond (Toronto):
Mills can’t think: Leibniz’ approach to the mind-body problem
15:15-16:30 Katherine Dunlop (Brown):
Newton on conservation and the activity of matter
16:45-18:00 Herman De Dijn (Leuven):
Reading the book of nature and reading the Bible
More information is available here.
Is Newton’s Explanation of Gravity a Hypothesis?
Kirsten Walsh writes…
In the General Scholium to Book 3 of Principia, Newton wrote:
- “Thus far I have explained the phenomena of the heavens and of our sea by the force of gravity, but I have not yet assigned a cause to gravity.”
He went on to explain that such a cause would be a hypothesis,
- “and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy.”
It might appear that Newton’s methodological statements don’t reflect his real attitude to causal explanations. He explained all the motions of bodies and the sea by the force of gravity. So in some sense, gravity was the cause of those motions. But if gravity was a cause, then wasn’t it a hypothesis? Was Newton’s famous statement “Hypotheses non fingo” a lie?
In this post, I’ll have a closer look at the role of causal explanations in Newton’s method of natural philosophy.
To begin, consider this statement from Query 28 of Opticks:
- “Whereas the main Business of natural Philosophy is to argue from Phaenomena without feigning Hypotheses, and to deduce Causes from Effects, till we come to the very first Cause, which certainly is not mechanical…”
Here, Newton outlined two central tasks for natural philosophers:
- To argue from phenomena without relying on, or giving credence to, hypotheses; and
- To infer causes from effects until you arrive at the first cause.
The first task is methodological, and it places a constraint on the kinds of inferences one may make from effect to cause. The second task is epistemological: it tells the philosopher what kind of knowledge to seek, and when to stop. Newton shed a little more light on this second task in Query 31:
- “By this way of Analysis we may proceed from Compounds to Ingredients, and from Motions to the Forces producing them; and in general, from Effects to their Causes, and from particular Causes to more general ones, till the Argument end in the most general.”
Perhaps recognising that, once constrained by task 1, task 2 would be too difficult for any single philosopher to complete, Newton wrote in Query 28:
- “And though every true Step made in this Philosophy brings us not immediately to the Knowledge of the first Cause, yet it brings us nearer to it, and on that account is to be highly valued.”
Furthermore, in Query 31, he writes:
- “And therefore I scruple not to propose the Principles of motion above-mention’d, they being of very general Extent, and leave their Causes to be found out.”
And so, in Principia, Newton inferred causes from effects as far as he was able to, while still following the advice of task 1. He stopped short of assigning a cause for gravity, because he could not deduce it from the phenomena. So as he wrote in the General Scholium of Principia:
- “It is enough [i.e. for the purposes of his argument] that gravity really exists and acts according to the laws that we have set forth and is sufficient to explain all the motions of the heavenly bodies and of our sea.”
To conclude, Newton doesn’t rail against causes per se, only against causes that cannot be proved by, or inferred from, experiment. I have argued that Newton was working with a clear distinction between theories and hypotheses, where a hypothesis is:
H1. Something that is, at best, only highly probable;
H2. A conjecture or speculation – something not based on empirical evidence; or
H3. A causal explanation – something concerning the nature of the phenomenon, rather than its physical properties.
I have changed the wording of H1 slightly from the definition I have given in previous posts. Now it looks like I might need to alter H3. What do you think?
Conflating the Experimental and Mechanical Philosophies
Kirsten Walsh writes…
Recently I read Alan Shapiro’s paper, ‘Newton’s “Experimental Philosophy”’, in which he argues that
- the apparent continuity between Newton’s usage [of the term ‘experimental philosophy’] and that of the early Royal Society is, however, largely an illusion.
To support this claim, Shapiro argues that, whereas ‘experimental philosophy’ was used as a synonym for ‘mechanical philosophy’ by the early Royal Society, for Newton, the two terms had different meanings. This is demonstrated by the fact that Newton adopted the experimental philosophy, but not the mechanical philosophy.
Shapiro explains that the mechanical philosophy is characterised by adherence to some or all of the following theses:
- the world and its components behave like a machine; or, more strongly, the world can be described solely by the mathematical laws of mechanics; all causation is by contact action so that the immaterial, spiritual agents are banished; matter is composed of invisible corpuscles; and hypotheses about the properties and motions of these invisible corpuscles may be formulated to explain visible effects.
Here Shapiro is conflating mechanism and corpuscularianism. However, Peter Anstey explains in his recent book, John Locke and Natural Philosophy, that these are distinct (but related) philosophies. The leading idea of the mechanical philosophy is that natural phenomena should be explained by analogy with the functioning of machines. The corpuscularian philosophy is primarily a philosophy about the underlying nature of matter, whereby explanations of natural phenomena are constrained by appeal to the invisible corpuscles which constitute all material bodies. Thus, the former is a theory of explanation; the latter, a theory of matter. There is a significant amount of overlap between the mechanical and corpuscularian philosophies, for example the focus on shape, size, motion and texture. But, they are not interchangeable. For example, Anstey points out that it wasn’t the case that everyone who held a corpuscularian theory of matter was a mechanical philosopher.
In contrast, the experimental philosophy emphasises that we can only acquire knowledge of nature by first accumulating observations and experiments and then turning to theory and hypotheses. Thus, the experimental philosophy is a theory of method, which can be viewed as placing epistemic constraints on philosophical endeavours, as opposed to the explanatory constraints of the mechanical philosophy, or the ontological constraints of the corpuscularian philosophy. So, at least notionally, these are three distinct philosophical positions.
Shapiro argues that, in practice, the early Royal Society didn’t distinguish between these philosophical positions. As evidence, he cites a passage from the preface to Robert Hooke’s Micrographia in which Hooke runs together “the real, the mechanical, the experimental philosophy”. But if we look at Hooke’s other work for uses of the term ‘mechanical’, we find that he can and does distinguish the mechanical from the experimental.
When Hooke explicitly discusses experimental philosophy, he emphasises the importance of constructing natural histories. For example, in his ‘General Scheme’, where he sets out his “Method of Improving Natural Philosophy”, Hooke explains that the best way to proceed is according to the Baconian method of natural history. He says there are three “ways of discovering the Properties and Powers [of bodies]”:
- I. By the Help of the Naked Senses.
- II. By the Senses assisted with Instruments, and arm’d with Engines.
- III. By Induction, or comparing the collected Observations, by the two preceding Helps, and ratiocinating from them.
When he discusses III, Hooke explains that an understanding of mathematics and mechanics “will most assist the Mind in making, examining, and ratiocinating from Experiments”:
- Mechanicks also being partly Physical, and partly Mathematical, do bring the Mind more closely to the business it designs, and shews it a Pattern of Demonstration, in Physical Operations, manifests the possible Ways, how Powers may act in the moving resisting Bodies: Gives a Scheme of the Laws and Rules of Motion, and as it were enters the Mind into a Method of accurate and demonstrative Inquiry and Examination of Physical Operations. For though the Operations of Nature are more secret and abstruse; and hid from our discerning, or discovering of them, than those more gross and obvious ones of Engines, yet it seems most probable, by the Effects and Circumstances; that most of them may be as capable of Demonstration and Reduction to a certain Rule, as the Operations of Mechanicks or Arts.
Later in the same discussion, Hooke enumerates the different kinds of observations one should make when constructing natural histories:
- 25ly, To enquire and try how many Mechanical Ways there may be of working on, or altering the Proprieties of several Bodies; such as hammering, pounding, grinding, rowling, steeping, soaking, dissolving, heating, burning, freezing, melting, &c.
Hooke is using the term ‘mechanical’ in (at least) two different senses. In the first sense, the term describes the processes of machines; in the second sense, the term describes manual work. But he conflates neither of these with the experimental philosophy. They are distinct, albeit related, philosophies.
Previously on this blog we have claimed that some features of Newton’s early methodology, for example his early use of queries, suggest that he was influenced by the new experimental philosophy of the early Royal Society. I do not claim that Newton’s experimental philosophy is continuous with the experimental philosophy of the early Royal Society, so I do not take issue with Shapiro’s main claim. But I do take issue with his claim that the ‘mechanical philosophy’ and ‘experimental philosophy’ were considered by the early Royal Society to be synonymous.
Hypotheses and Newton’s Epistemic Triad
Kirsten Walsh writes…
Over the weekend, I participated in a conference on ‘Newton and his Reception’, at Ghent University. I presented a paper based on my idea that Newton is working with an ‘epistemic triad’. I had an excellent audience in Ghent, and received some very helpful feedback, but I’d like to hear what you think…
To begin, what is Newton’s ‘epistemic triad’?
In his published work, Newton often makes statements about his purported method in order to justify his scientific claims. In these methodological statements, he contrasts things that have strong epistemic credentials with things that lack those credentials. Consider, for example, these passages from his early papers on optics:
- For what I shall tell concerning them is not an Hypothesis but most rigid consequence, not conjectured by barely inferring ’tis thus because not otherwise or because it satisfies all Phænomena … but evinced by ye mediation of experiments concluding directly & wthout any suspicion of doubt. (6 February 1672)
- I shall not mingle conjectures with certainties… (6 February 1672)
- To determine by experiments these & such like Queries wch involve the propounded Theory seems the most proper & direct way to a conclusion. (3 April 1673)
What these passages tell us is that Newton is making a distinction between theories, which are certain and experimentally confirmed, hypotheses, which are uncertain and speculative, and queries, which are not certain, but provide the proper means to establish the certainty of theories. I call this three-way division Newton’s ‘epistemic triad’, and argue that this triad provides the framework for Newton’s methodology.
To support this argument, I defended the following three theses:
Endurance thesis. There are some general features of Newton’s methodology that don’t change. These are characterised by the framework of the epistemic triad.
Developmental thesis. There are some particular features of Newton’s methodology that change over time. These can be characterised as a development of the epistemic triad.
Contextual thesis. There are some particular features of Newton’s methodology that vary with respect to context (namely, mechanics versus optics). These can be characterised as an adaptation of the epistemic triad to particular contexts.
The developmental and contextual theses are not news to most Newton scholars. It is commonly accepted that Newton’s methodology changed in important ways over the course of his life, and that there are methodological differences between Principia and Opticks. The endurance thesis is more problematic, so I made a special effort to show that Newton’s use of hypotheses is more consistent than we think. I argued that:
- In Principia, Newton appears to be working with the same implicit definition of ‘hypothesis’ that he works with in his early optical papers; and
- Hypotheses perform similar methodological roles in all of Newton’s natural philosophical work.
I need to do some more work to properly explicate this methodological role. But, to state it very broadly, Newton temporarily assumes hypotheses, which act as ‘helping premises’ in his inferences from phenomena. The fact that a statement may appear in Newton’s writing as a hypothesis, and then reappear later in a query, rule of reasoning, or phenomenon, has convinced many Newton scholars that Newton is inconsistent in his use of hypotheses. Against this conviction, I argue that Newton applies the label ‘hypothesis’ to things that perform a particular function, rather than to a particular claim.
Hypotheses versus Queries in Newton’s Opticks
Kirsten Walsh writes…
A while ago I argued that the queries in Newton’s early optical papers are not hypotheses. Rather, they are empirical questions that may be resolved by experiment. In Newton’s Opticks, however, his queries become increasingly speculative – especially the famous ‘Query 31’. What should we make of this? Did Newton abandon his early distinction between hypotheses and queries?
In his early optical papers, Newton explains that “the proper Method for inquiring after the properties of things is to deduce them from Experiments”. Having obtained a theory in this way, one should proceed as follows:
- specify queries that suggest experiments that will test the theory; and
- carry out those experiments.
He tells us that hypotheses have a role in this procedure. They may be useful for: (a) suggesting further experiments, as the first step toward specifying queries; and (b) ‘illustrating’ the theory to assist understanding.
The queries in Newton’s Opticks have been much talked about, and often Newton has been accused of slipping hypotheses into his work under the guise of the more-respectable query. To examine this claim, I looked at the draft manuscripts* of Newton’s Opticks; in particular, “The fourth book concerning the nature of light & ye power of bodies to refract & reflect it” (Add. 3970, 337-8).
The draft begins, as many of the other books of Opticks begin, with a list of observations, followed by numbered propositions. However, it contains little in the way of argument and virtually no discussion of experimental evidence. Shapiro points out that this is because this is a draft of an outline or plan of a book; not a draft of the book itself. The propositions are things that Newton hoped to prove. For example:
- Prop. 1. The refracting power of bodies in vacuo is proportional to their specific gravities.
Prop. 2. The refracting power of two contiguous bodies is the difference of their refracting powers in vacuo.
The draft contains a section entitled ‘The conclusion’, which contains five ‘hypotheses’. I am interested in ‘Hypothesis 2’:
- As all the great motions in the world depend upon a certain kind of force (wch in this earth we call gravity) whereby great bodies attract one another at great distances: so all the little motions in ye world depend upon certain kinds of forces whereby minute bodies attract or dispell one another at little distances.
- How the great bodies of ye earth Sun moon & Planets gravitate towards one another what are ye laws of & quantities of their gravitating forces at all distance from them & how all ye motions of those bodies are regulated by those their gravities I shewed in my Mathematical Principles of Philosophy to the satisfaction of my readers: And if Nature be most simple & fully consonant to her self she observes the same method in regulating the motions of smaller bodies wch she doth in regulating those of the greater… The truth of this Hypothesis I assert not because I cannot prove it. But I think it very probable because a great part of the phaenomena of nature do easily flow from it wch seem otherways inexplicable…
I. Bernard Cohen describes this as “a ‘whale’ of an hypothesis” – and he’s right! When Newton started writing out this statement, he intended for it to be ‘Proposition 18’. But at some point, he has scratched out ‘Prop 18’, and re-branded it as ‘Hypoth 2’. There is no real semantic difference between a proposition and a hypothesis, but, for Newton, there is an epistemic difference. Propositions are things that he is able to assert as true. Hypotheses are things that he is unable to assert, because he does not have the evidence. Newton clearly hoped to assert Proposition 18. But as he started to explicate it, he must have realised that he couldn’t prove it. Thus, he re-labelled it as a hypothesis.
When Newton abandoned the fourth book, and restructured the rest of his Opticks, this ‘Hypothesis 2’ appears to have been re-worked to become ‘Query 31’ in Opticks, 2nd edition (1717):
- 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 Phaenomena of Nature? For it’s well known, that Bodies act one upon another by the Attractions of 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. For Nature is very consonant and conformable to her self…
Here, there is an obvious semantic shift between hypothesis and query: the query is stated as a question. Some scholars have argued that this is the only difference between hypotheses and queries: in the Opticks, queries are simply Newton’s way of getting around his self-imposed ban on hypotheses. I claim that there is more to the shift than this. Newton is using the semantic structure of the query to explore a possible future research program. The epistemic difference between the query and the hypothesis is similar to the epistemic difference between Popper’s falsifiable and unfalsifiable theories. The former is testable-in-principle, whereas the latter is not; and testability is a necessary condition of something becoming well-tested.
There is a difference between Newton’s early queries and his later queries: the former are part of the process of justification; but the latter are part of the process of discovery. In a previous post I noted that:
- While Newton’s [early] method of queries is experimental, it does not appear to be strictly Baconian. For the Baconian-experimental philosopher, queries serve “to provoke and stimulate further inquiry”. Thus, for the Baconian-experimental philosopher, queries are part of the process of discovery. However, for Newton, queries serve to test the theory and to answer criticisms. Thus, they are part of the process of justification.
The queries in Newton’s later work seem closer to the Baconian tradition that inspired him.
That the themes of Hypothesis 2 and Query 31 appear in Rule 3 of Principia, raises questions about the status of Newton’s ‘Rules of Philosophising’ and how we should interpret the re-branding of ‘hypotheses’ as ‘rules’ in later editions of Principia. I’d love to hear what you think!
* Recently, Cambridge University put Newton’s papers online, making it possible for those of us who live ‘down under’ to examine copies of many of Newton’s manuscripts!
Explicating Newton’s Natural Philosophical Methodology: Part II
This is the second part of Steffen Ducheyne’s presentation of his new book, “The main Business of Natural Philosophy:” Isaac Newton’s Natural-Philosophical Methodology. You can find the first part here.
Steffen Ducheyne writes …
In the Principia (1687), Newton developed a detailed picture of how one may deduce causes from phenomena (for the technical details I refer to Chapters 2 and 3). Newton’s expression ‘deductions from phenomena’ has oftentimes been considered as a rhetorical tool by which he sought to distance himself from his opponents. However, close scrutiny shows, I believe, that Newton’s ‘deductions from phenomena’ have profound methodological significance as well. I do not, however, endorse the view that Newton’s Principia-style methodology was therefore non-hypothetical. Rather, what makes it methodologically interesting is that it encompassed procedures to minimize speculation and inductive risk in the process of theory formation. What is distinctive of Newton’s Principia-style methodology is that he established bi-conditional dependencies between causes and their effects from the laws of motion. In other words, the causes which Newton would later infer in Book III were backed-up and constrained by the laws of motion. Given these dependencies, Newton was able to present his derivations of the centripetal forces acting in our solar system as deductions and, hence, as ‘deductions from phenomena’. I want to emphasize, however, that Newton’s proceeding from phenomena to theory, i.e. his presenting of certain inferences as deductions from phenomena, taken as such is not what makes his method essentially different from hypothetico-deductivism. Rather, proceeding from phenomena to theory is the by-product of what genuinely makes Newton’s method distinctive from hypothetico-deductivism: the establishment of systematic dependencies backed-up by the laws of motion. These systematic dependencies, in other words, mediate between experimental or astronomical results and the very causes which account for these phenomena.
Portrait of Isaac Newton (1702)
Once he had finished the Principia, Newton returned to his optical studies, which would eventually lead to the publication of the Opticks in 1704. Could he now methodize optics according to the highly sophisticated standards which he had developed in the Principia? In my view, the answer is negative. For instance, I have argued that Newton’s argument for the heterogeneity of light rests on an argument of uniformity that cannot be licensed by Newton’s second rule of philosophizing. I have also paid considerable attention to the problem of transduction which Newton encountered in his optical studies. In mechanics, the affected entities, i.e. the explananda – bodies moving along specific trajectories, and their constituent elements, namely, the particles constituting these very bodies – all have a theoretically salient property in common, namely, mass. Because gravity is proportional to mass and because the latter is additive, gravity is likewise additive. This allowed Newton to show that a body’s overall force can be decomposed into the individual forces of each of the bodies constituting that body and vice versa. In optics, by contrast, we do not know – at least not without speculating on the matter – the constituting elements of the explananda. In the Opticks Newton could not establish ‘deductions from phenomena’ because, in contrast to the physico-mechanical theory of the Principia, a mixed science describes a given phenomenon mathematically without an accompanying explanatory story. In other words, in the Opticks the inference of causes could not be constrained by a set of laws which carry information about the proximate causes involved.
By way of outro and also as a teaser, I would like to conclude by devoting some words to the provisionalism that characterized Newton’s later methodological thought. Newton’s provisionalism pervades the third and especially the fourth regula philosophandi, which were added in the second (1713) and third (1726) edition of the Principia, respectively. The provisionalism which Newton envisioned did not apply to the ‘deductions from phenomena’, but rather to propositions ‘rendered general by induction’ – at least evidence from Newton’s manuscripts leads me to believe so. Based on a careful study of Newton’s manuscripts, I have also succeeded in clarifying what Newton understood by qualities which cannot be “intended and remitted” and, on the basis of this, I have concluded that the Cohen-Whitman translation of “intendi et remitti” as “increased and diminished” is incorrect. I could say much more about my book, but I hope that this will suffice to get you interested in reading it.
