What drives philosophical progress?
Kirsten Walsh and guest blogger Adrian Currie write…
A while ago, Peter Anstey argued that, while the traditional rationalist-empiricist distinction (RED) is primarily about epistemology, questioning the foundational sources of knowledge, evidence and justification from an a priori, first-person perspective, the experimental-speculative distinction (ESD) is primarily methodological, concerned with how knowledge is generated. In this highly speculative post, we consider a consequence of preferring one of these distinctions over the other, namely, its effect on our understanding of philosophical progress in the early modern period. Note that the ESD is just one way of providing a methodological (as opposed to epistemological) narrative about the history of ideas, and we think much of what we have to say is perfectly compatible with those who, for instance, take a non-traditional (specifically, methodological or technological) stance on empiricism (see, for instance, Newton and Empiricism).
We suspect that the RED and the ESD give very different answers to questions about what the main driver of change in early modern philosophy was. Insofar as the RED gives us an account of what mattered in early modern philosophy, it generates stories about foundational, a priori investigation into the nature of knowledge. In contrast, the ESD tells a story of philosophical progress driven by scientific achievement, technological development and methodological innovation. These are two very different narratives about the history of ideas. Moreover, they emphasise the contributions of different historical figures.
When the focus is epistemology, we fixate on theorists who provided accounts of knowledge and its justification—namely, the canonical seven: Descartes, Leibniz, Spinoza, Locke, Berkeley, Hume and Kant—to the exclusion of other historical figures. The early Royal Society, for instance, clearly influenced the direction of Western thought, i.e. Western philosophical thought, enormously. Yet its members are sidelined in favor of epistemologists.
The ESD’s methodological emphasis shifts our focus. Boyle, Hooke and Newton, for example, did not produce new theories of knowledge, but they made strides in terms of methodology. Their inquiries yielded original ideas about how to produce knowledge and utilise new technologies (e.g. experimental apparatuses and mathematics). On this view, Newton made an enormous contribution to (anachronistically) philosophy as well as science. Newton synthesized Baconian experimental philosophy with the mathematical rigour of geometric methods—as we have argued on this blog, this methodology was influential beyond natural philosophy. Newton didn’t tell us what it is to know, but he did tell us how to go about generating knowledge. On the RED, scientific advancement is at best a side-show, on the ESD it is (to misquote Newton) the main business of philosophy.
This bit of speculation raises some questions.
Firstly, presumably it is a mistake to think that any one factor has played a privileged role in shaping history, intellectual or otherwise. Thus, arguing that the history of ideas is methodology-driven, rather than epistemology-driven, creates far too stark a dichotomy. If our speculation holds water, then the upshot is that the role of epistemology is over-emphasized. But how much, and how might we go about attributing blame?
Secondly, it is not clear to what extent frameworks such as the RED and the ESD should be read as hypotheses about historical forces. We might simply interpret them as handy heuristics—giving direction to various legitimate research interests. Moreover, they might bring out narratives relevant for understanding other parts of history. For example, one might argue that the RED is important for examining how later philosophers understood and were influenced by the early moderns (something like this view is defended here). So, how should we understand the content and role of such frameworks?
Thirdly, historians these days don’t often go in for ‘grand narratives’—and with good reason. Human history is messy and, typically, simplistic, one-size-fits-all explanations are inapplicable. Moreover, it’s not clear what difference such macro-scale frameworks make at the coalface of academic history, where historians and philosophers must engage with complex ideas and even more complex individuals. Prima facie, seeing Newton as an experimental philosopher rather than an empiricist won’t affect our interpretation of query 31. It might seem that the business of academic history is far too fine-grained for those differences to matter often. So, how much do such frameworks effect the day-to-day work of philosophers and historians?
Regardless of our answer to that question, we think these grand narratives do matter. They help decide the direction of research, and what counts as a good question for serious academic history of philosophy. Moreover, they influence pedagogy: how and what we teach (see our discussion here). Finally, they might play a role in how we, as contemporary philosophers, see ourselves and our field’s development.
This thought raises a further question: what role has the RED’s historical narrative played in vindicating and perpetuating the idea that ‘core’ epistemology targets questions about the nature of knowledge and its justification from a first-person a priori perspective?
So far, these speculations have raised more questions than answers. We’d love to hear your thoughts on them.
Kant’s Campaign against the Synthesis of Empiricism and Rationalism
This is a guest post by Timmy de Goeij. Timmy is part of a research project “Thinking classified – Structuring the world of ideas around 1800”, based at Utrecht University. We are grateful to Timmy for sharing his current research on our blog.
Kant is generally considered to be the first philosopher who synthesized early modern rationalism and empiricism, and who, with this synthesis, set the terms of reference for much of nineteenth and twentieth century philosophy. Contrary to this view, I am currently writing a paper wherein I argue, first, that Kant never thought of himself as providing a synthesis of rationalism and empiricism but as providing a middle road between dogmatism and scepticism, and, second, that this middle road is provided precisely by rejecting the syntheses of rationalism and empiricism that he saw present in the dogmatic and skeptical traditions. Although the second of these theses is certainly more exciting, I will first need to shortly elaborate on the first thesis, and postpone a discussion of the second one to a later post.
A couple of simple searches through the works of Kant will reveal immediately that he never explicitly characterized his philosophy in terms of a synthesis of rationalism and empiricism. As has been argued on this blog, it was Reinhold who first propounded this reading of Kant’s critical philosophy – a reading which was then probably adopted by Wilhelm Gottlieb Tenneman in his History of Philosophy, but which actually took a far longer period of time to become the standard narrative in the historiography of philosophy. In “Kant on Empiricism and Rationalism”, Alberto Vanzo emphasized the fact that there are many passages spread throughout Kant’s works wherein he more or less explicitly sides with the rationalist tradition in his theoretical philosophy, ethics and aesthetics. However, important in this regard is Kant’s distinction between an immodest or dogmatic empiricism and a more moderate or scientific form of empiricism.
Immodest empiricism adopts “a principle of pure empiricism, not only in the explanation of appearances in the world, but also in the dissolution of the transcendental ideas of the world-whole itself” (A466/B494), whereas modest empiricism only adopts a principle of empiricism in the explanation of the phenomena in the sensible world and limits our speculative knowledge (Wissen) to this domain of sensible objects (A470-471/B498-499). Kant’s doctrine of the categories alone already implies a rejection of the immodest form of empiricism. However, Kant does not reject the modest form of empiricism (ibid.). My hypothesis is that he reconciled empiricism and rationalism neither by synthesizing them, nor by finding a middle road between them, but by relocating and limiting their principles and methods to different domains of objects and knowledge. The claim of modest empiricism that our knowledge must follow the guidance of experience is valid for the phenomena in the sensible world, which is the proper domain of theoretical scientific knowledge. But empiricism must withhold from making any dogmatic claims about non-sensible objects and the transcendental conditions of the possibility of experience, because this is the pure domain of philosophy proper. In this way Kant conceptually prepares the separation between the empirical sciences and rational philosophy proper, guaranteeing the autonomy of both. Accordingly, Kant’s real battle was never with empiricism as such, nor with rationalism, but with the dogmatic forms of both empiricism and rationalism.
Throughout his works Kant also argues that scepticism itself was merely a reaction to dogmatism, and he situates his own philosophy as the middle road between dogmatism and scepticism (see, for example, Kant’s unfinished Progress of Metaphysics and the introductions to the third and eight parts of Metaphysik Vigilantius). In my view, then, Kant does not reject empiricism as such, nor is he concerned with synthesizing empiricism and rationalism; his critical philosophy tries to walk the middle road between dogmatism and scepticism. Moreover, my further hypothesis is that according to Kant’s own diagnosis, the failures of the dogmatic and skeptical traditions derive from mixing up empirical cognitions with rational cognitions, so that it “is of the utmost importance to isolate cognitions that differ from one another in their species and origin, and carefully to avoid mixing them together with others with which they are usually connected in their use” (A842/B870), and that this critical project is precisely meant to counter the syntheses of rational elements with empirical elements that were prevalent in both traditions. But that would be a topic for a later post.
Currently, I am still in the process of writing the paper, so I would appreciate any comments or suggestions either on the blog or via email.
Newton the empiricist?
Kirsten Walsh writes…
Recently, Zvi Biener and Eric Schliesser’s long-awaited volume, Newton and Empiricism, appeared on the shelves. The book is an excellent collection of papers, which makes a significant new contribution to the field. Today I want to focus on one aspect of this volume: the decision to frame the collection in terms of empiricism rather than experimental philosophy.
Over the last four years, we have provided many arguments for the superiority of the ESD over the RED. An important line of argument has been to show that ‘experimental philosophy’ and ‘speculative philosophy’ were the key terms of reference used by the actors themselves, and that they characterised their own work in terms of this division. For example, I have argued here, here, here and here that Newton is best understood as an experimental philosopher.
In their introduction, Biener and Schliesser explain their decision. They acknowledge the ‘Otago School’, and argue that, while in general there may be some good reasons to prefer the ESD to the RED, they see various problems with labelling Newton an ‘experimental philosopher’. Their concerns amount to the following: labelling Newton an ‘experimental philosopher’ obscures the idiosyncrasies of his approach to natural philosophy. They argue, firstly, that the label belies the significant influence of non-experimental philosophers on Newton’s methodology, for example those who influenced his mathematical focus. Secondly, that the label unhelpfully groups Newton with Boyle and Locke, when many features of his work support a different grouping. For example, Newton’s mathematical-system building suggests that his work should be grouped with Descartes’. Thirdly, they argue that the fact that Newton did not employ the label himself until after the publication of the first edition of the Principia suggests that he did not fully identify with the label.
These are important issues about the ESD and Newton’s place in it. So today I want to reflect on the broad problem of Newton’s idiosyncratic position. I argue that Newton’s divergence from Baconian tradition of the Royal Society is best seen as a development of experimental philosophy.
On this blog, I have sketched many features of Newton’s natural philosophical methodology. I have argued that, if we look at Newton from within the framework of the ESD, he can be neatly and easily identified as an experimental philosopher. His use of queries, his cautious approach to hypotheses, and his many methodological statements decrying the construction of metaphysical systems, suggest that this is a label that Newton would have been comfortable with. However, there is an important caveat to note: while Newton was clearly influenced by the Baconian experimental tradition, he did not consider himself a Baconian experimental philosopher.
In the earliest statements of his mathematico-experimental approach, Newton set up his position in opposition to the Baconian experimental philosophers. In these passages, one feature of Newton’s methodology stands out in explicit rejection of the Baconian method: his claims to certainty. This feature, in itself, is not very significant – many experimental philosophers believed that, in the end, natural philosophy would be a form of scientia, i.e. a system of knowledge demonstrated from certain axioms. Indeed, Bacon shared this ideal of certainty. He thought that his method of induction could get around the problems usually associated with ampliative inference and deliver knowledge of the essences of things. Thus, Bacon’s method of natural history was ultimately supposed to provide the axioms on which scientia could be founded. The challenge, which everyone agreed on, was to discover those axioms on which the system would be built.
Newton and the Baconians seem to diverge on their responses to this challenge. Baconian experimental philosophers recommended that one should have all the facts before formulating generalisations or theories. In contrast, Newton thought that a few, or even just one, well-constructed experiment might be enough – provided you used it in the right way. This shows that Newton took a different view of the role of evidence in natural philosophy. This divergence amounts to three key differences between Newton and the Baconian experimental philosophers:
- Where the Baconian experimental philosophers advocated a two-stage model, in which construction of natural histories preceded theory construction, Newton appeared to reject this two-stage approach. Newton commenced theory-building before his knowledge of the facts was complete.
- Related to (1), the Baconian experimental philosophers conceived of phenomena as immediate facts, acquired via observation, and hence pre-theoretic. In contrast, Newton’s phenomena were generalised regularities, acquired via mediation between observation and theory.
- For the Baconian experimental philosophers, queries were used to give direction and define the scope of the inquiry. But Newton’s queries were more focussed on individual experiments.
There is strong textual evidence that the ESD was operative in Newton’s early natural philosophical work. We have good reason to suppose that Newton regarded his natural philosophical pursuits as experimental philosophy. This becomes clearer in Newton’s later work. For instance, in the General Scholium to the Principia (1713), Newton explicitly described his work as ‘experimental philosophy’ – indeed, Peter Anstey has noted that Roger Cotes also recognised this feature of Newton’s work. We also have good reason to suppose that, in important ways, Newton saw his work as aligned with the Royal Society and, by extension, with the Baconian movement. But Newton was also a mathematician, and he saw a role for mathematical reasoning in experimental philosophy. In many ways, it was this mathematical approach that led to his divergence from the Baconian experimental philosophy.
Biener and Schliesser are right to draw attention to the ways in which Newton’s position diverged from the experimental tradition of the Royal Society. However, they fail to recognise that Newton’s position diverged in a way that should be viewed as a development of this tradition. Indeed, the ‘Newtonian experimental philosophy’ eventually replaced the experimental philosophy of Boyle, Hooke and the other early members of the Royal Society. The label ’empiricism’ has no such historical relevance. But, more on this another time…
Colloquium: Principles in Early Modern Thought
University of Sydney
27–29 August 2014
Speakers:
Engraved word map by Leonhard Euler
- Professor Peter Anstey (Sydney), ‘Principles: the Contours of a Concept’ & ‘Principles of Religion’
- Mr Joe Campbell QC (Sydney), ‘Principles & the Development of English Equity Law’
- Professor James Franklin (UNSW), ‘Early modern Mathematical Principles’
- Professor Daniel Garber (Princeton), ‘Principles in Leibniz’s Philosophy’
- Professor Michael LeBuffe (Otago), ‘Principles of Spinoza’s Philosophy’
- Professor William R. Newman (Indiana), ‘Chymical Principles’
- Professor Sophie Roux (ENS, Paris), ‘Principles in French Philosophy’
- Professor Kiyoshi Shimokawa (Gakushuin, Tokyo), ‘A Conflict of Principles: Hume versus Modern Natural Lawyers’
- Dr Alberto Vanzo (Warwick), ‘Principles in Italian Natural Philosophy’
- Ms Kirsten Walsh (Otago and Calgary), ‘Principles in Newton’s Natural Philosophy’
Colloquium Sponsors:
This colloquium forms part of Professor Peter Anstey’s ARC Future Fellowship project on ‘The nature and status of principles in early modern philosophy’. It is sponsored by the School of Philosophical and Historical Inquiry and the Sydney Centre for the Foundations of Science.
Colloquium Organisers:
- Professor Peter Anstey
- Professor Stephen Gaukroger
Places are limited.
Program (Download PDF of the program here):
Wednesday 27 August:
9.00 Peter Anstey, ‘Principles: the Contours of a Concept’
10.30 Coffee Break
11.00 James Franklin, ‘Early modern Mathematical Principles’
12.30 Lunch
1.30 Joe Campbell, ‘Principles & the Development of English Equity Law’
3.00 Break
3.30 William Newman, ‘Chymical Principles’
5.00 End of Day
Thursday 28 August:
9.00 Sophie Roux, ‘Principles in French Philosophy’
10.30 Coffee Break
11.00 Kiyoshi Shimokawa, ‘Principles of Natural Jurisprudence’
12.30 Lunch
1.30 Alberto Vanzo, ‘Principles in Italian Natural Philosophy’
3.00 Break
3.30 Peter Anstey, ‘Principles of Religion’
5.00 End of Day
Friday 29 August:
9.00 Michael LeBuffe, ‘Principles of Spinoza’s Philosophy’
10.30 Coffee Break
11.00 Kirsten Walsh, ‘Principles in Newton’s Natural Philosophy’
12.30 Lunch
1.30 Daniel Garber, ‘Principles in Leibniz’s Philosophy’
3.00 Conclusion
7.00 Colloquium Dinner
Location: Darlington Centre H07, Boardroom
Contact: Prof Peter Anstey
Phone: 61 2 9351 2477
Email: peter.anstey@sydney.edu.au
Register: Here
‘Epistemic amplification’ and Newton’s laws
Kirsten Walsh writes…
In my last post, I considered the experimental support Newton offers for his laws of motion. In the scholium to the laws, Newton argues that his laws of motion are certainly true. However, in support he only cites a handful of experiments and the agreement of other mathematicians. I suggested that the experiments discussed do support his laws, but only in limited cases. This justifies their application in Newton’s mathematical theory, but does not justify Newton’s claims to certainty. In this post, I will speculate that the laws of motion were in fact better established than Newton’s discussion suggests. I introduce the notion ‘epistemic amplification’ – suggesting that Newton’s laws gain epistemic status by virtue of their relationship to the propositions they entail. That is, by reasoning mathematically from axioms to theorems, the axioms obtained higher epistemic status, and so the reasoning process effectively amplified the epistemic status of the axioms.
I am not arguing that epistemic amplification captures Newton’s thinking. In fact, Newton explicitly stated that epistemic gain was not possible. For him, the best one could achieve was avoiding epistemic loss. (I have discussed Newton’s aims of certainty and avoiding epistemic loss here and here.) I suggest that, objectively speaking, the epistemic status of Newton’s laws increases over the course of the Principia.
To begin, recall that Newton has two projects in relation to the laws:
- The specification of the laws as the axioms of a mathematical system; and
- The justification of laws as first principles in natural philosophy.
Let’s consider the first project. In addition to the support of mathematicians and the experiments that Newton cites, it is plausible that the epistemic status of the laws increases by virtue of their success in the mathematical system: in particular, by entailing Keplerian motion. Kepler’s rules and Newton’s laws of motion have independent evidence: as we have seen, Newton’s laws are weakly established by localised experiments and the ‘agreement of mathematicians’; Kepler’s rules are established by observed planetary motion and were widely accepted by astronomers prior to the Principia. Newton’s laws entail Kepler’s rules, which boosts Newton’s justification for his laws. Moreover, Newton’s laws provide additional support for Kepler’s rules, by telling us about the forces required to produce such motions. The likelihood of the two theories is coupled: evidence for one carries over to the other. So Newton’s laws also boost the justification for Kepler’s rules. Thus, Newton achieves epistemic gain: the epistemic status of the laws, qua mathematical axioms, has increased by virtue of their relationship to Kepler’s rules.
Now let’s consider the second project – the application of the laws to natural philosophy. Again, the discussion in the scholium justifies their use, but not their certainty. I now suggest that these laws, as physical principles, gain epistemic status through confirmation of Newton’s theory. This occurs in book 3, when Newton explicitly applies his mathematical theory to natural phenomena. As I have previously discussed, the phenomena (i.e. the motions of the planets and their moons) are employed as premises in Newton’s argument for universal gravitation. However, the phenomena also support the application of the mathematical theory to the physical world: they show that the planets and their moons move in ways that approximate Keplerian motion. As we saw above, the laws of motion entail Kepler’s rules. So, since the phenomena support Kepler’s rules, they also support the laws of motion. So this is a straightforward case of theory-confirmation.
There is also scope for theory-testing in book 1. Each time Newton introduces a new factor (e.g. an extra body, or a resisting medium), the mathematical theory is tested. For instance, the contrasting versions of the harmonic rule in one-body and two-body model systems provides a test: it allows the phenomena to empirically decide between two theories, one involving singly-directed central forces, the other involving mutually-interactive central forces. Similarly, the contrasting two-body and three-body mathematical systems provide a test: they allow the phenomena to select between a theory involving pair-wise interactions and a theory involving universal mutual interaction. Moreover, in the final section of book 2, Newton shows that, unlike his theory, Cartesian vortex theory does not predict Keplerian motion. Thus, the phenomena seem to support his theory, and by extension the laws of motion, and to refute the theory of vortices. Again, the laws seem to gain support by virtue of their relationship to the propositions they entail.
To summarise, Newton claims that his laws are certainly true, but the support he gives is insufficient. Here, I have sketched an account in which Newton’s laws gain epistemic status by virtue of their relationship to the propositions they entail. ‘Epistemic amplification’ is certainly not something which Newton himself would have had truck with, but the term does seem to capture the support actually acquired by Newton’s laws in the Principia. What do you think?
An Update…
Hello, Readers!
On 23rd August 2010, we published our first post, presenting our research project to the world. As ‘newbies’ to blogging, we weren’t quite sure how effective it would be. Four years later, there is no trace of those initial doubts. The capacity to regularly share new research has helped us to be productive, to keep abreast of each other’s work, and to grow as a team. Most of all, it has allowed us to engage with the wider community, and to receive feedback at a very early stage in our research.
In light of the project’s development, the nature of the blog will change somewhat. Our Marsden grant ended two years ago, and we have all gradually moved onto other new projects:
- Peter Anstey continues to work on early modern experimental philosophy, though he now has an additional cognate project on ‘The nature and status of principles in early modern philosophy’. He is currently an ARC Future Fellow at the University of Sydney where his principles project is based. He also continues to work on Locke, Boyle and Bacon.
- Alberto Vanzo is now a research associate at the Department of Philosophy at the University of Warwick. He is working on early modern experimental philosophy, Kant and the historiography of philosophy.
- Juan Gomez is still at the University of Otago, working as a casual lecturer and continuing his research on Early Modern Spain. He is in the process of developing an extensive research project regarding the introduction of experimental philosophy in Spain in the second half of the seventeenth century and the unique Spanish take on the methodological debate of the period.
- Kirsten Walsh is now a research associate at the University of Calgary. She continues to work on Newton’s methodology, both from a historical perspective and also relating this work to current debates in the philosophy of science.
Early modern experimental philosophy continues to be a research interest for all of us – we still have heaps to study and to blog about – so we will continue to contribute to this blog, along with the occasional guest-blogger. But in July we will start mostly to blog monthly instead of fortnightly. We value your interest in our blog, and we hope you will continue reading, commenting and criticising our research. Our posts will appear on the first Monday of every month.
We at Early Modern Experimental Philosophy thank you for your continued interest in our project.
Workshop: The Experimental Philosophy, the Mechanical Philosophy, and the Scientific Revolution
A one-day workshop at the Institute of Advanced Study, Durham University:
The Experimental Philosophy, the Mechanical Philosophy, and the Scientific Revolution
9:30am-5:30pm, Thursday 5th June 2014
The Scientific Revolution is often presented as involving the replacement of an Aristotelian world view by the Mechanical Philosophy. Another common theme is that central to the Scientific Revolution is a special emphasis on empirical observation and experiment as providing the basis for science, a theme often captured by the phrase ‘The Experimental Philosophy’. In the seventeenth century and thereafter, the terms ‘The Mechanical Philosophy’ and ‘The Experimental Philosophy’ were sometimes taken to be synonymous. If the Mechanical Philosophy is interpreted as an encouragement to search for explanations that appeal to mechanisms, as in the workings of a clock, then a close link with experiment seems plausible. On the other hand, if that philosophy is understood as a change in the ultimate ontology of the material world, with the replacement of Aristotelian forms by nothing other than moving corpuscles of matter possessing shape and size, then a link with experiment is less plausible. The aim of this workshop is to explore the range of theses that were involved in the Mechanical and Experimental Philosophies, and to explore the relationship between them.
Speakers and titles:
Prof. Alan F. Chalmers (University of Sydney) ‘Qualitative Novelty in Seventeenth-Century Science: Hydrostatics from Stevin to Pascal’.
Prof. Robert Iliffe (University of Sussex) Title to be confirmed
Prof. David M. Knight (Durham University) ‘Clockwork, Chemistry and the Scientific Revolution’.
Mr. Thomas Rossetter (Durham University) ‘No Mechanism for Miracles: John Keill vs. the World Makers’.
Dr. Sophie Weeks (University of York) ‘Experiment and Matter Theory in the Work of Francis Bacon’.
Prof. David Wootton (University of York) ‘In Defence of the Mechanical Philosophy’.
The workshop is open to all but there are limited places available so please email thomas.rossetter@durham.ac.uk to reserve a place.
There will be a registration fee of £10 to cover lunch and refreshments.
Are Newton’s Laws Experimentally Confirmed?
Kirsten Walsh writes…
Previously on this blog, I have argued that the combination of mathematics, experiment and certainty are an enduring feature of Newton’s methodology. I have also highlighted the epistemic tension between experiment and mathematical certainty found in Newton’s work. Today I shall examine this in relation to Newton’s ‘axioms or laws of motion’.
In the scholium to the laws, Newton argues that his laws of motion are certainly true. In support, however, he cites a handful of experiments and the agreement of other mathematicians: surprisingly weak justification for such strong claims! In this post, I show how Newton’s appeals to experiment justify the axioms’ inclusion in his system, but not with the certainty he claims.
Newton begins:
- “The principles I have set forth are accepted by mathematicians and confirmed by experiments of many kinds.”
Newton expands on this claim, discussing firstly, Galileo’s work on the descent of heavy bodies and the motion of projectiles, and secondly, the work conducted by Wren, Wallis and Huygens on the rules of collision and reflection of bodies. He argues that:
- The laws and their corollaries have been accepted by mathematicians such as Galileo, Wren, Wallis and Huygens (the latter three were “easily the foremost geometers of the previous generation”);
- The laws and their corollaries have been invoked to establish several theories involving the motions of bodies; and
- The theories established in (2) have been confirmed by the experiments of Galileo and Wren (which, in turn confirms the truth of the laws).
These claims show us that Newton regards his laws as well-established empirical propositions. However, Newton recognises that the experiments alone are not sufficient to establish the truth of the laws. After all, the theories apply exactly only in ideal situations, i.e. situations involving perfectly hard bodies in a vacuum. So Newton describes supplementary experiments that demonstrate that, once we control for air resistance and degree of elasticity, the rules for collisions hold. He concludes:
- “And in this manner the third law of motion – insofar as it relates to impacts and reflections – is proved by this theory [i.e. the rules of collisions], which plainly agrees with experiments.”
This passage suggests that the rules of collisions support a limited version of law 3, “to any action there is always an opposite and equal reaction”, and that the rules themselves appear to hold under experimental conditions. However, this doesn’t show that law 3 is universal: which Newton needs to establish universal gravitation. This argument is made by showing how the principle may be extended to other cases.
Firstly, Newton extends law 3 to cases of attraction. He considers a thought experiment in which two bodies attract one another to different degrees. Newton argues that if law 3 does not hold between these bodies the system will constantly accelerate without any external cause, in violation of law 1, which is a statement of the principle of inertia. Therefore, law 3 must hold. As the principle of inertia was already accepted, this supports the application of law 3 to attraction.
Newton then demonstrates law 3’s application to various machines. For example, he argues that two bodies suspended from opposite ends of a balance have equal downward force if their respective weights are inversely proportional to the distances between the axis of the balance and the points at which they are suspended. And he argues that a body, suspended on a pulley, is held in place by a downward force which is equal to the downward force exerted by the body. Newton explains that:
- “By these examples I wished only to show the wide range and the certainty of the third law of motion.”
What these examples in fact show is the explanatory power of the laws of motion – particularly law 3 – in natural philosophy. Starting with collision, which everyone accepts, Newton expands on his cases to show how law 3 explains many different physical situations. Why wouldn’t a magnet and an iron floating side-by-side float off together at an increasing speed? Because, by law 3, as the magnet attracts the iron, so the iron attracts the magnet, causing them to press against one another. Why do weights on a balance sometimes achieve equilibrium? Because, by law 3, the downward force at one end of the balance is equal to the upward force at the other end of the balance. These examples demonstrate law 3’s explanatory breadth. But these examples do not give us a compelling reason to think that law 3 should be extended to gravitational attraction (which seems to require some kind of action, or attraction, at a distance).
Newton, clearly, is convinced of the strength of his laws of motion. But this informal, discussion of the experiments he appeals to shows that he ought not be so convinced. As I see it, Newton has two projects in relation to his laws:
1) The specification of the laws as the axioms of a mathematical system; and
2) The justification of laws as first principles in natural philosophy.
I suggest that the experiments discussed give strong support for the laws in limited cases. This justifies their application in Newton’s mathematical model, but it does not justify Newton’s claims to certainty. In modern Bayesian terms, we might say that Newton’s laws have high subjective priors. In my next post, I shall sketch an account in which Newton’s laws gain epistemic status by virtue of their relationship to the propositions they entail.
Workshop: Early Eighteenth-century Experimental Philosophy in the Dutch Republic
The VUB’s Centre for Logic and Philosophy of Science and the National Committee for Logic, History and Philosophy of Science are proud to announce the international workshop:
Early Eighteenth-century Experimental Philosophy in the Dutch Republic.
Date: 7 July 2014
Venue: The Royal Academies for Science and the Arts of Belgium, Rubenszaal
Organizers: Steffen Ducheyne and Jip van Besouw
Programme:
8.15-8.40 a.m.: Welcome and coffee
8.40-8.45 a.m.: Introduction by Steffen Ducheyne (Free University Brussels)
8.45-9.30 a.m.: Lecture by Gerhard Wiesenfeldt (University of Melbourne): ‘Local traditions in the making of Dutch Newtonianism’
9.30-10.15 a.m.: Lecture by F. J. Dijksterhuis (University of Twente): ‘German traces in Dutch experimental philosophy’
10.15-10.45 a.m.: Coffee break
10.45-11.30 a.m.: Lecture by Steffen Ducheyne (Free University Brussels) ‘Aspects of Petrus van Musschenbroek’s appropriation of Newton’s natural-philosophical methodology’
11.30-12.00 a.m.: Presentation by Jip van Besouw (Free University Brussels) of the FWO-funded research project ‘In the footsteps of Isaac Newton? W. J. ’s Gravesande’s scientific methodology’
12.00-13.45 p.m.: Lunch break
13.45-14.30 p.m.: Lecture by Anne-Lise Rey (Université de Lille I): ‘Probability, moral certainty and evidence in Willem ’s Gravesande’s natural philosophy’
14.30-15.15 p.m.: Lecture by Tammy Nyden (Grinnell College, Iowa) ‘Experiment’s journey at Leiden: From compromise to justified scientific method’
15.15-15.45 p.m.: Coffee break
15.45-16.30 p.m.: Lecture by Ad Maas and Tiemen Cocquyt (Boerhaave Museum, Leiden): ‘The truth in a layer of clay: A replication of ’s Gravesande’s vis viva experiment’
16.30-17.00 p.m.: Concluding remarks by Eric Jorink (Huygens Institute for the History of the Netherlands and Leiden University)
Abstracts: download PDF here.
Attendance is free, but registration is mandatory. To register please send an e-mail to jip.van.besouw@vub.ac.be before 1 July.
Understanding Newton’s Experiments as Instances of Special Power
Kirsten Walsh writes…
In my last few posts, I have been discussing the nature of observations and experiments in Newton’s Opticks. In my first post on this topic, I argued that Newton’s distinction between observation and experiment turns on their function. That is, the experiments introduced in book 1 offered individual, and crucial, support for particular propositions, whereas the observations introduced in books 2 and 3 only supported propositions collectively. In my next post, I discussed the observations in more detail, arguing that they resemble Bacon’s ‘experientia literata’, the method by which natural histories were supposed to be generated. At the end of that post, I suggested that, in contrast to the observations, Newton’s experiments look like Bacon’s ‘instances of special power’, which are particularly illuminating cases introduced to provide support for specific propositions. Today I’ll develop this idea.
Note, before we continue, that there are two issues here that can be treated independently of one another. One is establishing the extent of Bacon’s historical influence on Newton; the other is establishing the extent to which Bacon’s methodology can illuminate Newton’s. In this post I am doing the latter – using Bacon’s view only as an interpretive tool.
Identifying ‘instances of special power’ (ISPs) was an important step in the construction of a Baconian natural history. ISPs were experiments, procedures, and instruments that were held to be particularly informative or illuminative. These served a variety of purposes. Some functioned as ‘core experiments’, introduced at the very beginning of a natural history, and serving as the basis for further experiments. Others played a role later in the process. They included experiments that were supposed to be especially representative of a certain class of experiments, tools and experimental procedures that provided interesting shortcuts in the investigation, and model examples that came very close to providing theoretical generalisations. In some cases, a collection of ISPs constituted a natural history.
The following features were typical of ISPs. Firstly, they were considered to be particularly illuminating experiments, procedures or tools. For example, a crucial instance, or a particularly clear or informative experiment, or experimental procedure. Secondly, they were supposed to be replicated. On Bacon’s view, replication was not merely an exercise for verifying evidence; it was an exercise for the mind, ensuring that one had truly grasped the phenomenon. Thirdly, they were versatile, in that they could be used in several different ways. As we shall see, the experiments of book 1 display these essential features.
In book 1 of the Opticks, Newton employed a method of ‘proof by experiments’ to support his propositions. Each experiment was introduced to reveal a specific property of light, which in turn proved a particular proposition. We know that Newton conducted many experiments in his optical investigations, so why did he present the experiments as he did, when he did? When we consider Newton’s experiments alongside Bacon’s instances of special power, common features start to emerge.
Firstly, for each proposition he asserted, Newton introduced a small selection of experiments in support – those that he considered to be particularly illuminating or, in his own words, “necessary to the Argument”. Unlike in his first paper, in the Opticks, Newton did not label any experiments ‘experimentum crucis’. But his use of terms such as ‘necessary’ and ‘proof’ make it clear that these experiments were supposed to provide strong support: just like ISPs.
Secondly, Newton usually provided more than one experiment to support each proposition. These were listed in order of increasing complexity and were carefully described and illustrated. That Newton took this approach, as opposed to just reporting on their results, suggests that these experiments were supposed to be an exercise for the reader: they were about more than just proof or confirmation of the proposition. The reader was supposed either to be able to replicate the experiment, or at least to understand its replicability. Starting with the simplest experiment, Newton led his reader by the hand through the relevant properties of light, to ensure that they were properly grasped. Like Bacon’s ISPs, then, Newton’s experiments were intended to be replicated.
Thirdly, Newton’s experiments were recycled in a variety of roles in the Opticks. For example, the experiments he used to support proposition 2 part II were experiments 12 and 14 from part I. Newton introduced and developed these experiments in several different contexts to illuminate and support different propositions. Again, this is typical of Bacon’s ISPs.
And so, Newton’s experiments in the Opticks play a role analogous to Bacon’s instances of special power, and thinking of them as such explains why they are presented as they are. They are particularly illuminating cases that are introduced to provide support for specific propositions. Newton selected the experiments which best functioned as ISPs for inclusion in the Opticks. Moreover, seen in this light, the seemingly disparate set of experiments start to look like a far more cohesive collection, or a natural history.
Many commentators have emphasised the ways that Newton deviated from Baconian method. Through this sequence of posts, I have argued that the Opticks provides a striking example of conformity to the Baconian method of natural history.
