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.
- 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?
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.
Peter Anstey writes …
James Bradley (c. 1692–1762) was one of the leading English astronomers of the eighteenth century, being appointed to the Savilian Chair in Astronomy at Oxford in 1721 on the death of John Keill, before being appointed as Astronomer Royal in 1742 on the death of Edmund Halley. He announced his discovery of the phenomenon of nutation in the movement of the Earth in 1748 and was subsequently awarded the Royal Society’s Copley Medal.
Our interest in Bradley, however, lies in his teaching of experimental philosophy at Oxford for over thirty years. We have already discussed on this blog the roles of John Keill and Jean Theophilus Desaguliers in the teaching of experimental philosophy at Oxford (and in the case of Desaguliers in London). Keill began teaching around 1700 and was succeeded by Desaguliers in 1713. After a hiatus of three or four years it seems that John Whiteside of Christ Church began to lecture on experimental philosophy (his lectures survive in Cambridge University Library) and he was replaced in 1729 by Bradley. Bradley gave a staggering 79 (at least) courses on experimental philosophy from 1729 to 1760. Thus, apart from a short break experimental philosophy was constantly taught in Oxford University for the first six decades of the eighteenth century. This was in spite of the fact that, unlike Cambridge University, there was no Chair in experimental philosophy.
Interestingly, a register of all those who attended Bradley’s lectures from April 1746 to April 1760 survives. It is reproduced as Appendix E of volume XI of Gunter’s Early Science in Oxford (Oxford, 1937) and shows the name and college affiliation of every student who attended the lectures. Each course averaged 57 students. The lectures were given in the Old Ashmolean Museum, which today is the History of Science Museum. Happily some of Bradley’s lecture notes survive in the Bodleian Library.
Since there was no Chair in experimental philosophy at Oxford, Bradley had to secure some source of income for his lectures. We know that for his last 33 courses he charged two guineas for the first lecture and one gineau for the second lecture. It must have been a handy little earner. According to the Memoirs of Bradley, thirty-one pounds had been set aside each year for a reader in experimental philosophy by convocation in 1731 from the estate of the late Bishop of Durham, Nathaniel Crewe, but Bradley didn’t see any of this money until 1749.
Bradley’s lectures were similar in content to those of Desaguliers and of Roger Cotes and William Whiston in Cambridge. The syllabus remained fairly static for sixty years. It included the laws of nature, mechanics, hydrostatics and optics. What this shows us is that the term ‘experimental philosophy’ didn’t only refer to a method of acquiring knowledge of nature, but also to the actual knowledge acquired through the application of this method. This may not seem a particularly deep historical insight, but it does reflect the success of experimental philosophy of the seventeenth century. The teaching of natural philosophy had come a very long way from its emergence in the 1660s to the time that an average of over 50 undergraduates were signing up for courses in it from 1746!
Juan Gomez writes…
One of the most exciting tasks of my research has been to track the introduction and reception of the ESD in early modern Spain. I have illustrated the adoption and praise of the spirit of experimental philosophy in various texts by the Spanish Novatores, and I looked in a bit more detail at the work of Benito Feijoo (posts 1, 2, and 3). In spite of the insistence to abandon scholastic and Aristotelian methods and science, the progress of natural philosophy in early modern Spain lagged in comparison to the rest of Europe. In fact, the Novatores themselves recognized this lack of progress, as is clear from a letter by Feijoo which I will be sharing with you today.
In 1745 Feijoo published a collection of letters, most of them responding to a range of criticisms directed against his Teatro Critico Universal. Letter 16 in the second volume of that collection is Causas del atraso que se padece en España en orden a las Ciencias Naturales (Causes for the backwardness of Spain regarding the Natural Sciences). Feijoo gives six reasons (causes) for this backwardness, in all of them placing the blame on the scholastic philosophers and their way of thinking.
The first cause is the narrowness of most of the teachers, whom Feijoo describes as “Everlasting ignorants, set on knowing only a few things, for no other reason that they think that there is nothing else to know, aside from those few things they know.” Feijoo goes on to describe this kind of teacher, who only knows scholastic logic and metaphysics, and laughs when hearing words like ‘new philosophy’ or ‘Descartes.’ However, when asked to explain the claims of the new philosophy or those held by Descartes, they stay silent because they have no knowledge of them. (Note: experimental philosophy and new philosophy are not identical, even though the former was sometimes referred to by the latter name. For example, Descartes was commonly regarded as a new philosopher, but not so much as an experimental philosopher.)
People like the teachers described above have spread throughout Spain a disdain for ‘the new’, the second cause identified by Feijoo. They think that, since every sacred doctrine labelled ‘new’ is rejected immediately for being suspicious, the same rule applies for theories about the natural world. So they must reject the teachings of Galileo, Huygens, and Harvey, as well as all the new instruments and machines developed in the seventeenth century, holding on to their scholastic and Aristotelian science as the one true system. Feijoo comments that this attitude backfires, since rejecting anything because it has been labelled ‘new’ entails that there could never have been any progress in natural science (the Aristotelian system was also ‘new’ at some point).
But aside from rejecting the new philosophy because it is ‘suspicious’, the Spanish scholastics also reject it because all it presents is “a few useless curiosities.” (This is the third cause given by Feijoo.) What the scholastics do not realize, Feijoo tells us, is that under this criterion their theories lose against those of the modern: “Which would be more useful: to explore in the physical world the works of the Author of Nature, or to investigate through large treatises derived from the Entity of Reason, and logical and metaphysical abstractions, the fictions of human understanding?” Feijoo also contrasts between the method of learning in the confines of the classroom of the scholastic, and that of the modern, based on experiments and observations.
The fourth cause rests on the mistaken notion held by the scholastics that the new philosophy is identical to Cartesian philosophy. Feijoo comments that although Cartesian philosophy might be new philosophy, new philosophy is not Cartesian philosophy, the same way men are animals but animals are not men. Highlighting the ESD, Feijoo goes on to divide philosophy into two kinds:
“Philosophy, taken in all its extension, can be divided into Systematic and Experimental. The Systematic has many different members, e.g. Pythagoric, Platonic, Peripatetic, Parascelsistic, or Chemical, that of Campanella, that of Descartes, that of Gassendi, etc.”
Feijoo clarifies that he advocates not that the Spaniards embrace one of the former systems, but rather that they do not close their eyes to “Experimental Physics”, which:
“without regard for any system, investigates the causes through the sensible effects; and where it cannot investigate the causes, it settles for the experimental knowledge of the effects… This is the physics that reigns in Nations: the one cultivated by many distinguished Academies as soon as it emerged in France, England, Holland, Etc.”
The achievements of this experimental physics are illustrated by the discoveries regarding our knowledge of the properties of air, of fluids and mechanics, all of them unattainable by relying on the physics of the schools.
Feijoo identifies as the last two causes the mistaken idea that the new philosophy clashes with religion, and the jealousy and pride of the scholastics in Spain that prevented them from accepting the triumphs of other men of science from different European nations. I will not examine them here. Instead I want to conclude the post by pointing out that, not only there is enough evidence to confirm the presence of the ESD (at least in some form) in early modern Spain, but also that it can provide us with an interesting framework to interpret the development of natural philosophy and science in early modern Spain.
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 email@example.com to reserve a place.
There will be a registration fee of £10 to cover lunch and refreshments.
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.
- “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.
Joseph Priestley is one of the most celebrated chemists of all time because of his role in the discovery of oxygen. So highly was he regarded that in 1922 the American Chemical Society named their most prestigious medal ‘The Priestley Medal’.
Priestley was born in 1733 and died in 1804. Thus, he flourished in the latter decades of the era of early modern experimental philosophy and a survey of his writings reveals that he embraced experimental philosophy. Indeed, by the late eighteenth century the experimental approach to natural philosophy was virtually without a rival in Britain. When analysing his writings on natural philosophy there is no sense that he believed that experimental philosophy needed to be defended or justified at all. To be sure, one finds the usual rhetoric of experimental philosophy, such as his comment in his Experiments and Observations relating to various Branches of Natural Philosophy (London, 1779) that:
Speculation without experiment has always been the bane of true philosophy. (Preface, vii)
Yet when one turns to his Heads of Lectures on a Course of Experimental Philosophy (London, 1794) the term ‘Experimental Philosophy’ in the title is entirely unselfconscious. He opens Lecture I with a statement of the aim of the discipline:
The object of experimental philosophy is the knowledge of nature in general, or more strictly, that of the properties of natural substances, and of the changes of those properties in different circumstances. This knowledge can only be attained by experiment, or observation. (p. 1)
He goes on to mention one of the ‘rules of philosophizing’ in this discipline: ‘to admit no more causes than are necessary to account for the effects’ (p. 3). Of course, this is Newton’s first rule of philosophizing from the second edition of the Principia and it is hardly surprising that Priestley goes on to claim that given the ‘power of gravity’ ‘we are authorized to reject the Cartesian Vortices’ (ibid.).
One might, therefore, regard Priestley’s writings as not having anything to teach us about early modern experimental philosophy. And yet there is at least one point that is worth highlighting, for, Priestley was the second person to use the term ‘empiricism’ in the title of a book in English. The first was Francis Guybon in his An Essay concerning the Growth of Empiricism; or the Encouragement of Quacks, London, 1712 which was an attack on medical quacks.
Then in 1775 Priestley published a book entitled Philosophical Empiricism: containing Remarks on a Charge of Plagiarism respecting Dr H––. He had been attacked by the Irish physician Bryan Higgins who had accused him of plagiarism and Priestley defended himself, attacking many claims in Higgins’ lectures and concluding:
These and suchlike long-exploded, and crude notions (so many of which I believe were never thrown together into the same compass since the age of Aristotle or Cartesius) are delivered in a manner and phrase so quaint, and a tone so solemn and authoritative, as gives me an idea that I cannot express otherwise than by the term Philosophical Empiricism. (p. 59)
What is interesting here is that ‘empiricism’ is used as a pejorative and is loosely associated with Descartes! This all predates the Kantian Rationalism and Empiricism distinction –– the RED. It is even tempting to claim that it shows the inappropriateness of foisting the term ‘empiricism’ in its Kantian sense on eighteenth century thinkers when it already had strong currency in eighteenth-century English with an entirely different meaning.
Juan Gomez writes…
For those familiar with the rhetoric and methodology of Early Modern Experimental Philosophy (the faithful readers of this blog among them) it is no surprise that the emphasis on facts, observation, and experiment as the only solid grounds of knowledge was highlighted in almost every published text by the promoters of the experimental method. Within natural philosophy, the relevant facts and experiments were confined to nature and its workings. However, pinpointing the relevant facts and observations for knowledge in areas outside of natural philosophy was a more delicate matter. As we have argued for in this blog, the methodology of Early Modern Experimental Philosophy was adopted by many eighteenth-century figures in areas traditionally contained under moral philosophy, such as ethics, aesthetics, and theology. But which sort of facts and observations entitled them to apply the same methodology that had contributed so much to the progress of mankind and our knowledge of the natural world?
George Turnbull (the philosopher, teacher, and theologian who has many times been the subject of our posts) thought that introspection could give us access to facts about the anatomy of our mind, and that paintings provided in moral philosophy the same role experiments did in natural. But what about facts and observations regarding religious thought? A couple of years ago I commented on Turnbull’s ‘experimental theism.’ We saw how Turnbull argued that the miracles performed by Jesus Christ serve as the samples and experiments that prove that he truly was the son of God and possessed knowledge of a more perfect stage in nature. However, the only evidence we have of those miracles is found in the gospels of the apostles, so why is it that those accounts of miracles count as proper evidence? David Hume’s rejection of miracles was based precisely on the claim that evidence from testimony would never be stronger than evidence from experience, and so belief in miracles from testimony of them is not justified. Turnbull, on the other hand, believed that the testimony given in the gospels was in fact enough evidence, and it is his argument that I want to focus on for the rest of today’s post.
In the conclusion to his Principles of Christian Philosophy (1749) Turnbull claims that he will show that “the christian revelation gives a very proper, full, and truly philosophical evidence for the truth of that doctrine concerning God, providence, virtue, and a future state. As I mentioned earlier, Jesus and his apostles had a first hand access to the evidence, i.e. the works and miracles of Jesus Christ. But what we have access to is testimony of that evidence, and not the evidence itself. This being the case, we must wonder if testimony is reliable enough. In an earlier section of his book, Turnbull argues that testimony, whether of the senses, or of introspection, or of whatever kind, must be examined under the same criteria:
- “[E]xperiences taken upon testimony, must all of them, whether concerning objects of the outward senses, or inward sentiments, operations, and affections of the mind, be tried, examined, and admitted, or repelled by the very same criteria, or rules of moral evidence.”
So the testimony from the gospels should be examined the same way we examine any testimony of experiments in natural philosophy. Turnbull then claims that we have no reason to doubt the testimony whether of Jesus or the apostles, just as we wouldn’t doubt the testimony of a skilled scientist:
- “For surely, one who had admitted the truth of a proposition in geometry, or of an experiment in natural philosophy, upon the testimony of one skill’d in these arts, in whom he had reason to confide, has no ground to doubt such testimony, when having made further advances in geometry or experimental philosophy, he comes to see the truths he had formerly received upon testimony, as it were, with his own eyes. And must not the same hold true with respect to moral truths?”
It seems that Turnbull does not confront the issue of the reliability of testimony as proper evidence. Of course, he could argue that we do not have any reason to doubt the account given by the apostles because they are characterized as having a virtuous moral character, and so is Jesus. But these accounts come from the gospels themselves, so unless we have an external account of the moral character of those giving the testimony, it seems that we might have grounds to doubt them.
Turnbull, however, seems to think that this is not an issue and that in fact “the enemies of Christianity have in no age ever attacked the evidence” for the history of Jesus Christ. In particular, Turnbull argues that the main reason to accept the evidence from testimony is the fact that it is not inconsistent with the knowledge we gain from our observation of the natural world. The main purpose of Turnbull’s text is to show that revealed religion confirms the knowledge accessed from natural religion, and it is in this sense that the former is useful. So as long as testimony agrees with experience, there is no reason to reject it.
- “Surely it cannot be said, that because one kind of evidence for a truth is good, that therefore another kind of evidence is not good. And therefore the evidence in such a case must stand thus. ‘Here is a double evidence for certain truths; an evidence from the nature of things; an intrinsick evidence; and likewise an extrinsick evidence, or an evidence from testimony, upon which there is a sufficient reason to rely independently of all other considerations.'”
It appears then that the testimony of the gospels is just a different kind of evidence for the Christian doctrines, and since it confirms the claims we have deduced from our experience of the world, then such testimony is reliable. Turnbull can only claim that testimony is reliable after proving the doctrines from natural religion, i.e. by examining the world and the workings of our mind. So Turnbull’s strategy is not to argue for the reliability of testimony itself, but rather to claim that since it is not inconsistent with what we have learnt from experience, then there is no reason to reject it.
A guest post by Wiep van Bunge.
Wiep van Bunge writes…
Rienk Vermij has demonstrated quite convincingly that the first Dutch Newtonians were actively engaged in countering the threat Spinoza posed (Vermij 2003). A crucial moment in the simultaneous demise of Spinozism and the rise of experimental philosophy was Bernard Nieuwentijt’s publication, in 1715, of his famous Het regt gebruik der wereldbeschouwingen – translated into English, French and German. Nieuwentijt specifically marked out Spinoza’s atheism as his main target, inspiring many dozens of countrymen and many others abroad to discern the providential reign of a supernatural Creator, who was not to be identified with Nature in the way the Spinozists had been doing for several decades.
More interesting, however, is his posthumous Gronden van zekerheid, in which he further developed a number of comments on mathematics made by one of Spinoza’s earliest critics, the linguist and philosopher Adriaen Verwer in his 1683 refutation of Spinoza’s Ethics. Verwer had warned his readers against Spinoza’s confusion of entia realia, things that really exist, and entia rationis, things we can talk about coherently but which are only supposed to exist even though we are able to conceive of them clearly and distinctly. Spinoza’s fundamental error, according to Verwer, consisted in supposing that once a clear and distinct idea has been formed, the ideatum conceived of in the idea really exists (Verwer 1683; 1–5).
In Gronden van zekerheid Nieuwentijt first elaborates on the distinction between ‘imaginary’ (denkbeeldige) and ‘realistic’ (zakelijke) mathematics, that is between a mathematics concerned with abstract notions without any corresponding objects in reality, and a mathematics concerned with objects the reality of which has been established by experience. Thus Nieuwentijt attempts to ensure that the use of mathematical reasoning is reserved for the behaviour of natural, observable objects. After having demonstrated the benefits of a ‘realistic’ use of mathematics, Nieuwentijt in the fourth part of Gronden van zekerheid accuses Spinoza of being merely an ‘imaginary’ mathematician, who just made it look as if his abstract metaphysics had anything to do with the real world. In reality, or so Nieuwentijt felt, Spinoza was only talking about his own, private ideas. What is worse, Spinoza consciously refused to acknowledge the need to ascertain the correspondence of these ideas to any external reality, as is evident, Nieuwentijt continued, from Spinoza’s conception of truth. Neither was he prepared to check the truth of his ‘deductions’ against any empirical evidence, which led him to preposterous conclusions, such as regarding the human intellect as being a part of God’s infinite intellect as well as an idea of an existing body (Nieuwentijt 1720: 244ff).
Throughout Gronden van zekerheid Nieuwentijt points to the obvious alternative to Spinoza’s ‘figments of the imagination’: the experiential ‘realistic mathematics’ adopted by the Royal academies of Britain, France and Prussia as well as by countless serious scientists across Europe. Philosophy, Nieuwentijt contended in the fifth and final part of his book, should become a ‘realistic metaphysics’ (sakelyke overnatuurkunde), which rests on the same foundations that realistic mathematicians build on: faith in the revealed Word of God and experience, to which he adds that philosophers are often best advised to suspend judgment because we simply lack the data necessary for answering many of the question traditionally raised by metaphysicians (Nieuwentijt 1720: 388ff). Newton, ‘the mathematical Knight’, had shown the way by setting up experiments in order to confirm the truth of conclusions arrived at by means of deduction and by making sure that the general principles from which these conclusions derived were the result of ‘empirical’ induction (Nieuwentijt 1720: 83–84; 188 ff). In addition, Nieuwentijt was happy to confirm that Newton’s work clearly established the providential reign of the Creator over His creation, making it an ideal weapon in the fight against atheism (Nieuwentijt 1720: 228).
It would seem, then, that in Nieuwentijt’s eyes, and Verwer appears to have been of the same opinion, Spinozism was actually a philosophical instance of ‘enthusiasm’ – not unlike the German theologian Buddeus’ earlier suggestion (Buddeus 1701: 15–16). Both were appalled to read that according to Spinoza ideas were true to the extent that he himself felt them to be true, instead of checking their correspondence to the world as we know it. Thus Nieuwentijt continued an Aristotelian and humanist tradition according to which ‘contemplative philosophy’ represented a type of ‘philosophical enthusiasm’ (Heyd 1995: Ch. 4).
Buddaeus, I.F., Dissertatio philosophica de Spinozismo ante Spinozam (Halle, 1701).
Heyd, Michael, ‘Be Sober and Reasonable’. The Critique of Enthusiasm in the Seventeenth and Early Eighteenth Centuries (Leiden, 1995).
Nieuwentijt, Bernard, Het regt gebruik der wereldtbeschouwingen, ter overtuiginge van ongodisten en en ongelovigen aangetoont (Amsterdam,1715).
–, Gronden van zekerheid, of de regte betoogwyse der wiskundigen, So in het denkbeeldige als in het het zakelyke (Amsterdam, 1720).
Vermij, Rienk, ‘The Formation of the Newtonian Natural Philosophy. The Case of the Amsterdam Mathematical Amateurs’, The British Journal for the History of Science 36 (2003), 183–200.
Verwer, Adriaen,’t Mom-Aensicht der atheisterij afgerukt door een verhandeling van den aengeboren stand der menschen (Amsterdam, 1683).
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
Organizers: Steffen Ducheyne and Jip van Besouw
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 firstname.lastname@example.org before 1 July.