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Joseph Priestley on experimental philosophy and empiricism

Joseph Priestley Rembrandt Peale [Public domain], via Wikimedia Commons

Joseph Priestley
Rembrandt Peale [Public domain], via Wikimedia Commons

Peter Anstey writes …

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.


The demise of Spinozism and the rise of Dutch experimental philosophy

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).


Margaret Cavendish: speculative philosopher

Peter Anstey writes …

Two years ago on this blog I addressed the ‘Straw Man Problem‘ for the distinction between experimental and speculative philosophy. The apparent problem, according to some critics of the ESD, is that there were no speculative philosophers in the early modern period. In my response to that problem I listed The Duchess of Newcastle, Margaret Cavendish, as one of the few advocates of speculative philosophy in seventeenth-century England and in this post I want to explore her views in a little more depth.

Cavendish wrote the most sustained critique of experimental philosophy in the seventeenth century. Her Observations upon Experimental Philosophy, comprising 318 pages, was first published in 1666 and went into a second edition in 1668. In this work Cavendish gives a critical reading of many works of the new experimental philosophy in order to justify her own speculative natural philosophy. Within her sights are Robert Boyle’s Sceptical Chymist (1661), Henry Power’s Experimental Philosophy (1664) and Robert Hooke’s Micrographia (1665).

Newcastle_Margaret_Cavendish-Observations_upon_experimental-Wing-N857-1532_17-p1to319 (dragged)It is interesting to compare Cavendish’s views in this work with those of the young Robert Boyle a decade earlier. As I pointed out in my last post, in his ‘Of Naturall Philosophie’ of c. 1654, Boyle claims that there are two principles of natural philosophy, the senses and reason. He plumps for the senses. Cavendish in her Observations acquiesces in the very same principles, but takes the opposing line: for her, reason trumps the senses.

What is important for our interests here is not only the direct contrast with Boyle’s embryonic experimental philosophy, but the manner in which, for Cavendish, the terms of reference for the choice are between experimental and speculative philosophy. The following extracts give a feel for her position:

I say, that sense, which is more apt to be deluded than reason, cannot be the ground of reason, no more than art can be the ground of nature: … For how can a fool order his understanding by art, if nature has made it defective? or, how can a wise man trust his senses, if either the objects be not truly presented according to their natural figure and shape, or if the senses be defective, either through age, sickness, or other accidents … And hence I conclude, that experimental and mechanic philosophy cannot be above the speculative part, by reason most experiments have their rise from the speculative, so that the artist or mechanic is but a servant to the student. (Cavendish, Observations, ed. O’Neill (Cambridge), p. 49, emphasis added)

experimental philosophy has but a brittle, inconstant, and uncertain ground. And these artificial instruments, as microscopes, telescopes, and the like, which are now so highly applauded, who knows but they may within a short time have the same fate; and upon a better and more rational enquiry, be found deluders, rather than true informers (ibid., p. 99)

And toward the end of a long discussion of chemistry and chemical principles she reiterates her conclusion:

if reason be above sense, then speculative philosophy ought to be preferred before the experimental, because there can no reason be given for anything without it (ibid., p. 241)

Cavendish’s Observations first appeared at a very sensitive time for the Royal Society, for it had been the subject of much criticism from without and was in the process of securing an apologetical History of the Royal-Society by Thomas Sprat.

Now, there is no doubt that some of the more prominent Fellows of the Society are in view in her critique. Yet, it is important that we do not over-extend the target of the Observations, for, it is very much aimed at experimental philosophy and hardly makes reference to the Royal Society at all. Within a year of its publication the Duchess was to make a famous visit to the Society and the correspondence that ensued does not suggest that Henry Oldenburg and others regarded her as a hostile critic of the Society. This reinforces the view that her focus was more specific, namely, experimental philosophy.

Interestingly, after Cavendish’s death the following lines appeared in A Collection of Letters and Poems (London, 1678) written in her honour:

Philosophers must wander in the dark;
Now they of Truth can find no certain mark;
Since She their surest Guide is gone away,
They cannot chuse but miserably stray.
All did depend on Her, but She on none,
For her Philosophy was all her own.
She never did to the poor Refuge fly
Of Occult Quality or Sympathy.
She could a Reason for each Cause present,
Not trusting wholly to Experiment,
No Principles from others she purloyn’d,
But wisely Practice she with Speculation joyn’d.
(A Collection, p. 166, emphasis added)

This poem in which these lines appear was penned by the poet Thomas Shadwell, author of The Virtuoso. Shadwell presents the Duchess as holding to a more balanced view of the relative value of practice and speculation than is warranted from her writings. But the fact that he has singled this out is indicative of just how central was this issue to thinkers of the day.

The formation of Boyle’s experimental philosophy

Peter Anstey writes …

It is not entirely clear when Robert Boyle (1627–1691) first used the term ‘experimental philosophy’, but what is clear is that his views on this new approach to natural philosophy began to form in the early 1650s, some years before the term came into common use.

Boyle’s earliest datable use of the term is from his Spring of the Air published in 1660. The reason for the lack of clarity about Boyle’s first use of the term arises from the fact that what appears to be a very early usage survives only in a fragment published by Thomas Birch in his ‘Life of Boyle’ in 1744: no manuscript version is extant. The context of Boyle’s reference to experimental philosophy in this text suggests that this fragment is associated with his ‘Essay of the Holy Scriptures’ composed in the mid-1650s. Boyle speaks of:

those excellent sciences, the mathematics, having been the first I addicted myself to, and was fond of, and experimental philosophy with its key, chemistry, succeeding them in my esteem and applications …

(Works of Robert Boyle, eds Hunter and Davis, London, vol. 12, p. 356)


However, the question of the precise dating of Boyle’s use of the term is hardly as significant as the formation of his views on his distinctive form of natural philosophy. And on this point we have some fascinating and chronologically unambiguous evidence, namely, Boyle’s outline of a work ‘Of Naturall Philosophie’ which dates from around 1654. This short manuscript in Boyle’s early hand survives among the Royal Society Boyle Papers in volume 36, folios 65–6. (It is transcribed in full in Michael Hunter, Robert Boyle 1627–1691: Scrupulosity and Science (Woodbridge, 2000), 30–1.)

In it Boyle outlines the two ‘Principles of naturall Philosophie’. They are Sense and Reason. As for Sense, in addition to its fallibility, Boyle stresses that:

it is requisite to be furnished with observations and Experiments.

Boyle then proceeds to give a set of seven ‘Directions concerning Experiments’. These directions provide an early adumbration of his later experimental methodology. They include the following:

1. Make all your Experiments if you can your selfe [even] though you be satisfyed beforehand of the Truth of them.

3. Be not discouraged from Experimentinge by haveing now & then your Expectation frustrated

5. Get acquainted with Experimentall Books & Men particularly Tradesmen.

7. After you have made any Experiment, not before, reflect upon the uses & Consequences of it either to establish truths, detect Errors, or improve some knowne or give hints of some new Experiment

As for the principle of Reason, Boyle gives five considerations concerning it. What is striking here is that each of them concerns the relation between Reason and experiments:

  1. That we consult nature to make her Instruct us what to beleeve not to confirme what we have beleeved
  2. That a perfect account of noe Experiment is to be looked for from the Experiment it selfe
  3. That it is more difficult then most men are aware of to find out the Causes of knowne effects
  4. That it is more difficult then men thinke to build principles upon or draw Consequences from Experiments
  5. That therefore Reason is not to be much trusted when she wanders far from Experiments & Systematical Bodyes of naturall Philosophie are not for a while to be attempted

Note here the caution about the difficulty of building natural philosophical principles from experiments and the warning about wandering from experiments and premature system building, points that were to become key motifs of the experimental philosophy that blossomed in the 1660s.

It may well be that the movement of experimental philosophy did not emerge until the early 1660s, but the conceptual foundations of its most able exponent were laid nearly a decade before.

Are there any parallel cases of natural philosophers who worked out an experimental philosophy in the early 1650s or was Boyle the first?



Experimental philosophy and religion

Peter Anstey writes …

From the first decade of its existence early modern experimental philosophy enjoyed an intimate relation with Christianity. This manifested itself in at least two ways. First, experimental philosophy, it was argued, was a great help in the development of the mind and character of the Christian. Second, and later, it came to play a central role in Christian apologetics. As for experimental philosophy and Christian living, some of the Fellows of the early Royal Society like Joseph Glanvill wrote extensively on the theme of the positive benefits of the practice of experimental philosophy for Christians. See, for example, Glanvill’s Philosopia Pia: or a Discourse of the Religious Temper, and Tendencies of the Experimental Philosophy (1671).

Once experimental philosophy had consolidated its position as a prominent new approach to natural philosophy it began to be used for the purposes of Christian apologetics. In Robert Boyle experimental philosophers had the archetypal Christian virtuoso who not only manifested the benefits of practising Christianity in his character but also did much to promote the link between the new experimental natural philosophy and the defense of the faith. In The Christian Virtuoso he claimed that:

the Experimental Philosophy giving us a more clear discovery, …, of the divine Excellencies display’d in the Fabrick and Conduct of the Universe, and of the Creatures it consists of, … leads it [the mind] directly to the acknowledgment and adoration of a most Intelligent, Powerful and Benign Author of things. (Works of Robert Boyle, 14 vols, eds Hunter and Davis, London, 1999–2000, 11, 293)

Boyle’s ultimate legacy in this regard was the provision in his will for the Boyle Lectures. And it was the inaugural Boyle Lecturer, Richard Bentley, who first mobilized Newton’s new natural philosophy in Christian apologetics in his seventh lecture, published after extensive correspondence with Newton himself (The Folly and Unreasonableness of Atheism, 1693). Once the precedent was established it was continued and augmented in works such as George Cheyne’s Philosophical Principles of Natural Religion (1705), William Derham’s Astro-Theology: or a Demonstration of the Being and Attributes of God, from a Survey of the Heavens (1715) and William Whiston’s Astronomical Principles of Religion, Natural and Revealed (1717).

Interestingly, it was actually the connection with religion that first raised the reading public’s consciousness of experimental philosophy in the Netherlands. For, it is now thought that the publication of Bernard Nieuwentijt’s Het regt gebruik in 1715 marks an important moment in the awakening to experimental philosophy in Holland. This work was translated into English in 1718 by Peter Chamberlayne as The Religious Philosopher with a prefatory letter to the translator by the leading pedagogue of experimental philosophy in England, John Theophilus Desaguliers. Desaguliers commends the work because:

it contains several fine Observations and Experiments, which are altogether new, as is also his manner of treating the most common Phaenomena; from which he deduces admirable Consequences in favour of a Religious Life.

Likewise, Ten Kate’s Dutch adaptation of George Cheyne’s Philosophical Principles of Natural Religion published in Amsterdam in 1716 turned experimental philosophy to apologetical use. Kate claims ‘some distinguished men in England, who disliked the uncertainties of hypotheses [of Cartesianism], have based themselves only on a Philosophia Experimentalis, by means of mathematics’ (Jorink and Zuidervaart, Newton and the Netherlands: how Isaac Newton was Fashioned in the Dutch Republic, 2012, 31). He drew a strong connection between Newton’s natural philosophy and evidence for God’s hand in creation.

Here then, we have an obvious difference between early modern experimental philosophy and its contemporary namesake. I would value references to other works, particularly works in languages other than English, that discuss the practical and apologetical benefits of experimental philosophy to the Christian religion. Let me know if you can help.



Cotes’ Preface and Experiment

Peter Anstey writes…

In my last post I introduced Roger Cotes’ famous Preface to the second edition of Newton’s Principia in order to show its importance as an expression of a commitment to experimental philosophy. In that post I focused on Cotes’ critique of the Cartesian vortex theory and the manner in which this attack on the archetypal speculative philosophy formed the bookends of the Principia. In this post I will discuss the role of experiment in Cotes’ comments on experimental philosophy.

The Preface is actually quite a complex essay that has both polemical and expository agendas. On the one hand, Cotes uses it to give a summary of the main theses of the Principia centred around Newton’s theory of gravity. On the other hand, Cotes uses it to defend the theory of gravity against the charge that it is an occult quality, to defend Newton’s system of the world against the Cartesian vortex theory, and to defend the methodology of the work against rival approaches.

On this latter point, Cotes begins by claiming that Newton’s method is ‘based upon experiment’ (The Principia, eds I.B. Cohen and A. Whitman, Berkeley: University of California Press, 1999, p. 386). One might expect here that Cotes will give a list of the sorts of experimental results that Newton achieved or some reference to crucial experiments, but instead he introduces another set of methodological notions: phenomena, principles, hypotheses, analysis and synthesis. It is only later when appealing to various laws, principles and axioms in his summary of Newton’s system of the world that Cotes refers to experiments.

Here is a summary of Cotes’ account of the method of the Principia. Natural philosophy attempts to derive the causes of all things from the simplest of principles and not from contrived hypotheses. These principles are derived from the phenomena by a two-step process of analysis and synthesis. From select phenomena the forces and simpler laws of these forces are ‘deduced’ by analysis. Then by synthesis ‘the constitution of the rest of the phenomena’ is given. In the case of the Principia the relevant force is gravitational attraction and the relevant law is the inverse square law. Though Cotes throws in the laws of planetary motion claiming that ‘it is reasonable to accept something that can be found by mathematics and proved with the greatest certainty’ (p. 389). He also claims, after presenting a summary of the system of the world, ‘the preceding conclusions are based upon an axiom which is accepted by every philosopher, namely, that effects of the same kind –– that is, effects whose known properties are the same –– have the same causes, and their properties which are not yet known are also the same’. Indeed, ‘all philosophy is based on this rule’ (p. 391).

Where then do experiments fit in this picture? The first mention of experiments is in relation to the law of fall. Cotes refers here to pendulum experiments and to Boyle’s air-pump. Next, Huygens’ pendulum experiments are referred to in the discussion of the determination of the centripetal force of the moon towards the centre of the Earth (p. 389). They then appear in the elaboration of the ‘same effect, same cause’ axiom and its application to the attribution of gravity to all matter. Cotes says ‘[t]he constitution of individual things can be found by observations and experiments’ and from these we make universal judgments (p. 391). Thus, ‘since all terrestrial and celestial bodies on which we can make experiments or observations are heavy, it must be acknowledged without exception that gravity belongs to all bodies universally. … extension, mobility, and impenetrability of bodies are known only through experiments’ and so too is gravity. Finally, in recapping the Newtonian method near the conclusion of the Preface Cotes repeats that ‘honest and fair judges will approve the best method of natural philosophy, which is based on experiments and observations’ (p. 398).

What are we to make of the role of experiments here? First, notice how experiments are appealed to in the establishment of laws and the ‘same effect, same cause’ axiom. Second, it is worth pointing out that the ‘same effect, same cause’ axiom is Newton’s second rule of philosophizing: indeed, Cotes uses the very same example as Newton, namely, the falling of stones in America and Europe (see p. 795). Third, notice how without any explanation Cotes extends experiments to experiments and observations. He begins by saying that there are those ‘whose natural philosophy is based on experiment’ and he ends by saying that ‘the best method of natural philosophy, … is based on experiments and observations’. This is not an equivalent expression and while it is consistent with many other methodological statements by experimental philosophers, it still calls out for explanation.

Has Cotes really given an adequate summary of the method of experimental philosophy and has he captured the manner in which experiments are used in Newton’s reasoning in the Principia? In my view he has not. I’d be interested to hear your views?

Roger Cotes’ ‘Preface’ and the ESD

Peter Anstey writes…

One of the main tasks of this blog over the last three years has been to provide evidence for our claim that from the 1660s the distinction between experimental and speculative philosophy is crucial for an understanding of early modern natural philosophy and even the philosophy of this period in general. More specifically, we have been furnishing evidence that the self-styled experimental philosophers both emphasized the importance of experiment and observation for the acquisition of knowledge, and decried the use of speculation and hypotheses that made little or no appeal to observation. We have also claimed that a prime example of a speculative philosophy that came under attack from experimental philosophers was the Cartesian vortex theory.

It may be surprising, therefore, that hitherto little has been said on this blog about Roger Cotes’ Preface to the second edition of Newton’s Principia published 300 years ago in 1713. For, Cotes’ Preface contains one of the most forthright and sustained defenses of experimental philosophy to be found in the early eighteenth century and it prefaces what can only be described as the most important contribution to natural philosophy in the early modern period.

Cotes begins his Preface with a tripartite distinction between ‘the whole of the Scholastic doctrine derived from Aristotle and the Peripatetics’, (The Principia, 1999, 385) ‘those who take the foundation of their speculations from hypotheses’ and ‘those whose natural philosophy is based upon experiment’. Needless to say, it is this latter method that is ‘incomparably [the] best way of philosophizing’ and ‘which our most celebrated author [Newton] thought should be justly embraced in preference to all others’. (386) The rest of the Preface is a justification of this method of experimental philosophy. First, he elaborates on the method in more detail. He then proceeds to show how Newton’s thesis of universal gravity was established according to this method. Next, he argues against the Cartesian vortex theory and plenist accounts of the universe and, finally, he brings it to a close claiming: ‘Therefore honest and fair judges will approve the best method of natural philosophy, which is based on experiments and observations’. (398).

In this post I shall outline one of the interesting features of Cotes’ critique of the Cartesian vortex theory. In my next post I’ll examine his view of the experimental philosophy in more detail. According to Cotes the speculators ‘are drifting off into dreams, … are merely putting together a romance, elegant perhaps and charming, but nevertheless a romance’ (386) One such romance is the Cartesian vortex theory.

Cometary motion through the vortices of Descartes

Cometary motion through the vortices of Descartes

In the first edition of the Principia (1687) Newton had advanced a number of arguments against the vortex theory at the end of Book Two, such as the claim that planets moving in a vortex would speed up at the point most distant from the sun when, in fact, the observational evidence and Kepler’s area law showed that they slowed down at this point. But apart from this, little mention is made of the theory. By contrast, in the second edition of the Principia the critique of the vortex theory is a prominent theme. In addition to the arguments at the end of Book Two, the new ‘General Scholium’ appended to the book begins ‘The hypothesis of vortices is beset with many difficulties’ (939) and there follows a whole paragraph on the problems with the theory. The final two sentences deal with the motion of comets, claiming that their regular motion ‘cannot be explained by vortices and that their eccentric motions can only be explained if ‘vortices are eliminated’. These are not claims that Newton makes in the Principia but are rather summaries of arguments that Cotes presents in his Preface.

About one quarter of the Preface is given over to a critique of vortices. In this section, Cotes develops the arguments from cometary motion that are alluded to in Newton’s Scholium. First he claims that bodies in a vortex must move in the same direction and with the same velocity as the surrounding fluid and must have the same density as the fluid that surrounds them. But comets and planets orbit the sun with different velocities and different directions even when they are in the same region of the heavens. Therefore, ‘those parts of the celestial fluid that are at the same distances from the sun revolve in the same time in different directions with different velocities’. But this cannot be accounted for by one vortex, so there will have to be more than one vortex ‘going through the same space surrounding the sun’. It must be asked then ‘how these same vortices keep their integrity without being in the least perturbed through so many centuries by the interactions of their matter’. (394 ) Moreover, because ‘the number of comets is huge’ and they obey the same laws as the planets going ‘everywhere into all parts of the heavens and pass very freely through the regions of the planets, often contrary to the order of the signs … [t]here will be no room at all for the motions of the comets unless that imaginary matter [of the vortices] is completely removed from the heavens’. (395)

What is striking about these arguments is that they are, in effect, the bookends of the Principia. They don’t appear in the body of the work, but are a kind of polemical after thought, and most importantly, they are set within the context of a defense of experimental philosophy. What is it that accounts for the extraordinary fact that Cotes introduced this material in the opening preface and that Newton should allude to it at the end when the arguments are absent from the book? This is not merely a rhetorical question. I would value any comments you may have.

Experimental philosophy in France

Peter Anstey writes…

When did the French embrace experimental philosophy? There is no doubt that the early Académie des Sciences was committed to the use of experimental methods in natural philosophy from its inception in 1666. But there is little evidence of French natural philosophers self-identifying as experimental philosophers, of the teaching of experimental philosophy or of institutional recognition of experimental philosophy before the 1730s.

In 1735 Abbé Nollet offered the first course in experimental philosophy in France and two years later he published Programme ou idée générale d’un cours de physique expérimentale which was strongly influenced by John Theophilus Desaguliers whom he had met in England around 1734. By the late 1730s, however, it is not hard to find explicit endorsements of experimental philosophy and the deployment of the experimental/speculative distinction. The reviewer of Abbé Pluche’s Spectacle de la Nature in 1739 claims that Pluche rightly prefers experimental natural philosophy to speculative (Physique spéculative à laquelle il préfére avec raison la Physique) and that experimental philosophy is ‘so à la mode today’ (qui est aujourd’hui si à la mode).

By the early 1750s experimental philosophy is part and parcel of French natural philosophy. We have discussed this before on this blog in relation to Denis Diderot, but the following nice, clear, anonymous dictionary entry reinforces the point. In the Dictionnaire philosophique ou Introduction à la connoisance de l’homme, London (?), 1751 we find the following entry under ‘Physique’:

Natural philosophy is the knowledge of causes and effects of nature. It is experimental or conjectural. Experimental natural philosophy is certain knowledge; conjectural natural philosophy is often only ingenious. The one leads us to the truth, the other leads to error.

La Physique est la connoissance des causes & des effets de la nature: elle est expérimentale, or conjecturale. La Physique expérimentale est une connoissance certaine; la Physique conjecturale n’est souvent qu’ingénieuse: l’une nous conduit à la vérité, & l’autre nous mene à l’erreur.

The parallels with our oft-cited passage from John Dunton’s student manual in 1692 are striking:

Philosophy may be consider’d under these two Heads, Natural and Moral: The first of which, by Reason of the strange Alterations that have been made in it; may be again Subdivided into Speculative and Experimental.

… we must consider, the distinction we have made of Speculative and Experimental, and, as much as possible, Exclude the first, for an indefatigable and laborious Search into Natural Experiments, they being only the Certain, Sure Method to gather a true Body of Philosophy, for the Antient Way of clapping up an entire building of Sciences, upon pure Contemplation, may make indeed an Admirable Fabrick, but the Materials are such as can promise no lasting one.

(The Young-Students-Library, London, 1692, vi–vii)

And yet the two passages are six decades apart. Why did it take so long for the French to take up experimental philosophy? Why is it, for example, that the first chair in experimental philosophy in England was the Cambridge Plumian Chair in Experimental Philosophy and Astronomy founded in 1708 and first held by Roger Cotes, whereas the first chair of experimental philosophy in France was held by Abbé Nollet who was appointed as Professeur Royal de Physique Expérimentale au College de Navarre in 1753?

Any light that our readers can shed on these questions would be most welcome.


Teaching Experimental Philosophy IV: the case of John Keill

Peter Anstey writes …

In my last post we met the instrument maker and promoter of experimental philosophy Francis Hauksbee the Elder. Hauksbee, however, wasn’t the first lecturer to give public lectures in England on the exciting new developments in natural philosophy. That honour rests with a Scotsman called John Keill.

John Keill (1671–1721) came under the tutelage of the first Newtonian David Gregory in Edinburgh. He followed Gregory to Oxford in 1691 and by 1699 was giving lectures. Around 1704/95, according to his student John Theophilus Desaguliers, Keill became ‘the first who publickly taught Natural Philosophy by Experiments in a mathematical Manner’ (A Course of Experimental Philosophy, Volume 1, 1734, Preface). His lectures were published in Latin in 1702 and in English translation in 1720 under the title of An Introduction to Natural Philosophy: or, Philosophical Lectures read in the University of Oxford Anno Dom. 1700.

It is not clear, however, that Keill saw himself as teaching experimental philosophy. Some scholars have claimed that Keill was appointed as a lecturer in experimental philosophy at Oxford in 1704 and that he was the first to teach experimental philosophy there. Indeed, in 1707 The Oxford Intelligencer advertised his ‘Course of Mechanical and Experimental Philosophy’. Moreover, in the preface to his Introduction to Natural Philosophy he does express his opposition to speculative natural philosophy, particularly Cartesianism, singling out the Cartesian theory of gravity for particularly harsh treatment (pp. iv–vii).

Hence, one might naturally assume that he is a straightforward advocate of experimental philosophy, and yet this is not the case. For, in the first lecture Keill proceeds to distinguish four ‘Sects of Philosophers’: the Pythagoreans and Platonists; the Peripatetics; those who ‘proceed upon Experiments; and the Mechanical’ (pp. 1–3). He then informs the reader that ‘Amongst these various ways of Philosophizing, there is no particular one, wherein we do intirely acquiesce’ (p. 3). In fact, Keill saw himself as pursuing, not the new experimental philosophy, but what he calls ‘Mathematical Philosophy’ inspired by Newton and characterized by ‘applying Geometry to Natural Philosophy’.

As for experimental philosophy, Keill warns that:

    many of the Experiments that the third Sect of Philosophers [experimental philosophers] have delivered down to us, must be made use of: tho this ought not to be done without great Caution; for we are well apprised how fond these Gentlemen are of their Theories, how willing they are that they should be true, and how easily they deceive both others and themselves, in trying their Experiments (p. 7).

It is clear from this passage that Keill’s conception of what constitutes an experimental philosopher differs from that of Boyle and others, for Keill finds them too fond of their theories, whereas what characterises the experimental philosophers throughout the latter decades of the seventeenth century is their extreme caution in making any theoretical commitments until the observational and experimental data is assembled. Keill’s experimental philosopher would be foreign to most who aligned themselves with the movement.

The method that Keill follows instead is that of ‘The great Philosopher of this age, the most Ingenious and Incomparable Mr. Newton’ who ‘by his great and deep skill in Geometry’ was able to show the inconsistencies of Descartes’ vortex theory. Keill’s opponents in natural philosophy were not the speculative philosophers but ‘our ungeometrical Philosophers’ (p. 24). Thus Keill is representative of the first generation of those, like John Arbuthnot and John Harris who, inspired by Newton, adopted a straightforwardly mathematical approach to natural philosophy. Surprisingly, Keill’s reservations about experimental philosophy were completely ignored by the likes of Hauksbee the Elder and Desaguliers who preferred to see their efforts in promoting experimental philosophy as following Keill’s example and, in Desaguliers’ case, even recycling some of his lectures.


Teaching Experimental Philosophy III: the case of Francis Hauksbee the Elder

Peter Anstey writes …

In two previous posts I examined an early teacher of experimental philosophy, John Theophilus Desaguliers and a later one, George Adams. In this post I turn to a third teacher of experimental philosophy, Francis Hauksbee the Elder (1660–1713). (He was called ‘the Elder’ to differentiate him from his nephew of the same name who also taught experimental philosophy.) Hauksbee was one of the two most important first-generation pedagogues. (We will examine the other, John Keill, in my next post.)

He was a gifted instrument maker who not only developed a new much improved design of Robert Boyle’s air-pump, but also conducted a series of very important new experiments using this instrument. Many of these were published in the Philosophical Transactions. As a result of his proficiency with experimental apparatus he became a kind of de facto curator of experiments at the Royal Society in c. 1704 after Robert Hooke’s death. In addition he seconded James Hodgson FRS to carry out public lectures on experimental philosophy in London while he acted as the demonstrator.

By 1709 he himself was lecturing on experimental philosophy and continued this until his death in 1713. In 1709 he published a compilation volume of his air-pump experiments entitled Physico-Mechanical Experiments … touching Light and Electricity. This volume, in many ways, mimicked Boyle’s ground-breaking New Experiments Physico-mechanical touching the Spring of the Air (1660). (Even the titles are similar.) Hauksbee clearly saw himself as working in a tradition of experimental natural philosophy that extended back to Boyle.

The work gives us an interesting insight into how he viewed natural philosophy. He begins by telling us that:

The Learned World is now almost generally convinc’d, that instead of amusing themselves with Vain Hypotheses, which seem to differ little from Romances, there’s no other way of Improving Natural Philosophy, but by Demonstrations and Conclusions founded upon Experiments judiciously and accurately made. (Preface)

By now our readers should recognize the standard tropes of the experimental philosopher: the decrying of hypotheses; the likening of them to romances; the appeal to the necessity of experiment for the improving of natural philosophy.

Hauksbee goes on in the Preface to mention ‘The Honourable and most Excellent Mr. Boyle’ and ‘the … Incomparable Sir Isaac Newton’ implying that he himself is engaged in the same natural philosophical project. It is interesting to note, however, that there is no mention of the method of natural history as practised and promoted by Boyle in the Preface or in Hauksbee’s work. Hauksbee’s experimental practice was a natural extension of Boyle’s work, but at the same time methodologically discontinuous with it.

Hauksbee was also much quicker than Boyle to draw natural philosophical conclusions from his experiments. He did not, however, apply mathematics to his discoveries and he was later criticized by Desaguliers in his Course of Experimental Philosophy (1734) in so far as his experiments

were only shewn and explain’d as so many curious Phaenomena, and not made Use of as Mediums to prove a Series of philosophical Propositions in a mathematical Order, they laid no such Foundation for true Philosophy. (vol. 1, Preface)

Hauksbee may not have had developed views on the methodology of natural philosophy or much aptitude in mathematics, but he was a gifted experimenter and a keen promoter of experimental philosophy.