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Tag Archives: history of science

A new Hume find

Peter Anstey writes…

While the ‘Experimental Philosophy: Old and New’ exhibition was under construction, the Special Collections Librarian at Otago, Dr Donald Kerr, happened to notice that the copy of George Berkeley’s An Essay Towards a New Theory of Vision (2nd edn, 1709) that we were about to display, had the bookplate of David Hume Esquire. It has long been known that this book was in the library of the philosopher David Hume’s nephew Baron David Hume, but until now its whereabouts have been unknown. We are very pleased to announce, therefore, that it is in the Hewitson Library of Knox College at the University of Otago, New Zealand (for full bibliographic details see the online exhibition).

The question naturally arises: did the book belong to the philosopher or the Baron? What complicates matters is that David Hume the philosopher left his library to his nephew of the same name and that the latter also used a David Hume bookplate.

Now the David Hume bookplate exists in two states, A and B. They are easily distinguished because State A has a more elongated calligraphic hood on the second stem of the letter ‘H’ than that of State B. Brian Hillyard and David Fate Norton have pointed out (The Book Collector, 40 [1991], 539–45) that all of the thirteen items that they have examined with State A are on laid paper and are in books that predate the death of David Hume the philosopher. This is not the case for books bearing the State B bookplate. They propose the plausible hypothesis that all books bearing the bookplate in State A belonged to Hume the philosopher. Happily, we can report that the bookplate that here at Otago is State A on laid paper. It is almost certain, therefore, that this copy of George Berkeley’s New Theory of Vision belonged to the philosopher David Hume.

The provenance of the book provides important additional evidence that Hume was familiar with Berkeley’s writings, something that was famously denied by the historian of philosophy Richard Popkin in 1959. Popkin claimed that ‘there is no actual evidence that Hume was seriously concerned about Berkeley’s views’. He was subsequently proven wrong and retracted his claim. However, until now there has been no concrete evidence that Hume owned a copy of a work by Berkeley, let alone one as important as the New Theory of Vision.

This volume came into the possession of the Hewitson Library in 1948. Its title page bears a stamp from the ‘Presbyterian Church of Otago & Southland Theological Library, Dunedin’. So far attempts to ascertain which other books were in this theological library and when and how it arrived in New Zealand have proven fruitless. (Though the copy of William Whiston’s A New Theory of the Earth, 1722 on display bears the same stamp.) If any reader can supply further leads on these matters we would be most grateful. Meanwhile please take time to examine the images of the bookplate and title page, which are included in our online exhibition available here.

Anik Waldow on ‘Jean Le Rond d’Alembert and the experimental philosophy’

Anik Waldow writes …

Peter Anstey’s essayJean Le Rond d’Alembert and the experimental philosophy” sets out to confirm his claim that the distinction between experimental philosophy and speculative philosophy “provided the dominant terms of reference for early modern philosophy before Kant” (p.1) by examining the Preliminary Discourse of the Encyclopédie.  Anstey comes to the conclusion that d’Alembert, who identified metaphysical speculation as the reason why experimental science had “hardly progressed” (p.3), was highly influenced by Locke and clearly reflected Newton’s anti-hypothetical stance.

The paper contains two major lines of argument, which are interconnected but possess slightly different focuses. The first is concerned with the correction of our understanding of particular philosophers and their commitment to the experimental tradition of Locke, Boyle and Newton. The second intends to alter the way we approach the history of philosophy. In this context Peter’s discussion of d’Alembert amounts to a defense of a new conceptual scheme that ought to replace the rationalist/empiricist distinction, thus enabling us to correct our knowledge of early modern philosophy in general. I will merely focus here on the first of these two points, leaving my worries concerning Anstey’s suggestion that Newton’s own experimental practice is able to clearly demarcate the line between experimental and speculative natural philosophy for another occasion.

Much of Anstey’s essay hinges on the claim that d’Alembert’s own rational mechanics is not hostile to experimentalism, but “an extreme application of the new Newtonian mathematical method that came to predominate the manner in which the experimental philosophy was understood in the mid-eighteenth century.” (p. 12) Rational mechanics is a discipline committed to an a priori methodology that seems to be diametrically opposed to the inductive practice of the experimenter and her strict quantitative treatment of observable phenomena. And even though one may argue that experiments are in some restricted sense relevant to rational mechanics, it is clear that this discipline is not committed to the kind of “systematic collection of experiments and observations” (Preliminary Discourse to the Encyclopedia of Diderot, trans and intro. Richard N. Schwab, Chicago,1995, p.24) that d’Alembert regards as the defining feature of experimental physics. To identify d’Alembert as a defender of experimentalism therefore requires Anstey to show that there is no contradiction involved in practising rational mechanics, on the one hand, and defending Lockean experimentalism, on the other.

Anstey’s argument is convincing as long as natural philosophy is treated as a whole that is able to integrate various methodologies. In this form the argument makes a good case against the rigid dichotomies that the rationalist/empiricist distinction introduces, because it shows that we need not endorse what I call an ‘either-or conception’ of experimentalism: either we are experimenters and reject rational mechanics as a speculative discipline because of its detachment from observable phenomena; or we conceive of natural philosophy as a broadly mathematical enterprise and attack experimentalism for its lack of scientific rigour.

Having said that, however, I should like to raise the following question. How well supported is Anstey’s claim that d’Alembert believed that rational mechanics, and in particular demonstrative reasoning, was not merely compatible with experimentalism, but an integral part of it? The reason I ask this question is that we must distinguish between two positions: the first accepts demonstrative mathematics as a methodology in an area of natural philosophy that, strictly speaking, does not qualify as experimental in itself; the second endorses the claim that all natural philosophy ought to be experimental. Hence, the first position regards experimentalism as a specific branch of natural philosophy, while the second takes the whole of natural philosophy to be committed to the tenets of experimentalism.

By aligning d’Alembert’s own methodology with Newton’s mathematized experimentalism, Anstey suggests that d’Alembert was a proponent of the second position. However, I think that d’Alembert’s conception of rational mechanics as the queen among the various natural philosophical disciplines reveals him to be more inclined to the first position. In thinking of rational mechanics as taking the lead in the generation of natural philosophical knowledge, d’Alembert turns experimentalism (conceived as the systematic collection of experiments and observations) into no more than a useful addition to a natural philosophical practice firmly rested on a priori reasoning. Experimentalism is here appreciated only in so far as it is able to generate solutions to problems where rational mechanics can advance no further. Or slightly differently put, experimentalism is acknowledged for its usefulness, but far from being regarded as the discipline that gives the whole of natural philosophy its tone and direction.

In short, Anstey’s paper may have shown that d’Alembert sympathized with Lockean experimentalism. However, more needs to be said in order to clarify how it is possible to think of rational mechanics as a discipline that is, in and of itself, experimental in spirit. Otherwise it is hard to see why we should agree with Anstey’s claim that d’Alembert thought of the whole of natural philosophy as an essentially experimental discipline.

Keith Hutchison on ‘De Gravitatione’ and Newton’s Mathematical Method

Keith Hutchison writes…

The core of Kirsten Walsh’s paper is a defence of her proposal that Newton’s De Gravitatione was composed after the publication of the new theory of colours (in 1672-3).  Kirsten compares the methodology of the optical writings with that of De Grav. and notes that despite the similarity there are significant differences. Yet the methodology of De Grav. is effectively identical to that of the Principia, so is plausibly interpreted as the one preferred by Newton.  So Newton would have displayed this methodology in the optical writings, Kirsten concludes, had De Grav. already been composed.

Isaac Newton, 1689

Isaac Newton, 1642-1727

Though I am (tentatively) happy with Kirsten’s observation that it is uncontroversial to see Newton’s Principia as deploying the methodology of De Grav., part of the reason for this is surely the fact that the discussion of methodology in De Grav. is so brief, and hardly exemplified in the actual science that Newton so fleetingly displays in his text.  The little that we find in De Grav. does indeed seem concordant with much that happens in the Principia, but it is easy – too easy – to find agreement between a pair of texts if one of them is vague enough.  Given that the identity between the two methodologies is so important to Kirsten’s case, she needs to find some way of sharpening this step of the argument.

She could, for instance, identify far more thoroughly the small differences between the methodology of the optical writings and that of De Grav.  If each of these differences could be consistently found in the Principia as well, Kirsten would have a much better case, as long as there were not something about the optical investigations that required the alternative approach.  Kirsten notes indeed, that Cohen has suggested that the Principia is primarily a mathematical investigation, but the optical work is overwhelmingly experimental.  Cohen seems to be significantly wrong here, for investigations of the context of Newton’s treatment of chromatic aberration show that Newton originally dreamt of creating a mathematical science of colours – until he found that refraction was puzzlingly idiosyncratic, and so unlike the extremely orderly gravitational interaction that provided much of the mathematics of the Principia.  But it remains true that the optical work is saturated with experiment, and it could be this that allows an earlier (?) De Grav. to seem more like the Principia.

From Experimental Philosophy to Empiricism: 20 Theses for Discussion

Before our recent symposium, we decided to imitate our early modern heroes by preparing a set of queries or articles of inquiry. They are a list of 20 claims that we are sharing with you below. They summarize what we take to be our main claims and findings so far in our study of early modern experimental philosophy and the genesis of empiricism.

After many posts on rather specific points, hopefully our 20 theses will give you an idea of the big picture within which all the topics we blog about fit together, from Baconian natural histories and optical experiments to moral inquiries or long-forgotten historians of philosophy.

Most importantly, we’d love to hear your thoughts! Do you find any of our claims unconvincing, inaccurate, or plainly wrong? Do let us know in the comments!

Is there some important piece of evidence that you’d like to point our attention to? Please get in touch!

Are you working on any of these areas and you’d like to share your thoughts? We’d like to hear from you (our contacts are listed here).

Would you like to know more on some of our 20 claims? Please tell us, we might write a post on that (or see if there’s anything hidden in the archives that may satisfy your curiosity).

Here are our articles, divided into six handy categories:


1. The distinction between experimental and speculative philosophy (ESD) provided the most widespread terms of reference for philosophy from the 1660s until Kant.

2. The ESD emerged in England in the late 1650s, and while a practical/speculative distinction in philosophy can be traced back to Aristotle, the ESD cannot be found in the late Renaissance or the early seventeenth century.

3. The main way in which the experimental philosophy was practised from the 1660s until the 1690s was according to the Baconian method of natural history.

4. The Baconian method of natural history fell into serious decline in the 1690s and is all but absent in the eighteenth century. The Baconian method of natural history was superseded by an approach to natural philosophy that emulated Newton’s mathematical experimental philosophy.


5. The ESD is operative in Newton’s early optical papers.

6. In his early optical papers, Newton’s use of queries represents both a Baconian influence and (conversely) a break with Baconian experimental philosophy.

7. While Newton’s anti-hypothetical stance was typical of Fellows of the early Royal Society and consistent with their methodology, his mathematisation of optics and claims to absolute certainty were not.

8. The development of Newton’s method from 1672 to 1687 appears to display a shift in emphasis from experiment to mathematics.


9. Unlike natural philosophy, where a Baconian methodology was supplanted by a Newtonian one, moral philosophers borrowed their methods from both traditions. This is revealed in the range of different approaches to moral philosophy in the Scottish Enlightenment, approaches that were all unified under the banner of experimental philosophy.

10. Two distinctive features of the texts on moral philosophy in the Scottish Enlightenment are: first, the appeal to the experimental method; and second, the explicit rejection of conjectures and unfounded hypotheses.

11. Experimental philosophy provided learned societies (like the Aberdeen Philosophical Society and the Philosophical Society of Edinburgh) with an approach to knowledge that placed an emphasis on the practical outcomes of science.


12. The ESD is prominent in the methodological writings of the French philosophes associated with Diderot’s Encyclopédie project, including the writings of Condillac, d’Alembert, Helvétius and Diderot himself.


13. German philosophers in the first decades of the eighteenth century knew the main works of British experimental philosophers, including Boyle, Hooke, other members of the Royal Society, Locke, Newton, and the Newtonians.

14. Christian Wolff emphasized the importance of experiments and placed limitations on the use of hypotheses. Yet unlike British experimental philosophers, Wolff held that data collection and theory building are simultaneous and interdependent and he stressed the importance of a priori principles for natural philosophy.

15. Most German philosophers between 1770 and 1790 regarded themselves as experimental philosophers (in their terms, “observational philosophers”). They regarded experimental philosophy as a tradition initiated by Bacon, extended to the study of the mind by Locke, and developed by Hume and Reid.

16. Friends and foes of Kantian and post-Kantian philosophies in the 1780s and 1790s saw them as examples of speculative philosophy, in competition with the experimental tradition.

From Experimental Philosophy to Empiricism

17. Kant coined the now-standard epistemological definitions of empiricism and rationalism, but he did not regard them as purely epistemological positions. He saw them as comprehensive philosophical options, with a core rooted in epistemology and philosophy of mind and consequences for natural philosophy, metaphysics, and ethics.

18. Karl Leonhard Reinhold was the first philosopher to outline a schema for the interpretation of early modern philosophy based (a) on the opposition between Lockean empiricism (leading to Humean scepticism) and Leibnizian rationalism, and (b) Kant’s Critical synthesis of empiricism and rationalism.

19. Wilhelm Gottlieb Tennemann was the first historian to craft a detailed, historically accurate, and methodologically sophisticated history of early modern philosophy based on Reinhold’s schema. [Possibly with the exception of Johann Gottlieb Buhle.]

20. Tennemann’s direct and indirect influence is partially responsible for the popularity of the standard narratives of early modern philosophy based on the conflict between empiricism and rationalism.

That’s it for now. Come back next Monday for Gideon Manning‘s comments on the origins of the experimental-speculative distinction.

(in their terms, “observational philosophers”)

Newton’s Method in ‘De gravitatione’

Kirsten Walsh writes…

Newton’s manuscript De Gravitatione (‘De Grav.’ for short) was published for the first time in 1962, but no one knows when it was written.  Some scholars have argued that Newton wrote De Grav. as early as 1664, others, as late as 1685, and there have been arguments for almost every period in between.

Ostensibly, the topic of De Grav. is “the science of the weight and of the equilibrium of fluids and solids in fluids”.  Newton discusses this topic in the form of definitions, axioms, propositions, corollaries, and finally a scholium.  However, the scholium ends abruptly and the manuscript is unfinished.  One of the most notable features of this manuscript is what Hall & Hall describe as a “structural failure”: what begins as a brief discussion of a definition turns into a lengthy and detailed attack on the Cartesian conception of space and time.  This digression is significant.  Firstly, it is useful for understanding the development of Newton’s thoughts on many topics.  Secondly, it supports the view that, in Principia, Newton’s intended opponent was Cartesian, rather than Leibnizian.

In this post, I am not going to talk about Newton’s 23-page digression (which may well form the basis of another post).  Rather, I am interested in the opening paragraph of this manuscript, in which Newton describes his method.  He begins:

    “It is fitting to treat the science of the weight and of the equilibrium of fluids and solids in fluids by a twofold method.”

The first, he tells us, is a geometrical method.  He says he plans to demonstrate his propositions “strictly and geometrically” by:

  1. Abstracting the phenomena from physical considerations;
  2. Establishing a strong foundation of definitions, axioms and postulates; and
  3. Formulating lemmas, propositions and corollaries.

The second is a natural philosophical method.  He says he plans to explicate and confirm the certainty of his propositions by the use of experiments.  He says that these discussions will be restricted to scholia, to ensure that the two methods are kept separate.

This twofold method bears striking resemblance to two other aspects of Newton’s work:

  1. It accurately describes the method and structure of Principia; and
  2. It resembles the quasi-mathematical method he uses to ‘prove’ his theory of colours.

The first point is uncontroversial – almost boring, given how many times it has been mentioned in the literature.  But it shows that this method is in use by Newton at least by the mid-1680s.  My second point, however, requires some explanation.

In an earlier post I argued that, at least in the early 1670s, Newton’s goal is absolute certainty.  He hopes to achieve certainty in the science of colours by making it ‘mathematical’.  The clearest demonstration of his quasi-mathematical method is found in Newton’s reply to Huygens, where he sets out his theory of colours in a series of definitions and propositions, in the style of a geometrical proof.

Despite the resemblance, this is not precisely the same method that Newton is advocating in De Grav. Experiment appears to play a different role.

In his early optical work, propositions are founded on experiment.  So experiment should be the first step in any inquiry.  For example, in a letter written in 1673, Newton says:

    “I drew up a series of such Expts on designe to reduce the Theory of colours to Propositions & prove each Proposition from one or more of those Expts by the assistance of common notions set down in the form of Definitions & Axioms in imitation of the Method by which Mathematicians are wont to prove their doctrines.”

But in De Grav., Newton says that experiment is employed to ‘illustrate and confirm’ the propositions.  That is, experiment is supposed to occur as a later step.

This raises several questions about Newton’s methodology.  Is there any practical difference between the two methods?  Does this represent a significant shift in the role Newton assigned to experiment?  Can methodology shed any light on the dating of De Grav.?  What do you think?

Next week, we’ll hear from Peter Anstey.

Galileo and Experimental Philosophy

Greg Dawes writes…

In a recent conference paper I have argued that in some key respects Galileo’s natural philosophy anticipates the experimental philosophy of the later seventeenth century.  I am not claiming that Galileo uses the term “experimental philosophy.” Nor do I claim that he makes any distinction comparable to that between experimental and speculative natural philosophy. His Italian followers in the Accademia del Cimento would later do so, but he does not. Nonetheless, the way in which Galileo undertakes natural philosophy displays at least two of the features that Peter Anstey and his collaborators have argued are characteristic of experimental philosophy.


Galileo's sketch of a device to demonstrate the power of a vacuum.

The first of these has to do with the role of experiment. Much of the twentieth-century debate centred on whether Galileo actually performed the experiments about which he writes. But the more important question has to do with the role of experiments in Galileo’s thought. Like his Aristotelian predecessors, Galileo seeks to construct a demonstrative natural philosophy: one in which the conclusions follow with certainty from the premises. But unlike the Aristotelian, he relies on geometrical proofs. Like any mathematical proofs, these can be elaborated in an a priori fashion, without any reference to experience. But whether a particular proof applies to the world of experience – or, better still, whether it accurately describes the structure of the world – can only be ascertained experimentally. It is experiment which tells us which geometrical proof is to be used, even if the geometrical proof itself can be developed independently of experience. (I am relying here on the work of Martha Féher, Peter Machamer, and others.)

Perhaps more importantly, Stephen Gaukroger has argued that experimentation shaped the very way in which Galileo’s physical theories are framed and formulated. Alexander Koyré and others have argued that the laws of Galilean physics are “abstract” laws which refer to an ideal reality. It is true, of course, that in setting aside “impediments” (impedimenti), such as the resistance of the air, Galileo’s proofs do not refer to the world of everyday experience. But it is unhelpful to think of them as an idealisations of, or abstractions from, experienced reality. There is an experienced reality to which they conform. It may not be that of everyday experience, but it is that of carefully controlled physical experiments. It follows that in Galileo’s work, the task of natural philosophy is being rethought. It is no longer the study of reality as revealed to everyday observation; it is the study of that reality revealed in experimental situations.

The second way in which Galileo’s natural philosophy anticipates the later experimental philosophy is in its comparative lack of interest in the mechanisms thought to underlie phenomena. It is not that Galileo was a positivist in our modern sense. There are passages in which he engages in speculation regarding matter theory and on these occasions he favours a corpuscularian view. But such speculations are, as Salviati says in the Two New Sciences, a mere “digression.” Galileo does not consider that his new science requires them. Indeed his work on motion is almost entirely a kinematics – as he freely admits, it says nothing about the causes of motion – but Galileo does not consider it any less significant as a result.


Galileo's solution of the "rota Aristotelis" paradox, demonstrating that a body could be composed of an infinite number of unquantifiable atoms.

This should not be interpreted as a general lack of interest in causation, as Stillman Drake suggests. Galileo shares the ancient desire cognoscere rerum causas (to know the causes of things). But the causal properties Galileo seeks are different from those sought by his predecessors. His causes are the mathematically describable properties of the objects whose behaviour is being explained, properties that no Aristotelian would regard as essential. (Even his atoms are more akin to mathematical points than physical objects.) It is, once again, experimentation that allows us to pick up which of those mathematically describable properties are generally operative and therefore the proper subject of a science. It is this move that allows Galileo, as it would later allow Newton, to be content with a causal account that remains on the level of phenomena, rather than speculating about a realm inaccessible to observation.

In an early dialogue, Galileo has two rustics (contadini) speculating about the new star of 1605. One of them advises his companion to listen to the mathematicians rather than the philosophers, for they can measure the sky the way he himself can measure a field. It doesn’t matter of what material the heavens are made. “If the sky were made of polenta,” he says, “couldn’t they still see it alright?” This is surely something new in the history of natural philosophy.


While I would still defend the individual claims contained here, my continued study of Galileo has made me increasingly cautious about the usefulness of a distinction between experimental and speculative natural philosophy.  It is certainly the case that many late seventeenth-century thinkers made such a distinction, but is it a useful one for us to make? I’m not confident that it is.

Experiment certainly played an important role in Galileo’s work, although precisely what that role was continues to be contested. And it is true that Galileo has little interest in speculating about the underlying structure of the world: even if, as he writes, the sky were made of polenta, the mathematicians could still measure it. The problem is that the classical, mathematical tradition out of which he comes — that of astronomy, statics, optics, and (after Galileo) the study of local motion — cannot be helpfully characterized as either experimental or speculative. It certainly uses experiment, but it also reasons a priori, in ways that seem independent of experience.

So perhaps it would be better to have a threefold classification of early modern scientific traditions. (A classification of this kind is suggested by Casper Hakfoort in the last chapter of his Optics in the Age of Euler.) A first tradition would be that of matter theory, which is inevitably speculative insofar as it deals with matters not accessible to direct observation. (This is the realm of Newton’s “hypotheses.”) Corpuscularian proposals would fall into this category, as would Descartes’s vortex theory. A second tradition would be that of experimental natural philosophy, which regarded the results of experiment as themselves significant forms of knowledge, whether or not they could be connected with an underlying theory of the nature of matter. Finally, there is the mathematical tradition that Galileo transformed, so successfully, by producing a mathematical account of local motion.

Individual natural philosophers could engage in all three kinds of activities, but will differ according to the emphasis they place on one or other of them. So although Galileo certainly engaged in experiments, his emphasis was on the kind of reasoning characteristic of the mathematical tradition. It is this form of reasoning, I have come to believe, that cannot be easily fitted into the experimental-speculative scheme.

Symposium on Experimental Philosophy and the Origins of Empiricism

St Margaret’s College, University of Otago, 18-19 April 2011

Monday 18 April

9.00 Introductory Session (Peter Anstey and Alberto Vanzo)

9.30 Discussion of Peter Anstey, The Origins of the Experimental/Speculative Distinction
Discussant: Gideon Manning
Chair: Alberto Vanzo

11:30 Discussion of Juan Gomez, The Experimental Method and Moral Philosophy in the Scottish Enlightenment
Discussant: Charles Pigden
Chair: Kirsten Walsh

14:30 Discussion of Kirsten Walsh, De Gravitatione and Newton’s Mathematical Method
Discussant: Keith Hutchison
Chair: Philip Catton

20:00 European Panel of Experts (video conference)
Chair: Peter Anstey

Tuesday 19 April

9:30 Discussion of Peter Anstey, Jean Le Rond d’Alembert and the Experimental Philosophy
Discussant: Anik Waldow
Chair: Juan Gomez

11:30 Discussion of Alberto Vanzo, Empiricism vs Rationalism: Kant, Reinhold, and Tennemann
Discussant: Tim Mehigan
Chair: Philip Catton

14:30 Discussion of Alberto Vanzo, Experimental Philosophy in Eighteenth Century Germany
Discussant: Eric Watkins
Chair: Peter Anstey

16:30 Final plenary session, led by Gideon Manning

17:00 Conclusion

Attendance at the symposium is free. However, space is limited, so we advise you to register early. To register and for information, please email

Abstracts of all papers are available here. If you cannot attend, but would like to read some of the papers, send us an email.

Speculative and Experimental Philosophy in Universities: (Post-)Cartesianism

This is the second post in Dr Gerhard Wiesenfeldt‘s series on speculative and experimental philosophy in early modern universities.

Gerhard Wiesenfeldt writes…

In my last post, I wrote about Johann Christoph Sturm’s experimental philosophy and his eclectic approach to speculative philosophy. A very different route to natural philosophy was taken by his colleague and friend, Burchard de Volder. De Volder was professor of philosophy at Leiden University and in 1675 became the first university lecturer to be officially charged with teaching ‘physica experimentalis’. While hardly known today, he was considered an important natural philosopher during his lifetime, he also was a correspondent of Newton, Leibniz and Huygens (who considered him to be the only other Dutchman to have understood Newton’s Principia). When he started teaching at Leiden, he was a clear-cut Cartesian with little inclination for experimental philosophy. He took up experimental philosophy only after the controversies on Cartesian philosophy at Leiden had reached such a level that the university (and in particular the faculty of philosophy) was seriously disrupted in its working. His decision to introduce experimental philosophy was probably motivated both by political considerations (the Cartesians at the university were under serious pressure and de Volder had reasons to fear being expelled) and by the urge to find ways of teaching philosophy that would not lead to conflict and even physical violence. In this he was supported by his conservative anti-Cartesian colleague Wolferd Senguerd, who started teaching experimental philosophy shortly after de Volder had began his lectures.

De Volder's airpump as illustrated by his colleague Wolferd Senguerd

De Volder's airpump as illustrated by his colleague Wolferd Senguerd

While de Volder’s experimental lectures were largely based on Boyle’s New Experiments Physico-Mechanicall with some mathematical splashes from Stevin, he continued to teach speculative philosophy based solely on Descartes’ Principles of Philosophy. De Volder explicitly rejected Sturm’s eclectic approach and argued that speculative philosophy needed to be based on certain, universal principles, such as the Cartesian principle of clear and distinct ideas, in order to create a comprehensive philosophical system. Experimental and speculative philosophy had thus different foundations and remained largely unrelated. Occasionally, there were even contradictions between the two, when De Volder pointed out errors in Cartesian philosophy in his experimental lectures. Still, he maintained that natural philosophy needed to be developed in a systematic way, and that the Cartesian system was the best available.

Yet, over time, his judgment on this matter changed. In the 1690s he argued that Cartesian methodology worked only in the res cogitans, i.e. in mathematics and metaphysics, but not in natural philosophy, as there was no way to establish clear and distinct ideas on the physical world with certainty. While de Volder rejected Cartesian natural philosophy, he did not take up any of the other systems. He remained reluctant about Newton’s Principia and was not persuaded by Leibniz’s attempts to win him over. Instead, he ended up with a methodology not too far from Sturm’s, in stating that one needed to divide the physical world into parts on which certain hypotheses could be developed. He did not elaborate whether this still left room for speculative natural philosophy, but it is hard to see how such a science could have been maintained under these principles.

One of the contentions of these entries on university philosophy relates to the debate in this blog on the experimental/speculative versus rationalist/empiricist distinction. In terms of early 18th century university philosophy these distinctions are on an essentially different level. The distinction between rationalism and empiricism pertains to understanding philosophy as being divided into different schools (or sects). While one might describe rationalism and empiricism as the two biggest philosophical schools (or groups of schools), they were by no means the only ones – one philosopher at Helmstedt University counted no less than 26 different philosophical schools in 1735. The distinction between experimental and speculative philosophy, however, referred to different manners to practise philosophy independent of a particular school. Sturm and de Volder practised both experimental and speculative philosophy, but maintained that they were different enterprises, as did their students Wolff, ’s Gravesande and van Musschenbroek later on. At the same time experimental philosophy transcended philosophical schools, practised by Cartesians, Newtonians, Aristotelians, and Wolffians alike.

Speculative and Experimental Philosophy in Universities: Eclecticism

This is the first of two guest posts by Dr Gerhard Wiesenfeldt on speculative and experimental philosophy in late 17th century universities. Gerhard has published on early modern Dutch science, the visual culture of experiments, science in popular movies, biographies of ‘fameless’ scientists and romantic self-experiments. He is currently working on the different local cultures of science in the 17th and 18th centuries and their mutual interactions.

Gerhard Wiesenfeldt writes…

In late 17th century universities, experimental philosophy played a significant role, yet in a different manner to the role it played in the Royal Society. One of the traditional roles of universities had been to evaluate new knowledge and new knowledge systems and relate them to the existing sciences. In this context, the relation between experimental and traditional natural philosophy had to be addressed. Here, I want to discuss one of the various ways in which this relation was maintained, a way that became influential for the development of experimental philosophy in German speaking countries.

Johann Christoph Sturm, professor of mathematics and philosophy at the University of Altdorf in central Germany, was probably the leading university-based German natural philosopher of the late 17th century: he wrote the most widely read textbooks and many of his students went on to teach natural philosophy at other universities. He first taught a full course on experimental philosophy in 1672 and published its contents under the title Collegium experimentale sive curiosum in 1676. As the title suggests, the book presents a style of experimental philosophy similar to the experimental natural history of the early Royal Society. It is divided into a series of ‘tentamina’, which describe either one experiment, or a series of experiments, or an instrument. What is of particular interest, however, is Sturm’s concern with the way speculative natural philosophy ought to be taught.

A page from Sturm's <em>Collegium Experimentale</em> describing the Torricellian apparatus

Sturm's description of the Torricellian apparatus

He wrote three different books on this subject, which show a development of the manner that he related speculative philosophy to experimentation: the Physica conciliatrix (1684), the Physica electiva sive hypothetica (1697) and finally the Physicae modernae sanioris compendium (1704). In the Physica conciliatrix, Sturm argues for philosophical eclecticism: given the variety of philosophical schools, it was improbable that one was correct in all cases, so speculative philosophy should not be based on one particular school (whether Aristotelian, Cartesian or atomistic), but take all existing hypotheses into account. While experiments would give some guidance in the matter, they could not solve the issue, because experimentation could not explain the causes of the observed phenomena (his earlier discussion of Henry More’s hylarchic spirit in Collegium experimentale exemplifies this issue for him).

The Physica electiva (later re-edited by Christian Wolff) follows on from that position, the search for causes remains the domain of speculative philosophy and cannot be based on one school, precisely because all schools have been shown to be incomplete in their explanations. The eclecticism he develops in this book is one of methodological diversity. Just as mathematics has developed different and unrelated methods that can be applied to different mathematical problems, speculative philosophy needs a variety of methods that provide a way to choose from a range of hypotheses put forward to explain a particular phenomenon.

To achieve this it was necessary to establish the principles on which these methods can be derived and justified, something that had already been established in mathematics. Philosophical analysis had to start with an account of the phenomena in question that was precise and true, but also included all circumstances. Then, all existing hypotheses explaining the phenomena had to be taken into account and analysed. Accounting for all phenomena was to be considered an argument for the truth of the hypothesis, contradiction by a single phenomenon refutes the hypothesis. Yet, even false hypotheses should be discussed further, as their refutation would lead to improved knowledge of the subject matter (see Michael Albrecht’s Eklektik for details on these principles).

While the Physicae modernae compendium was intended as a textbook that would work out this form of natural philosophy, it contains an important methodological development. Whereas the Physica electiva presents the notion of a complete speculative natural philosophy, i.e. a discussion of all known phenomena and the selection of the most probable hypotheses for each phenomenon, the preface of the Physicae modernae compendium restricts the content of ‘textbook natural philosophy’ to those phenomena that can be predicted with certainty.

Not all university philosophers went the route of eclecticism. In my next post, I will discuss the radically different approach that was developed by someone who was acquainted with Sturm from their common student days at Leiden University and later became one of his critics, Burchard de Volder.

Experiment and Hypothesis, Theory and Observation: Wolff vs Newton

Alberto Vanzo writes…

Looking for sources for knowledge of experimental philosophy in eighteenth century Germany, I found some interesting texts by relatively unknown authors (at least beyond the circle of specialists). Christian Wolff is one of them. He was the most famous German philosopher in the first half of the eighteenth century. His philosophy was taught in many universities and his works were very popular. For instance, his German Logic knew no less than 14 editions during Wolff’s life.

Wolff knew several British experimental philosophers. He cited works by Robert Boyle and Robert Hooke, he was the Locke reviewer for an important journal (the Acta eruditorum), and he polemized with the Newtonian John Keill on the existence of the vacuum. He is a good example of the fact that German thinkers were acquainted with the works and the methodological views of British experimental philosophers in the first half of the eighteenth century.

A number of Wolff’s statements might make us think that he was himself an adherent to the early modern version of x-phi. Like British experimental philosophers, Wolff criticizes Descartes’ attempt to explain a great variety of natural phenomena in the light of few general principles that he established a priori. Like Hume and Hutcheson, Wolff is eager to extend the dominion of experimental philosophy beyond the boundaries of physics. He projects the disciplines of experimental cosmology, experimental teleology, experimental theology, experimental politics, and even experimental ontology. For his philosophical system as a whole, he chooses the name of “universal experimental philosophy” (philosophia experimentalis universalis). How could Wolff have been a more enthusiastic adherent to the program of experimental philosophy?

Yet contrary to the appearances, Wolff’s views were quite different from those of his British counterparts. This can be seen by comparing him with Newton. Newton, like virtually every other early modern experimental philosopher, claimed that he did not feign any hypothesis (his famous hypotheses non fingo). Wolff rebuts that Newton

    indulges in hypotheses in those very areas in which they think he abstained from employing them […] In fact, what else is universal attraction or gravity, which is represented by a measure of attraction, if not a hypothesis which is assumed because of certain phenomena and then is extended to all matter?

According to Wolff, not only did Newton feign hypotheses, but he did well to do so. This is because natural philosophers must proceed like astronomers:

Christian Wolff

Christian Wolff

From some present events, they infer what they have to assume, in order for [the events] to follow [from it], and they posit that their hypothesis applies to all [similar] events […] To determine whether they did well to assume the hypothesis, they infer what follows from it on the basis of a correct reasoning, in order to compare it with the remaining events that they have either observed, or that they derive from observations. [They do this] in order to see whether what has been observed agrees with the hypothesis. If they find that [observations and hypothesis] are in contrast with one another, then they improve the hypothesis, and in this way they constantly move closer to the truth.

Wolff holds that there is a circular relationship between observation or experiment on the one hand, and theory on the other hand. He stresses

    how much theory owes to observations and how much, on the other hand, observations owe to theory, since observations perfect theory and theory in turn continuously perfects observations. He who is ignorant of any theory and does not have much ability to use the faculty of knowing will only discover obvious and mostly imprecise [truths] on the basis of observations. There would not be much progress, unless one could presuppose some theory; and the more [a theory] is developed, the more discoveries one will make by means of observation[s].

Unlike Newton, Wolff was no great scientist. However, the quotes above suggest that his methodology of science is worth a serious reading. His acknowledgments of the interaction between theory and observation sound modern. They sketch a version of the hypothetico-deductive method that might provide an interesting alternative to Newton’s strict inductivism.

In summary, Wolff is a good example of the Germans’ knowledge of British experimental philosophy in the first half of the eighteenth century. His views are also interesting in their own right. So are Johann Nicolaus Tetens’ comments on observational vs speculative philosophy or Johann Heinrich Lambert’s distinction between theory-testing experiments and experiments that have a life of their own – two hundred years before Ian Hacking. More on this another time.

In the next post, Kirsten will discuss Newton’s method, in particular his rejection of hypotheses and his use of queries. See you next Monday!