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Monthly Archives: April 2013

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.


Newton on Experiment and Mathematics

Kirsten Walsh writes…

In my last post, I discussed our 20 revised theses and why I altered thesis 5.  In this post, I’ll discuss why I replaced thesis 8.

In 2011, I claimed that:

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

But at the start of this year, I replaced this thesis with a new thesis 8:

    8.  In his early work, Newton’s use of the terms ‘hypothesis’ and ‘query’ are Baconian.  However, as Newton’s distinctive methodology develops, these terms take on different meanings.

Since my new thesis is a replacement of the original thesis, rather than a modification, two explanations are required.  So in today’s post, I’ll tell you why I decided to remove my original thesis 8, and in my next post, I’ll tell you about my new thesis 8.

I originally included thesis 8 because there are some obvious differences in the styles of Newton’s early work on optics and his Principia.  In Newton’s first paper on optics (1672), there is a strong emphasis on experiment.  Experiment drives his research and guides his rejection of various possible explanations of the phenomena under consideration.  Ultimately, he presents an Experimentum Crucis as proof for the certainty of his proposition that white light is heterogeneous.  In contrast, the Principia (1687) displays a strong emphasis on mathematics.  The full title of the work, the Author’s Preface to the Reader, and the fact that Book I opens with 11 lemmas outlining the mathematical framework of the work are just a few features that make it clear that Principia is primarily a mathematical treatise.

I now think that my original thesis 8 is misleading.

Firstly, as I have emphasised on this blog, Newton’s early work had a mathematical style that made it unique among his contemporaries.  While they recognised him as an experimental philosopher, his claims of obtaining certainty via geometrical proofs set him apart from the Baconian-experimental philosophers.  Moreover, his methodological statements show evidence of a tension between experiment and mathematical certainty.  For example, he says that the science of colours,

    “depend[s] as well on Physicall Principles as on Mathematicall Demonstrations: And the absolute certainty of a Science cannot exceed the certainty of its Principles.  Now the evidence by wch I asserted the Propositions of colours is in the next words expressed to be from Experiments & so but Physicall: Whence the Propositions themselves can be esteemed no more then Physicall Principles of a Science.”

Secondly, Newton continued to identify as an experimental philosopher until the end of his life.  For example, in the General Scholium at the end of Principia, he says:

    “and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy.”

This resembles Newton’s earlier emphasis on grounding propositions on empirical evidence, rather than on speculative conjectures.

Thirdly, in Principia, Newton appears to be negotiating a similar tension between experiment and mathematical certainty that we saw in his early work.  For example, in the Scholium to the Laws of Motion he asserts the certainty of his Laws, while at the same time, acknowledging their experimental basis:

    “The principles I have set forth are accepted by mathematicians and confirmed by experiments of many kinds.”


    “By these examples [i.e. the experiments mentioned above] I wished only to show the wide range and the certainty of the third law of motion.”

From these three points, we can see that the methodological differences between Newton’s early papers and Principia aren’t as great as they first appear.  But I did not remove my original thesis 8 because I think that the methodology of the 1672 paper is precisely the same as the methodology displayed in Principia.  Rather, I don’t think my original thesis 8 captures what is important about these differences.

As I have explained here, my project is to distinguish between those features of Newton’s methodology that changed, and those that stayed the same.  Some aspects of Newton’s methodology developed over time.  For example, he came to value geometrical synthesis over algebraic analysis.  Other aspects of his methodology varied according to context.  For example, in Opticks, he employs ‘experiments’ and ‘observations’, but in Principia, he employs ‘phenomena’.  But this triumvirate of methodological ideas – experiment, mathematics and certainty – should be considered an enduring feature of Newton’s methodology.

Geminiano Montanari on Natural History and Explanations

Alberto Vanzo writes…

A while ago, I wrote a post on the late seventeenth-century Italian natural philosopher, Geminiano Montanari. I argued that his stints of speculative reasoning were, after all, compatible with his allegiance to the experimental philosophy. In this post, I will focus on another aspect of Montanari’s experimentalism that appears to clash with his natural-philosophical practice: his view that, before even attempting to explain natural phenomena, we should compile a universal natural history.

The problem: disagreements and errors in natural philosophy

Montanari sees the compilation of a universal natural history as way of overcoming disagreements among philosophers. Having noted the many competing views on what “the first principles of natural things” may be, Montanari explains that this variety is due to the excessive self-confidence of “nearly all great minds”. Instead of jumping to first principles,

    It was necessary to start philosophy from particular things, examining the whole of nature one piece after another, and to amass a rich capital of experiences so as to prepare the historical matter on whose basis one should later speculate about the reasons [of those experiences].

The solution: building a universal natural history

We can avoid errors and reach agreement on the principles of things by following Francis Bacon’s suggestion of building a natural history including “all experiences and other certain information that one could get from faithful sources”.

How much information should be gathered before we can discover the first principles of natural things?

    [I]n order to find what the true, first and most universal principles of all things may be, it is not sufficient to make an induction from few terms, but it is necessary first to cognize all natural effects, so that one can later find a common reason which satisfies all experiences. But who can already boast to possess such an universal information?

Montanari’s answer is: nobody. It is still too early to make an induction from the observation of everything to its first cause. We must postpone the task of explaining the whole of nature and focus our strengths on the task of compiling natural histories.

Did Montanari do what he says?

He certainly collected many experiments and observations on manifold phenomena, from the capillary behaviour of liquids to the comets and celestial bodies. But he did not refrain from developing explanations of those phenomena, even though he was aware that his experiences were limited and many phenomena had not yet been observed. It is tempting to conclude that Montanari did not do what he says, that his allegiance to the Baconian view that a comprehensive data collection must precede natural-philosophical explanations was merely verbal, and that he was merely paying lip-service to the Baconian fashion of the time.

I do not think that this is the case. Montanari claims that completing a universal natural history is necessary to establish the “true, first and most universal principles of all things”. However, he does not claim that completing a universal natural history is necessary to explain specific natural phenomena, nor does he think that we must first establish the first principles of all things in order to explain specific phenomena. On the contrary, Montanari thinks that, upon completing a universal natural history, we will have to to advance piecemeal toward the first principles, by formulating explanations of specific phenomena and proceeding to increasingly higher levels of generality.

Montanari’s two-part discussions of specific phenomena follow, on a small scale, his favoured Baconian method that for establishing first principles. Regardless of whether he is discussing the capillary action, the behaviour of hot spheres of glass in water, or the position of a comet, Montanari starts by providing a natural history of the phenomenon at hand in the form of a list of observations and experiments. He then proceeds from the “historical matter” to its “reasons”, that is, he provides natural-philosophical explanations of the phenomena.

These explanations are fallible. Natural histories are inescapably incomplete and it is always possible that future experiments or observations invalidate his explanations. However, Montanari holds that it is possible to “deduce” explanations “with physico-mathematical evidence” from a suitable, even if limited, natural-historical basis. What warrants his explanations is the fact that they “explain all the other effects we have observed.”

In conclusion, Montanari does not violate his claim that we should build a universal natural history before identifying the very first principles of the whole nature. The magnitude of the task suggests that this may be only a regulative ideal and may even warrant a certain scepticism on whether we will ever be able to discover the first principles. However, discovering these principles is not necessary to do science for Montanari. What drives Montanari’s natural philosophy is the fact that he allows for fallible natural-philosophical explanations which are based on small-scale, necessarily incomplete, subject-specific natural histories.