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Halley’s Comet and Christmas Day

Monday, December 23rd, 2013 | Kirsten Walsh | No Comments

Kirsten Walsh writes…

Hello Readers!

Since this is our last post for the year, and the holidays are almost upon us, I thought I’d tell you a Christmas story:

On Christmas day in 1758, Johann Georg Palitzsch, a German farmer and amateur astronomer, became the first person to witness the return of, what would become known as, Halley’s comet.

Halley’s comet is the only short-period comet (i.e. comet that completes an orbit in under 200 years) that is visible with the naked eye.  It has featured in astronomical reports since at least 240 BC.  However, it wasn’t until 1705 that it was recognised as the same object.  That year, the English astronomer Edmund Halley determined the periodicity of the comet, writing about it in his Synopsis Astronomia Cometicae.  With the help of Newton’s theories of elliptical orbit, Halley had studied the data of the comets that had appeared in 1531, 1607 and 1682, and recognised that they all followed similar paths.  He made a rough estimate that the comet would return in 1758.

Halley died in 1742, and so he never saw the return of the comet.  But Palitzsch’s Christmas day observation confirmed his claim that, indeed, there was a comet, visible by the naked eye, that had period of approximately 76 years.  It was the first time anything other than a planet had been shown to orbit the earth.  In 1759, the French astronomer Nicolas Louis de Lacaille named the comet after Halley.

This prediction counts, not only as a confirmation of Halley’s theory, but also of Newtonian physics, and of the mathematico-experimental method more generally.  It seems fitting that this confirmation happened on the 116th anniversary of Newton’s birth!*

We at Early Modern Experimental Philosophy wish you a happy holiday.  We look forward to hearing from you in 2014!

 

*Actually, Newton was born in England on 25 December 1642, but Palitzsch saw Halley’s comet in Germany on 25 December 1758.  Until 1752, England used the Julian (‘Old Style’) calendar, whereas Europe had adopted the Gregorian (‘New Style’) calendar much earlier.  There is a 10-day difference between the two calendars, so Newton’s birthdate adjusts to 4 January 1643 on the Gregorian calendar.  So while both events happened on Christmas day, they happened on different Christmas days.  (Also, I hope you will forgive me for this picture, that I couldn’t resist posting!)

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Categories: Ideas

Birth stats and Divine Providence

Monday, December 9th, 2013 | Juan Manuel Gomez Paris | 1 Comment

Juan Gomez writes…

In a number of posts in this blog we have examined how some philosophers in the eighteenth century were carrying out moral enquiries by following the experimental method that had achieved so much for natural philosophers. The subtitle of Hume’s famous Treatise clearly states the “attempt to introduce the experimental method in morals,” and we know that Turnbull, Butler and Hutcheson were also using this method in their arguments regarding morality, the human mind, and the existence of God. Regarding this latter issue, theistic philosophers like Butler and Turnbull argued that the order and perfection of the natural world (deduced from facts and observation) was clear proof of the wisdom and goodness of God. In this post I want to examine one of such arguments given not by a moral philosopher, but by a famous physician and mathematician: Dr. John Aburthnot.

Dr. Arbuthnot was a fellow of the Royal Society and Physician to the Queen, a fellow Scriblerian of Swift and Pope, a mathematician and a very interesting figure in general. Best known for his work in medicine and his satires, this fascinating polymath wrote a short paper that appeared in the Philosophical Transactions for 1710 titled “An Argument for Divine Providence, Taken from the Constant Regularity Observ’d in the Births of Both Sexes.” He explains how probability works in a situation involving a two-sided dice, and then proceeds to argue that the number of males and females born in England from 1629 to 1710 shows that it was not mere chance, but rather Divine Providence that explains the regularity between the sexes. Let’s examine his argument in more detail.

Arbuthnot begins by considering the purely mathematical aspect of an event where we want to find out the chances of throwing a particular number of two-sided dice (or a coin for that matter). The simplest case is that of 2 coins, where we have that there is one chance of both coins landing on heads, one chance of both coins landing on tails, and two chances where each of the coins lands on a different side. The mathematical details need not detain us here; the main conclusion drawn form this exposition is that the chances of getting an equal number of heads and tails grows slimmer as the number of coins augments. For example, the chances of this happening with ten coins is less than 25%. If instead of coins we consider all human beings which, Arbuthnott assumes, are born either male or female, the chances of there being equal number of each of the sexes are very, very low.

However, Arbuthnot acknowledges that the physical world is not equivalent to the mathematical, and this changes his calculations. If it was just mere chance that operated in the world, the balance between the number of males and females would lean to one or the other, and perhaps even reach extremes. But this is not the case. In fact, or so Arbuthnott argues, nature has even taken into account the fact that males have a higher mortality rate than females, given that the former “must seek their Food with danger…and that this loss exceeds far that of the other Sex, occasioned by Diseases incident to it, as Experience convinces us.” The wisdom of the Author of nature is witnessed in this situation, as the tables of births in England show that every year slightly more males than females are born, in order to compensate for the loss mentioned above and keep the balance. For example in 1629, Arbuthnot’s table list 5218 males to 4683 females; in 1659, 3209 males to 2781 females; in 1709, 7840 males to 7380 females; and so on for all the years recorded.

Arbuthnot concludes that from his argument “it follows, that it is Art, not Chance , that governs,” and adds a scholium where he states that polygamy is contrary to the law of nature.

What can we make of Arbuthnot’s paper? Instead of discussing how effective the argument is (I leave that for the readers to discuss with us in the comments!!), I want to focus on the fact that Arbuthnot’s argument illustrates the call for the use of mathematics in natural philosophy. Philosophers like Arbuthnot and John Keill thought that the use of mathematics had been neglected in natural philosophy and believed that it should play a greater role. From the 1690′s onwards the work of experimental philosphers reveals this use of mathematics in natural philosophical reasoning. The structure of Arbuthnot’s argument resembles that of the natural philosophers who, like Newton, were using mathematics to explain natural phenomena. The mathematical calculation is extrapolated to the case of human births (in this case). Arbuthnot recognizes an issue central to the application of maths in natural philosophy: while the former deals with abstract objects, the latter deals with the natural world. However, in this particular case Arbuthnot uses the asymmetry between the mathematical and physical realms to show that Divine Providence is a better explanation than mere chance when it comes to the balance and regularity of human births. I would like to hear what our readers think of arguments like the one constructed by Arbuthnot.

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Categories: Ideas

Cotes’ Preface and Experiment

Monday, November 25th, 2013 | Peter Anstey | No Comments

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?

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Categories: Ideas

Observation, experiment and intervention in Newton’s Opticks

Monday, November 11th, 2013 | Kirsten Walsh | No Comments

Kirsten Walsh writes…

In my last post, my analysis of the phenomena in Principia revealed a continuity in Newton’s methodology.  I said:

    In the Opticks, Newton isolated his explanatory targets by making observations under controlled, experimental conditions.  In Principia, Newton isolated his explanatory targets mathematically: from astronomical data, he calculated the motions of bodies with respect to a central focus.  Viewed in this way, Newton’s phenomena and experiments are different ways of achieving the same thing: isolating explananda.

In this post, I’ll have a closer look at Newton’s method of isolating explananda in the Opticks.  It looks like Newton made a distinction between experiment and observation: book 1, contained ‘experiments’, but books 2 and 3, contained ‘observations’.  I’ll argue that the distinction in operation here was not the standard one, which turns on level of intervention.

In current philosophy of science, the distinction between experiment and observation concerns the level of intervention involved.  In scientific investigation, intervention has two related functions: isolating a target system, and creating novel scenarios.  On this view, experiment involves intervention on a target system, and manipulation of independent variables.  In contrast, the term ‘observation’ is usually applied to any empirical investigation that does not involve intervention or manipulation.  This distinction is fuzzy at best: usually level of intervention is seen as a continuum, with observation nearer to one end and experiment nearer to the other.

If Newton was working with this sort of distinction, then we should find that the experiments in book 1 involve a higher level of intervention than the observations in books 2 and 3.  That is, in contrast to the experiments in book 1, the observations should involve fewer prisms, lenses, isolated light rays, and artificially created scenarios.  However, this is not what we find.  Instead we find that, in every book of the Opticks, Newton employed instruments to create novel scenarios that allowed him to isolate and identify certain properties of light.  It is difficult to quantify the level of intervention involved, but it seems safe to conclude that Newton’s use of the terms ‘observation’ and ‘experiment’ doesn’t reflect this distinction.

To understand what kind of distinction Newton was making, we need to look at the experiments and observations more closely.  In Opticks book 1, Newton employed a method of ‘proof by experiments’ to support his propositions.  Each experiment was designed to reveal a specific property of light.  Consider for example, proposition 1, part I: Lights which differ in Colour, differ also in Degrees of Refrangibility.  Newton provided two experiments to support this proposition.  These experiments involved the use of prisms, lenses, candles, and red and blue coloured paper.  From these experiments, Newton concluded that blue light refracts to a greater degree than red light, and hence that blue light is more refrangible than red light.

Opticks, part I, figure 12.

In the scholium that followed, Newton pointed out that the red and blue light in these experiments was not strictly homogeneous.  Rather, both colours were, to some extent, heterogeneous mixtures of different colours.  So it’s not the case, when conducting these experiments, that all the blue light was more refrangible than all the red light.  And yet, these experiments demonstrate a general effect.  This highlights the fact that, in book 1, Newton was describing ideal experiments in which the target system had been perfectly isolated.

Book 2 concerned the phenomenon now known as ‘Newton’s Rings’: the coloured rings produced by a thin film of air or water compressed between two glasses.  It had a different structure to book 1: Newton listed twenty-four observations in part I, then compiled the results in part II, explained them in propositions in part III, and described a new set of observations in part IV.  The observations in parts I and IV explored the phenomena of coloured rings in a sequence of increasingly sophisticated experiments.

Consider, for example, the observations in part I.  Observation 1 was relatively simple: Newton pressed together two prisms, and noticed that, at the point where the two prisms touched, there was a transparent spot.  The next couple of observations were variations on that first one: Newton rotated the prisms and noticed that coloured rings became visible when the incident rays hit the prisms at a particular angle.  But Newton steadily progressed, step-by-step, from prisms to convex lenses, and then to bubbles and thin plates of glass.  He varied the amount, colour and angle of the incident light, and the angle of observation.  The result was a detailed, but open ended, survey of the phenomena.

I have argued that Newton’s experiments and observations cannot be differentiated on the basis of intervention, but there are two other differences worth noting.  Firstly, whereas the experiments described in book 1 were ideal experiments, involving perfectly isolated explanatory targets, the observations in books 2 and 3 were not ideal.  Rather, through a complex sequence of observations, as the level of sophistication increased, the explanatory target was increasingly well isolated.  When viewed in this way, the phenomena of Principia seem to have more in common with the experiments of book 1 than the observations of books 2 and 3.

Secondly, the experiments of book 1 were employed to support particular propositions, and so, individually, they were held to be particularly relevant and informative.  In contrast, the observations of books 2 and 3 were only collectively relevant and informative.  Moreover, the sequence of observations was open ended: there were always more variations one could try.

What are we to make of these differences between observation and experiment in the Opticks?  I have previously argued that, while Newton never constructed Baconian natural histories, his work contained other features of the Baconian experimental philosophy, such as experiments, queries and an anti-hypothetical stance.  However, in viewing them as complex, open ended series’ of experiments, I now suggest that the observations of books 2 and 3 look a lot like what Bacon called experientia literata, the method by which natural histories are generated.  I’ll discuss this in my next post, but in the mean time, I’d like to hear what our readers think.

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Categories: Ideas

Defining early modern experimental philosophy (3): Some clarifications

Wednesday, October 30th, 2013 | Kirsten Walsh | No Comments

Alberto Vanzo writes…

This is the third post in a series on defining early modern philosophy. In my earlier posts (1, 2), I claimed that

[E] To endorse the method of (early modern) experimental philosophy is to believe that one should only firmly commit to those substantive claims and theories that are warranted by experiments and observations.

In this post, I will clarify three related points in order to address some misunderstandings concerning the nature and the usefulness of the notion of experimental philosophy. I will make three claims. First, experimental philosophers did not need to eschew any theories altogether. Second, this does not entail that even Descartes, Leibniz, or some Scholastics were experimental philosophers. Third, the difficulty in classifying certain authors as experimental philosophers is not as worrying as it is sometimes portrayed.

Experiments and theories

As it should be clear from [E], one need not take on a fully a-theoretical attitude in order to endorse the method of experimental philosophy. The Proem of the Saggi di naturali esperienze, alongside other texts by experimental philosophers, states that the sole purpose of the Accademia del Cimento is “experimenting and narrating”, while eschewing any “hint of anything speculative”. Nevertheless, experimental philosophers were not required to completely avoid any theories. Those who endorse the method of experimental philosophy can consistently entertain theories, put them forward as hypotheses to be tested experimentally, reject theories that are incompatible with experimental evidence, tentatively or provisionally endorse the theories that they take to be more probable than their competitors, and even firmly endorse certain theories (such as corpuscularism), insofar they are warranted by experience. In the light of this, Boyle, Hooke, Locke and Newton can be said to have endorsed the method of experimental philosophy, even though they did not endorse the fully a-theoretical stance that is often associated with the movement.

Who wasn’t an experimental philosopher?

One may fear that, once we grant that experimental philosophers could be engaged in some forms of theorizing, the notion of experimental philosophy becomes too inclusive, so that Descartes, Leibniz, and even certain Aristotelians can be classed as experimental philosophers. This is not the case. The fact that an experimental philosopher can endorse theories and substantive natural-philosophical claims does not entail that there is no real distinction between those who endorsed and those who did not endorse the method of experimental philosophy.

Descartes and Leibniz too engaged in experiments. Leibniz even claimed to be “strongly in favour of the experimental philosophy”. However, insofar as Descartes thought that he had firmly established the highly speculative cosmogonical theories of the Principles of Philosophy, in spite of the scant empirical evidence with which he backed them up, he was hardly following the methodological prescription spelt out in [E]. As for Leibniz, although he stressed the importance of experience for natural philosophy, he also held that some basic propositions of natural philosophy (like the principle of uniformity of nature) could be established only a priori. This view is incompatible with [E], we should not take Leibniz to be an experimental philosopher even though he stressed the importance of experience.

Problems of classification

Although there is a real distinction between those who endorsed the method of experimental philosophy and those who did not, establishing whether an early modern author really was an experimental philosopher is sometimes difficult. There can be a disconnect between rhetoric and methodology, or methodology (understood in the etymological sense of method-talk) and actual, practised method.

Some philosophers called themselves experimental philosophers, or endorsed the rhetoric of the movement (e.g. using “hypothesis” and “speculation” as a term of abuse), but they thought they were entitled to endorse certain natural-philosophical claims a priori. Others claimed that they were following the method of experimental philosophy, but they endorsed theories that outstripped the empirical evidence. Leibniz, as we have seen, is an example of the disconnect between rhetoric and methodology. Another example is provided by those Jesuits, like Daniello Bartoli, who rehearsed the experimentalist rhetoric, but attempted to take the sting out of experimentalism and to combine it with some Aristotelian doctrines that were hardly warranted by experience. In other cases, there was a disconnect between methodology and actual method. An example is provided by the account of vision of the late seventeenth-century Italian natural philosopher Francesco Bianchini. Not only his rhetoric, but also his methodological pronouncements were in line with [E]. However, his account of vision was far more speculative than those pronouncements allowed.

The disconnect between rhetoric, methodology, and practised method determines a difficulty in establishing whether certain authors were experimental philosophers. This would be worrying if a primary aim of the study of early modern experimental philosophy were providing a handy classification of early modern authors. However, the point of studying early modern experimental philosophy is not pigeonholing early modern authors, but understanding their philosophical views and practices, even when the former were not in line with the latter. Finding these discrepancies should not be surprising. People sometimes fail to practice what they preach. Other times, they use a rhetoric that is at least partly out of step with their actual views. Early modern philosophers were no exception.

Categories: Ideas

Butler and Clarke on the infinity of God

Monday, October 14th, 2013 | Juan Manuel Gomez Paris | No Comments

Juan Gomez writes…

In my three previous posts I have been commenting on the experimental methodology in religion and the contrast between the preferred methods of Samuel Clarke and Joseph Butler. We saw bishop Halifax’s general description of the a priori and a posteriori methods, and then we examined Butler’s preference for the latter and Clarke’s adoption of the former. Today I want to conclude this series of posts on religion by focusing on one specific application of the a priori method and Butler’s criticism of it.

In his A Demonstration of the being and attributes of God (1704) Clarke provides an argument for the infinity of God. As we have already mentioned in previous posts, Clarke prefers the a priori method because it provides ‘demonstrable proof’ of the attributes of God, while the a posteriori method can only provide probable knowledge. Clarke appeals to a set of premises from which he concludes that God, i.e. the only self-existing being, must be infinite. The following is Jonathan Bennett’s rephrasing of Clarke’s argument:

    ‘x is self-existent’ means that it’s a contradiction to suppose that x doesn’t exist
    ‘x is finite’ implies that there are places at which x doesn’t exist.

Therefore:

    It is a flat-out contradiction to suppose that something is both self-existent and finite.

So if you accept that God is self-existent, then you must also accept that he possesses the attribute of infinity. However, Butler is not convinced by this argument. In particular, Butler thinks that Clarke cannot say that if a being can be absent, without contradiction, from one place, then it can also be absent, without contradiction, from all places, which is exactly what Clarke claims is absurd. This is the passage that Butler criticises:

    “To suppose a Finite Being, to be Self-Existent; is to say that it is a Contradiction for that Being not to exist, the Absence of which may yet be conceived without a Contradiction: which is the greatest Absurdity in the  World: For if a Being can without Contradiction be absent from one place, it may without a Contradiction be absent likewise from another Place, and from all Places…”

Butler points out that a being, without contradiction can be absent from another and all places as long as it is at different times, but it is most certainly an absurdity to claim that a finite being can be absent from all places at the same time, since this would entail that it ceases to exist. Clarke replies that Butler is mistaken here, since it is indeed possible for a finite being to be absent of all places and all times, since such being is not necessary. Clarke appropriately switches back the conversation to talk of necessary beings, but this still is not enough to satisfy Butler.

In a follow up letter to Clarke’s reply, Butler now objects to the definition of self-existence. Butler argues that from the claim that a being necessarily exists it does not follow that it exists everywhere; it only follows that such being must exist somewhere, but there is no contradiction in supposing it is absent from other places at the same time.

It seems that the key to the whole discussion is the idea of necessity. If the self-existent being is necessary, then this must be the case everywhere, so it would be a contradiction to think that a necessary being is absent at one place. Butler seems to be missing this point in his exchange with Clarke. However, to be fair to Butler, at the time the correspondence took place, Butler was still very young (21 years old), and he eventually changed his mind and accepted Clarke’s argument.

However interesting the discussion between Butler and Clarke, I only wanted to provide an example of the way the debate between a priori and a posteriori methods took place within a religious context. Butler might have eventually accepted Clarke’s argument for the infinity of God, but 20 years after his correspondence with Clarke he was going to prefer the a posteriori method in his Analogy (1736), holding on to his belief that in matters of faith probable knowledge is all we need.

Why did Butler end up preferring the a posteriori method even though he accepted Clarke’s argument? The answer lies in the limits of knowledge that resulted from a commitment to experimental philosophy. Figures like Butler and Turnbull applied the experimental method to subjects that went beyond the observation of the natural world. This meant that the application of the experimental method could not be as straightforward as it was in natural philosophy, for the objects under consideration (‘moral objects’) are unobservable in the sense that they cannot be experienced via the five external senses. Knowledge of the existence of a future state and the attributes of God is not directly accessible to us, given our human nature. Anything we can possibly now about such things must be by analogy to the knowledge we gain from the observation of the natural world. This is why our knowledge of these ‘moral objects’ can never be demonstrable, but only probable. From our observation of the natural world we can safely conclude that it is probable that there is a future state, and highly probable that God is infinite (omnipresent), but we can never construct a demonstrable proof of these conclusions.

In one of the final exchanges on this topic Butler confesses that he insisted on his objection because he wanted a demonstrable proof of the infinity of God, and this misled him:

    “…your argument for the omnipresence of God seemed always to me very probable. But being very desirous to have it appear demonstrably conclusive, I was sometimes forced to say what was not altogether my opinion.”

Clarke suggests in his reply that this is a fault many are mislead into, and he blames one of the preferred targets of advocates of experimental philosophy, René Descartes:

    “…the universal prevalency of Cartes’s absurd notions (teaching that matter is necessarily infinite and necessarily eternal, and ascribing all things to mere mechanic laws of motion, exclusive of final causes, and of all will and intelligence and divine Providence from the government of the world) hath incredibly blinded the eyes of common reason, and prevented men from discerning him in whom they live and move and have their being…”

The upshot of applying the experimental method to moral topics was that it could only provide probable (not demonstrable) knowledge. However, recognizing this limitation was far more reasonable than those chimeras constructed by speculative philosophers.

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Categories: Ideas

Cartesianism, experimentalism, and the experimental-speculative distinction

Monday, September 30th, 2013 | Kirsten Walsh | 5 Comments

A guest post by Tammy Nyden and Mihnea Dobre.

Tammy Nyden and Mihnea Dobre write…

A while ago, we published an announcement on this blog of our forthcoming edited volume, Cartesian Empiricisms (Springer 2013). A claim in that post – that some Cartesians “seem to escape the ESD distinction” – has been questioned by Peter Anstey in another post. We thank him for the intervention and would like to push forward our claim and discuss it in more detail as this will reveal some of our concerns with the ESD (experimental-speculative distinction).

In his reply, Peter Anstey asked, “Did the Cartesians practise a form of experimental philosophy analogous to that of the Fellows of the early Royal Society?” We would argue that the question itself is problematic, as there are not two practices or worldviews to compare. There is variation among the Cartesians as well as among the fellows of early Royal Society.  In order to gain a nuanced understanding of these historical actors, we suggest a rather different question: “What role did Cartesian philosophy play in the acceptance and spread of experimental practices in late seventeenth-century philosophy?” When we ask this question, we recognize the experiments of Robert Desgabets on blood transfusion, Henricus Regius on liquids, Burchard de Volder’s with air-pumps, etc., and consider how their work improved experimental technologies, influenced a theoretical reflection on the role of experiments and the senses in natural philosophy, and influenced institutional change that was favorable to experimental science.

Because Cartesians took various aspects of Descartes’ system and merged it with various aspects of experimentalism, there is not one ‘Cartesian’ use of experiment, but several. For example, both Regius and de Volder promoted experiment, but Regius rejects Descartes’ theory of innate ideas while de Volder defends it. Many Cartesians came to reject hyperbolic doubt, some defended vortex theory, some did not. Cartesian Empiricisms is not a complete inventory of such views expressed by Descartes’ followers. Rather our goal was to encourage the discussion of the above-mentioned question and to reveal some aspects that have been unfortunately neglected so far by both historians of philosophy and science.

Readers of this blog are familiar with the objection that traditional historiography of science was built on the Rationalist-Empiricist distinction (RED). A consequence is the exclusion of so-called “rationalists” from the histories of science, particularly history of the use, development and acceptance of experiment. This is problematic because recent research (e.g., Ariew, Lennon and Easton, Easton, Schmaltz, Cook, Nyden, Dobre, etc.) shows that many so-called rationalists were deeply involved in the practice and spread of the acceptance of experiment in natural philosophy. Cartesian Empiricisms gives further emphasis to this issue, as it examines several philosophers who identified as committed Cartesians who were deeply involved in experiment. According to historiographies that divide the period into two mutually exclusive epistemologies or methodologies these philosophers either do not exist (i.e., they are overlooked by histories of philosophy and science) or are seen as “not really Cartesian” or “not really experimentalist,” as it would be needed by that particular narrative. Thus, we do share the concern of the authors of this blog, that such binaries as RED force us to fit philosophers into categories that they would not themselves recognize and causes us to misrepresent seventeenth-century natural philosophy. Moreover, we acknowledge that this blog importantly shows the anachronism of the RED, a way of viewing the period that is constructed later by what may be called Kantian propaganda. However, we would like to raise now some of our concerns with the distinction promoted by this blog, the experimental-speculative distinction (ESD) and explain why some Cartesians would escape the ESD. Our worries cover two important aspects of the ESD: the label “speculative” and the actor-category problem.

(1) In a very recent post, Peter Anstey argued that eighteenth-century Newtonians pointed out Cartesian vortex theory as a prime representative of speculative philosophy (our emphasis). We caution against letting eighteenth-century Newtonian propaganda color a historical interpretation of seventeenth-century natural philosophy. Voltaire, d’Alembert and others took great pains to contrast Newtonianism from Cartesianism as two mutually exclusive worldviews who battled it out, with Newton’s natural philosophy as the victor. But the reality is that after Descartes’ death (1650) and before the victory of Newtonianism in the middle of the eighteenth century, followers of both Descartes and Newton had more in common than we are led to believe. More importantly, both “camps” had more diversity than we were ready to accept in the traditional histories. Cartesian Empiricisms draws attention to that diversity within Cartesianism. Perhaps the one thing Cartesians discussed in the chapters of this volume do have in common is that they do both experimental and speculative philosophy, as these two categories are sometimes defined on this blog. But this last claim leads to our second concern with the ESD.

(2) A reader of this blog will find that when ESD is compared to RED, the first advantage highlighted over the latter is that “the ESD distinction provided the actual historical terms of reference that many philosophers and natural philosophers used from the 1660s until late into the 18th century.” While there is no doubt that many early modern philosophers were using this language (i.e., “experimental” and “speculative”) in their writings, it is equally true that such language is not in use by the Cartesians. If one would be very strict with picking up “the actual historical terms of reference,” one will see another pair of terms keep mentioned by various Cartesians, “experience” and “reason.” Of course, one can read this pair as another form of the ESD, but that would be an interpretation, and a problematic one at that. Both the Cartesians and the so-called “experimentalists” were trying to determine the proper relationship between reason and experience and when one looks at their attempts, it becomes even more difficult to draw a clear line between speculative philosophers and experimentalist philosophers.

Our concern is the possible danger of transforming ESD into a new RED. Experimental and speculative may be useful adjectives to describe aspects of a particular philosophy or particular commitments of a philosopher (especially when the two terms are clearly stated in one’s writings). However, they are not useful for dividing philosophers or their natural philosophies, particularly when they are not already conceived as falling within the “experimental philosophy” camp, as is the case for Cartesians at the end of the seventeenth century.

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Roger Cotes’ ‘Preface’ and the ESD

Monday, September 16th, 2013 | Peter Anstey | No Comments

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.

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Newton’s ‘Phenomena’ continued…

Monday, September 2nd, 2013 | Kirsten Walsh | 1 Comment

Kirsten Walsh writes…

In my last post, I considered the phenomena in book 3 of Newton’s Principia.  Newton’s decision to label these propositions ‘phenomena’ is puzzling, as they do not seem to fit any standard definition of the term.  In this post, I’ll consider Bogen & Woodward’s (1988) distinction between data, phenomena and theories, and suggest that it sheds light both on Newton’s use of ‘phenomena’ and on the connection between his methodology in Opticks and Principia.

Bogen & Woodward (B&W) have argued for a 3-level picture of scientific theories in which:

  1. ‘Data’ are records produced by measurement and experiment that serve as evidence or features of phenomena.  E.g. bubble chamber photographs, and patterns of discharge in electronic particle detectors.
  2. ‘Phenomena’ are features of the world that in principle could recur under different contexts or conditions.  E.g. weak neutral currents, and the decay of a proton.
  3. ‘Theories’ are explanations of the phenomena.

B&W argue that theories explain phenomena, but not data.  Data usually reflect many causal influences besides the explanatory target, while phenomena typically reflect single, or small, manageable numbers of causal influences.  For example, General Relativity explains the phenomenon of bending light, but doesn’t explain the workings of the cameras, optical telescopes, etc. that causally influence the data.

Can we characterise Newton’s phenomena in terms of these three levels of theory?  Let’s consider phenomenon 1:

    “The circumjovial planets, by radii drawn to the centre of Jupiter, describe areas proportional to the times, and their periodic times – the fixed stars being at rest – are as the 3/2 powers of their distances from that centre.”

In his discussion of this phenomenon Newton explained, “This is established from astronomical observations.”  He provided the following table:

These observations are not data in the ‘pure’ sense that B&W discuss.  Rather, they are generalisations: average distances and calculated periods of orbit.  Moreover, the bottom row contains the average distances calculated from the period and the Harmonic rule (that the periods are as the 3/2 power of the semidiameters of their orbits).  These calculations illustrate the ‘fit’ between the expected distance and the observed distance.  Nevertheless, they provide a good example of how we might get from a set of data to a phenomenon.  So perhaps we can think of them as ‘data’ in a methodological sense: they are records from which phenomenal patterns can be drawn.

I have another reason for considering these calculations ‘data’ in B&W’s sense of the term.  In his discussion of phenomenon 1, Newton indicated that these calculations reflect a number of causal influences besides gravity.  For instance, he explained that the length of the telescope affected the measurement of Jupiter’s diameter, because

    “the light of Jupiter is somewhat dilated by its nonuniform refrangibility, and this dilation has a smaller ratio to the diameter of Jupiter in longer and more perfect telescopes than in shorter and less perfect ones.”

This is a nice illustration of B&W’s notion of the shift from data to phenomena.  By attending to his theory about telescopes, Newton was able to manipulate the data to control for distortion.

Now let’s consider the role of phenomenon 1 in Principia.  Phenomenon 1 is employed (in conjunction with proposition 2 or 3, book 1, and corollary 6 to proposition 4, book 1) to support proposition 1, theorem 1, book 3:

    “The forces by which the circumjovial planets are continually drawn away from rectilinear motions and are maintained in their respective orbits are directed to the centre of Jupiter and are inversely as the squares of the distances of their places from that centre.”

This theorem doesn’t contain any information about the sizes or positions of the satellites of Jupiter, or about the workings of telescopes.  So, while it explains the phenomenon, it gives no direct explanation of the data.  This suggests that, in the Principia, data and phenomena are methodologically distinct.

B&W’s distinction between ‘data’ and ‘phenomena’ reveals two methodological features of Newton’s phenomena:

Firstly, Newton’s phenomena are explananda, but not appearances.  Traditionally, ‘phenomenon’ seems to have been synonymous with both ‘appearance’ and ‘explanandum’.  For example, the ancient Greeks were concerned to construct a system that explained and preserved the motions of the celestial bodies as they appeared to terrestrial observers.  2000 years later, Galileo and Cardinal Bellarmine argued over which system, heliocentric or geocentric, provided a better fit and explanation of these appearances.  This suggests that, traditionally, there was no real difference between phenomena and data.  For Newton, however, these come apart.  The six phenomena of Principia describe the motions of celestial bodies, but not as they appear to terrestrial observers.  In this sense, they are not appearances, but they do require an explanation.

Secondly, this reveals a continuity in Newton’s methodology.  The point of Newton’s articulation of ‘phenomena’ in Principia is the same as his experiments in Opticks.  Both identify and isolate a pattern or regularity.  In the Opticks, Newton isolated his explanatory targets by making observations under controlled, experimental conditions.  In Principia, Newton isolated his explanatory targets mathematically: from astronomical data, he calculated the motions of bodies with respect to a central focus.  Viewed in this way, Newton’s phenomena and experiments are different ways of achieving the same thing: isolating explananda.

These considerations are admittedly speculative, so I’m keen to hear what our readers think.  Does this look like a good way of characterising Newton’s phenomena?

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Newton’s ‘Phenomena’

Monday, August 19th, 2013 | Kirsten Walsh | 4 Comments

Kirsten Walsh writes…

On this blog, I have often argued that Newton’s Principia should be characterised as a work of experimental philosophy (for example, here, here and here).  To support this argument, I have tended to emphasise similarities between Newton’s work in optics and mechanics.  Recently, however, I have noted that some aspects of Newton’s methodology varied according to context.  For example, in the Opticks, Newton employed ‘experiments’, but in the Principia, he employed ‘phenomena’.  Given that experimental philosophy emphasises observation- and experiment-based knowledge, it is important for my project that I understand Newton’s use of phenomena, and its relationship to observation.  In this post, I’ll discuss the phenomena in Principia, and in my next, I’ll discuss the relationship between phenomena and experiments in more detail.

Firstly, let’s consider the origin of the phenomena of Principia.  In the first edition of Principia (1687), book 3 contained nine hypotheses.  But in the second edition (1713), Newton re-structured book 3 so that it contained only two hypotheses.  Five of the old hypotheses were re-labelled ‘phenomena’, and he added one more (phenomenon 2), to bring the total to six:

Phenomenon 1: The circumjovial planets, by radii drawn to the centre of Jupiter, describe areas proportional to the times, and their periodic times – the fixed stars being at rest – are as the 3/2 powers of their distances from that centre.

Phenomenon 2: The circumsaturnian planets, by radii drawn to the centre of Saturn, describe areas proportional to the times, and their periodic times – the fixed stars being at rest – are as the 3/2 powers of their distances from that centre.

Phenomenon 3: The orbits of the five primary planets – Mercury, Venus, Mars, Jupiter, and Saturn – encircle the sun.

Phenomenon 4: The periodic times of the five primary planets and of either the sun about the earth or the earth about the sun – the fixed stars being at rest – are as the 3/2 powers of their mean distances from the sun.

Phenomenon 5: The primary planets, by radii drawn to the earth, describe areas in no way proportional to the times but, by radii drawn to the sun, traverse areas proportional to the times.

Phenomenon 6: The moon, by a radius drawn to the centre of the earth, describes areas proportional to the times.

There are several things to notice about these phenomena.  Firstly, they are distinct from data, in that they describe general patterns of motion, rather than measurements of the positions of planetary bodies at particular times.  So, while the phenomena are detected and supported by astronomical observations, they are not observed or perceived directly.

Secondly, they are distinct from noumena (or the nature or essence of things), in that they are facts inferred from the observable, measurable properties of the world.  They describe the motions, sizes and locations of bodies, but not the substance or causes of these properties of bodies.

Thirdly, they describe relative motions of bodies.  That is, in each case, the orbit is described around a fixed point.  For example, phenomenon 1 describes the motions of the satellites of Jupiter around Jupiter, which is taken as a stationary body for the purposes of this proposition.  In phenomena 4 and 5, the motion of Jupiter is described around the sun, which is taken as stationary.

Fourthly, these phenomena do not prioritise the observer.  Rather, each motion is described from the ideal standpoint of the centre of the relevant system: the satellites of Jupiter and Saturn are described from the standpoints of Jupiter and Saturn respectively, the primary planets are described from the standpoint of the sun, and the moon is described from the standpoint of the Earth.  And because Newton doesn’t prioritise the observer, effects such the phases and retrograde motions of the planets are not phenomena but only evidence of phenomena.

The re-labelling of these propositions as ‘phenomena’ is somewhat puzzling.  The term ‘phenomenon’ has a variety of uses, such as:*

  1. A particular (kind of) fact, occurrence, or change, which is perceived or observed, the cause or explanation of which is in question;
  2. An immediate object of sensation or perception (often as distinguished from a real thing or substance); or
  3. An exceptional or unaccountable thing, fact or occurrence.

But, as we’ve seen, Newton’s ‘phenomena’ don’t properly fit any of these definitions.  Can any reader shed light on what Newton really meant by the term?

 

* Definitions (a) and (c) feature in both C18th and C21st dictionaries, but in the C21st, definition (b) has become more prominent, particularly in philosophy.

 

UPDATE: I have written a follow-up post.

 

 

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