Observation and Experiment in the Opticks: A Baconian Interpretation
Kirsten Walsh writes…
In a recent post, I considered Newton’s use of observation and experiment in the Opticks. I suggested that there is a functional (rather than semantic) difference between Newton’s ‘experiments’ and ‘observations’. Although both observations and experiments were reports of observations involving intervention on target systems and manipulation of independent variables, experiments offered individual, and crucial, support for particular propositions, whereas observations only supported propositions collectively.
At the end of the post, I suggested that, if we view them as complex, open ended series’ of experiments, the observations of books 2 and 3 look a lot like what Bacon called ‘experientia literata’, the method by which natural histories were supposed to be generated. In this post, I’ll discuss this suggestion in more detail, following Dana Jalobeanu’s recent work on Bacon’s Latin natural histories and the art of ‘experientia literata’.
The ‘Latin natural histories’ were Bacon’s works of natural history, as opposed to his works about natural history. A notable feature of Bacon’s Latin natural histories is that they were produced from relatively few ‘core experiments’. By varying these core experiments, Bacon generated new cases, observations and facts. The method by which this generation occurs is called the art of ‘experientia literata’. Experientia literata (often referred to as ‘learned experience’) was a late addition to Bacon’s program, developed in De Augmentis scientiarum (1623). It is a tool or technique for guiding the intellect. By following this method, discoveries will be made, not by chance, but by moving from one experiment to the next in a guided, systematic way.
The following features were typical of the experientia literata:
- The series of observations was built around a few core experiments;
- New observations were generated by the systematic variation of experimental parameters;
- The variation could continue indefinitely, so the observation sequence was open-ended;
- The experimental process itself could reveal things about the phenomena, beyond what was revealed by a collection of facts;
- The trajectory of the experimental series was towards increasingly general facts about the phenomena; and
- The results of the observations were collated and presented as tables. These constituted the ‘experimental facts’ to be explained.
Now let’s turn to Newton’s observations. For the sake of brevity, my discussion will focus on the observations in book 2 part I of the Opticks, but most of these features are also found in the observations of book 2 part IV, and in book 3 part I.
Figure 1 (Opticks, book 2 part I)
The Opticks 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. Part I consisted of twenty-four observations. 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. Newton 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. Part II consisted of tables that contained the results of part I. These constituted the experimental facts to be explained in propositions in part III. In part IV, Newton described a new set of observations, which built on the discussions of propositions from part III.
When we consider Newton’s observations alongside Bacon’s experientia literata, we notice some common features.
Firstly, the series of observations was built around the core experiment involving pressing together two prisms to observe the rings that appeared.
Secondly, new observations were generated by the variation of experimental parameters: i.e. new observations were generated, first by varying the obliquity of the incident rays, then by varying the glass instruments, then by varying the colour of the incident light, and so on.
Thirdly, the sequence of observations was open-ended. Newton could have extended the sequence by varying the medium, or some other experimental parameter. Moreover, at the end of the sequence, Newton noted further variations to be carried out by others, which might yield new or more precise observations.
Fourthly, the experimental process itself revealed things about the phenomenon, beyond what was revealed by a collection of facts. For example, in observation 1, Newton noticed that increasing the pressure on the two prisms produced a transparent spot. The process of varying the pressure, and hence the thickness of the film of air between the two prisms, suggested to Newton a way of learning more about the phenomenon of thin plates. He realised he could quantify the phenomenon by introducing regularly curved object glasses, which would make the variation in thickness regular, and hence, calculable.
Fifthly, the trajectory of the experimental series was towards increasingly general facts about the phenomenon. Newton began by simply counting the number of rings and describing the sequence of colours under specific experimental parameters. But eventually he showed that the number of rings and their colours was a function of the thickness and density of the film. Thus, he was able to give a much broader account of the phenomenon.
Finally, these general results were collated and presented as tables in part II. Thus, the tables in part II constituted the facts to be explained by propositions in part III.
Many commentators have emphasised the ways that Newton deviated from Baconian method. However, when viewed in this light, book 2 of the Opticks provides a striking example of conformity to the Baconian method of natural history: Newton led the reader from observations in part I, to tables of facts in part II, to propositions in part III. Moreover, it ended with a further series of observations in part IV, emphasising the open-endedness of the art of experientia literata.
In contrast to the observations in book 2, Newton’s experiments in book 1 look like Bacon’s ‘instances of special power’, which are particularly illuminating cases introduced to provide support for specific propositions. I’ll discuss this next time. For now, I’d like to hear what our readers think of my Baconian interpretation of Newton’s observations.
Experimental philosophy and religion
Peter Anstey writes …
From the first decade of its existence early modern experimental philosophy enjoyed an intimate relation with Christianity. This manifested itself in at least two ways. First, experimental philosophy, it was argued, was a great help in the development of the mind and character of the Christian. Second, and later, it came to play a central role in Christian apologetics. As for experimental philosophy and Christian living, some of the Fellows of the early Royal Society like Joseph Glanvill wrote extensively on the theme of the positive benefits of the practice of experimental philosophy for Christians. See, for example, Glanvill’s Philosopia Pia: or a Discourse of the Religious Temper, and Tendencies of the Experimental Philosophy (1671).
Once experimental philosophy had consolidated its position as a prominent new approach to natural philosophy it began to be used for the purposes of Christian apologetics. In Robert Boyle experimental philosophers had the archetypal Christian virtuoso who not only manifested the benefits of practising Christianity in his character but also did much to promote the link between the new experimental natural philosophy and the defense of the faith. In The Christian Virtuoso he claimed that:
the Experimental Philosophy giving us a more clear discovery, …, of the divine Excellencies display’d in the Fabrick and Conduct of the Universe, and of the Creatures it consists of, … leads it [the mind] directly to the acknowledgment and adoration of a most Intelligent, Powerful and Benign Author of things. (Works of Robert Boyle, 14 vols, eds Hunter and Davis, London, 1999–2000, 11, 293)
Boyle’s ultimate legacy in this regard was the provision in his will for the Boyle Lectures. And it was the inaugural Boyle Lecturer, Richard Bentley, who first mobilized Newton’s new natural philosophy in Christian apologetics in his seventh lecture, published after extensive correspondence with Newton himself (The Folly and Unreasonableness of Atheism, 1693). Once the precedent was established it was continued and augmented in works such as George Cheyne’s Philosophical Principles of Natural Religion (1705), William Derham’s Astro-Theology: or a Demonstration of the Being and Attributes of God, from a Survey of the Heavens (1715) and William Whiston’s Astronomical Principles of Religion, Natural and Revealed (1717).
Interestingly, it was actually the connection with religion that first raised the reading public’s consciousness of experimental philosophy in the Netherlands. For, it is now thought that the publication of Bernard Nieuwentijt’s Het regt gebruik in 1715 marks an important moment in the awakening to experimental philosophy in Holland. This work was translated into English in 1718 by Peter Chamberlayne as The Religious Philosopher with a prefatory letter to the translator by the leading pedagogue of experimental philosophy in England, John Theophilus Desaguliers. Desaguliers commends the work because:
it contains several fine Observations and Experiments, which are altogether new, as is also his manner of treating the most common Phaenomena; from which he deduces admirable Consequences in favour of a Religious Life.
Likewise, Ten Kate’s Dutch adaptation of George Cheyne’s Philosophical Principles of Natural Religion published in Amsterdam in 1716 turned experimental philosophy to apologetical use. Kate claims ‘some distinguished men in England, who disliked the uncertainties of hypotheses [of Cartesianism], have based themselves only on a Philosophia Experimentalis, by means of mathematics’ (Jorink and Zuidervaart, Newton and the Netherlands: how Isaac Newton was Fashioned in the Dutch Republic, 2012, 31). He drew a strong connection between Newton’s natural philosophy and evidence for God’s hand in creation.
Here then, we have an obvious difference between early modern experimental philosophy and its contemporary namesake. I would value references to other works, particularly works in languages other than English, that discuss the practical and apologetical benefits of experimental philosophy to the Christian religion. Let me know if you can help.
Halley’s Comet and Christmas Day
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!)
Birth stats and Divine Providence
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.
Cotes’ Preface and Experiment
Peter Anstey writes…
In my last post I introduced Roger Cotes’ famous Preface to the second edition of Newton’s Principia in order to show its importance as an expression of a commitment to experimental philosophy. In that post I focused on Cotes’ critique of the Cartesian vortex theory and the manner in which this attack on the archetypal speculative philosophy formed the bookends of the Principia. In this post I will discuss the role of experiment in Cotes’ comments on experimental philosophy.
The Preface is actually quite a complex essay that has both polemical and expository agendas. On the one hand, Cotes uses it to give a summary of the main theses of the Principia centred around Newton’s theory of gravity. On the other hand, Cotes uses it to defend the theory of gravity against the charge that it is an occult quality, to defend Newton’s system of the world against the Cartesian vortex theory, and to defend the methodology of the work against rival approaches.
On this latter point, Cotes begins by claiming that Newton’s method is ‘based upon experiment’ (The Principia, eds I.B. Cohen and A. Whitman, Berkeley: University of California Press, 1999, p. 386). One might expect here that Cotes will give a list of the sorts of experimental results that Newton achieved or some reference to crucial experiments, but instead he introduces another set of methodological notions: phenomena, principles, hypotheses, analysis and synthesis. It is only later when appealing to various laws, principles and axioms in his summary of Newton’s system of the world that Cotes refers to experiments.
Here is a summary of Cotes’ account of the method of the Principia. Natural philosophy attempts to derive the causes of all things from the simplest of principles and not from contrived hypotheses. These principles are derived from the phenomena by a two-step process of analysis and synthesis. From select phenomena the forces and simpler laws of these forces are ‘deduced’ by analysis. Then by synthesis ‘the constitution of the rest of the phenomena’ is given. In the case of the Principia the relevant force is gravitational attraction and the relevant law is the inverse square law. Though Cotes throws in the laws of planetary motion claiming that ‘it is reasonable to accept something that can be found by mathematics and proved with the greatest certainty’ (p. 389). He also claims, after presenting a summary of the system of the world, ‘the preceding conclusions are based upon an axiom which is accepted by every philosopher, namely, that effects of the same kind –– that is, effects whose known properties are the same –– have the same causes, and their properties which are not yet known are also the same’. Indeed, ‘all philosophy is based on this rule’ (p. 391).
Where then do experiments fit in this picture? The first mention of experiments is in relation to the law of fall. Cotes refers here to pendulum experiments and to Boyle’s air-pump. Next, Huygens’ pendulum experiments are referred to in the discussion of the determination of the centripetal force of the moon towards the centre of the Earth (p. 389). They then appear in the elaboration of the ‘same effect, same cause’ axiom and its application to the attribution of gravity to all matter. Cotes says ‘[t]he constitution of individual things can be found by observations and experiments’ and from these we make universal judgments (p. 391). Thus, ‘since all terrestrial and celestial bodies on which we can make experiments or observations are heavy, it must be acknowledged without exception that gravity belongs to all bodies universally. … extension, mobility, and impenetrability of bodies are known only through experiments’ and so too is gravity. Finally, in recapping the Newtonian method near the conclusion of the Preface Cotes repeats that ‘honest and fair judges will approve the best method of natural philosophy, which is based on experiments and observations’ (p. 398).
What are we to make of the role of experiments here? First, notice how experiments are appealed to in the establishment of laws and the ‘same effect, same cause’ axiom. Second, it is worth pointing out that the ‘same effect, same cause’ axiom is Newton’s second rule of philosophizing: indeed, Cotes uses the very same example as Newton, namely, the falling of stones in America and Europe (see p. 795). Third, notice how without any explanation Cotes extends experiments to experiments and observations. He begins by saying that there are those ‘whose natural philosophy is based on experiment’ and he ends by saying that ‘the best method of natural philosophy, … is based on experiments and observations’. This is not an equivalent expression and while it is consistent with many other methodological statements by experimental philosophers, it still calls out for explanation.
Has Cotes really given an adequate summary of the method of experimental philosophy and has he captured the manner in which experiments are used in Newton’s reasoning in the Principia? In my view he has not. I’d be interested to hear your views?
Observation, experiment and intervention in Newton’s Opticks
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.
Defining early modern experimental philosophy (3): Some clarifications
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.
Butler and Clarke on the infinity of God
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.
Cartesianism, experimentalism, and the experimental-speculative distinction
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.
Roger Cotes’ ‘Preface’ and the ESD
Peter Anstey writes…
One of the main tasks of this blog over the last three years has been to provide evidence for our claim that from the 1660s the distinction between experimental and speculative philosophy is crucial for an understanding of early modern natural philosophy and even the philosophy of this period in general. More specifically, we have been furnishing evidence that the self-styled experimental philosophers both emphasized the importance of experiment and observation for the acquisition of knowledge, and decried the use of speculation and hypotheses that made little or no appeal to observation. We have also claimed that a prime example of a speculative philosophy that came under attack from experimental philosophers was the Cartesian vortex theory.
It may be surprising, therefore, that hitherto little has been said on this blog about Roger Cotes’ Preface to the second edition of Newton’s Principia published 300 years ago in 1713. For, Cotes’ Preface contains one of the most forthright and sustained defenses of experimental philosophy to be found in the early eighteenth century and it prefaces what can only be described as the most important contribution to natural philosophy in the early modern period.
Cotes begins his Preface with a tripartite distinction between ‘the whole of the Scholastic doctrine derived from Aristotle and the Peripatetics’, (The Principia, 1999, 385) ‘those who take the foundation of their speculations from hypotheses’ and ‘those whose natural philosophy is based upon experiment’. Needless to say, it is this latter method that is ‘incomparably [the] best way of philosophizing’ and ‘which our most celebrated author [Newton] thought should be justly embraced in preference to all others’. (386) The rest of the Preface is a justification of this method of experimental philosophy. First, he elaborates on the method in more detail. He then proceeds to show how Newton’s thesis of universal gravity was established according to this method. Next, he argues against the Cartesian vortex theory and plenist accounts of the universe and, finally, he brings it to a close claiming: ‘Therefore honest and fair judges will approve the best method of natural philosophy, which is based on experiments and observations’. (398).
In this post I shall outline one of the interesting features of Cotes’ critique of the Cartesian vortex theory. In my next post I’ll examine his view of the experimental philosophy in more detail. According to Cotes the speculators ‘are drifting off into dreams, … are merely putting together a romance, elegant perhaps and charming, but nevertheless a romance’ (386) One such romance is the Cartesian vortex theory.
Cometary motion through the vortices of Descartes
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.
