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Monthly Archives: September 2013

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

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.

Newton’s ‘Phenomena’ continued…

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?