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Tag Archives: natural history

Physics: from experimental philosophy to experimental science

Alberto Vanzo writes…

I have been wondering recently when German thinkers ceased considering physics as a part of philosophy and whether this may be related to the demise of experimental philosophy in late eighteenth-century Germany. I think that this may have well been the case. My hypothesis is that experimental philosophy declined as the result of the influence of Kantian and post-Kantian idealism and that the distinction between physics and philosophy gained foot in the 1830s and the 1840s as a reaction to post-Kantian idealism. In this post, I would like to expand on this suggestion and ask you for comments and pointers for further research.

As is well-known, physics was generally regarded as a part of philosophy in the early modern age. This is true for most early modern German writers, including several German experimental philosophers who, in the 1770s and 1780s, attempted to develop their systems on the basis of experiments and observations and eschewed hypotheses and a priori speculations. They held that the whole of philosophy relied on the same method as physics.

In the last two decades of the eighteenth century, Kantian and post-Kantian philosophies came to dominate the philosophical scene and eclipsed the German tradition of experimental philosophy. Kant vindicated a metaphysics based on a priori reasonings rather than observations and experiments. Kant held that we can discover some features of the natural world a priori. He distinguished this a priori, metaphysical study of nature from empirical, experimental physics, which he regarded as a part of philosophy too. However, at the end of the Critique of Pure Reason he introduced a narrow notion of philosophy that includes only a priori disciplines and excludes empirical physics from the domain of philosophy:

    Thus the metaphysics of nature as well as morals, but above all the preparatory (propaedeutic) critique of reason that dares to fly with its own wings, alone constitute that which we can call philosophy in a genuine sense. (A850/B878)

Early-day Kantians agreed with Kant that experimental physics was part of philosophy in the broad sense, but not of philosophy in the narrow sense. However, many of their pronouncements imply that physics (tacitly identified with experimental physics) is not part of philosophy (tacitly identified with Kant’s narrow notion of philosophy). For instance, the Kantian Johann Gottlieb Buhle wrote that, when seventeenth-century writers used the expression “Cartesian philosophy”, they were often thinking “about his physics and cosmogony rather than about his philosophy in the proper sense”. With statements like this, Kant and his disciplines promoted a division of labour between the a priori inquiries of philosophers and the a posteriori research of physicists.

Did German authors start distinguishing between physics and philosophy once the Neo-Kantians started spreading Kant’s outlook in the 1860s, as Richard Rorty claimed? I believe that several German authors started distinguishing physics from philosophy much earlier, in the 1830s or 1840s. One of the most important events in the German intellectual scene between Kant’s death in 1804 and the 1840s was the rise and decline of post-Kantian idealism. Post-Kantian idealists like Schelling and Hegel pursued an approach to the study of nature that was heavily influenced by their own philosophical speculations (Schelling, for instance, founded a Journal for Speculative Physics). I believe that the tendency to distinguish physics from philosophy spread as a reaction to the attitude of post-Kantian idealists towards physics. The entry “Physik” published in the Brockhaus Conversations-Lexicon in 1833, two years after Hegel’s death, states:

    philosophy, at least in Germany, has again attempted to gain influence on physics. However, after all attempts to found physics from this side [i.e. on philosophy] proved unfruitful, only very few physicists, and actually not the most thorough ones, still believe that they could replace the secure footing that mathematics made possible to give [to physics] with the still very shaky concepts of philosophy. Hence, even if the so-called dynamical conception of physics that is related to this philosophical point of view still survives in some speculations, nevertheless we must admit that now only the mechanical point of view is influential and valid in real-life physics [im Leben der Physik].

Although suggestive, this single quote is hardly sufficient to prove my hypothesis that German authors started distinguishing physics from philosophy as a reaction to the post-Kantian idealistic tendencies that had in turn eclipsed experimental philosophy. Do you think that this view is persuasive? Also, when did physics stop being regarded as a part of philosophy in Great Britain and France? I would be grateful for any comments and suggestions.

Leibniz: An Experimental Philosopher?

Alberto Vanzo writes…

In an essay that he published anonymously, Newton used the distinction between experimental and speculative philosophy to attack Leibniz. Newton wrote: “The Philosophy which Mr. Newton in his Principles and Optiques has pursued is Experimental.” Newton went on claiming that Leibniz, instead, “is taken up with Hypotheses, and propounds them, not to be examined by experiments, but to be believed without Examination.”

Leibniz did not accept being classed as a speculative armchair philosopher. He retorted: “I am strongly in favour of the experimental philosophy, but M. Newton is departing very far from it”.

In this post, I will discuss what Leibniz’s professed sympathy for experimental philosophy amounts to. Was Newton right in depicting him as a foe of experimental philosophy?

To answer this question, let us consider four typical features of early modern experimental philosophers:

  1. self-descriptions: experimental philosophers typically called themselves such. At the very least, they professed their sympathy towards experimental philosophy.
  2. friends and foes: experimental philosophers saw themselves as part of a tradition whose “patriarch” was Bacon and whose sworn enemy was Cartesian natural philosophy.
  3. method:experimental philosophers put forward a two-stage model of natural philosophical inquiry: first, collect data by means of experiments and observations; second, build theories on the basis of them. In general, experimental philosophers emphasized the a posteriori origins of our knowledge of nature and they were wary of a priori reasonings.
  4. rhetoric: in the jargon of experimental philosophers, the terms “experiments” and “observations” are good, “hypotheses” and “speculations” are bad. They were often described as fictions, romances, or castles in the air.
  5. Did Leibniz have the four typical features of experimental philosophers?

    First, he declared his sympathy for experimental philosophy in passage quoted at the beginning of this post.

    Second, Leibniz had the same friends and foes of experimental philosophers. He praised Bacon for ably introducing “the art of experimenting”. Speaking of Robert Boyle’s air pump experiments, he called him “the highest of men”. He also criticized Descartes in the same terms as British philosophers:

      if Descartes had relied less on his imaginary hypotheses and had been more attached to experience, I believe that his physics would have been worth following […] (Letter to C. Philipp, 1679)

    Third, the natural-philosophical method of the mature Leibniz displays many affinities with the method of experimental philosophers. To know nature, a “catalogue of experiments is to be compiled” [source]. We must write Baconian natural histories. Then we should “infer a maximum from experience before giving ourselves a freer way to hypotheses” (letter to P.A. Michelotti, 1715). This sounds like the two-stage method that experimental philosophers advocated: first, collect data; second, theorize on the basis of the data.

    Fourth, Leibniz embraces the rhetoric of experimental philosophers, but only in part. He places great importance on experiments and observations. However, he does not criticize hypotheses, speculations, or demonstrative reasonings from first principles as such. This is because demonstrative, a priori reasonings play an important role in Leibniz’s natural philosophy.

    Leibniz thinks that we can prove some general truths about the natural world a priori: for instance, the non-existence of atoms and the law of equality of cause and effect. More importantly, a priori reasonings are necessary to justify our inductive practices.

    When experimental natural philosophers make inductions, they presuppose the truth of certain principles, like the principle of the uniformity of nature: “if the cause is the same or similar in all cases, the effect will be the same or similar in all”. Why should we take this and similar principles to be true? Leibniz notes:

      [I]f these helping propositions, too, were derived from induction, they would need new helping propositions, and so on to infinity, and moral certainty would never be attained. [source]

    There is the danger of an infinite regress. Leibniz avoided it by claiming that the assumption of the uniformity of nature is warranted by a priori arguments. These prove that the world God created obeys to simple and uniform natural laws.

    In conclusion, Leibniz really was, as he wrote, “strongly in favour of the experimental philosophy”. However, he aimed to combine it with a set of a priori, speculative reasonings. These enable us to prove some truths on the constitution of the natural world and justify our inductive practices. Leibniz’s reflections are best seen not as examples of experimental or speculative natural philosophy, but as eclectic attempts to combine the best features of both approaches. In his own words, Leibniz intended “to unite in a happy wedding theoreticians and observers so as to improve on incomplete and particular elements of knowledge” (Grundriss eines Bedenckens […], 1669-1670).

Early modern x-phi: a genre free zone

Peter Anstey writes…

One feature of early modern experimental philosophy that has been brought home to us as we have prepared the exhibition entitled ‘Experimental Philosophy: Old and New’ (soon to appear online) is the broad range of disciplinary domains in which the experimental philosophy was applied in the 17th and 18th centuries. Some of the works on display are books from what we now call the history of science, some are works in the history of medicine, some are works of literature, others are works in moral philosophy, and yet they all have the unifying thread of being related in some way to the experimental philosophy.

Two lessons can be drawn from this. First – and this is a simple point that may not be immediately obvious – there is no distinct genre of experimental philosophical writing. Senac’s Treatise on the Structure of the Heart is just as much a work of experimental philosophy as Newton’s Principia or Hume’s Enquiry concerning the Principles of Morals. To be sure, if one turns to the works from the 1660s to the 1690s written after the method of Baconian natural history, one can find a fairly well-defined genre. But, as we have already argued on this blog, this approach to the experimental philosophy was short-lived and by no means exhausts the works from those decades that employed the new experimental method.

Second, disciplinary boundaries in the 17th and 18th centuries were quite different from those of today. The experimental philosophy emerged in natural philosophy in the 1650s and early 1660s and was quickly applied to medicine, which was widely regarded as continuous with natural philosophy. By the 1670s it was being applied to the study of the understanding in France by Jean-Baptiste du Hamel and later by John Locke. Then from the 1720s and ’30s it began to be applied in moral philosophy and aesthetics. But the salient point here is that in the early modern period there was no clear demarcation between natural philosophy and philosophy as there is today between science and philosophy. Thus Robert Boyle was called ‘the English Philosopher’ and yet today he is remembered as a great scientist. This is one of the most important differences between early modern x-phi and the contemporary phenomenon: early modern x-phi was endorsed and applied across a broad range of disciplines, whereas contemporary x-phi is a methodological stance within philosophy itself.

What is it then that makes an early modern book a work of experimental philosophy? There are at least three qualities each of which is sufficient to qualify a book as a work of experimental philosophy:

  1. an explicit endorsement of the experimental philosophy and its salient doctrines (such as an emphasis on the acquisition of knowledge by observation and experiment, opposition to speculative philosophy);
  2. an explicit application of the general method of the experimental philosophy;
  3. acknowledgment by others that a book is a work of experimental philosophy.

Now, some of the books in the exhibition are precursors  to the emergence of the experimental philosophy (such as Bacon’s Sylva sylvarum). Some of them are comments on the experimental philosophy by sympathetic observers (Sprat’s History of the Royal Society), and others poke fun at the new experimental approach (Swift’s Gulliver’s Travels). But this still leaves a large number of very diverse works, which qualify as works of experimental philosophy. Early modern x-phi is a genre free zone.

From Experimental Philosophy to Empiricism: 20 Theses for Discussion

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

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

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

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

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

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

Here are our articles, divided into six handy categories:


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

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

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

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


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

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

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

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


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

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

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


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


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

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

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

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

From Experimental Philosophy to Empiricism

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

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

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

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

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

(in their terms, “observational philosophers”)

Two Forms of Natural History

Peter Anstey writes…

There were two forms of natural history in the early modern period: traditional natural history and Baconian natural history. The distinction between them becomes clear in the light of the development of the experimental philosophy in the mid-17th century. Unfortunately, however, this distinction is almost always elided in the secondary literature on natural history.

Traditional natural history, deriving from Pliny the Elder and Dioscorides, had flourished in the late Renaissance. It involved the mapping of nature through the classification of plants and animals and the assembling of information about their uses and habits. This traditional natural history continued throughout the 17th century and reached its zenith in the 18th century in the work of the likes of Carl Linnaeus. But this was neither the only form of natural history, nor, for that matter, was it the most important form for the experimental philosophers. Let me explain.

The experimental philosophy of the seventeenth century developed as a method of knowledge acquisition in natural philosophy. However, unlike the division between science and philosophy today, in the early modern period natural philosophy and philosophy were not regarded as discrete disciplinary domains. Natural philosophy was thought to be the philosophy of nature, rather than, say, the philosophy of morality or metaphysics. Thus Descartes’ Principles of Philosophy are principles of natural philosophy and this work presents his mature natural philosophical system.

Robert Boyle's General History of the Air

Robert Boyle's General History of the Air

The experimental philosophy was initially developed and applied in the study of nature and only later was it applied more broadly to the other parts of philosophy. The first ‘version’ of the experimental philosophy was the Baconian method of natural history. This was inspired by Francis Bacon’s grand scheme for the renovation of knowledge of nature and in particular his novel approach to natural history.

The Baconian method involved the assembling of vast amounts of data about particular substances, qualities or states of bodies. In this way it was far broader in its scope than traditional natural history. To be sure, it included facts about generations––that is animal, plant and insect species-–but it included much more, such as histories of cold, of the air, of electrostatic phenomena and of fluidity and solidity, etc. According to the Baconian method, once all of the facts were collected they were to be ordered and structured in such a way as to facilitate theoretical, or speculative, reflection upon the phenomenon at hand. Thus, once all the facts about, say, human blood or the air, were gathered, then the natural philosopher would be in a position to develop a true and accurate philosophy of the blood or air.

It was this method that was developed in a detailed and sophisticated way by the early Royal Society and which became popular across Europe in the second half of the 17th century. This Baconian natural history encompassed traditional natural history and as a result traditional natural history flourished under its aegis. But, the Baconian form of natural history was short-lived: it was in serious decline in the 1690s and all but disappeared in the first decades of the 18th century. All the while traditional natural history was going from strength to strength and was soon to become one of the most important branches of 18th century science.

The reasons for the decline of Baconian natural history need not detain us here, but the reason for the eliding of the distinction between it and traditional natural history is of great importance. I contend that scholars have failed to distinguish between the two because of their failure to appreciate the nature and significance of the experimental philosophy in general. When we view early modern natural history through the lens of the experimental philosophy the distinction between the two forms of natural history becomes clear. This is another reason why, as I claimed in an earlier post, ESP is best!