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Monthly Archives: January 2012

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.

Aberdeen’s 1755 Plan of Education

Juan Gomez writes …

One of the topics we have covered in this blog is education. I have commented on David Fordyce’s ideas, and Gerhard Wiesenfeldt contributed to the blog with two very interesting posts on Speculative and Experimental Philosophy in Universities (Post-Cartesianism and Eclecticism). In this post I want to expand on this topic and tell you about Alexander Gerard‘s Plan of Education.

As we have mentioned throughout various posts in this blog, one of the features of those allied with experimental philosophy was their disdain for the scholastic school of thought and the rejection of mere speculation. This led the regents and teachers in Colleges and Universities to revolt against the scholastic teaching system and promote a change in the way education was structured. In Aberdeen, the first stages of this project of reformation started with the teachings of George Turnbull and Colin MacLaurin in the 1720’s, but we had to wait until the 1750’s for the reform of the curriculum. It was written by Alexander Gerard and published in 1755. It gives us a good overview of what the members of the faculty found wrong with the scholastic mode of thinking and the central role experimental philosophy (and the experimental method) should take in the colleges and universities.

Gerard begins by explaining why the faculty members at Marischal college have decided to reform the method of education. The method used in most European universities, Gerard tells us, was that of the Peripatetic Philosophy ‘espoused by the Scholastics’. This is his description:

    The chief business of that Philosophy, was, to express opinions in hard and unintelligible terms; the student needed a dictionary or nomenclature of the technical words and authorized distinctions; experiment was quite neglected, science was to be reasoned out from general principles, either taken for granted, or deduced by comparison of general ideas, or founded on very narrow and inadequate observation: Ontology, which explained these terms and distinctions, and laid down these principles, was therefore introduced immediately after logic. By these two, the student was sufficiently prepared for the verbal, or at best, ideal inquiries of the other parts.

Fortunately, the state of philosophy had changed:

    [Philosophy] is become an image, not of human phantasies and conceits, but of the reality of nature, and truth of things. The only basis of Philosophy is now acknowledged to be an accurate and extensive history of nature, exhibiting an exact view of the various Phenomena for which Philosophy is to account, and on which it is to found its reasonings.

This change in Philosophy posed a problem for a system that was based on Scholastic methods. If philosophy is founded on facts and observation, from which we then derive the terms or notions, the system of education was flawed by teaching first the notions and principles without any experience of the facts they refer to. The teachers at Marischal proposed to restructure the order in which the different subjects were taught. Instead of starting with Logic and Ontology, the students “after being instructed in languages and classical learning, be made acquainted with the Elements of History, Natural and Civil, of Geography and Chronology, accompanied with the Elements of Mathematics; that they should then proceed to Natural Philosophy, and, last of all, to Morals, Politics, Logic and Metaphysics.” This new curriculum was much better suited for the pursuit of knowledge and the aims and methods of the new philosophy.

Most of the pamphlet is an attack on the scholastic system that justifies the decision of the Masters of the college to leave the teaching of Logic to the final year. There are constant references made to the importance of facts, experiments, and observations as the sole foundation of knowledge. Any sort of purely speculative way of thinking was not to be included in education. But the promoters of this reform were not claiming that logic and metaphysics were of no use at all; what we need to understand is that they are entirely dependent on all the other sciences, and if they are to contribute in our search for knowledge, then they must come after all the other sciences. The attack of the promoters of the methods of the experimental philosophy was not against speculative subjects themselves, but against the scholastic methods of education that considered speculation to be more important than our knowledge of the natural world.

Experimental Philosophy and the Straw Man Problem

Peter Anstey writes …

One common objection against the experimental–speculative distinction (ESD) as an alternative historiographical framework for understanding early modern philosophy is the Straw Man Problem. Our interlocutors are prepared to admit the importance of the emergence of the experimental philosophy in Britain in the mid-seventeenth century and its subsequent uptake across the Continent. However, they object that, in spite of all the experimental philosophers’ rhetoric, there were few, if any, speculative philosophers. The speculative philosopher, in their view, is merely a straw man, a creation of the experimental philosophers who needed someone or something to define themselves against. The claim, then, is that there was not really any substantive experimental–speculative distinction because there were not really any speculative philosophers.

In my view this objection is based upon a superficial understanding of the ESD. Moreover, I believe that providing an adequate response to the Straw Man Problem is a good way to highlight what is at the core of the ESD framework.

A weakness of the Straw Man objection is the presumption of parity: it is assumed that if we have an actual distinction then we have practitioners of, more or less, equal number on both sides of the distinction. This presumption may derive from the Kantian rationalism–empiricism historiography with its two triumvirates of Descartes, Leibniz and Spinoza versus Locke, Berkeley and Hume. Be that as it may, it is certainly true that there were very few advocates of speculative philosophy after the 1660s. In Britain, Thomas Hobbes, Margaret Cavendish and John Sergeant were all opponents of the experimental philosophy and so might be classed as speculative philosophers, but it’s hard to name any others.

Nevertheless, this lack of parity does nothing to undermine the ESD. For, what is important is that it is the method, content and characteristics of speculative philosophy that were the focus of experimental philosophers’ attacks and disdain and not, on the whole, the practitioners themselves.

The ESD is, therefore, in the first instance a distinction that pertains to natural philosophical (and later philosophical) methodology and only secondarily to individuals. A nice analogue here is found in twentieth-century philosophy of mind. From the 1970s most philosophers were materialists or physicalists about the mind and it became hard to name any substance dualists. And yet physicalists about the mind defined their position, in large part, as being distinct from and opposed to dualism. Anyone who has done even the most cursory reading in the philosophy of mind knows that there is an historical explanation of this phenomenon. The Identity Theory emerged in the 1960s on the back of the attack on the ‘ghost in the machine’ by Gilbert Ryle and others. Early materialist theories of the mind were new and radical in so far as they defined themselves against dualism, even if within a few decades there were hardly any dualists to be found.

A similar situation is to be found with the emergence and growth of early modern experimental philosophy. There had been a long tradition in philosophy of distinguishing between speculative and operative philosophy, between speculative and operative knowledge and even speculative and operative intellects. Natural philosophy had almost invariably been classified as a speculative science. The conceit of the Fellows of the early Royal Society (among others) was to claim not only that natural philosophy could also be an operative (that is, experimental) science, but that the operative method of natural philosophy is far superior to the old speculative approach.

Thus, in order to explain the nature of the ESD, we shouldn’t look forward from the mid-seventeenth century for parity among practitioners from either side, rather we should look back to the origins of the distinction. In so doing it becomes clear that the speculative philosopher is no straw man.



Hypotheses and Newton’s Rings

Kirsten Walsh writes…

In Ian Lawson’s recent post, he mentioned Hooke’s work on colours in thin films.  In this post, I’ll look at how Newton used his hypotheses on light to build on Hooke’s work in some interesting and important ways.

In his optical work of the early 1670s, while Newton prefers theories to hypotheses, he thinks that hypotheses are acceptable, even useful, for two purposes:

  1. To ‘illustrate’ (i.e. provide an intuitively plausible explanation of) the theory; and
  2. To ‘suggest’ experiments.

However, he insists that hypotheses should always be removed from the final version of the theory.  Recall Newton’s claim from his 1672 paper: “I shall not mingle conjectures with certainties”.

In December 1675, Newton wrote his paper, “An hypothesis explaining the Properties of Light”.  Here, he published his hypotheses on the nature of light for the first time.  To summarise them briefly:

  1. There is an ‘aethereal medium’;
  2. Aether vibrates, carrying sounds, smells and light;
  3. Aether penetrates and passes through the pores of solid substances;
  4. Light is neither the aether itself, nor the vibrations, but a substance that is propagated from ‘lucid’ bodies and travels through the aether;
  5. Light warms the aether and the aether refracts the light; and
  6. The rays (or bodies) of which light consists differ from one another physically.

In this paper, Newton claims that he is only discussing these hypotheses for the purposes of ‘illuminating’ his theory.  Moreover, he does not assert that these hypotheses are true, and emphatically does not use them to support his theory.  For example, when he discusses hypothesis (4), Newton is careful not to push too forcefully for any particular account of light.  He says one might suppose light to be “an aggregate of various peripatetic qualities”, or “unimaginably small and swift” corpuscles of various sizes, or “any other corporeal emanation or impulse or motion of any other medium diffused through the body of the aether”:

    Onely whatever Light be, I would suppose, it consists of Successive rayes differing from one another in contingent circumstances, as bignes, forme or vigour…  And further I would suppose it divers from the vibrations of the aether.

In this paper, there is a notable emphasis on experiment.  For example, when Newton discusses hypothesis (1), he gives an account of a new electrical experiment which seems to support his claim.  And when he discusses hypothesis (3), he discusses the implications for Boyle’s tadpole experiments.  But the most important experiments in this paper are his investigations on the colours that appear between two glass surfaces.

Alan Shapiro notes that Newton began these investigations while he was reading Hooke’s Micrographia.  But his experiments and mathematical descriptions quickly developed into something well beyond the scope of Hooke’s investigations.  Hooke described the colours that appear when two thin sheets of glass are placed one on top of the other.  When he made the thin film of air between the two sheets thicker or thinner by pressing the two sheets together with greater or lesser force, the colours changed.  He observed that different colours appeared at different thicknesses, but he was unable to quantify this observation as he was unable to measure accurately the thickness of the film at any given point.  Newton had the idea of placing a convex lens on top of a flat sheet of glass.  This enabled him to easily calculate the thickness of the film of air, and the colours appeared as a set of concentric coloured circles centred at the point of contact between the two surfaces.  These concentric circles are now known as ‘Newton’s Rings’.

Opticks, Book 2, Figure 3






Next Newton considered his hypotheses.  According to hypothesis (2) the vibrations of the aether vary in size, according to hypothesis (3) aether passes through the pores of solid substances, and according to hypothesis (6) rays of different colours will cause aethereal vibrations of different sizes.  If these hypotheses were correct, he argued, then light of a particular colour would be reflected either when the length of the vibration, or some multiple of the length of the vibration, matched the thickness of the film, and transmitted otherwise.  So he predicted that:

    if the Glasses in this posture be looked upon, there ought to appear at A [the centre], the contact of the Glasses, a black spott, & about that many concentric circles of light & darknesse, the squares of whose semidiameters are to sense in arithmetical progression.

Newton’s “Hypothesis” paper provides a good example of his method of hypotheses.  He remains carefully detached from his own hypothesis, using it only to ‘illustrate’ his theory and to suggest further experiments.  Newton was also careful to keep his hypotheses well separate from his theory; the paper ends with a series of ‘Observations’ that contain no reference to his hypotheses at all!

Workshop: Letters by Early Modern Philosophers

The workshop is part of the 13th International Conference of the International Society for the Study of European Ideas which will take place in Cyprus on 2-6 July 2012.

The workshop focuses on letters written in the seventeenth century on themes at the border between art, science, and philosophy. A presentation of the workshop topic can be found here.

Abstracts of up to 500 words should be sent to the workshop organiser, Filip Buyse, at