Active-Passive Instruments

W. D. HACKMANN, Scientific Instruments, “passive” and “active” explorers of nature. 1987.

It could be argued that what makes an instrument scientific (that is successful in scientific terms) is not the device per se but the success of its manipulator. A powerful example is Anthony van Leeuwenhoek’s simple lens microscope with which he made more scientific discoveries in the 1680s than all the contemporary ‘superior’ compound-lens microscopes put together [1].

No scientific apparatus is intrinsically self-evidently superior. Its value lies in its power of persuasion. Bachelard has likened an instrument to un “théorème réifié”, and sociologists have analysed the part played by instruments in the scientific and psychological strategies developed to reach a consensus of opinion about a particular theory [2]. From a historian’s point of view such analyses are often ahistorical, [3] but at least they have resulted in a focus on one of the key issues exercising the minds of a number of instruments.


Instrument and Reality

Before I proceed I had better define the different categories of scientific instruments and then focus on the category most pertinent to this paper. Some instruments, such as armillary spheres and orreries were models of how the natural world was perceived. Others, such as clocks, chemical balances, electrometers, galvanometers, and graduated astronomical angle-measuring instruments, were tools of measurement. Increasing their precision made scientific breakthroughs possible but, of course, not inevitable. Tycho Brahe’s new angular measurements were necessary for Kepler’s work, and Flamsteed’s for Newton. A third category, such as telescopes and microscopes, could be classed as observational instruments with which nature was observed passively, while a fourth category, such as electrical machines and air pumps, allowed the manipulator to become an active participant in nature’s laboratory, in this case in space between the electrodes, or in the artificial space inside the bell jar. Thus, certain instruments could be passive or active explorers of nature. This can be a fruitful distinction when analyzing the development of the scientific method. However when looked at historically, these categories blur at the edges, in the same way that armillary spheres when suitably arranged could be used for astronomical observations.

Anthony van Leeuwenhoek’s microscope was the most scientific because of the way it was used (which led to its scientific success). In the same way, instruments such Newton’s prism, can be used passively or actively [4], although it can be argued that there is generally a class of difference between ‘optical instruments’, such as telescopes and microscopes, and ‘philosophical instruments’, such as air pumps and electrical machines. Telescopes and microscopes did not ‘rearrange’ nature, but revealed hitherto unsuspected phenomena and structures not observable with the naked eye. The distinction between passive (purely observational) and active (phenomena-interactive) instruments may help us to understand the basic features of experimental philosophy as reflected for example, in the study of atmospheric electricity [5], or of the aurora borealis.





[1] Success in these terms is judged (a) by the discovery of a new phenomenon, in Leeuwenhoek’s case that bacteria, and (b) persuading fellow practitioners that this phenomenon really exists, primarily by making replication possible (see note 8). In the case of Faraday, the only way he could get fellow practitioners to replicate a specific experiment was by sending them a miniature version of the apparatus.

[2] See G. Bachelard, Les institutions atomistiques (Paris: Presses Universitaires de France, 1933), La formation de l’ésprit scientifique (Paris: Presses Universitaires de France, 1938), and L’activité rationaliste de physique contemporaine (Paris: Presses Universitaires de France, 1951), and for a discussion of his work, see S. Gaukroger, ‘Bachelard and the problem of epistomological analysis’, Studies in the History and Philosophy of Science, vol. 7 (1976), pp. 189-244, and S. Schaffer, ‘Natural philosophy’, in G. S. Rousseau and R. Porter (eds), the The The Ferment of Knowledge, Studies in the Historiography of Eighteenth-Century Science Cambridge University Press, 1980], pp.77-91.

[3] A classic example is T. S. Kuhn’s account of the discovery of the Leyden jar in The structure of scientific Revolutions (University of Chicago Press, 1962), pp. 61-62, which Kuhn agrues as ‘theory-induced’. I would describe such a development much more in terms of organic development and natural selection. See also note 47.

[4] Newton turned an optical toy that could be bought at any fair into a scientific instruments, see Simon Schaffer, ‘Glass works: Newton’s prisms and the uses of experiment’, in Gooding et al., The Uses of Experiment, pp.67-104, esp. p.78.

[5] I have made a similar study of this topic in ‘Instrument and experiments. The case of atmospheric electricity in eighteenth-century Holland’ Tijdschrift voor de Geschiedenis der Geneeskunde, Natuurwetenschappen, Wiskunde en Techniek, vol. 10 (1987), pp. 190 (60)-207 (77). See also my essay review, ‘Lightning rods and model experiments: Franklin’s science comes of ages’, Studies in History and Philosophy of Science, vol. 22 (1991), pp. 679-684. My distinction of passive and active instruments has not won universal acceptance, see for instance J. A. Bennett, A viol of water or a wedge of glass’, in Gooding et al. The Uses of Experiment, pp. 105-114, in which he demonstrates that an instrument can be transformed from being active or passive depending on its use with which I would agree. Bennett appreciates the problems of definition within the context of the various sciences (e.g. optical versus natural philosophy), but suggests that historians should preserve the distinctions (or classifications) established by the practitioners themselves. Thus, the categories ‘mathematical, optical and philosophical instruments’ grew out of the intellectual and craft distinctions of the late seventeenth century. However, as demonstrated by his paper ‘The mechanics’ philosophy and the mechanical philosophy’, History of Science, vol. 24 (1986), pp. 1-28, Bennett in his criticism is too biased towards the seventeenth century, and even here he sticks too rigidly to what he considers to be the category of ‘practical mathematics’. In fact, categories have always been quite fluid, as can be discovered when analysing the shift of the categories of instruments over time in contemporary encyclopedia, such as the various editions of John Harris’s Lexicon technicum; or an Universal Dictionary of Arts and Sciences, explaining not only the terms of Arts, but the Arts themselves (1704). Such a study has not yet been undertaken. At any time, the act of categorizing must be to some extent ahistorical. What Bennett has not appreciated is that my distinction of ‘passive’ and ‘active’ was simply to facilitate a discussion about the role of instruments in experimental philosophy – for which our language is still inadequate. Historians like Bennett have concentrated on the history of astronomy and not on the development of laboratory practices.