Instruments: meaning is use

Wittgenstein's well known definition of meaning (Bedeutung) is found in § 43 of the Philosophical Investigations, and Anscombe's English rendering is: "the meaning of a word is its use in the language". Just after this sentence we read: "And the meaning of a name is sometimes explained by pointing to its bearer." (Wittgenstein 1986, pp. 20-21; italics in the text) Wittgenstein's suggestions may be useful in the present research from several points of view. In the first place, we may look at the use of the word 'instrument' in the contemporary historiography and philosophy of science in order to obtain a few traits of the meaning of the word, and the correlate traits of the historians' and philosophers' interpretation of what is an object named 'instrument'. In the second place, we will briefly consider the lexical and semantic fields which the word 'instrument' belongs to, within the obvious limits of the particular natural language that we are using (e.g. English); in this way we will able to collect the traits of the meaning which are useful for an understanding of the likening 'chemicals as instruments'. In the third place, we will later reflect on Wittgenstein's stress on that particular relationship between the meaning of a name and the bearer of the name which is - often only tentatively - realized by ostension; 'ostension' may acquire a particular meaning in the context of chemical research (vide infra, section 5). Lastly, I mention here that when we choose a particular instrument we can, at any time, list its actual uses, and describe the rules of use in different experimental circumstances. The list of uses and the description of their rules are important parts of the meaning of the name of an instrument, moreover the meaning is changing along with the changes in the actual use of the instrument (sometimes during the same process of its 'construction'). This diachronic aspect is important because it reveals several similarities between chemicals and the instruments used in physics or astronomy. 

The scope of the current, implicit definition of 'instrument' is well documented in an issue of Osiris (Vol. 9, 1994) in which instruments are discussed in different contexts, ranging from authority and audience, to culture at large and life sciences. The instruments treated includes very different 'objects': the classical telescopes (from Galileo to Cassini), Lavoisier's apparatus (calorimeter, gasometer, etc.), devices used in precise electrical measurement, compasses of different kinds, the Stanford's supervoltage X-ray tube, charge-coupled devices used in the Hubble space telescope, the observational instrumentation of the Imperial Astronomical Bureau of the Ming dynasty (armillary sphere, gnomon, water clock, etc.), and so on, through a very dubious, and only imagined instrument as Castel's ocular harpsichord, and the demonstration devices in Georgian mechanics (including Atwood's machine). An analogous amazing variety of devices is found in the important book edited in 1989 by Gooding, Pinch and Schaffer, under the programmatic title The Uses of Experiment. Here we found, near the ubiquitous Atwood's machine, "the biggest machine in the world" for accelerating elementary particles, planned by CERN in the first 1950's (Krige 1989, p. 401). In the same book two very interesting essays discuss in particular the relevance of the uses of instruments for an understanding of the science endeavor. Their titles too are evocative: "Scientific instruments: models of brass and aids to discovery" (Hackmann 1989) and "A viol of water or a wedge of glass" (Bennett 1989).

Many of the 'instruments' discussed in Osiris and in The Uses of Experiment were connected with measurement procedures of physical nature (including Lavoisier's apparatus); other were constructed in order to create and observe new, unusual phenomena (in our times typically the particle accelerators, but in the seventeenth century also Boyle's air pump). These two aspects, obvious in our days, were not always so granted. Referring to the Scientific Revolution, and commenting on the essays of the quoted Osiris issue, van Helden and Hankins stress that "In the seventeenth century it was unclear how instruments like the telescope, microscope, and air pump should be used to obtain natural knowledge. [...] the instruments were new and there was no established convention for using them or for validating their results. [...] the new instruments of the Scientific Revolution seldom measured anything, at least not at first." (van Helden and Hankins 1994, p. 3)

The historical perspective discloses a whole collection of disparate 'objects' which functioned or function as scientific instrument. Usually the contemporary philosophical perspective has been dramatically narrower, focusing on the research results (in connection with a so-and-so theory) and not on the experimental procedures which led to theses results. The editors of The uses of experiments stated: "The invisibility of instruments is [...] an important if paradoxical consequence of experimental achievement. Recovering the role of instruments in experiment represents an important advance in the understanding of how scientists achieve certainty." (Gooding et al. 1989, p. 5; my italics) However, the attention to the actual laboratory practices has been present in the philosophical analysis also before the ethnological study of the Laboratory Life by Latour and Woolgar (first edn. 1979). I refer, for example, to Michael Polanyi. After he contrasts "the supposed supremacy of experiment over theory" and illustrates the "power of scientific theory over scientific facts" (Polanyi 1983, p. 167; 1st edn. 1958), he discusses the relation between science and technology and introduces the notion of 'practical performance' to which "three kinds of observable things" belong: "(1) materials, (2) tools, including all manner of installations, and (3) processes"; "hammers, engines, houses, railways, are tools or installations". A page later he states: "Technology teaches only actions to be undertaken for material advantages by use of implements according to (more or less) specifiable rules", and in a note he explains that "The word 'implements' is meant to designate all three classes of useful things: materials, devices and processes" (Polanyi 1983, pp. 175-176).

To be sure, Polanyi's separation between science and technology is too sharp, especially in the case of chemistry, a science that was always cultivated by scientists proud of their practical performances in laboratory. But I agree with Polanyi's focus on 'implements', and with his wide definition of the things useful for research, because in the epistemological analysis of experimental procedures it is crucial to appreciate that - generally speaking - no 'instrument' may function isolated from other instruments. Distinctions have been made between devices and systems, in that systems are composed of devices put together for a practical performance, whereas devices are themselves 'single entities' (references in Smith and Tatarewicz 1994). However, it is highly questionable whether a bit of scientific equipment was or is really a single entity; anyway, scientists have worked at any time with systems of devices of many different kinds. It was so at the same beginning of the Scientific Revolution: it is sufficient to look at the famous tables which illustrates the experimental devices used by Boyle for his New Experiments Physico-Mechanical, Touching the Spring of the Air (1660). To this, the second aspect stressed by Polanyi is also to be added, namely the specifiable rules to be followed in the actual use of instruments. These rules are not at all simple, or stated once for ever. In this context the arguments developed by Bridgman regarding the measurement of temperature by a thermometer are important, because Bridgman considers the use of a very simple, well-known instrument (a bulb thermometer), and demonstrates the difficulty of being sure about what one is actually measuring (Bridgman 1927).

In Hacking's "primer on the epistemology of experiment" (definition in Fuller 1989, p. 132), we found a good example of the multiplicity of names (and, implicitly, of 'objects' referred to) used in the description of the scientific activity by means of 'instruments'. At the beginning of the chapter dedicated to 'observation' Hacking uses three different terms, whose generality may be appreciated reading them in their immediate context: "Often the experimental task, [...] is less to observe and report, than to get some bit of equipment to exhibit phenomena in a reliable way. […] The good experimenter is often the observant one who sees the instructive quirks or unexpected outcomes of this or that bit of the equipment. You will not get the apparatus working unless you are observant. […] We usually observe objects or events with instruments." (Hacking 1990, pp. 167-168, my emphasis) The coherence of Hacking's discourse assures us that 'instrument', 'apparatus', and 'bit of equipment' belong to the same lexical field. To these terms we can add the other ones used by the authors of the preceding quotes: 'device', 'demonstration device', 'observational instrumentation', 'machine', 'models', 'tool', 'installation', 'implement'. It is a fundamental principle of the linguistic field theory that the value of a word is recognized only when the word is considered together with the other ones, which are 'near' or 'in opposition' to it (Geckeler 1971). It is obvious that in many contexts of the scientific discourse 'instrument' cannot be substituted by 'installation', but many other contexts might be found where the substitution is feasible without any difficulty (I think, for example, of installations for the research in hydraulics, as the test-tanks). We can now look for the traits of the semantic field which are able 'to attract' so different words in the same lexical field.

For the aims of the present paper it is not necessary to go beyond a simple consideration: all the listed 'useful things' function as 'instruments' when, and only when, they are used according to a set of rules in the context of a scientific and/or technological research. It is a particular knowledge function that gives something the status of an instrument. (If an alembic is used as a knick-knack, it is no more an instrument; it is a piece of furniture.) Thus, the semantic traits, which bring together those disparate words, must be connected to the practical, particular use of the referred 'objects' - and to the particular rules of their use (of the objects and of the words). An instrument has to exhibit "phenomena in a reliable way", but it may also disclose "instructive quirks or unexpected outcomes"; it is used to "observe objects or events" (Hacking, as quoted above), both "for qualitative observations" and "for quantitative measurement of properties" (Krige 1989, p. 402; italics in the text). Thus "The instrument must be able to isolate, physically, the properties of the entities that we wish to use" (Hacking 1990, p. 265); eventually, and classically, scientific instruments make "visible what could not be seen by the unaided senses" (Hackmann 1989, p. 31). To these very general traits, another one, extremely important from the historical and epistemological points of view, is to be added. Van Helden and Hankins point out that "Because instruments determine what can be done, they also determine to some extent what can be thought". The authors stress a positive aspect: "Often the instrument provides a possibility; it is an initiator of investigation." (Van Helden and Hankins 1994, p. 4) I agree, and later we will see several related examples, but I also suggest that there is a dark side of the question, namely that many fashioned instruments have erased other valuable knowledge procedures, and that their academically profitable use has concealed other research opportunities.

In this section we have seen that several traits of the semantic content of the word 'instrument' are present in many other words, and that these particular traits became pertinent and evident when those words are used in the scientific/technological discourse. In the next three sections I will consider the uses of two classes of chemicals (solvents and indicators), and of few other substances: it will be easy to demonstrate that in many cases their scientific and technological use correspond to that of an 'instrument'.