by Hasok Chang
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understandable, but I believe it can be dispelled through a more careful consideration of what it means to generate knowledge. I will make such a consideration in this section, with illustrations from the material covered in previous chapters and occasional references to other works. There are three main ways in which complementary science can add to scientific knowledge, which I will address in turn.
Recovery
First of all, history can teach us about nature through the recovery of forgotten scientific knowledge. The potential for such recovery is shown amply in the material uncovered in chapter 1. Many investigators starting from De Luc in the late eighteenth century knew that pure water did not always boil at the "boiling point" even under standard pressure. They built up a growing and sophisticated body of knowledge about the "superheating" of water and other liquids that took place under various circumstances, and at least in one case observed that boiling could also take place slightly under the boiling point as well. But by the end of the nineteenth century we witness Aitken's complaint that authoritative texts were neglecting this body of knowledge, either through ignorance or through oversimplification. Personally, I can say that I have received a fair amount of higher education in physics at reputable institutions, but I do not recall ever learning about the superheating of water and the threat it might pose to the fixity of the boiling point. All I know about it has been learned from reading papers and textbooks from the eighteenth and nineteenth centuries. I predict that most readers of this book will have learned about it from here for the first time.
This is not to say that knowledge of superheating has been lost entirely to modern science. The relevant specialists do know that liquid water can reach temperatures beyond the normal boiling point without boiling, and standard textbooks of physical chemistry often mention that fact in passing.3 Much less commonly noted is the old observation that water that is actually boiling can have various temperatures deviating from the standard boiling point. There are vast numbers of scientifically educated people today who do not know anything about these very basic and important phenomena. In fact, what they do claim to know is that superheating does not happen, when they unsuspectingly recite from their textbooks that pure water always boils at 100°C under standard atmospheric pressure. Most people are not taught about superheating because they do not need to know about it. As explained in "The Defense of Fixity" in chapter 1, the routine conditions under which thermometers are calibrated easily prevent superheating, so that people who use thermometers or even those who make thermometers need not
3. See, for example, Oxtoby et al. 1999, 153; Atkins 1987, 154; Silbey and Alberty 2001, 190; Rowlinson 1969, 20. Interestingly, the explanations of superheating they offer are quite diverse, though not necessarily mutually contradictory. Silbey and Alberty attribute it to the collapse of nascent vapor bubbles due to surface tension (cf. De Luc's account of "hissing" before full boil). According to Atkins it occurs "because the vapor pressure inside a cavity is artificially low," which can happen for instance when the water is not stirred. But Oxtoby et al. imply that superheating can only occur when water is heated rapidly.
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have any knowledge of superheating. Only those whose business it is to study changes of state under unusual circumstances need to be aware of superheating. This is a case of knowledge that is not widely remembered because knowing it does not help the pursuit of most of current specialist research.
There is another category of experimental knowledge that tends to get lost, namely facts that actively disturb our basic conceptual schemes. The best example of this category that I know is Pictet's experiment discussed in "Temperature, Heat, and Cold" in chapter 4, in which there is an apparent radiation and reflection of rays of cold, as well as rays of heat. This experiment received a good deal of attention at the time and it seems that most people who were knowledgeable about heat in the early nineteenth century knew about it, but gradually it became forgotten (see Chang 2002 and references therein). Nowadays only the most knowledgeable historians of that period of physics seem to know about this experiment at all. Unlike superheating, the radiation of cold is not a phenomenon recognized by most modern specialists on heat and radiation, to the best of my knowledge. It just does not fit into a scheme in which heat is a form of energy and cold can only be a relative deficit of energy, not something positive; remembering the existence of cold radiation will only create cognitive dissonance for the energy-based specialist.
When we make a recovery of forgotten empirical knowledge from the historical record, the claimed observation of the seemingly unlikely phenomenon is likely to arouse curiosity, if not suspicion. Can water really reach 200°C without boiling, as observed by Krebs?4 Other people's observations can and should be subjected to doubt when there is good reason; otherwise we would have to take all testimony as equally valid, whether they be of N-rays, alien abductions, or spontaneous human combustion. Radical skepticism would lead us to conclude that there is no way to verify past observations, but more pragmatic doubts would lead to an attempt to re-create past experiments where possible.
In conducting the studies included in this book, I have not been in a position to make any laboratory experiments. However, historians of science have begun to re-create various past experiments.5 Most of those works have not been carried out for complementary-scientific reasons, but the potential is obvious. One case that illustrates the potential amply is the replication of Pictet's experiment on the radiation and reflection of cold, published by James Evans and Brian Popp in the American Journal of Physics in 1985, in which they report (p. *738): "Most physicists, on seeing it demonstrated for the first time, find it surprising and even puzzling." Through this work, Evans and Popp brought back the apparent radiation and reflection of cold as a recognized real phenomenon (though they do not regard it as a manifestation of any positive reality of "cold"). However, all indications are that it
4. Rowlinson (1969, 20) actually notes a 1924 experiment in which a temperature of 270°C was achieved.
5. Salient examples include the replication of Coulomb's electrostatic torsion-balance experiment by Peter Heering (1992, 1994), and Joule's paddle-wheel experiment by H. Otto Sibum (1995). Currently William Newman is working on repeating Newton's alchemical experiment, and Jed Buchwald has been teaching laboratory courses at MIT and Caltech in which students replicate significant experiments from the history of science.
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was quickly forgotten all over again, or not noticed very much. This is not only based on my own patchy impressions of what people do and do not seem to know. A search in the combined Science Citation Index (Expanded), the Social Sciences Citation Index and the Arts and Humanities Citation Index, conducted in March 2003, turned up only two citations. One was a one-paragraph query published in the Letters section of a subsequent number of the American Journal of Physics (Penn 1986), and the other was my own article on this subject (Chang 2002)!
The recovery of forgotten knowledge is not restricted to facts, but extends to ideas as well (and it is, after all, very difficult to separate facts and ideas cleanly). In fact, historians of science for many decades have made great efforts to remember all sorts of ideas that have been forgotten by modern science. This kind of recovery is the mainstay of the history of science, so much so that there is no point in picking out a few examples out of the great multitude. But in order for the recovered ideas to enter the realm of complementary science, we need to get beyond thinking that they are merely curious notions from the past that are either plainly incorrect or at least irrelevant to our own current knowledge of nature. I will be considering that point in more detail later.
The consideration of recovery raises a basic question about what it means for knowledge to exist. When we say we have knowledge, it must mean that we have knowledge; it is no use if the ultimate truth about the universe was known by a clan of people who died off 500 years ago without leaving any records or
by some space aliens unknown to us. Conversely, in a very real sense, we create knowledge when we give it to more people. And the acquisition of the "same" piece of knowledge by every new person will have a distinct meaning and import within that individual's system of beliefs. When it comes to knowledge, dissemination is a genuine form of creation, and recovery from the historical record is a form of dissemination—from the past to the present across a gap created by institutional amnesia, bridged by the durability of paper, ink, and libraries.
Critical Awareness
Superficially, it might appear that much of the work in complementary science actually undermines scientific knowledge because it tends to generate various degrees of doubt about the accepted truths of science, as we have seen in each of the first three chapters of this book. Generating doubt may seem like the precise opposite of generating knowledge, but I would argue that constructive skepticism can enhance the quality of knowledge, if not its quantity. If something is actually uncertain, our knowledge is superior if it is accompanied by an appropriate degree of doubt rather than blind faith. If the reasons we have for a certain belief are inconclusive, being aware of the inconclusiveness prepares us better for the possibility that other reasons may emerge to overturn our belief. With a critical awareness of uncertainty and inconclusiveness, our knowledge reaches a higher level of flexibility and sophistication. Strictly speaking, complementary science is not necessary for such a critical awareness in each case; in principle, specialist scientists could take care not to forget the imperfection of existing knowledge. However, in practice it is going to be very difficult for specialists to maintain this kind of critical
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vigilance on the foundations of their own practice, except in isolated cases. The task is much more easily and naturally undertaken by philosophers and historians of science.
Even philosophers tend not to recognize critical awareness and its productive consequences as contributions to scientific knowledge. But there philosophy is underselling itself. There is a sense in which we do not truly know anything unless we know how we know it, and on reflection few people would doubt that our knowledge is superior when we are also aware of the arguments that support our beliefs, and those that undermine them. That is not incompatible with the fact that such superior knowledge can constitute a hindrance in the achievement of certain aims that require an effective non-questioning application of the knowledge. I am not able to give a full-fledged argument as to why critical awareness makes superior knowledge, but I will at least describe more fully what I believe in this regard, especially in relation to the fruits of complementary science.
For example, there is little that deserves the name of knowledge in being able to recite that the earth revolves around the sun. The belief carries more intellectual value if it is accompanied by the understanding of the evidence and the arguments that convinced Copernicus and his followers to reject the firmly established, highly developed, and eminently sensible system of geocentric astronomy established by Ptolemy, as detailed by Kuhn (1957) for instance. This is exactly the kind of scientific knowledge that is not available in current specialist science but can be given by HPS. There are many other examples in which work in HPS has raised and examined very legitimate questions about the way in which certain scientific controversies were settled. For example, many scholars have shown just how inconclusive Antoine Lavoisier's arguments against the phlogiston theory were.6 Gerald Holton (1978) revealed that Robert Millikan was guided by an ineffable intuition to reject his own observations that seemed to show the existence of electric charges smaller than what he recognized as the elementary charge belonging to an individual electron. Allan Franklin (1981) has furthered this debate by challenging Holton's analysis (see also Fairbank and Franklin 1982). Klaus Hentschel (2002) has shown that there were sensible reasons for which John William Draper maintained longer than most physicists that there were three distinct types of rays in the sunbeam.7 I once added a small contribution in this direction, by showing the legitimate reasons that prompted Herbert Dingle to argue that special relativity did not predict the effect known as the "twin paradox" (Chang 1993).
There is no space here to list all the examples of HPS works that have raised the level of critical awareness in our scientific knowledge. However, I cannot abandon the list without mentioning the thriving tradition in the philosophy of modern
6. In my view, the most convenient and insightful overview of this matter is given by Alan Musgrave (1976). According to Musgrave, the superiority of Lavoisier's research program to the phlogiston program can only be understood in terms of Lakatos's criterion of progress. Morris (1972) gives a detailed presentation of Lavoisier's theory of combustion, including its many problems.
7. See also Chang and Leonelli (forthcoming) for a further sympathetic discussion of Draper's reasons.
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physics, in which a community of philosophers have been questioning and re-examining the orthodox formulations and interpretation of various theories, especially quantum mechanics. Works in this tradition are often criticized as being neither philosophy nor physics. I think that criticism is understandable, but misguided. Much of the work in the philosophy of modern physics should be regarded as valuable works of complementary science, not as poor pieces of philosophy that do not address general and abstract philosophical concerns sufficiently. An exemplary instance of what I have in mind is James Cushing's (1994) scrutiny of the rejection of the Bohmian formulation of quantum mechanics.
Coming back to the topics discussed in this book, the critical awareness achieved in complementary science is best illustrated in chapter 2. There it was revealed that scientists found it impossible to reach a conclusive positive solution to the problem of choosing the correct thermometric fluid, though Regnault's comparability criterion was effective in ruling out most alternatives except for a few simple gases. Similarly, in chapter 3 we saw that the extension of the thermometric scale to the realms of the very hot and the very cold suffered from similar problems, and that scientists forged ahead without being able to say conclusively which of the competing standards were correct. That is how matters stood at least until Kelvin's concept of absolute temperature was operationalized in the late nineteenth century, as discussed in chapter 4. But the discussion in that chapter showed the futility of the hope that a highly theoretical concept of temperature would eliminate the inconclusiveness in measurement, since the problem of judging the correctness of operationalization was never solved completely, though the iterative solution adopted by the end of the nineteenth century was admirable. And in chapter 1 it was shown that even the most basic task of finding fixed points for thermometric scales was fraught with difficulties that only had serendipitous solutions. I would submit that when we know everything discussed in the first four chapters of this book, our scientific knowledge of what temperature means and how it is measured is immeasurably improved.
New Developments
Recovery and critical awareness are valuable in themselves, but they can also stimulate the production of genuinely novel knowledge. Historians have generally shrunk from further developing the valid systems of knowledge that they uncover from the past record of science. The most emblematic example of such a historian is Kuhn. Having made such strenuous and persuasive arguments that certain discarded systems of knowledge were coherent and could not be pronounced to be simply incorrect, Kuhn gave no explicit indication that these theories deserved to be developed further. Why not? According to his own criterion of judgment, scientific revolutions constitute progress when the newer paradigm acquires a greater problem-solving ability than ever achieved by the older paradigm (Kuhn 1970c, ch. 13). But how do we know that the discrepancy in problem-solving ability is not merely a result of the fact that scientists abandoned the older paradigm and gave up the effort to improve its problem-solving ability? A similar question also arises at the conclusion of some other historians' works on scientific controversy. For example,
Steven Shapin and Simon Schaffer (1985) strongly challenged the received wisdom that Thomas Hobbes's ideas about pneumatics were rightly rejected, in favor of the superior knowledge advanced by Robert Boyle. But they gave no indication that it would be worthwhile to try developing Hobbes's ideas further.
The historian of science, of course, has an easy answer here: it is not the job of the historian to develop scientific ideas actively. But whose job is it? It is perfectly understandable that current specialist scientists would not want to be drawn into developing research programs that have been rejected long ago, because from their point of view those old research programs are, quite simply, wrong. This is where complementary science enters. Lacking the obligation to conform to the current orthodoxy, the complementary scientist is free to invest some time and energy in developing things that fall outside the orthodox domain. In this book, or elsewhere, I have not yet engaged very much in such new developments. That is partly because a great deal of confidence is required to warrant this aspect of complementary science, and I have only begun to gain such confidence in the course of writing this book. But some clues have already emerged for potential future work, which I think are worth noting here.
One clear step is to extend the experimental knowledge that has been recovered. We can go beyond simply reproducing curious past experiments. Historians of science have tended to put an emphasis on replicating the conditions of the historical experiments as closely as possible. That serves the purpose of historiography, but does not necessarily serve the purpose of complementary science. In complementary science, if a curious experiment has been recovered from the past, the natural next step is to build on it. This can be done by performing better versions of it using up-to-date technology and the best available materials, and by thinking up variations on the old experiments that would not only confirm but extend the old empirical knowledge. For example, various experiments on boiling, discussed in chapter 1, would be worth developing further. In another case, I have proposed some instructive variations of Count Rumford's ingenious experiments intended to demonstrate the positive reality of what he called "frigorific radiation," following Pictet's experiment on the apparent radiation of cold (Chang 2002, 163). I have not had the resources with which to perform those experiments, but I hope there will be opportunities to carry them out.