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The actual title of our fourth assignment was “Normal Science, Puzzle Solving, and Scientific Revolutions”. It centres on the debate over whether scientific knowledge and the development of new scientific theories is a cumulative process or a revolutionary one. We are asked to examine the work of Thomas Kuhn1 (see notes at the end of this article) in this respect. As with previous articles, I list the assignment questions below, followed by my answers:
In its simplest terms, what is Kuhn’s main objection to the inductivist/falsificationist accounts of the scientific method?
“Popper, the logical positivists2 and the logical empiricists3 disagreed on a lot, but there were a number of things they agreed on. They agreed for example that the accrual of scientific knowledge is cumulative, that there is a set of fundamental methods for all the sciences, and that all of the natural sciences at least are ultimately reducible to physics (a view known as reductionism). They believed in the distinction between the contexts of discovery and justification, whilst at the same time claiming that a clear demarcation existed between scientific theories and other types of belief system. Furthermore, they held that observation and experiment provided a neutral foundation for the testing of theories, and that scientific terms must have fixed and precise meanings.
Kuhn didn’t agree. His interest in and study of the Copernican Revolution led him to the belief that the accepted view – that the argument was a clear-cut case of reason and experiment versus religious dogma – was both a distortion and a gross over simplification of what really occurred. He argued that the real history of the Copernican Revolution, and that of other paradigm shifts in the history of science, was incompatible with both the inductivist and the falsificationist versions of the scientific method.
Rather than a steady accumulation of scientific knowledge, Kuhn argues, the history of science has typically involved the ‘wholesale abandonment of past theories’. He also seems to reject the notion of a clear demarcation between the origins of scientific ideas – and those individuals from whom they spring – and their justification. Whilst conceding that observation and experience constrain scientific beliefs, he asserts that personal factors, together with local circumstances and history, have a major role in shaping the beliefs of a scientific community. He also suggests that the very observations used to support a theory are ‘contaminated’ by the theory itself.
He thinks that the personal values of scientist at least in part determine both how they develop new theories, and which theories the scientific community they belong to regards as being justified. This clearly contradicts the idea of clear lines of demarcation between scientific theories and other types of belief described by the inductivists and falsificationists. He goes so far as to suggest that, far from being ‘maximally rational agents’, scientists often cling to a paradigm they are attached to regardless of evidence that contradicts it.
On the other hand, Kuhn points out that most scientists are engaged in work of a relatively routine nature most of the time, and seldom if ever have to deal with a crisis of faith. And, although much of his early work seems to point to scientific progress as being a non-rational process, he appears to take a far more muted approach in his later work, and even suggests a set of core values that are common to all scientific paradigms. This requires that a theory should be accurate within its domain, be consistent with other theories, be broad in scope, be as simple as possible, and provide a framework for ongoing research.”
Explain, in your own words, the disciplinary matrix account of paradigms.
“The disciplinary matrix account of paradigms describes the structure of the models used by various scientific disciplines (the word paradigm apparently having been popularised by Kuhn, essentially means model). A scientific community working in some domain or other must agree on a number of things before they can even begin to undertake a process of scientific enquiry. First and foremost, the terms of reference that they will use to describe their particular scientific domain and all that lies therein must be established.
The relationships between the things that belong to a particular domain, the interactions between them, and how they affect our senses, are attributes of the model. We need to know what kinds of questions we can legitimately ask about the things in the domain, and what kind of techniques we can employ in order to obtain the answers to those questions.
The disciplinary matrix is what gives us this information. It is learned by scientists as part of their education and the process of becoming a scientist. It prepares them for the task of scientific research, and provides the framework within which that research will take place.
As well as theoretical knowledge, the disciplinary matrix will incorporate the set of all practical skills required to undertake the work involved (for example, how to use test equipment correctly, or how to collect samples for analysis). It also includes exemplars – essentially success stories concerning scientific achievements in the particular field of science being pursued that all scientists starting their training or career in this field must study. The exemplar is held up as a model for future developments and achievements.”
What does it mean to say that ‘normal science consists of puzzle solving’?
“What Kuhn refers to as normal science is the practice of science that takes place within an established paradigm. It involves making new observations and fitting them within the accepted theories, and solving relatively minor problems related to the paradigm. He refers to it as a puzzle solving activity, because any such problems must be solved in accordance with rules that have already been established by the paradigm.
Examples of normal science would include things like carrying out a scheduled number of astronomical observations using an array of radio telescopes, testing the properties of a new semiconductor material, or undertaking the chemical analysis of arctic ice core samples. It could also include more mundane activities such as the routine testing of blood samples in hospitals and laboratories, or the chemical analysis of water samples taken from streams and rivers.
Most of these activities are carried out in order to find the answer to well-defined questions that have been asked many times before. The answers will fall within well-defined parameters. The objective of the activities is to apply accepted theories to the solution of some real-world problem, rather than to seek new knowledge.
The purpose of a geological survey, for example, might be to discover whether a given location may have valuable mineral deposits. It is highly unlikely that it will result in any extension of existing theoretical knowledge in the field of geology (although I suppose that if sufficient volume of data is collected and analysed over time, it is always possible that something hitherto unknown might emerge). I believe the term problem solving is used here in the same way it is used when setting a mathematical problem. The answer is not known in advance, but the techniques used to solve it are well established, and the answer will emerge in a known format and be within predictable parameters.”
Contrast Kuhn’s view about revolutionary scientific theory change with the standard conception of scientific theory change via a cumulative growth of knowledge.
“The standard conception of scientific theory (as generally agreed upon by Popper, the logical positivists and the logical empiricists) is that scientific knowledge is cumulative, i.e. it is accrued over time. Scientists build on the work of their predecessors, and the development of scientific knowledge proceeds in the form of steady growth. This is contrasted with other areas of human endeavour such as art, literature and philosophy.
The standard conception of these areas is that while they may be considered progressive, they do not exhibit the same step-by-step kind of developmental growth as science. Kuhn examined the history of scientific theory change closely, particularly the Copernican Revolution in which the theory of geocentrism was (eventually) displaced by the theory of heliocentrism, and was led to the conclusion that this was not the case.
He argues that scientist often have a distorted and over-simplified view of the history of their own subject areas and the way in which scientific theories have developed and changed, and likens the popular scientific historical texts to guide books that highlight the attractive features of a typical tourist destination whilst completely ignoring its less desirable aspects. Kuhn claims that the history of science is not a story of the steady growth of knowledge, and that theories have frequently been completely abandoned in favour of a completely new paradigm.
The process of theory change itself is also often misrepresented, according to Kuhn. The Copernican Revolution was not the simple triumph of logic and scientific interpretation of observational data over superstition and religious dogma that is represented in many text books on the subject. The various supporters of Copernicus’ theories were quite diverse in their motivations and approach to the new theory.
Furthermore, the observational data was just as difficult to fit to the new theory as it was to the old – perhaps more so. Claims that the geocentric view was abandoned because the observational data could no longer support it are therefore perhaps more an embellishment added by historians than an account of any actual intellectual processes that are supposed to have occurred.”
According to Kuhn, what role do social/cultural contexts play in scientific theory choice? What effect does including such contexts have on e.g. the ‘purely logical’ relationship between a scientific theory and its supporting/falsifying observations?
“According to Kuhn, scientists’ values, together with psychological and sociological factors, are influential in determining whether or not they accept a new paradigm. Some people, he says are highly conservative in nature. At the other end of the spectrum there are those that enjoy taking risks. The rest of us fall somewhere in between these two extremes. External influences will include social and economic factors.
Scientists just setting out on their careers, for example, will be influenced by their teachers and those that mentor them. At the same time, they will be constrained by the economic necessities of making a living in the world, and the need to build a career. This is likely to make them less likely to wander outside the established norms of a given paradigm, whereas those nearing the end of their career have possibly far less to lose by challenging those norms (on the other hand, of course, someone who has built a reputation based on their work in a particular field over many years might well be highly resistant to the idea of theory change if it refuted one or more of the theoretical principles underpinning their work).
Scientific communities are social groups, and as such have their own rules and conventions. These are determined not just by the relevant scientific paradigm, but by diverse external factors, such as government regulation, or the nature of the organisation actually funding the work being undertaken. Kuhn felt that such factors should be taken into consideration when trying to understand the process of scientific change. If true, this undermines the assumption that scientific theories are justified by observational data alone.
The free exchange of scientific knowledge, for example, which one assumes would be not only beneficial but essential within the scientific community in order to foster both understanding and the optimisation of scientific development, is often at odds with the commercial interests of those funding a particular scientific endeavour.
A case in point – probably just one of many, but notable nonetheless – is that of Clair Patterson’s4 research into the age of the Earth. Given the task of dating igneous rocks using a process involving the measurement of lead isotopes contained within them, Patterson was continually frustrated by the contamination of his samples, which of course rendered his results meaningless. He eventually discovered that the contamination was due to the presence of much higher levels of lead in the environment than there should have been.
He traced the cause to the use of lead in many manufacturing processes – notably the production of gasoline. His campaign to reduce or eliminate the use of lead was eventually successful, but for a long time he was virtually shunned by many of his peers, and attempts to discredit him were made by commercial organisations with vested interests to protect.
Patterson’s main antagonist in this struggle was fellow scientist Robert A. Kehoe, a former doctor of medicine, who was the medical spokesperson for the Ethyl Corporation and other producers of leaded gasoline. Kehoe maintained for many years that there was no evidence that the levels of lead entering the environment posed a threat to health.”
Explain, in your own words, Kuhn’s notion of meaning incommensurability.
“What Kuhn is saying, if effect, is that there is very often no way of comparing the characteristics of successive scientific theories, even though they deal with the same phenomenon. The word incommensurability (from the domain of mathematics) means ‘lack of common measure’, the implication in its use being that there is often little or no common ground to be found between a particular theory and its successor / predecessor. Nor is there any convenient universal yardstick against which two such theories can be compared. I think if I had to boil it down to one sentence, I would say that he is saying that it is like comparing apples and pears.
The evidence supporting each theory – or more to the point, what is generally accepted as evidence – is often dependent on the background paradigm. When one theory is displaced by another, the occurrence is often accompanied by a radical paradigm shift, rendering useful comparison virtually impossible. Kuhn goes so far as to say that the choice between competing paradigms is often a choice between ‘incompatible modes of community life’.
The Copernican Revolution gives us an extreme example of such a conflict. The required paradigm shift was of such magnitude that there was far more at stake than the mere credibility of the theorists on either side. Those who adopted Copernicus’ heliocentric view of the universe were challenging the doctrines of the Catholic Church in a time when to do so could have serious consequences. Galileo Galilei was a notable advocate of heliocentrism, and continued to express his beliefs despite being banned from doing so. He was eventually forced to recant, and spent his last nine years under house arrest.
From a purely scientific point of view, however, the incommensurability between the Aristotelian and Copernican theories centred largely on the fact that they could not agree on the meaning of something as fundamental as motion. The same observations could be differently interpreted, and lead to completely different conclusions, depending on whether you considered the Earth to be at rest (which would appear to be the case, since no motion could be felt) or not. It was thus pointless to attempt to compare one theory with the other by examining the observational data, since neither side would agree about what was actually being observed.
Kuhn points out that even in the relatively recent history of science, the meaning of terms we tend to assume are well understood can differ from one paradigm to another. For example, scientists still use the word mass, but Newton’s concept of mass is fundamentally different from Einstein’s. We also still use the term atom, but our conceptual model of the atom today is very different from that of Neils Bohr. Even a relatively minor paradigm shift, it seems, would imply that we often cannot make cross-theoretical comparisons because we are looking at new and different versions of reality. As Ladyman puts it ‘the world of Einstein is literally a different world from that of Newton’.”
Notes: