Sunday, October 24, 2004

Structure of Scientific Revolutions Chap. 2

I've been forgetting about writing about this for awhile, so before I go to bed this evening, I'll catch up about.

Chapter 2 -- The Route to Normal Science

In this chapter TK discusses how we go about getting into a paradigm in the first place. Obviously, people who have never encountered a phenomenon can't have a paradigm that explains it. The researchers have to fumble along until the gain enough knowledge to explain what they know and what they don't know. There are some very interesting results of this process evident in the scientific literature.

The word 'paradigm' is first defined in this chapter as scientific achievements that are both "sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity, and are sufficiently open-ended to leave all sorts of problems for the redefined group of practictioners to resolve." It is through paradigms that normal science must progress. Students are indoctrinated into the field through roughly the same textbooks as every other practitioner of the field. Because of the similar indoctrination, the members of a shared paradigm will rarely disagree over fundementals (F=ma means the same to all physicists).

TK examines the progression of study of both physical optics and electricity to illustrate the state of science before a dominant paradigm arises, and why it is necessary for a dominant paradigm to arise so that scientific advancement can proceed more quickly. In physical optics,

" no period between remote antiquity and the end of the seventeeth century exhibited a single generally accepted view about the nature of light. Instead there were a number of competing schools and sub-schools, most of them espousing one variant or another of Epicurean, Aristotelian, or Platonictheory. One group took light to be particles; for another it was a modification of the medium that intervened between the body and the eye; still another explained light in terms of an interaction of the medium with an emanation from the eye."

TK describes how Newton was able to draw pieces from all of these different 'pre-paradigms', to create a universally accepted dominant paradigm. It is interesting to note, TK's discussion of the men (possibly women) who studied light before Newton:

"Any definition of the scientist taht excludes at least the more creative members of these various schools will exclude their modern successors as well. Those men were scientists."

You'll remember that Newton himself was wrong about optics. Newton's optics is an entirely particle based theory of light. Newton does not introduce waves. Newton's paradigm was replaced by the wave theory of Young and Fresnel in the 19th century, because this new paradigm was able to explain much more of the world. These scientists were also wrong, however, in that the quantum theory of the 1920's replaced them as well.

Why might we view the predecessors of Newton as unscientific, viewed through his paradigm? Previous to Newton, there was no paradigm, so that,

"Being able to take no common body of belief for granted, each writer on physical optics felt forced to build his field anew from its foundations. In doing so, his choice of supporting observations and experiment was relatively free, for there was no standard set of methods or of phenomena that every optical writer felt forced to employ and explain. Under these circumstances, the dialogue of the resulting books was often directed as much to the members of other schools as it was to nature."

Paradigms provide the structure in which scientists can work. Paradigms not only provide accepted explanations of certain phenomena, but they also provide a direction for questions and research. Without a paradigm, it is hard to know what facts are important, and how they fit together. TK cites Pliny and Bacon's writings as examples of pre-paradigm fact collecting. These authors were able to complile enormous collections of observations, but the observations were often juxtaposed in odd ways. That different observers will also juxtapose the same observations in very different manners is also a typical occurence in pre-paradigm science.

Also, Early observers often miss minor details that will later become important. TK cites that "none of the early histories of electricity mention that chaff, attrated to a rubbed glass rod, bounces off again." These authors assumed that the "bouncing" was caused by a mechanical explanation, as opposed to the reversal of charge, and ignored the effect as being trivial.

Eventually, all of these divergent observations and explanations are overwhelmed by a dominant paradigm (which most likely grew out of one of the competing paradigms). This process is unique to the fields that we refer to as science and is suprising. Why is it that one paradigm takes hold over all the practitioners of a certain field? TK explains that it is usually that a certain paradigm is able to explain most of the pressing questions of the day. He cites Franklin's model of electricity as a prime example. "Most" is an important qualification, though.

"To be accepted as a paradigm, a theory must seem better than its competitors, but it need not, and in fact never does, explain all the facts which it can be confronted."

TK discusses how the adoption of a paradigm causes changes within a scientific society. First of all, the younger students of the field are indoctrinated solely into the paradigm, and do not need to learn the world from first principles as did their predecessors. Textbooks become common place in the field to the exclusion of all other books. The only books that are written by practicing scientists in a field are either popularizations or memoirs. Scientists begin to communicate solely by condensed journal articles that are only understandable to other scientists in their field. The scientists do not need to write the initial chapters that explain the reasons for choosing the observations/experiments that they have chosen, since those reasons are implicit in the paradigm. Scientists can begin to focus on much more narrow and esoteric research pursuits, since the large questions are explained, again, implicitly by the paradigm. The overall speed of scientific progress increases due to the focusing of research. The practitioners of the field may begin to form professional societies and demand that their field be taught as a separate subject from earlier, more general topics.

It is interesting how the progress of science, as viewed in this framework, is in someways opposed to the popular understanding of science. As research becomes more esoteric, the usefulness of explaining what a scientist is doing to others not in that subfield diminishes. Yet, as the rate of scientific progress increases, the results of this progress are certain to have more and more of an impact on the general public's life. At one time, a well educated person (Franklin or Newton, say) could understand all of physics. Now, that is not the case. However, neither Franklin nor Newton had to operate in a world dominated by airplanes, cellphones, computers, and missile defense systems. Now would seem to be the time that a wide knowledge of physics would be most useful, but it is less possible because of specialization. Is it possible to teach a broad knowledge of physics to all students? Is specialization a good thing?


At 8:50 PM, Blogger maki-girl said...

Thank you for your prolific and enlightening book review. I had never thought about science in this way. I had always thought about you can't be a "renaissance man" (woman) anymore because there are just too many things to know about! But I did not think beyond that. I wonder if it would help my students in astronomy to learn about "paradigms" instead of "theories." They tend to think in terms of "the truth" and a "theory" although I have gotten them to the point where they (or many of them) seem to get that a theory is not just an idea, but the dominant theory is the one that the evidence "works with" the best. Which is what it sounds like are meaning when you say paradigm.

To answer your (possibly) rhetorical question ... I think teaching a broad physics knowledge is possible, and I don't think teaching specialized physics knowledge is useful at all unless you want to do research in that area. I would much rather understand the basic ideas (paradigms) about various branches of physics than the nitty gritty about each one. And that is also what I think is more valuable to teach.

I had a conversation today with a secondary school science teacher who says he is really fed up with the education department wanting him to teach everything as "discovery" and not conveying ANY knowledge to the students. I asked him which way would work better if your goal was to teach students how science was done. And if your goal was to give them content knowledge.

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