Focus
of lecture: Kuhn views the development of scientific knowledge and scientific
disciplines as analogous to biological evolution.
Outline:
I.
Sample talk delivered at a physics conference
II.
The sociology of scientific communities
III.
Biological evolution as an analog for the evolution of scientific knowledge and
disciplines
IV.
Kuhn's view of scientific progress and his influence
________________________________________
Freshman Studies
Lecture on The Structure of Scientific Revolutions, by Thomas Kuhn.
Matthew
R. Stoneking, 4 February 2002
I. Sample talk delivered at a physics conference
Title:
Coherent oscillations observed in a toroidal pure electron plasma; diocotron
mode or magnetron mode?
1. title slide: I am reporting
today on work done in a toroidal pure electron plasma at Lawrence University in
Appleton, Wisconsin.
2. Here are the parameters for our
system... major radius is 43 cm, minor radius is 4.5 cm, density is in the
range ..., and the magnetic field is about 200 G. The density is therefore
quite low compared to the Brillouin limit, but sufficiently dense that the
Debye length is smaller than the minor radius. Collective effects are therefore
expected to be important. Note also, the electrons are well-magnetized as
evidenced by the range of Larmor radius values
3. We have measured the confinement
time for this plasma, by the same method used in Malmberg-Penning traps. The
collector signal, shown here, has a prominent feature around 90 - 100
microseconds.
4. Plasma modes are observed with a
wall probe diagnostic. In this
trace, the coherent oscillation is observed prior to the trapping phase of the
experiment. The power spectrum for
that signal shows a distinct feature at around 100 thousand REVOLUTIONS per
second, with a couple of harmonics also evident.
5. The oscillation frequency is inversely proportional to the strength of the magnetic field, an observation that first led us to interpret this oscillation as a diocotron mode. However, the frequency does not depend on plasma density, but does show substantial dependence on the vacuum electric field… a result that seems more consistent with the magnetron mode.
II. The sociology of scientific communities
scientific
jargon
Whew
... not too many people walked out. I expect that none of you understood what I
have been talking about for the last few minutes. Just now, you were the
recipients of information "formatted," so to speak, for a different
audience... an audience of plasma physicists. Last summer, I attended a
workshop where I presented something similar to what you just heard. I expect (and hope) that everyone in
that room did understand everything I said.
Well... had I actually used this figure in that presentation, somebody would
have stopped me. That is because this graph does not display data from a
"collecter," and does not represent a measurement of the
"confinement time" for the plasma. Rather this graph should be
labeled like this... This is a graph of the number times the word 'paradigm'
(or variations like 'paradigmatic') appears on each page of Thomas Kuhn's The
Structure of Scientific Revolution (third edition). Yes, 'paradigm' shows up 13 times on page 94 alone!
Check for yourself. The word
'paradigm' certainly must be connected to Thomas Kuhn's main points in a fundamental
way. In fact, Kuhn coined a new
use for this word in the very essay you are reading, which was published in
1962. You have probably read it or
heard people use it in ways that are descended from Kuhn’s work. I know I used the word in a distinctly Kuhnian
sense long before I picked up the book at a bookstore in Madison more than five
years ago. A search of newspapers
on the web last week yielded number of instances of ‘paradigm’ used
in this way. From a New York
Times article on President
Bush’s State of the Union address on the 30th of
January… a foreign policy specialist at the Brookings Institution is
quoted as saying,
“The hard-liners have been arguing that
after September 11 it is intolerable to live in a world in which Iraq, Iran,
and North Korea have weapons of mass destruction. Bush has now fully embraced this paradigm.” (article by Michael R. Gordon, 30 Jan.
2002, New York Times)
In
the Los Angeles Times, from a theater review of a new musical based on the
legend of John Henry,
“…Whether founded in fact or wholly
fictitious, John Henry has obvious historical significance, both as a
post-slavery paradigm of
black proficiency and as a proletarian prototype in an era before the rise of
American labor unions.” (article by F. Kathleen Foley, 31 Jan. 2002, Los
Angeles Times)
In
Madison, where I lived for quite a few years, a popular bumper sticker read ...
"subvert the dominant paradigm." I doubt that Mr. Kuhn intended his
pet word to become a tool for political revolutionaries... or wannabe revolutionaries
at least. Sometimes the uses of
‘paradigm’, or ‘paradigm shift’ in popular culture
strike closer to Kuhn’s original sense, but one has the suspicion this
might be purely coincidence given the extent to which the term has permeated
our culture. On the 29th
of January a Washington Post columnist wrote about the timely way that a new cancer drug has
found its way into the scripts of TV’s “The West Wing” and
“Law and Order.” In that article she quoted a drug development
expert at the National Cancer Institute,
“The development of Gleevec can be used as
a paradigm for the
development of other agents.” (column by Abigail Trafford, 29 Jan. 2002, Washington
Post)
If
you have not noticed phrases like these, you will in the future, now that you
have read (or are reading) the book that launched ‘paradigm’ into
the popular usage it now enjoys.
Most of the popular uses of the word go far beyond the intentions of Mr.
Kuhn, but they are testimony to the influence his essay has had in our larger
culture.
My
goals in this lecture are first to provide you with some background information
on how scientific communities function and second to more discuss a metaphor
that Kuhn introduces near the end of the essay, a metaphor that illustrates the
most controversial element of his thesis. Both of these objectives are intended to aid you in
your struggle to subdue this work.
After all, you probably already have the feeling that this book was not
written with college freshmen in mind. My guess is that you reacted to your
first contact with this book like you did to my physics talk. In both cases, the author and the intended audience share much more common background
information than either of us do with the people in this room. The Structure of Scientific Revolutions is an academic essay written for philosophers
and historians of science.
My presentation was a non-neutral plasma physics presentation, meant for
an audience of fellow plasma physicists.
The
point of the partial physics conference presentation with which I began, was to
begin to give you some understanding of aspects of the operation of scientific
communities. The first aspect of
scientific communities I wish to discuss is the specialized language that
members of the community employ to communicate with other members of the same
community.
language barrier between the scientist and non-scientist
Why
was my physics presentation so opaque to you? And why would I be reasonable in
supposing that my colleagues in the COMMUNITY of plasma physicists would find
it transparent? The public at large often views scientists as speaking another
language. At times that view takes on the form of admiration. Some segment of
the public associates the fact that they cannot understand the
scientist’s language with the superior intelligence of the scientist. The
real reason scientists understand each other is because they have been trained
(some might say indoctrinated) to speak the language of their discipline. At
other times, the 'language barrier' between scientists and non-scientists is a
source of suspicion. Perhaps
scientists use complicated jargon to hide what they are doing with taxpayer
dollars.
Why do scientists speak in 'jargon'? Must there be a 'language barrier' between
non-scientist and scientists? The specialized use of words (many of which are
used in common speech with different meanings) represents a shorthand for
concepts, phenomena and practices that the scientists have incorporated into
their view of their work (and perhaps of the world). The scientists who heard
my talk in San Diego last summer and I share a common set of views about plasma
physics, views we share because we have had very similar training, we read the
same scientific journals, and attend the same scientific conferences. In Kuhn's
terminology, we share a common 'paradigm' or 'set of paradigms' or as he calls
them in the post-script of Structure,
a common 'disciplinary matrix.' All the people in the audience of last summer's
workshop were familiar with what I meant when I said 'diocotron mode' or
'confinement time' or 'power spectrum.’ I did not need to start from scratch and explain these ideas
to them. I could start with those concepts, principles, and techniques and
build on them. You can imagine how much longer my talk would have been if I had
had to teach them (as I would have to teach all of you if I wanted you to
understand the results of my experiments) all the fundamental ideas on which my
work is built. Given all the background knowledge we shared, I could proceed
very quickly to a presentation of extremely esoteric aspects of my work and be
reasonably certain that I would be understood. The scientific enterprise functions efficiently because the
participants in scientific dialogue share a common paradigm.
As he all but admits in the post-script to Structure, Professor Kuhn was not completely certain what
he meant by his new use of the word ‘paradigm” when he wrote the
original essay. There, he
enumerates more carefully the kinds of things he meant. He identifies new terms like 'symbolic
generalizations,' 'models,' 'values,' and 'exemplars' as being varieties of
‘paradigm.’ For
philosophers and historians of science such distinctions are important. I recommend, however, that you keep the
following, somewhat plastic definition of ‘paradigm’ in your mind
while you read the essay: let the word ‘paradigm’ represent all the
things that a scientist can assume that his or her colleagues will understand
about their common subject of study without explicitly explaining them ... all the
major prior results in the field... all the important experimental techniques
... all the important theoretical ideas or concepts that guide their
research… all the basic examples or categories of examples that the
members of a scientific community learned as a part of their training, i.e. the end-of-chapter problems in the textbooks
that Kuhn writes about.
So please excuse scientists for speaking in jargon... at least when we are
speaking amongst ourselves. We
save a lot of time by referring to all the above elements of our paradigm in
the shorthand of our discipline-specific jargon. If we did not use jargon, the scientific enterprise would
not function as efficiently as it does.
language
barrier between scientists of difference disciplines
I
was careful to identify the intended audience for my earlier presentation as an
audience of plasma physicists. I did not say an audience of scientists. I did
not even say, an audience of physicists.
I said an audience of plasma physicists, and perhaps I should have further specified the
audience as a collection of plasma physicists who study non-neutral
plasmas. The distinction is significant, because much of
the jargon I used would only be completely understood by men and women who
study non-neutral plasmas. If
I were to show up at a conference on protein chemistry or sedimentary geology
or aquatic ecology or even a physics conference on string theory and give the
talk I gave in San Diego, my audience would be nearly as much in the dark as
you were. And, likewise, if I were to stay and listen to some of the
presentations at any of those conferences, I would not come away knowing any
more than when I entered ... other than something about my ignorance of those
fields. The language barrier that exists between the scientist and the
non-scientist also exists between members of different scientific DISCIPLINES.
There are as many scientific dialects as there are scientific disciplines or
sub-disciplines. To be sure,
I will probably get a little more out of a talk given by a physicist, than I
will from a talk given by a chemist.
My paradigm, or disciplinary matrix has a greater overlap with those of
other physicists in other sub-disciplines, than it does with the chemist’s.
The language barrier exists even between members of closely allied
disciplines. Jonathan
Weiner’s excellent book titled The Beak of the Finch is about recent research in the field of
evolutionary biology. The book was
on the term II Freshman Studies reading list the two years prior to this one. Weiner quotes one of the evolutionary
biologists commenting on the field of molecular biology,
" 'It really is a foreign language, ' ... 'I
suppose ours is too, but I do have the impression that theirs is harder.'"
-Beak of the Finch, p.
215
This quotation reveals not only the perception of a language barrier that
exists between members of two sub-disciplines of biology, but also a hint of a
sense of inferiority of one sub-discipline with respect to another. Scientific communities are communities
of humans and as such their members display all the typical aspects of human
nature that are so readily observed in other human communities…
prejudice, intolerance, etc.
Thomas Kuhn has this to say (on p. 21) about the language barrier that exists
between scientists in different disciplines,
"Although it is customary, and is surely proper to deplore the widening
gulf that separates the professional scientist from his colleagues in other
fields, too little attention is paid to the essential relationship between that
gulf and the mechanisms intrinsic to scientific advance." -SSR p. 21
He is referring to his contention that the specialized language of a scientific
community is central to its efficient operation, not only because it is a
powerful shorthand or abbreviation for an enormous amount of collectively
agreed upon background material for other member of one's own community... but
also because it prevents the polluting influence of others who might distract
the work of the community with too many questions about fundamental and already
resolved issues. Since the 'others' do not speak the language, they are
effectively prevented from communicating with 'us' about our work.
professional
societies, scientific conferences and workshops
Scientists
can be "labeled" as members of a particular discipline or community
in a number of interrelated ways. If you observe a large group of scientists
speaking their special language, chances are you are in the middle of a
scientific conference, where members of a scientific community gather to
present and discuss their work face-to-face. Scientific conferences are usually
organized by professional societies or associations. All the right people end
up coming to a particular scientific conference because they are all members of
the professional society that is sponsoring the conference. They are all on the
society's mailing list and receive its newsletters, etc. For example, most
physicists in this country belong to the American Physical Society (or APS).
Most chemists belong to the American Chemical Society (or ACS), etc. Scientific societies have a long
history. Galileo was inducted into
one of the first such societies, the Lyncean or “Lynx” Academy of
Rome, immediately following the sensational response to the publication of his
astronomical observations, Sidereus Nuncius, the work you have just finished reading (from Galileo’s
Daughter, pp. 42-3). Isaac Newton was the president of the
Royal Society in England for the last twenty-five years of his life.
Today,
most scientific societies are subdivided into smaller units or divisions. So
for example the American Physical Society has a Division of Nuclear Physics, a
Division of Particle Physics, a Division of Plasma Physics, and others. Each of
these divisions may organize their own specialized conferences attended by
specialists working in for example, plasma physics. The subdivision of the
discipline reaches even further down with topical workshops organized by
members of a division who are working on a very specific problem or small set
of problems. The workshop I attended last summer was such a topical workshop.
scientific journals
Besides
organizing conferences, another primary function of professional societies like
the APS is to edit and publish scientific journals, conference proceedings and
research monographs. The Lyncean
Academy was one of Galileo’s principle publishers. The Proceedings of the Royal Society in
England continues to be an important scientific publication.
Presentations
at scientific conferences and publications in scientific journals are the two
principal ways that scientists communicate their results to the rest of the
community. And, just as there is a hierarchy of specialization within the
membership of the society (nuclear physicists, particle physicists, plasma
physicists, etc.) and in the organization of conferences, there is also a
hierarchy of specialization within the set of journals read by members of the
society. For example, the American Association for the Advancement of Science
(AAAS), a society that includes all of the natural sciences, publishes a
journal called Science.
Science contains
articles from a wide range of scientific disciplines, and is therefore read by
scientists from a wide range of disciplines. The American Physical Society
publishes a journal titled Physical Review Letters, a journal that is widely read by physicists in
many subspecialties. The APS also publishes a series of journals titled Physical
Review A, Physical Review B, Physical Review C, Physical Review D, and, most creative of all, Physical
Review E. Phys. Rev. A contains only articles on atomic, molecular and
optical physics and is read almost exclusively by physicists working in the
area of atomic, molecular and optical physics. Phys. Rev. B contains articles pertaining to condensed matter
and materials physics and is read by researchers working in those areas. You
get the point. For each level in the hierarchy of scientific disciplines there
are professional societies that 1) organize conferences and 2) edit and publish
journals or conference proceedings. They do other things like communicate
scientific results to the public, advise governmental organizations on science
policy, etc... but their primary function is to facilitate communication
between their members.
the family tree of natural science
I
have attempted to draw an oral sketch of the way scientists identify themselves
in relation to other scientists, how that association is facilitated by
professional societies, and how scientists communicate their work to each
other. The image I would like you to hold in your mind is, like most
organizational diagrams, something like a tree. At the top we have all natural
sciences, a representative society being the AAAS with its journal Science. One level down are the major disciplines of the
natural sciences.. with abbreviations given for a few representative societies
and journals. I then break down the discipline of physics into some of its
sub-disciplines and the sub-discipline of plasma physics into some its primary
research areas. You can imagine how the chart would be completed by breaking
down each of the major disciplines into its sub-disciplines and further into
major areas of research. The most
frequent and the most complete communication occurs between members at the
finest subdivision of the sciences... between scientists who are working on
very similar types of problems. For example, I will very rarely read more than
the title of a physics article in the area of particle physics or condensed
matter physics. I will read abstracts of articles in most areas of plasma
physics, but will read entire articles in only two or three narrowly defined
research areas. Likewise my
attendance at conferences will be most frequent in areas close to my research
work. The proximity of members of
one research group to another in this organizational tree reflects the
closeness of their scientific jargon and therefore the extent of the overlap of
their set of paradigms. You should
therefore add to your evolving definition of paradigm, the notion that there is
a hierarchy of paradigms that reflects the general structure of this tree. There are some paradigms that all
natural scientists share, others that only chemists share, others that only
organic chemists share, etc.
The image is very rough and can be misleading, for there are twigs of this tree
that one could easily identify with two or more of its major branches. For
example, on which branch of this tree should I place biochemistry or
geophysics. These are examples of interdisciplinary fields. Their existence reminds us of the
limitations of using any organizational structure to simplify a complex
network. Despite the limitations
of this way of viewing the way scientists are related through their
professional associations and personal identifications, I think it captures
some aspects of the relationships between members of different scientific
disciplines and the hierarchy of underlying paradigms that members of different
disciplines possess. One can also
view this chart as a crude representation of the historical origins of the
various sub-disciplines of chemistry, physics, etc. , as a family tree for
scientific disciplines. In the late nineteenth century, there were few or no
sub-fields of physics. Although physicists were working on a wide range of
problems, many of which were the seeds for future sub-disciplines, the
community of physicists was both smaller and more unified. Over the course of
the last century, the sub-disciplines of atomic physics, nuclear physics, particle
physics split off. Going further back into the nineteenth century the
distinction between physicist and chemist was nonexistent. So I think you can view this tree
(again with some caution) as a depiction of the historical relations of these
sub-fields to each other.
distinguishing
scientific from non-scientific academic communities
Much
of what I have said about the sociology of science applies also to
nonscientific disciplines ... to the community of scholars of English poetry...
to the community of economists ... to the community of scholars of American
history ... etc. What is it that makes scientific communities different from
other academic communities? In
Kuhn's view, what makes a community scientific is its almost universal
agreement about the set of paradigms that they share... an agreed upon world
view (at least in so far as the subject of their communal professional
interests go). In most social sciences (at least at the time Kuhn was writing)
and especially in the creative arts and humanities, disciplines are
characterized by competing schools of thought. The observation that social
scientific communities were characterized by severe disagreements over very
fundamental issues that went to the heart of the communities subject of study, whereas
scientific communities almost never engaged in this kind of debate, was
critical to Kuhn's initial conception of a 'paradigm.' In the preface to Structure he writes,
"...at the Center for Advanced Studies in the Behavioral Sciences ... I
was struck by the number and the extent of the overt disagreements between
social scientists about the nature of legitimate scientific problems and
methods ... Attempting to discover the source of [the] difference [between the
natural and social sciences] led me to recognize the role in scientific
research of what I have since called 'paradigms.' " -SSR, preface p.x
The existence of a universally accepted 'paradigm' within a given academic discipline is for Kuhn the criterion by which we should determine whether the discipline is scientific or not. Several key sentences from section II of Kuhn's essay illustrate the point:
"Men whose research is based on shared paradigms are committed to the same
rules and standards for scientific practice. That commitment and the apparent
consensus it produces are prerequisites for normal science... Acquisition of a
paradigm and of the more esoteric type of research it permits is a sign of
maturity in the development of any given scientific field." -SSR p. 11
"... and it remains an open question what parts of social science have yet
acquired such paradigms at all." -SSR p. 15
"What is surprising, and perhaps also unique in its degree to the fields
we call science, is that such initial divergences [competing schools] should
ever largely disappear. For they do disappear to a very considerable extent and
then apparently once and for all." -SSR p. 17
"Except with the advantage of hindsight, it is hard to find another
criterion [other than the acquisition of a paradigm] that so clearly proclaims
a field a science." -SSR p. 22
Scientific communities are unusually united in their view of their own
discipline. They agree on what types of questions are worth asking and what
constitutes an acceptable answer to a question. They share a common paradigm (or set of paradigms or
disciplinary matrix). In disciplines of the social sciences, humanities and
arts, there are frequently competing schools of thought ... adherents to
competing paradigms. Exceptions to the rule that scientific communities are
unified in the way described are scientific communities in crisis or dealing
with anomalies ... communities ripe for revolution.
In light of Kuhn's view of science as inherently a social enterprise, you might
want to think about how Kuhn would view Victor Frankenstein's status as
scientist at various stages of Frankenstein's career. Can one be a scientist in
Kuhn's view if you are working alone and not communicating your results to
anyone else? I can imagine such a question would make a fine midterm exam
question.
III. Biological
evolution as a metaphor for the evolution of scientific knowledge and
disciplines
How
does my overview of the sociology of science help you to understand Thomas
Kuhn's The Structure of Scientific Revolutions? Let's look at the very last section of Structure... not the post-script, but Section XIII:
Progress Through Revolutions, and read some of Kuhn's parting words from 1962.
Probably none of you have yet read to the end of this book. I hope you are not
offended by my giving away the ending, but after all you are not reading an
Agatha Christie mystery, but rather an academic essay. On page 170, Kuhn
writes,
"The developmental process described in this essay has been a process of evolution [my emphasis] from [Kuhn's emphasis] primitive beginnings - a
process whose successive stages are characterized by an increasingly detailed
and refined understanding of nature." -SSR p. 170.
Kuhn asks us to view the development of science as analogous to the development
of biological organisms. Darwin's
evolution is to be a metaphor for how the scientific enterprise
“evolves.” Kuhn
introduces this analogy in the very last section of the essay, in a section
that he probably viewed as the most speculative and preliminary. It is also the
section that contains the most serious implications for the philosophy of
science and made this essay as influential and controversial as it has been for
forty years. The reason for introducing the analogy is to reinforce his
argument about what kind of scientific "progress" can occur over the
course of a scientific revolution... do we step closer to ultimate Truth? I
will return to this import issue briefly at the end of my lecture, but for the
moment I would like to take Kuhn's evolution metaphor and see how it plays out
for the less controversial elements of his thesis. As Kuhn himself warns not
two pages after he first introduces it that...
"The analogy that relates the evolution of organisms to the evolution of
scientific ideas can easily be pushed too far." -SSR p. 172.
I will take my license to push this one a little further from Kuhn himself, who
extended the evolution analogy in some of the ways I will lay out now. He did
so in a lecture titled The Road Since Structure delivered in 1990.
scientific disciplines as species
If
the scientific enterprise develops in a manner analogous to biological
evolution, then what is it that corresponds to the concept of a species? After
all the concept of species is central to biology and evolutionary theory
purports to describe how species emerge and evolve. So let's step back and ask
'what are biological species?' A species is a geographically and/or
reproductively isolated population of organisms. A species maintains its
identity due to its isolation. If members of a population frequently bred with
members of another group ... the first population would soon lose its separate
identity; it would be swallowed up or incorporated into the larger population
with which it is mixing. My discussion of the sociology of scientific
communities led to an image of a "family tree" for scientific
disciplines. My intent was to prepare you for the suggestion that scientific
disciplines (or communities) are the entities that correspond to species in the
Darwinian metaphor for scientific development. How are scientific disciplines
"isolated" in a manner analogous to the reproductive or geographic
isolation of a biological species? In The Road Since Structure, Kuhn says,
"... the unit [i.e. species] is a community of intercommunicating specialists,
a unit whose members share a lexicon [i.e. jargon] that provides the basis for
both the conduct and the evaluation of their research and which simultaneously,
by barring full communication with those outside the group, maintains their
isolation from practitioners of other specialties." --Road Since
Structure, p. 98
Members of a scientific discipline are isolated by their specialized language
... their jargon. They are isolated by the inability to easily communicate with
members of other disciplines on matters that relate to their scientific work.
Let me say it another way... a scientist can only engage in
"intercourse" (in the sense of communication) easily with another
member of his own discipline, just as an animal can only engage in
"intercourse" (of the other kind) easily with another member of its
own species. So it is the language
barrier that I spoke of earlier… the barrier between scientists of
different disciplines that isolates them in a manner analogous to the
reproductive (or geographic) isolation of biological species.
interdisciplinary fields as hybrids
Is
it really impossible for scientists in different disciplines to communicate
about their science? No, but there
are significant obstacles, the language barrier is the surface manifestation of
a more profound barrier … the paradigm barrier. Scientists in different disciplines have acquired, in
Kuhn’s view, a different way of “perceiving” the world, or at
least that part of the world that they study most intensely. Occasionally, however, the paradigm
barrier is broken and scientists from different disciplines collaborate and
achieve something that neither of them could have achieved separately. I am speaking of interdisciplinary
research. In fact, many of the most interesting and promising avenues for
scientific research these days lie at the boundaries between traditional
disciplines... in such areas as environmental science, materials science,
biophysics, neuroscience, etc. The
existence and success of interdisciplinary efforts within the world of
scientific research does not make Kuhn's Darwinian metaphor less
illuminating. Biological species
are also not completely isolated either geographically or reproductively. And, just as the boundaries of
scientific disciplines are fuzzy, frequently the boundaries between closely
related species are also permeable.
Hybridization among members of different animal species is not the rule,
but neither is it extremely uncommon.
Usually the products of such hybrid matings are not likely to gain an
advantage over members of the existing species. However such hybridization does
occur and occasionally provides a fortuitous combination of traits that imparts
an advantage to the products of that union. Interdisciplinary work represents
hybridization in the evolution analogy.
If hybridization of scientific disciplines produces a successful
offspring, a new discipline can be spawned. The field of biochemistry is such
an example.
scientific revolutions as speciation events
Let's
continue to extend the analogy. The title of Darwin's greatest work was Origin
of Species. If the analogy
holds, what, in the course of scientific development corresponds to the origin
of species... or the origin of new scientific disciplines. What corresponds to
"speciation?' I just mentioned one possible way new disciplines can arise
... through hybridization, or interdisciplinary "unions" between
members of separate disciplines. But there is a more natural origin for new
disciplines and that is the scientific revolution. In Kuhn's view a scientific
revolution rearranges the concepts that form the foundation of the worldview
for members of the community experiencing it. After a revolution, they view
their discipline in an entirely different way. Kuhn suggests they are practicing
a different discipline than they were before the revolution.
In addition, a revolution introduces new concepts, maybe even new elements of
reality that are open to future investigation. For example, prior to about 1900
the atom was the fundamental constituent of matter. There were a fairly large
number of atomic flavors, roughly 100, corresponding to the different chemical
elements. Atoms of each element emitted and absorbed their own characteristic
wavelengths of light. The atoms of different elements interacted with each
other in different ways; they had different chemical properties. As a part of
the revolution that brought quantum physics onto the scene in the early decades
of the 20th century, the internal structure of the atom became a subject for
investigation. The disciplines of nuclear physics and nuclear chemistry could
not even have been imagined 25 years prior. The quantum revolution did indeed
spawn new disciplines.
In
a similar way, the astronomical observations of Galileo introduced new elements
of reality into the worldview of astronomers. Prior to Galileo’s application of the spyglass to
observations of the sky, the sole phenomenon of interest associated with the
planets was how they moved against the fixed stars. After Galileo, other internal properties of the planets
became subjects for investigation.
Through the telescope the planets were not just brighter points of light
as the stars were in fact. Jupiter
had an entourage of satellites.
Saturn was not quite round.
Venus displayed phases like the Moon. And the Moon itself revealed a fascinating landscape of
“mountains” and “valleys.” After Galileo, astronomy became a different
discipline… one that asked questions about the nature of heavenly objects
and not just about their locations.
The larger territory for investigation opened up new research niches and
therefore to a proliferation subfields of astronomy. For the discipline of astronomy, Galileo’s
observations were revolutionary and represent the rise of a new paradigm. If we reduce the magnification of our
historical lens, his observations were important in persuading scientists and
intellectuals of the superiority of the Copernican paradigm. Galileo was an early convert to Copernicanism
and a principle advocate for it during the time of paradigm choice associated
with the resolution of the Coperrnican Revolution.
Getting
back to the development of the evolution metaphor, I suggest that scientific
revolutions are represented by "speciation events.”
scientific communities in crisis as extinction events
The
fossil record that chronicles the history of life to those with enough skill
and training to read it, reveals that that life on earth has sustained a fair
number of mass extinctions over the course of its history. As Harvard
paleontologist and prodigious author Stephen Jay Gould puts it in his book Wonderful
Life,
"The history of life is not a continuum of development, but a record
punctuated by brief, sometimes geologically instantaneous, episodes of mass
extinction and subsequent diversification." --Wonderful Life p. 54
The most famous mass extinction was about 65 million years ago at the end of
the Cretaceous Period when it is likely that a comet impact altered the earth's
climate for a period long enough to wipe out many species including the
dominant large animals of the day ... the dinosaurs. Notice however in the
quotation from Professor Gould's book that episodes of mass extinction are
coupled to periods of subsequent diversification, i.e. speciation. I have already
identified scientific revolutions as a primary origin for new scientific
disciplines. If the analogy holds, there may be a corresponding extinction
event prior to a major speciation event. I suggest that the period prior to a scientific
revolution, the period of crisis that Kuhn describes in section VII of Structure is a time when the "environment" in
which a scientific community is "living" begins to change. The old
way of doing things does not work for the new problems that are emerging. Those
who learn to adopt a new (and successful paradigm) at the time of a revolution
survive as members of a new discipline. Those who cannot adapt eventually die
out.
The
world of science was struck by a 'comet' during the 17th century. The man most
responsible for the impact was Isaac Newton. Galileo’s experiments with
falling objects, balls rolling down inclines and the pendulum laid important
foundations for Newton’s revolution. It is this work that Kuhn cites extensively in Structure, rather than the astronomical work (although you
will find an oblique reference to Galileo’s astronomical observations on
page 154). When the dust settled,
the scientists who lived and worked under a paradigm going back to Aristotle,
were extinct. There are no Aristotelian physicists around. They are the
dinosaurs of the scientific world. And similar to the dinosaurs, they ruled the
earth a lot longer than their successors have so far. Your modern physicist
bears a much stronger resemblance to his Newtonian ancestor than he does to the
Aristotelian. The Newtonian physicist is perhaps the rodent who emerged from
obscurity once the behemoths had died out. In another rendition of the
metaphor, the Aristotelian is the Neandertal, a vaguely human creature, but
from whom we are not directly descended, and the Newtonian physicist is
represented by our true ancestor, Homo erectus.
normal science as microevolution / local adaptation
In
Kuhn's view of scientific development, all of most scientists' lives are spent
doing normal science. The normal scientific period is the period between
revolutions, when there is nearly universal agreement within a scientific
community about what kinds of problems are worth attacking and what techniques
should be used to attack them. In this phase of the scientific enterprise, the
paradigm (or disciplinary matrix) provides the big picture. It is important to
realize that it does not immediately provide all the answers. There is
substantial fine-tuning to be done to make the paradigm work in as many
specific cases as it possibly can. There are also specific questions that the
paradigm can in principle provide answers to, but that require substantial work
to derive them from the paradigm.
I must say, as a practicing scientist, that I find Kuhn’s
description of normal science rings especially true. Kuhn’s description
of the educational process, the apprenticeship that initiates new members of a
discipline, the way that training guides the kinds of research questions that
asked and how they come to be answered… al that resonates with my
experiences.
The work I presented to you at the beginning of this lecture is surely, as
Professor DeStasio suggested an example of normal science. I do not take
offense that she did does not see the revolutionary aspects of my work, for in
truth I do not think there are any. Answering the question of whether the
observed oscillations are magnetron or diocotron in origin will not incite a
revolution even among the very small community of nonneutral plasma physicists.
In principle the answer to that type of question exists within the mathematical
framework of nonneutral plasma physics theory. If I was smart enough, I could
just do a calculation to get the answer. But in fact, the system is too complex
to work out the answers to all such questions. Even though the fundamental
physical principles, the elements of the disciplinary matrix are not expected
to fail, there are too many particles involved to calculate exactly what they
will do. Approximations must be made and then justified on the basis of correct
predictions for the outcome of real experimental measurements. This is classic
normal science.
In the Darwinian analogy normal science corresponds to
“microevolution.” I am
not certain that is a real term in the field of evolutionary biology, but I am
sure the concept exists. What I
mean by microevolution is adaptation of existing species to relatively short
term changes in the environment.
The research described in Jonathan Weiner’s The Beak of the
Finch illuminates exactly
this kind of process. Weiner
describes the study of a handful of finch species on a small atoll on the
Galapogos Islands by a team of Princeton evolutionary biologists over the
course of more than a decade. The
biologists did not observe the origin of any new finch species in the
Galapogos. Rather they saw
existing species adapting to short term changes in their environment. The
mechanism that drove this microevolution was the inherent variation that exists
within any single species. If all members of a species were identical in all
features, then the species would be extremely vulnerable to even minor changes
in the environment. As it is, when the environment changes, there are usually
members of the species who are better suited to survive under the new conditions.
The offspring of those individuals tend to be more numerous and better able to
compete for resources than the offspring of other members of the species. The
species survives by moving in the direction of those individuals who are best
suited to the new environment.
This gradual adaptation, in Darwin’s original conception led to
the origin of species over much longer time periods. The possibility of rapid speciation following a mass
extinction event is a relatively new articulation of Darwin’s paradigm, but
the basic mechanism is believed to be the same one… following a mass
extinction there are many unoccupied niches in the environment. There are bound to be some individual
members of the surviving species that are more suited to one of the unoccupied
niches. Those individuals are
successful in occupying the niche, become isolated, adapt more and more to that
environment until they become a distinct species.
During
periods of normal science, members of a given discipline adapt the paradigm
theory to fit observation in as many specific cases as possible. The outcome of
that work is a better-articulated paradigm... one that works better in a wider
range phenomena. During periods of normal science, the paradigm evolves in a
smooth way, in a way analogous to the minor adaptations of species to short
term changes in the environment.
At this point let me offer a summary of the Darwinian analogy for Thomas Kuhn's
view of scientific development:
Summary of the Darwinian analogy for scientific development:
scientific
communities/disciplines <---> species
linguistic
isolation <--> reproductive or geographic isolation
interdisciplinary
fields <---> hybrids
scientific
revolutions <---> speciation events
scientific
communities in crisis <---> extinction events
emergence
of a dominant paradigm <---> survival of the fittest
normal
science <---> adaptation or microevolution
The match that this analogy seems to provide leads me to wonder why Kuhn chose
for the title of his essay... The Structure of Scientific Revolutions, when a more appropriate title
would seem to be ... The Structure of Scientific (r)Evolution(s).
IV. Kuhn's view of scientific progress and
his influence
scientific development is contingent
Where does this metaphor lead? Let's allow it to lead us back to Kuhn's original intention when he introduced the metaphor. Recall the quotation from section XIII:
"The developmental process [of scientific knowledge and disciplines]
described in this essay has been a process of evolution [my emphasis] from [Kuhn's emphasis] primitive beginnings - a process
whose successive stages are characterized by an increasingly detailed and
refined understanding of nature." -SSR p. 170.
The next sentence on page 170 is ...
"...But nothing that has been or will be said makes it a process of evolution [my emphasis] toward
anything." -SSR p.170.
This is why Kuhn introduces the analogy, because he sees scientific development
as a process with profound historical/social influences. He knows that science
is a human social enterprise and being so means it is subject to many of the
same kinds of influences that affect the development of other human social
enterprises. This is his most controversial point. Also from page 170:
"We may have to relinquish the notion, explicit or implicit, that changes
of paradigm carry scientists and those who learn from them closer and closer to
the truth." -SSR p.170
In Kuhn's description, the worldview that emerges from a period of crisis in a scientific community ... the result of a revolution ... is strongly influenced by factors other than whether the new paradigm is the truest one in any objective sense. Kuhn sees no reason to believe that the progress of science is one that brings humanity closer to an understanding of an objective Reality. His evidence for this view is built up throughout the essay and includes examples of influences such as aesthetics upon the choice of a new paradigm theory. There is plenty of grist here for the millstone of your discussions in your individual sections. I warn you though, if you and your classmates set off down the path of pursuing objective truth, it is a long and deep sojourn underground and no one has yet emerged on the other side. Many of us continue to believe that there is a promised land on the other side, a land of eternal truth. Meanwhile we wait for an enlightened philosopher, a Platonic Moses to lead us there.
I do not have time to fully
explore Kuhn’s argument for the importance of nonscientific influences on
the outcome of scientific revolutions, but I will pursue how it relates to his
introduction of the Darwinian metaphor. Kuhn introduces the Darwinian metaphor
to illustrate his view that the process of scientific development is contingent
upon non-scientific influences, influences that arise from the social context
in which science is practiced.
"All the well-known pre-Darwinian evolutionary theories ... had taken
evolution to be a goal-directed process. The 'idea' of man and of the
contemporary flora and fauna was thought to have been present from the first
creation of life, perhaps in the mind of God... [Darwin's work,] Origin of
Species recognized no goal set either by God or nature. Instead, natural
selection, operating in the given environment and with the actual organisms
presently at hand, was responsible for the gradual but steady emergence of more
elaborate, further articulated, and vastly more specialized organisms." -SSR
p.171
This last quotation emphasizes a feature of Darwinian evolution that is largely misunderstood by the general public. The misunderstanding is illustrated by a typical image representing Darwin’s evolution… an image of homo sapiens as the culmination of an evolutionary process that has steadily produced more and more sophisticated creatures. The mechanism of Darwinian evolution assures no such thing. Debunking this stereotypical iconography of evolution is one of Stephen Jay Gould’s goals in writing Wonderful Life. In fact, this image was lifted from that book, although images like it are pervasive in our culture. In explaining Darwinian evolution in action, Gould emphasizes the profound extent to which the detailed progress of biological evolution is historically contingent, that if we were to rewind the tape and start evolution over again from very nearly the same initial conditions, the likelihood that any creature remotely similar to homo sapiens would emerge is vanishingly small.
The principle of contingency is one historians must run up against daily. Change one small detail of the past and what followed would have been entirely different. The title of Gould's book is at once a reference to the author's state of awe at the natural world and a reference to the famous film, starring Jimmy Stewart. In that film, the main character, George Bailey gets to see how things might have been different in his hometown of Bedford Falls had he never existed. Another, more recent, popular film, Back to the Future also explores the idea of historical contingency. Marty McFly goes back in time to witness events surrounding his parents’ courtship. Of course his presence in the past has the potential to influence his own existence in the future. It makes great entertainment, and I suppose is part of the fascination historians have with their field.
As a physicist I would say that the flow of history is extremely sensitive to
initial conditions. Many physical
systems, including some relatively simple ones exhibit this feature. Start two identical systems out with
very nearly the same, but not precisely the same starting conditions, wait long
enough and the two systems will evolve to very different later states. Some of the simplest climate models
exhibit this feature. In that
context it is sometimes called the “butterfly effect.” A butterfly
flaps its wings in the Amazon rainforest… leading to a snowstorm in
Wisconsin three weeks later. I
think we all have a sense that human history exhibits this kind of contingent
development… or sensitivity to initial conditions. What if my mother had turned my dad
down when he asked her out? What
if my grandfather had not survived a grazing gunshot wound, but instead had
received a mortal wound? What if
the butterfly ballot in West Palm Beach had not been a butterfly? Now there’s a butterfly effect!
Here then is the reason for the metaphor Kuhn introduces. He suggests that the particular scientific theories that emerge from a revolution are contingent upon many details of the scientific communities experiencing them. At least some of the significant influences are in no way connected to the goal of moving toward an objective truth. Using the Darwinian metaphor, Kuhn says,
"... the resolution of revolutions is the selection by conflict within the
scientific community of the fittest way to practice further science... And the
entire process may have occurred, as we now suppose biological evolution did,
without benefit of a set goal, a permanent fixed scientific truth ..." -SSR p. 172
Unlike the global communist revolution that Marx believed was inevitable, the
outcome of scientific revolutions is in Kuhn's view far from predetermined.
This is controversial stuff, especially if you are a scientist who has
dedicated her professional life to the pursuit of objective truth. I think it
is fair to say that most scientists in almost all disciplines are realists,
that is they believe there is an objective reality out there and that their
work makes contact with that reality somehow. That view of the cumulative
achievements of science permeates much of our larger culture. Here is Jonathan
Weiner, on page 286 of The Beak of the Finch,
"Science formalizes our special kind of collective memory, or species
memory, in which each generation builds on what has been learned by those that
came before, following in each other's footsteps, standing on each other's
shoulders." -The Beak of the Finch, p. 286
And here is Columbia string theorist and a Lawrence convocation speaker a year
ago, Brian Greene from his book, The Elegant Universe,
"...science proceeds along a zig-zag path toward what we hope will be
ultimate truth, a path that began with humanity's earliest attempts to fathom
the cosmos and whose end we cannot predict." -The Elegant Universe, p. 20
And here is Steven Weinberg, a Nobel-prize-winning physicist and sometime
spokesman for the discipline of physics itself, from an article that appeared
in the New York Review, an article in which he voices his opposition to Kuhn's view of
scientific progress,
"...for me as a physicist the laws of nature are real in the same sense
(whatever that is) as the rocks on the ground... I know that it is terribly
hard to say precisely what we mean by 'real' and 'true.' That is why... I added
in parentheses 'whatever that is.' I respect the efforts of philosophers to
clarify these concepts..." -Steven Weinberg, The NY Review, Oct. 8, 1998.
Although he realizes he is out of his depth when entering the philosophical
arena, Weinberg makes his personal views known, views that I daresay resonate
with many scientists,
"Kuhn's view of scientific progress would leave us with a mystery: Why
does anyone bother? If one scientific theory is only better than another in its
ability to solve the problems that happen to be on our minds today, then why
not save ourselves a lot trouble by putting these problems out of our minds? ...
What drives us onward in the work of science is precisely the sense that there
are truths out there to be discovered, truths that once discovered will form a
permanent part of human knowledge." --Steven Weinberg, The NY Review, Oct. 9, 1998.
At the same time, some of these same scientists readily admit that there are
non-scientific influences, particularly aesthetic ones, on the choice of
scientific theories. Here is Brian
Greene again,
"It is certainly the case that some decisions made by theoretical
physicists are founded upon an aesthetic sense -- a sense of which theories
have an elegance and beauty of structure on a par with the world we experience.
Of course, nothing ensures that this strategy leads to truth." --The
Elegant Universe
p.167
And here is Steven Weinberg again, from the same New York Review article,
"Any set of data can be fit by many different theories. In deciding among
these theories we have to judge which ones have the kind of elegance and
consistency that make them worth taking seriously." -Steven Weinberg, The
NY Review Oct. 8,
1998.
So Kuhn's point is that the scientists present at the time when a new paradigm
is being chosen do not necessarily have as their one and only guide ... some
objective, ultimate truth. The paradigm that emerges is one with strong
historical influences in the same way that the species that emerge as
successful from a period of rapid speciation (perhaps following a mass
extinction) have their origins in species that existed formerly. Nature does
not have access to all possible biological design plans at the time of
speciation. Nature had to work with what she had on hand. In the same way, a
scientific community in a time of crisis does not have access to all possible
theories from which to choose. Inevitably, as many of the old concepts will be
preserved as is possible. Others will be modified as little as need be to solve
the crisis problems. Does this get us closer to ultimate truth? I have a few thoughts along these
lines, but this lecture is about Thomas Kuhn’s ideas and no so much my
own. In any case, my
qualifications to expound upon the philosophy of science are nonexistent. Instead, if I believed in such things,
I would have us hold a seance in which we would summon the spirit of Plato and
ask his guidance in this matter. I don't know if any one else can help us
here. Of course, I would run the
risk he might turn to me and say… “Mister… can you
paradigm?”
how
the analogy is circular
It is important to keep Kuhn's warning in mind... that the analogy (probably any analogy) can easily be pushed too far. Maybe I have already done so. There are a couple of curious ways in which this metaphor is circular: First, Darwin's theory of evolution is a scientific paradigm of the kind Kuhn's framework seeks to explain. In Kuhn's view of scientific development, it is perhaps only a matter of time before Darwin's theory is replaced through a revolutionary event. Darwinian evolution then becomes an "extinct" scientific theory that presumably still functions as a good metaphor for continued scientific development.
On the other hand, assuming Kuhn’s framework of paradigm’s governing the work of a community can be extended to nonscientific disciplines, perhaps including the disciplines of philosophy and history of science, then Kuhn’s ideas about how science develops represents a paradigm within those fields… a paradigm that will also, ultimately be replaced. Perhaps it already has?
Gould,
Stephen Jay, Wonderful Life,
Norton (1990).
Greene,
Brian, The Elegant Universe,
Vintage Books (2000).
Kuhn, Thomas S., The
Structure of Scientific Revolutions, 3rd edition, University of Chicago Press (1962).
Kuhn, Thomas S. ed. by J. Haugeland
and J. Conant, The Road Since Structure, University of Chicago Press (2000).
Weinberg, Steven, The Revolution
That Didn't Happen, The New
York Review (8 October 1998).
Weiner,
Jonathan, The Beak of the Finch, Vintage Books (1994).