From: Keith Henson (hkhenson@rogers.com)
Date: Sun 16 Mar 2003 - 19:07:13 GMT
From: http://cogsci.uwaterloo.ca/Articles/Pages/Ulcers.one.html
*****************
Ulcers and Bacteria I:
Discovery and Acceptance*
Paul Thagard
Philosophy Department
University of Waterloo
In 1983, Dr. J. Robin Warren and Dr. Barry Marshall reported finding a new
kind of bacteria in the stomachs of people with gastritis. Warren and
Marshall were soon led to the hypothesis that peptic ulcers are generally
caused, not by excess acidity or stress, but by a bacterial infection.
Initially, this hypothesis was viewed as preposterous, and it is still
somewhat controversial. In 1994, however, a U. S. National Institutes of
Health Consensus Development Panel concluded that infection appears to play
an important contributory role in the pathogenesis of peptic ulcers, and
recommended that antibiotics be used in their treatment. Peptic ulcers are
common, affecting up to 10% of the population, and evidence has mounted
that many ulcers can be cured by eradicating the bacteria responsible for them.
(large snip to conclusion)
Initially, Marshall thought that his hypothesis about a bacterial cause for
ulcers would gain quick acceptance. Discouraged by the negative reception,
he came to believe that only the development of a new generation of
gastroenterologists would bring acceptance of the new ideas. This
prediction has proven to be unduly pessimistic, even as the early estimate
of quick acceptance was unduly optimistic. Increasingly, the view that
peptic ulcers are caused by H. pylori is being accepted by medical
researchers, although acceptance by practitioners has been much slower. Not
surprisingly, the process has been very complex, and a variety of studies
have contributed to displaying the greater explanatory coherence of the new
theory.
I have shown how the hypothesis that Helicobacter pylori is the principal
cause of peptic ulcers, which was largely rejected as absurd in 1983, could
be on the way to medical orthodoxy in 1995. Satisfying Koch's postulates is
not a necessary condition of showing that a microorganism causes a disease.
Curing the disease by eliminating the microorganism is a powerful
manipulation that provides substantial evidence that the microorganism
causes the disease, and this kind of intervention has been repeatedly
successful in the ulcers/bacteria case. However, accepting the hypothesis
that bacteria cause ulcers is not just a matter of appreciating one kind of
evidence, but rather of appreciating how the hypothesis coheres with
various kinds of evidence and with other hypotheses. For most researchers,
the claim that ulcers cause bacteria was not part of the most coherent
account in 1983, but it is maximally coherent in 1996.
Cognitive coherence is, however, only part of the story about why the
bacterial theory of ulcers has been increasingly accepted. This paper has
treated belief change as a largely psychological phenomenon, a process in
the minds of medical researchers. But the development of medical science
also requires attention to the interactions of researchers with the world
by means of instruments and experiments and the social interactions of
researchers with each other and other parts of society (see Thagard,
forthcoming-b). A full naturalistic account of the rise of the bacterial
theory of ulcers should eventually specify how the cognitive aspects of
belief formation and change described in this paper interact with the
physical and social aspects of the development of science.
***************** (end of quote)
While not analyzed in memetics terms in this paper, the change in the way
peptic ulcers are viewed and treated over the last 20 years certainly makes
a very nice example of the spread of a meme from nothing to approaching
universal. The previous dominate meme, that ulcers were caused entirely by
stress, was largely displaced over that time period. It would have been
fascinating to survey researchers and practitioners at intervals to see
where support for the previously dominant meme fell below half. This past
information might be recoverable from medical journal articles and similar
sources over the past two decades, retrospective surveys of
gastroenterologists, or patient treatment records (when did a particular
doctor in a substantial random sample start treating ulcers with
antibiotics?). It is noted in the article that the meme penetrated
research and practitioner populations at a different rate.
The spread of a meme (Bacteria cause most ulcers) displacing a previous one
(Stress causes ulcers) is a really neat type case. It would not take a lot
of work to graph the change over curves for researcher and practitioner
populations. (S shaped in both cases I bet.) Since we don't need really
high accuracy to resolve the displacement curve, satisfactory research for
a paper on this subject could be done for a few hundred dollars or an
equivalent amount of time.
Any takers?
Keith Henson
===============================================================
This was distributed via the memetics list associated with the
Journal of Memetics - Evolutionary Models of Information Transmission
For information about the journal and the list (e.g. unsubscribing)
see: http://www.cpm.mmu.ac.uk/jom-emit
This archive was generated by hypermail 2.1.5 : Sun 16 Mar 2003 - 22:04:05 GMT