A lot has been written in this list about postmodern philosophy after
the recent publication of an article "Deconstructing the evidence-based
discourse in health sciences: truth, power and fascism" by Holmes et al.

I've read a lot of this commentary, but didn't find anything that
reflected my opinion about this issue, so I thought I'd put some of
these ideas down in an email. My apologies if I am prolonging a thread
that deserves to be put to rest.

A careful definition of post-modernism is hard to find, and many people
define it in a way that it represents everything that is good, and
others define in a way so that it represents everything that is bad. I
like the Wikipedia for its efforts to present controversial topics from
a neutral point of view (an effort that some post modern thinkers would
argue is not possible). The web page on postmodernism:

http://en.wikipedia.org/wiki/Postmodernism

offers a range of definitions, three of which I believe are relevant to
EBM. First postmodernism is

> A continual skepticism towards the ideas and ideals of the
> modern era, especially the ideas of progress, objectivity,
> reason, certainty & personal identity, and grand narrative in
> general

This definition places postmodernism in conflict with EBM, which often
cites examples of medical progress through the careful application of
medical research. For example, we have learned that folate
supplementation during pregnancy reduces the risk of neural tube defects
through the use of several randomized trials. 

Postmodernism and EBM also conflict over the concept of objectivity. EBM
promotes objectivity through the use of grading scales, user guides to
the literature, systematic overviews, and so forth.

Two other definitions on the Wikipedia page represent skepticism about
objectivity.

Postmodernism can be defined as

> The belief that all communication is shaped by cultural
> bias, myth, metaphor, and political content.

Or as

> The assertion that meaning and experience can only be
> created by the individual, and cannot be made objective by an author
> or narrator.

Perhaps the most popular exposition of a postmodern philosophy is the
claim in Dan Brown's DaVinci Code that "history is written by the
winners." It is actually through an analogy of historical thought that
the concept of postmodernism became clearer to me.

Can historians reach an objective conclusion about something like the
existence of the Holocaust? That's a topic tackled early in a book by
Michael Shermer and Alex Grobman, "Denying History: Who Says the
Holocaust Never Happened and Why Do They Say It?" The book reviews the
evolution of historical thought which started as a belief that an
objective account of history was an achievable goal. It then evolved
into a postmodern belief that all historical accounts reflect the
viewpoint of the historian. Note the quote on the Wikipedia page on
history

http://en.wikipedia.org/wiki/History 

> In recent years, postmodernists have challenged the
> validity and need for the study of history on the basis that all
> history is based on the personal interpretation of sources.

The most recent perspective on history, according to Shermer and
Grobman, is that personal interpretations do influence historical
accounts to some extent and some historical facts will always remain in
dispute. But historians can indeed arrive at objective conclusions.

> "We prove the Holocaust through a convergence of data that
> include: Written documents-letters, memos, blueprints of the
> camps, orders, bills, speeches, articles, memoirs and
> confessions. Eyewitness testimony accounts from survivors, members of
> the Jewish sonderkomandos who took bodies out of the gas
> chambers, SS guards, commandants, local townspeople and
> high-ranking nazi officials. We have many letters from German soldiers
> stationed on the Russian front to their families in, which they
> describe the mass shooting of Jews. Photographs-including
> official military and press photographs, civilian photographs,
> secret photographs taken by survivors, aerial photographs,
> German and allied film footage and photographs taken by the German
> military. The camps themselves; And inferential
> evidence-population demographic, reconstructed from pre-World War II.
For
> example, if six million were not killed, what happened to all these
> people?"

(as quoted in www.holocaust-trc.org/deny_history.htm).

The Shermer and Grobman argument shows the folly of a total embrace of
postmodern thought. If you believe that there is no possibility of an
objective account of history, then you have to accept the possibility
that the Holocaust was a creation of a Jewish conspiracy.

The recent push in the United States to "teach the controversy" about
evolution and intelligent design also represents a postmodern approach,
in my opinion, though I suspect that both the intelligent design
community and the postmodern community would dispute it. But note a
comment in Wikipedia that Philip Johnson has

> appropriated the concept to cast doubt upon the very
> concept of established knowledge.

en.wikipedia.org/wiki/Teach_the_controversy 

That sounds very postmodern to me.

So a total embrace of postmodern philosophy would leave us open to any
crackpot theory that might come along. 

On the other hand, a wholesale rejection of postmodern philosophy would
lead to problems as well. When journal editors require disclaimers about
financial conflicts of interest, it is done with the understanding that
readers will interpret the data differently when they realize the source
of the data. That sounds kind of postmodern to me.

Joel Best, in his book, Damned Lies and Statistics, has a very nice
argument for postmodernism when he states:

"We sometimes talk about statistics as though they are facts that simply
exist, like rocks, completely independent of people, and that people
gather statistics much as rock collectors pick up stones. This is wrong.
All statistics are created through people's action: people have to
decide what to count and how to count it, people have to do the
counting, and people have to interpret the resulting statistics, to
decide what the numbers mean. All statistics are social products, the
results of people's efforts." 

This is not to say that all statistics are bad, just that you can't
interpret them without first understanding the context in which they
were created.

The same can be argued about EBM. Medical research is produced in a
social context, and failure to recognize this is a serious limitation of
EBM. Not to pick on a single medical specialty, but when someone argues
"they're only saying this because they're surgeons" that is probably a
good thing as long as you don't take it to the point of "you can't trust
anything that a surgeon tells you."

I suspect (but have to admit that this is just speculation) that the
authors of "Deconstructing the evidence-based discourse in health
sciences: truth, power and fascism" have adopted a postmodern position
because they are upset at the EBM rejection of some forms of alternative
medicine. Indeed there are some in the alternative medicine community
who adopt an evidentiary perspective that places individual patient
narratives above randomized trials. Many alternative medicine websites
offer wholesale criticisms of the medical research enterprise and offer
anecdotal evidence in its place.

This antipathy is reflected from the opposite perspective by the
comments of Angell and Kassirer in a famous NEJM editorial 

> There cannot be two kinds of medicine - conventional and
> alternative. There is only medicine that has been adequately tested
and
> medicine that has not, medicine that works and medicine that may or
> may not work. Once a treatment has been tested rigorously, it no
> longer matters whether it was considered alternative at the
> outset. If it is found to be reasonably safe and effective, it will be
> accepted.

Angell M, Kassirer JP, Alternative medicine--the risks of untested and
unregulated remedies. N Engl J Med 1998;339:839.

There are, however, just as many proponents of alternative medicine who
have embraced EBM and believe that when the proper research studies are
done, they will support alternative medicine as superior to traditional
Western medicine. There are also advocates of EBM who admit that the
randomized control trial is not the ideal arbitrator of truth when
evaluating alternative medicine. 

Mason S, Tovey P, Long AF. Evaluating complementary medicine:
methodological challenges of randomised controlled trials. BMJ. 2002 Oct
12;325(7368):832-4.

So a bit of postmodernism is probably good medicine, as long as you
don't overdose on it.

Steve Simon, [log in to unmask], Standard Disclaimer.
Look for my book "Statistical Evidence in Medical Trials"
newly published by OUP. For more details, see
http://www.childrens-mercy.org/stats/evidence.asp