I believe that the Pluto story is actually a better example of paragraph
2 than of paragraph 1 in Marc's post. I don't think it is a good example
at all of how scientists expect change in our conclusions as data
accumulates. No new data accumulated to make this change. It is an
excellent example of operational definitions in science. In psychology,
intelligence is what the intelligence test measures and in astronomy,
whether or not Pluto is a planet depends on a scientist's definition of
the word, "planet". My paperback dictionary, obviously way out of date,
says that a planet is any heavenly body that revolves around the sun. I
think that definition would not exclude any planet's moon or some
asteroids. By the way, the current planetary definition only applies to
our solar system which seems strangely parochial for a science like
astronomy. Evidently, there is not enough agreement yet about what makes
something a planet outside of our solar system. The current operational
definition for our solar system, set by the International Astronomical
Union by a vote is: a celestial body that is (a) in orbit around the
Sun, (b) has sufficient mass for its self-gravity to overcome rigid body
forces so that it assumes a hydrostatic equilibrium (nearly round)
shape, and (c) has cleared the neighborhood around its orbit.
I think it is interesting that, other than in the area of diagnoses of
psychological disorders (set by a vote of the American Psychiatric
Association), we don't have such a mechanism for voting operational
definitions up or down in psychology ("The ayes have it! A person shall
be considered to have good self-esteem if they score above x on the
Coopersmith Self-Esteem Inventory."). I wonder if this is a good thing
or a bad thing.
Rick
Dr. Rick Froman, Chair
Division of Humanities and Social Sciences
Box 3055
x7295
[EMAIL PROTECTED]
Proverbs 14:15 "A simple man believes anything, but a prudent man gives
thought to his steps."
-----Original Message-----
From: Marc Carter [mailto:[EMAIL PROTECTED]
Sent: Friday, August 25, 2006 9:15 AM
To: Teaching in the Psychological Sciences (TIPS)
Subject: [tips] RE: Pluto's chromosomes
That turned out to be a perfect lesson for my first research methods lab
yesterday. We talked about the sort of "truth" that we do in science
(way different from Plato's idea), and how we have to expect change as
new data come in.
It also afforded an opportunity to talk about operational definitions,
theoretical constructs, and like that. Pluto the object hasn't changed,
but the way we conceptualize it has.
It was fun (there were the Mickey Mouse/Pluto jokes, too), and very
timely.
Cheers,
m
-------
"Whatever power the United States Constitution
envisions for the Executive in its exchanges with
other nations or with enemy organizations in times
of conflict, it most assuredly envisions a role
for all three branches when individual liberties
are at stake."
---
July 20,2006
US District Court for Northern California
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Sent: Friday, August 25, 2006 6:25 AM
> To: Teaching in the Psychological Sciences (TIPS)
> Subject: [tips] Pluto's chromosomes
>
> Now that Pluto's been booted out of the solar system, it's
> time to reflect. What it reminds me of is a day long ago in
> high school. That was the day our biology teacher walked into
> class and told us with annoyance that the number of
> chromosomes had changed. "They" apparently had decided that
> we no longer had 48 chromosomes. We had 46, and that's what
> we had to learn from now on. She seemed quite put out about it.
>
> I now know what that was about. In the early days, it was
> very difficult to count human chromosomes because the
> preparations were so poor. They were too long and tangled to
> count easily, and went in and out of the plane of the
> microscope, where they might appear to be two rather than
> just one. One of the recognized authorities did a careful
> study of them
> and reached a conclusion that went something like this:
> "Well, sometimes I get 46 chromosomes and sometimes I get 48.
> I can't be sure, but maybe the 48 count is the best estimate".
>
> Over time, that n = 48 number became reified, and people
> forgot about the doubts expressed in the original paper.
> Instead, whenever they counted chromosomes and got 46, they
> said "Nah, couldn't be", and counted again.
> They kept counting until they got the right answer, which
> they knew was 48. And the 48 number would be confirmed.
>
> Finally, chromosomal preparations improved so much that it
> became blindingly obvious that there were only 46, and at
> last one brave soul said so. Eventually it filtered down to
> the high school textbook level.
> Enter my teacher.
>
> So the moral seems to be that science does change (see
> Pluto). But more attention to the primary literature, and to
> the data, not to mention to using an appropriate technique to
> avoid contaminating results with expectations wouldn't hurt.
> Also, it wouldn't hurt to have less respect for authority.
>
> Stephen
>
> -----------------------------------------------------------------
> Stephen L. Black, Ph.D.
> Department of Psychology
> Bishop's University e-mail: [EMAIL PROTECTED]
> 2600 College St.
> Sherbrooke QC J1M 0C8
> Canada
>
> Dept web page at http://www.ubishops.ca/ccc/div/soc/psy
> TIPS discussion list for psychology teachers at
> http://faculty.frostburg.edu/psyc/southerly/tips/index.htm
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