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[Phys-L] Re: Scientific methods



At 15:06 -0500 2/5/05, Ludwik Kowalski wrote:

It is not possible to "stop taking things on faith" and to help
students to master material in any science course. The laboratory
discovery approach is extremely important but it is used to learn only
a small percentage of what is in a typical textbook. Even scientists do
not perform all experiments in their specialties; they often accept
discoveries made (and published in refereed journals) by other
scientists. How many high school teachers had an opportunity to
experiment with scattering of alpha particles, as Rutherford and Geiger
did in 1911? How many university teachers had opportunities to perform
experiments through which existence of quarks was discovered in 1960s
and 1970s? Not too many. We read about such experiments in reputable
journals, and in textbooks. Then we accept what was discovered by
others. And we teach it. Should we feel guilty? We trust that contents
of science textbooks are verified by recognized authorities in relevant
fields. Yes, I know, it is a complicated issue.

Ludwik, you have defined "faith" vary narrowly--as anything that we
accept other than that which we have personally experienced. I see
that definition as flawed for two reasons,

First, as you have cogently pointed out, we can't directly experience
everything, but we can examine the evidence presented, as well as
other corroborating evidence, and the consequences of the findings,
and come to a pretty reliable conclusion about what is being
asserted. Factored into our acceptance or non-acceptance of the claim
has to be such things as the methodology of the experiment reported,
the nature of the data presented (size of error bars, number of data
points, etc.), the reputation of the investigator (for honesty,
objectivity, integrity, and skill as an investigator), how it fits in
with, or explains other related results, and what it predicts that
can be tested and verified, and others that depend on the nature of
the experiment and the methodology of the particular discipline.

And second, personal experience is a notoriously poor indicator of
reality. We all know about experiments that showed the results the
investigator wanted to see. N-rays are the classic example of that,
but the Vienese laboratory that was looking at the energy
distribution of beta-rays during the 20s and found evidence of
definite energies of the electrons emitted in beta-decay, because
that was what they were looking for, is another and somewhat more
subtle example (see Andrew Brown's biography of Chadwick, "The
Neutron and the Bomb," for more on this). And of course, there are
all forms of hallucinations, flawed memories, and other non-events
that take on a compelling reality to the observer. So to be able to
say, "I saw it with my own eyes," is not necessarily as reliable as
looking at the record of data taken and examining the experimental
set-up, so see if there were any missed systematic errors built into
it.

One of the things that makes science more reliable now than in past
centuries is the existence of permanent, more or less objective
recordings of what happened--chart recorder tapes, photographs,
automated data files, etc., instead of just hand-written collections
of manually taken observations. this allows others to see exactly the
same thing that the original investigator saw, and so provide it with
a more or less objective analysis.

One can argue that all of that is fine, but the farther one is from
the original, the weaker is the connection. So the textbook or
monograph reader pretty much has to accept what book's author says is
the truth. And where does that leave the student?

To an extent, that is true, but that chain also provides much
reinforcement of the result, since each person who passes the result
along, has at least given it enough examination to decide that it is
of enough importance and reliability to include, and that it fits
into the overall picture the author wants to paint. Of course that
doesn't rule out all of the human fallibilities that befall textbook
writers, and which can make almost anything is a textbook wrong.
Keeping textbooks "honest" is a continuing process, and students need
to know this.

Of course the original result can still be wrong, or incomplete, or
not sufficiently accurate to account for subsequent results, or any
of a number of things that can happen to experimental results over
the years. But the big difference between scientific, or
evidence-based conclusions and faith-based conclusion is that they
are much more subject to change in the face of new evidence.

The faithful say, "I hear what you have said, and it's good enough
for me. I believe." The scientist says, "OK, that sounds reasonable,
and it fits with the accepted theories (or it explains something that
current theories don't), so I'll take it and use it until I see
evidence that it wasn't correct, in which case I will change my mind."

I think there is a huge difference between these two stances.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

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