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[Phys-l] DATA, FACTS, LAWS, THEORIES

Hi Ludwik,

I also read Wade's article.

I disagree; I don't think a meaningful distinction can be drawn between fact, theory and law. For starters, Newton's laws are wrong but Einstein's theory is correct. Kepler's laws are only approximate. So we don't use these terms consistently (perhaps we should but it is too late, we don't).

Second, facts are contingent on theory in at least two ways. The fact that we observe current flow is contingent on our theories of how ammeters and voltmeters work. There are few observations made today that don't depend on starting with some assumed (theoretical) knowledge. This is ok, we can't test everything at once so we assume some things are true while we test other things. Theories also tell us where to look for facts. We don't just go out and start measuring stuff to see if there is some correlation somewhere. For example the data supporting black holes only makes sense because we have a theory of black holes. We have to know to look for gravitational lensing before we can discover the fact that black holes exist. It doesn't make sense to try to separate facts from theory.

I think Wade in the NYT book review was trying to get at how science can be right at the same time that it can change over time. Here is a better way to think about it. We are perfectly rational to believe (and I mean really believe) that something is true if all the data supports it and, upon trying to find counter evidence we find none (this is important- finding data in support is often easier but one good counter example destroys the theory). It is equally rational to change your mind if you get better information. I really believe my breakfast cereal is nutritious. Then I read in the news about a contamination problem and change my mind. I am not being silly or irrational, rather I am being very rational.

Now, any good scientific concept is fruitful- it suggests new ideas to try. So sure, the testing process is never done but just because you can think of some new test doesn't mean you should abandon the concept. In the history of science we almost never abandon a theory or law until we have something better to replace it. This also is rational; a well established theory is worth keeping, even if it might suggest new ways to test it.

We should believe (I mean really believe it is true) in evolution as the best truth that is available. Until we have evidence to the contrary. And it also makes sense to keep testing it, even while believing it is true.

Oh and hypothesis are a nice idea but I don't think very many scientists actually operate that way. We start with something that looks interesting or puzzling and start playing around with it; our intuition outruns our rational mind at first. Usually after the fact we can come up with a hypothesis but more often we start with a hunch or a dream or an idea. The guy who discovered the benzene ring didn't have a hypothesis initially- he dreamed of a snake rolling down a hill by biting its tail and forming a hoop. But it doesn't matter where we get ideas from (hypothesis or dreams). What matters is if we can back them up with physical data and, after trying hard to knock them down, they are still standing. I have noticed that biology papers tend to state a formal hypothesis but I don't see this done in many physics papers.

kyle
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Message: 2
Date: Sat, 17 Oct 2009 10:51:14 -0400
From: ludwik kowalski <kowalskil@mail.montclair.edu>
Subject: [Phys-l] DATA, FACTS, LAWS, THEORIES
To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Message-ID: <B2AC1943-5ADA-4EFE-84D3-E1DFB539F6B4@mail.montclair.edu>
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What follows was prompted by Nicholas Wade?s New York Times Book
Review (October 11, 2009). My comment is about scientific DATA, FACTS,
LAWS, THEORIES, ETC. I hope this will be useful. Distinctions between
DATA and FACTS, or between LAWS and THEORIES are important. Comments,
as always, will be appreciated.

Ludwik

= = = = = = = = = = = = = =

Cognitive Structure of Science (This is my title, not his.)

a) Any recorded piece of information, about a natural phenomenon, is
DATA. It can be the result of an observation or an experiment; it can
be qualitative or quantitative.

b) A piece of data recognized as valid, by most practitioners in a
given field, becomes a FACT. Laboratory facts are confirmed data; any
scientist using the same protocol is expected to obtain the same data;
at a specified level of reproducibility. Science is not mathematics;
that is why the level of reproducibility, for example 90%, should be
reported.

c) A LAW is a generalization of facts. I am thinking about Kepler?s
Laws (how planets move), about Mendeleyev?s Law (how elements are
ordered in a chart), Faraday?s Law (how changing currents can be
induced), etc.

d) A THEORY is an explanation of a law. I am thinking about Newton?s
gravitational theory, about Maxwell?s equations, about quantum
mechanics, about Heizenberg?s principle, etc. Distinctions between
laws and theories (and between facts and theories) are worth
recognizing. Unfortunately, this is not always done.

e) Theories are based on assumptions which may or may not be valid.
Assumptions can be based on facts, on laws, or on intuition.

f) Scientific theories are validated not only on the basis of their
logical (mathematical) correctness but also on the basis of their
ability to guide to discoveries of unknown facts. Scientific theories
evolve; some theories are more powerful, more general, and more
elegant, than others.

g) The concept of ?absolute truth,? often used by mathematicians and
theologians, does not belong to science. Wade wrote: ?A theory,
however strongly you believe it, inherently holds a small question
mark. The minute you erase the question mark, you?ve got yourself a
dogma.?

h) An hypothesis is a tentative idea to be confirmed. It is a common
instrument of human thinking. Hypothesizing is used by all those who
collect data, who turn data into facts, who generalize from individual
facts, and by those who explain facts of nature. Tentative assumptions
are made by all thinking people, not only by physical scientists.

i) To avoid confusion, scientists try to define their terminology. The
term ?theory,? for example, does not mean the same thing as the term
?hypothesis.? But non-scientists often confuse these two terms. In
common language the words ?theory? and ?speculation? are often used as
if they were synonyms.

j) ?Force,? ?energy,? and ?power? are commonly used interchangeably by
non-scientists. Novice physics students often find this confusing.

= = = = = = = = = = = = = =

Ludwik Kowalski, a retired physics teacher
5 Horizon Road, Apt. 2702, Fort Lee, NJ, 07024, USA
Also an amateur journalist.

Food for thought:
"Absence of proof is not proof of absence."

Updated links to his selected publications are at:
http://csam.montclair.edu/~kowalski/cf/ , http://csam.montclair.edu/~kowalski/my_opeds.html
and http://csam.montclair.edu/~kowalski/revcom.html




--
------------------------------------------
"The modern conservative is engaged in one
of man's oldest exercises in moral philosophy;
that is, the search for a superior moral justification for selfishness."
- John Kenneth Galbraith

kyle forinash kforinas@ius.edu -----------------------------------------