Re: [asa] Theory of gravity

Hi Jon,

Definitions of words are always important, and nearly always broken. Even within the scientific community, I think there are multiple ways the words law, theory, & hypothesis are used. I tend to think, however, that this is mainly a result of a lack of careful education & thinking about them, rather than they really having multiple meanings. That's an opinion that others might not share, of course - there are many ways that people use terms, and we sometimes define the meaning of terms based on how they are used, yet at the same time terms are not always used correctly. Further, people are sometimes inconsistent in their own usage of terms.

I tend to agree with where you landed at the end of your 3rd paragraph. If one looks for definitions of these things, the main ideas that jump out are empirical, explanation, and tested. After some looking into this and thinking about it, here's my best stab:

Laws are empirical, based on observation, never have been found to be violated, & typically have associated mathematical formulae. They do not explain why phenomena happen, only describe what occurs. Examples include the laws of thermodynamics, gravitational attraction, diffusion, refraction of light, etc. etc. They are also most often named after individuals who discovered/described them. They also tend to be "old" science - there aren't a whole lot of new laws being described or put forth in the literature.

Hypotheses are tentative explanations. They are models that try to explain WHY some thing is the way it is. Tentative meaning they may have been tested some or held up to some scrutiny, but they are not yet accepted by the vast majority of the scientific community, but rather there are often numerous competing hypotheses proposed by various "camps" or "schools of thought". This, in my opinion, is where most modern science is done and how most of it moves forward. Competing models drive different workers to collect new data to support their own work or disprove another's work.

Theories can be thought of as hypotheses that have taken over the vast majority of science. They have been tested by numerous workers, in some cases over generations, in many different ways, and they have held up to all of that testing such that they are accepted as truth statements within the scientific community. The key factor in both hypotheses and theories is their explanatory power - they attempt to explain WHY things are the way they are - theories do it so well that virtually everyone working in the field accepts them as correct explanations and interpretations of the world. While they do continue to be tested, they also serve as the paradigm of understanding within which scientists work. As such, they drive the collection and interpretation of new data in ways we may not always be aware of ourselves.

I think the wiki article you described uses the words theory and law incorrectly. A theory cannot become a law by enough testing. A law describes, a theory explains; they are different creatures.

As you say, different parts of gravity are law or theory, depending on if we are simply describing phenomena that consistently occur, or if we are attempting to explain why those phenomena are occurring.

I'll stop there and let others chime in.

Best,
Charles

_______________________________
Charles W. Carrigan, Ph.D.
Assistant Professor of Geology
Olivet Nazarene Univ., Dept. of Physical Sciences
One University Ave.
Bourbonnais, IL 60914
PH: (815) 939-5346
FX: (815) 939-5071
ccarriga@olivet.edu
http://geology.olivet.edu/

"To a naturalist nothing is indifferent;
the humble moss that creeps upon the stone
is equally interesting as the lofty pine which so beautifully adorns the valley or the mountain:
but to a naturalist who is reading in the face of the rocks the annals of a former world,
the mossy covering which obstructs his view,
and renders indistinguishable the different species of stone,
is no less than a serious subject of regret."
          - James Hutton
_______________________________

>>> "Jon Tandy" <tandyland@earthlink.net> 11/21/07 6:23 AM >>>
Having now finally watched the rest of the PBS special on the Dover trial, I
have a few questions. I'll just start with one for now.
 
I recall it being mentioned that the "theory of gravity" is the same as the
"theory of evolution" -- both are tentative and could potentially be
disproved, although both have substantially large bodies of evidence in
support of them. I thought that was a good argument at the time, but later
I imagined that someone will criticize that argument on the grounds that
Newton's "laws" are no longer considered scientific theory but laws. As an
example of the confusion of terms, Wikipedia's article "Newton's law of
universal gravitation"
(http://en.wikipedia.org/wiki/Newton%E2%80%99s_law_of_gravitation) starts
with the statement: "Isaac Newton's THEORY of universal gravitation is a
physical LAW describing the gravitational attraction between bodies with
mass."
 
As someone with a fair amount of education in science, I realized I didn't
have a completely solid grasp of the difference between a law and a theory.
My first thought was a law is more sufficiently proven or demonstrated than
a theory. However, on reflection, I think a better explanation is that a
scientific law attempts to describe an observation in nature with
empirically derived analytical formulas, while a scientific theory attempts
to explain the observations (causes, etc.). So is gravity a law or a
theory? If I'm not mistaken, it's both. The law of gravity (Newton's
generalization, now superceded by Einstein's equations) is given by
F=G(m1*m2)/r^2. This is empirically derived and demonstrable (again, with
qualification by Einstein in special cases). However, the theory of gravity
seeks explanation by proposing the source of the force of gravity, such as
gravitons, etc., which is still in the theoretical stages, with various
alternative proposals. Is this a fair assessment? Is it true that
gravitation, or at least some aspect of it, is still "only a theory" (to use
derogatory YEC-speak)?
 
The "theory of evolution" attempts to explain the mechanisms of observed
phenemona. It's clear that this is still a theory in flux, with new
discoveries such as lateral gene transfer, DNA replication errors, etc.,
contributing to biological development in ways not completely understood.
But if a "scientific law" describes observations in nature, at what point
could the observations of evolutionary inheritance be called a "law"? Could
there come a point where certain observations or mechanisms of biological
evolution could become quantified to an extent like Newton's formula for the
law of gravity? Is it there yet? I don't know of anyone using the
terminology "law of evolution" on either side of the debate, although there
was something (either in the program or in a forum discussion on our local
PBS station after the program), where the assertion was made by ID advocates
that "evolution is not the 'law of evolution', but only the 'theory of
evolution' ".
 
 
Jon Tandy
 

To unsubscribe, send a message to majordomo@calvin.edu with
"unsubscribe asa" (no quotes) as the body of the message.
Received on Thu Nov 22 00:13:02 2007