John Clement wrote:
> Boyles law, Newton's laws, Kepler's laws, Hooke's law, The law of
> conservation of energy... have very little in common except for the fact
> that they are called laws and that they are relationships between
variables.
... and that they are all generalizations of facts. In physics, we tend
to generalize by making equations with variables.
However, given that the genesis of this discussion was evolution, one
might like to choose definitions that apply in biology. How do
biologists use the term law? A little googling reveals that although
there is some disagreement about whether biology can have laws (see
<http://www.springerlink.com/content/g0gj47u3q5716250/>), the term is
used for generalizations that cannot be expressed in terms of variables
(see <http://en.wikipedia.org/wiki/Dollo%27s_law>).
> Why not have E=mC^2 as a law? But for some historical
> reason it is not.
> ...
> I could just publish an
> experiment and generalize it and call it a law according to your
definition.
> Is Hooke's law general? Is F=mg also a law? Or how about Ff=mu Fn?
I think it is clear that Ludwik is using 'generalize' in the sense of
'summarize,' not in the sense of 'extrapolate.' Perhaps there is a
wording that is less open to misinterpretation.
Nevertheless, I would have no trouble calling E=mc^2 and F_f= mu F_N
'laws.' They are not traditionally associated with someone's name, but
I can easily imagine using the word 'law' while describing them to a
student.
> Sometimes they may be considered laws, but sometimes not.
Taking this in context, I believe what is intended by this sentence is
"Sometimes they may be considered accurate, but sometimes not." The
usage of "law" here would then be consistent with
> The term law would seem to imply that it is absolute,
But of course Hooke's law famously demonstrates that this is not
consistent with normal usage -- as John explicitly states. Whether some
generalization is 'sufficiently accurate' in any _specific_ situation is
not pertinent to whether it can appropriately be called a law.
Cheers,
-- James
--
Dr. James McLean phone: (585) 245-5897
Dept. of Physics and Astronomy FAX: (585) 245-5668
SUNY Geneseo email: mclean@geneseo.edu
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