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Of course, all these terms means what enough people want them to mean, and meanings shift. But I agree with John that laws and theories are quite different. (Perhaps it gets confusing when we also consider models - as models can overlap with both - so let's not go there right now.)
There seems however to be a common perception among school age students (certainly from some recent interviews for a project I am involved in) that theories can become laws. This seems to be linked to the recognised conjectured nature of theories and the apparent definitiveness of laws. Of course the mistake there is to see laws as actual knowledge (because they seem exact) and theories as hypothetical (because 'theory' suggests something we cannot be sure about) whereas both law and theory can be seen as part of scientific knowledge - and so in principle provisional as all scientific knowledge is open to revision in the light of new evidence.
The interesting question (to my mind) is to what extent this is influenced by the way we teach or how these terms are used in the media and the 'lifeworld', and so how we could help learners acquire a more sophisticated understanding of such term.
This is of more than academic interest when global warning or ozone depletion (etc) is seen as just a 'just a theory'
Keith
At 13:08 -0500 16/9/12, John Clement wrote:
But a theory is NEVER promoted to be called a law. That was a misconcepted
idea promoted in the mid 20th century. Look at all the things called laws
and they are basically principles or equations.
Boyle's law
Gay Lussacs law
Newton's laws
Ohm's law
.... Please come up with more items on the list.
Quantum theory is never called a law.
Relativity theory is never called a law
Classical mechanics is never called a law
The standard model is not called a law
Electromagnetic theory is not called a law
... Any other examples???
Can you name one theory which was promoted to be called a law??? I can't.
And Boyle's law is falsifiable at some pressures and temperatures, so laws
are not even absolute. Ohm's law is also not true for very high currents.
Some are merely empirical principles or equations, while others are
considered to be more fundamental. Newton's gravitational law has to be
modified in the light of relativity and QM, but it is still called a law and
is used.
So the idea that a theory becomes a law is not really correct. Now a
hypothesis or a postulate can be come a law if it is established as a
verifiable relationship. But a law is a limited thing and usually contains
not explanation and many may be part of theories. This was obviously
someone thinking that theories are tentative and laws are facts. If you
type in a search engine "theory becomes a law" virtually all of the early
hits deny that this ever happens. I think that creationist sites may buy
into this linguistic misconception, so they can say the evolution is just a
theory and not a law.
Unfortunately this misconception appeared in all mid 20th century texts and
is still in some modern ones, so many people still harbor this idea. I
suspect that most elementary and HS teachers still harbor this linguistic
misconception. Incidentally there have been some Physics Teacher articles
about this. I am shocked that the abstract got past the reviewers. But
then lots of things get past the reviewers.
John M. Clement
Houston, TX
Here is a relevant fragment of my paper which will be
published in the proceedings of the Society of Philosophy of
Science (SPS) conference in Montreal (June 2012):
"3. Levels of Confidence in Scientific Claims: Data and Explanations.
A discovered experimental fact is usually presented to the
scientific community, to be independently confirmed or
refuted. Experimental results are accepted--at a high level
of confidence--when they become reproducible on demand.
Absence of such reproducibility justifies suspicion of
possible errors or fraud. Methods of validation of theories
(explanations of facts) are slightly different. A new
scientific theory is also presented to a community of
experts, to be independently evaluated. Their level of
confidence in a theory depends on the validity of underlying
assumptions and on the rigor of quantitative analysis. But
even a most reliable scientific theory, called a law, is said
to be falsifiable, in principle, when conflict with
reproducible-on-demand data becomes undeniable (15). Such
unusual conflict could trigger a scientific revolution (16).
To explain something usually means to identify causes and
to construct a logically satisfying model of reality. An
attempt to explain a fact, or to resolve an apparent logical
conflict, usually leads to discoveries of other facts. A
classical example was the discovery of planet Neptune, in
1846. A more recent and less widely known example was the
discovery of a subatomic particle named neutrino.
Experimental data collected in the 1920's showed that beta
rays (electrons emitted in radioactive decay) had lower mean
energies than expected on the basis of the theoretical E=mc2
formula. Austrian theoretical physicist W. Pauli solved this
"logical inconsistency" by suggesting that tiny neutral
particles, later named neutrinos, were responsible for the
missing energy. His hypothesis was formulated in 1933.
Experiments confirming the reality of neutrinos were
performed, 23 years later. "
Ludwik Kowalski
http://pages.csam.montclair.edu/~kowalski/life/intro.html
P.S. The title of the paper is "Philosophical and Social
Aspects of the Cold Fusion Controversy."
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Dr. Keith S. Taber
Editor: Chemistry Education Research and Practice
(Published by the Royal Society of Chemistry)
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