Dear All, (01)
This my answer to John Sowa goes, I think, beyond what is of direct
relevance for computer ontologies. It diplays the difference between my
brand of scientific-fallibilistic realism and John's brand of pragmatism.
But I decided to send it to the whole forum anyway. (02)
Dear John, (03)
> Ingvar,
>
> The important point for the UoM is that we agree that the details
> of the physical theories are not relevant to the ontology:
>
> IJ> Nonetheless, I am of course of the opinion that this is not
> > something that computer ontologists should worry about.
>
> In any case, I certainly admit that the definitions of the physical
> units normally uses theoretical terminology of the time when the
> definition was stated. But I would claim that those definitions
> can be mapped to experimental methods that do not depend on the
> theory. (04)
I think you are wrong. All experimental methods that measure forces rely
on Newton's second law, F = m x a. The Kelvin (ratio) scale for
temperature is dependent on the theory of statistical thermodynamics. It
has an absolute zero point that presupposes the view that temperature at
bottom is caused by, or even identical to, kinetic energy. As long as it
was physically meaningful to think of arbitrary low temperatures, only
ratio scales (such as those of Celsius and Fahrenheit) made physical
sense. (05)
> > The meter is defined as "the length of the PATH TRAVELLED BY LIGHT
> > IN VACUUM during a time interval of 1/299 792 458 of a second"....
> > If, somewhere in the future, physicists will come to the conclusion
> > that this is not completely true, then the definition will in all
> > probability be modified.
>
> I certainly agree. But note that the first sentence can be restated
> in terms of the technology in use at the time the definition was made. (06)
I think it cannot. Supply the definition, and I will tell you what I think
is flawed with your pragmatist restatement. (07)
> Whatever future discoveries change the assumption about the speed of
> light, they would undoubtedly use technology and conditions far
> beyond anything possible at the time the above definition was stated. (08)
No, a new theory that denies that the speed of light in vacuum is
constant, but contains the relativity theories as some kind of
approximations, and is empirically supported with the old technology,
would do the job you regard as impossible. (09)
> Therefore, they would not have any effect on the length of the meter
> that was measurable at the time of that definition.
>
> > The ampere is defined as "that constant current which, if maintained
> > in two straight parallel conductors of INFINITE LENGTH, of negligible
> > circular cross-section, and placed 1 metre apart in vacuum, would
> > produce between these conductors a force equal to 2 x 10-7 newton
> > per metre of length". No one has ever made an experiment with
> > "conductors of INFINITE LENGTH".
>
> I agree. But I would claim that the above definition is flawed
> because it depends on the terms 'infinite' and 'negligible'.
>
> To be precise, the standards documents that include such definitions
> should clarify limit terms such as 'infinite', 'negligible', 'vacuum',
> and 'absolute zero'. They can be replaced by limiting statements:
>
> 1. 'infinite length' means a length that is sufficiently long that
> no further increase has a measurable effect. (010)
To me, 'infinite length' MEANS infinite length. When mathematical formulas
that allow talk of infinite extensions are applied in physics, I don't
think the meaning of 'infinite length' changes as drastically as you and
classical pragmatists are prone to suppose. Every experimenter knows how
to handle things like these when doing experiments. No redefinitions are
needed. (011)
>
> 2. 'negligible' means sufficiently small that no further decrease
> has a measurable effect.
>
> 3. 'vacuum' means sufficiently rarified that no further decrease
> has a measurable effect.
>
> In short, all such definitions should be modified to indicate
> a procedure for showing how the unreachable limit term can be
> approximated while still allowing for improvements in the ways
> of determining what is measurable. (012)
One of the classical criticisms of operationalism and pragmatism is that
such attempted definitions are trying to do the impossible. They are
trying both to restrict the definition to existing measurement procedures,
and at the same time allow (JS: "while still allowing") new not hitherto
seen ones. (013)
Ingvar J (014)
>
> John
>
>
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> (015)
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