John Sowa wrote, (01)
> It is true that the latest and greatest science and technology was
> necessary to define the units of measure to the current degree of
> precision. However, we must remember that the same words were
> used for those units in the 19th century. The values used then
> differ from the current values by much less than 1%. (02)
> The UoM ontology should be little more than a compendium of the
> values of the units and the relations among them. The details
> of how they were derived is not necessary for using them. (03)
Not contesting what John here says, I would like to add that I think that
it is good for UoM ontology constructors to be aware of the following four
facts: (04)
1. Ratio scales, interval scales, and ordinal scales require different
formalisms. (05)
2. Out of every ratio scale an interval scale can be constructed, and out
of every interval scale an ordinal scale can be constructed, but not
conversely. (06)
3. In the late nineteenth century, physics was able to replace the
existing interval scales for temperature with a ratio scale for
temperature (the Kelvin scale). (07)
4. There is no axiom or theorem to the effect that science can turn all
ordinal scales into interval scales, and all interval scales into ratio
scales. (08)
Ingvar J (09)
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