Dear Ed, (01)
> > There are at least two ideas of what the members of "1.3 kg" are,
> including:
> > a) the members are mass tropes of different individual quantities
> of matter;
> > b) the members are different individual quantities of matter.
> >
>
> I don't know what David's (b) means. I would have said the members
> of
> the equivalence class designated "1.3kg" are either:
> a) 'mass tropes' of different individual things, or
> b) measurements of the 'mass tropes' of individual things. (02)
MW: I would say neither of these, but the individual things themselves.
The measurements are of these. (03)
E.g. My lump of cheese is a member of the 1.3Kg equivalence class. (04)
<snip>
> I am coming to the conclusion that "1.3 kg" is an equivalence class
> of
> measurements that is defined in part by some specification of the
> tolerable variance in those measurements. Put another way, the
> ratio of
> the measurements to the reference kilogram in Paris is 1.3 to the
> accuracy that we decided to express them (which includes both the
> uncertainty in the measurement and the practical tolerance).
> Scientific
> measures have no notion of tolerance, but they express uncertainty;
> business measures tend to assume that the uncertainty is very small
> relative to the tolerance. In both cases, the "1.3 kg" is a
> 'nominal
> value' that denotes a classification of the measurements. (05)
MW: That sounds OK, but it is something else. I think it is important to
distinguish two concepts: (06)
1. The mass something has,
2. A measurement of the mass something has. (07)
We should not be choosing to be interested in one or the other, but
both. (08)
Regards (09)
Matthew West
Information Junction
Tel: +44 560 302 3685
Mobile: +44 750 3385279
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.informationjunction.co.uk/
http://www.matthew-west.org.uk/ (010)
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