Not sure I agree. Anything which is a unit at least implies that there
could be a multiple of that unit (theological concepts aside), which
implies counting which is a form of measurement. (01)
On the other hand, getting into concepts of measurement and
observation themselves will bloat an ontology of units beyond
recognition. Certainly there are methods of measurement for properties
such as hardness which are only faintly comparable in detail, but I
would hope that concepts such as scales / coordinate systems would
help with this, since some of those can be mapped precisely from one
to the other, but not all of them even if they purport to represent
the same property. (02)
Josh (03)
On Aug 7, 2009, at 9:30 AM, Mike Bennett wrote: (04)
> True, but we need to also remember that not all units are units of
> physical measurement, i.e. not all measured amounts of something are
> measured amounts of some physical thing. In particular, the concepts
> of
> "Amount", "Unit" and so on are applied equally to amounts of money and
> units of currency. Though you could argue that apart from the US
> Dollar,
> units of currency are defined by some process of measurement (the rate
> against the US Dollar).
>
> Therefore I would hope that the fundamental properties at the core of
> this, are not prematurely committed to the physical world. Rather,
> there
> are amounts and units, and there are physical amounts and physical
> units
> which are kinds of these, as well as currency amounts and currency
> units
> which are kinds of these (and all the other interesting variations we
> have seen). Perhaps things like hardness would fit into that kind of
> framework more easily than if we pre-commit to a physical-only view of
> measurement and units.
>
> Mike
>
> John F. Sowa wrote:
>> David,
>>
>> All units of measure are ultimately defined by some process
>> of measurement. The meter was formerly defined by a comparison
>> with a standard held in a vault in Paris. Now it's defined as
>> a wavelength of light emitted by a certain type of atom under
>> certain conditions.
>>
>> There is no difference, in principle, between the definition of
>> 'meter' or the definition of 'standard candle':
>>
>> The Standard, or International, Candle is a measurement
>> of light source intensity. It was originally defined as
>> a one-sixth-pound candle of sperm wax, burning at the rate
>> of 120 grains per hour. This intensity of light was standardized
>> in 1921 in terms of incandescent lamps, and candles are no
>> longer used for reference. (From Britannica online)
>>
>> The definition of 'hardness' by various methods is no different in
>> principle from the definition of any other kind of physical unit.
>>
>> John Sowa
>>
>>
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>>
>
>
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