Dear all, (01)
Pehaps this is of interest for more than Pat. (02)
Ingvar (03)
---------------------------- Original Message ----------------------------
Subject: Re: [uom-ontology-std] What is mass?
From: "ingvar_johansson" <ingvar.johansson@xxxxxxxxxxxxx>
Date: Mon, September 28, 2009 19:47
To: "Pat Hayes" <phayes@xxxxxxx>
-------------------------------------------------------------------------- (04)
Dear Pat, (05)
I had got the impression that most UoM ontologists in this discussion had
opted for "the equivalence class view", and so I put forward a question to
David Leal in order better to understand this view. I am myself an
immanent realist with respect to universals, and think that when such a
realism is enlarged with a determinate-determinable distinction, most
issues around quantities can be solved in an easy way. Nonetheless I think
that "the equivalence class view" (with its nominalist leaning) very well
might be able to create a good UoM ontology. (06)
This being said, I will now make some comments on your mail. (07)
> On Sep 28, 2009, at 10:13 AM, ingvar_johansson wrote:
>
>> Dear Pat,
>>
>> you wrote:
>>> Agreed, but they too often stray from being an arriving at a common
>>> understanding, into what might be called a confusion of amateur
>>> ontology-hacking. The current noise about 'equivalence classes' (with
>>> no mention of any equivalence relations) is a good example.
>>
>> If you were thinking of me, I took it for granted that the relation
>> is a
>> similarity relation.
>
> Hmm. But 'similar to' is typically not transitive, so not an
> equivalence relation. (08)
O.K., but the relation 'exactly similar' is, and with its help one can
probably construct classes that correspond to 'similar within a certain
range'. (09)
>
>> Take mass as an example. If one wants to take one's departure in
>> individual instances of mass (what VIM calls quantity values of mass),
>> then generic quantity values such as 1.53 kg and 137.999 kg can be
>> regarded as being classes of exactly similar instances
>
> 'similar' in what sense? (010)
Good question. To me similarity is always similarity in a certain respect.
Or, in other and more philosophical terms, similarity is always similarity
between determinates of the same determinable. But many philosophers and
information scientists seem to me to be of another opinion. (011)
> The only useful sense that I can determine is
> that they are both measures of the same quantity. So all this
> equivalence-class talk does not eliminate the idea of kind of
> quantity, or reduce it to something conceptually simpler or ontology
> more fundamental. (012)
I regard the base kind-of-quantities as universals, and I find this view
both conceptually simpler and ontologically more correct than the "the
equivalence class view". But nominalists have it the other way round. So,
let's try to make metrology that can be understood from both a realist and
a nominalist point of view. (013)
>
> BTW, the fact that one has to start with 'individual instances of
> mass' is itself a large mark against this POV, as these individual
> instances are ontologically useless and intuitively very opaque. I
> personally do not think they exist. If they do, then each act of
> measurement measures a distinct one of them, distinct - indeed,
> *necessarily* distinct - from those measured by all other acts of
> measurement. (014)
Some philosophers (so-called 'trope theorists') regard such individual
instances as simple, and try to bind them into natural classes by means of
relations of exact similarity. I, however, regard such individual
instances as complex, and as having a universal as one of their
constituents. To me the universal grounds the exact similarity, which
otherwise seems to come from out of nowhere. (015)
> Regardless of the authority of the VIM, this seems to me
> to be close to incoherent as a basis for a theory of measurement. (016)
VIM defines 'kind of quantity' before it defines 'quantity value' (=
individual property instances). (017)
>
>> ; and the dimension
>> mass can be regarded as the class of all such equivalence classes
>> whose
>> instances are physical-chemically comparable.
>
> Well, perhaps it can, but what is gained by this re-regarding? (018)
To me: nothing. But for nominalists it saves their ontological commitments. (019)
> This
> account is certainly not simpler or easier to formalize than the one
> which has kinds-of-quantity as an explicit concept. If we are going to
> be strictly mathematical about it, in fact, they are exactly
> equivalent (each can be defined from the other, with some basic
> mathematical assumptions such as the axiom of choice); but the
> equivalence-class way of talking is less natural and more long-winded,
> without adding any insight or expressiveness. (020)
I have no opinion on this; I leave it to the UoM project. (021)
>
> Best
>
> Pat Hayes
>
> PS. Another remark about QVMs. You appeal to a similarity relation of
> 'being a measurement of the same quantity kind'. (022)
No, I didn't. I treated the similarity relation as a primitive, despite
the fact that I am more than well aware of the fact that different
ontological commitments will give rise to different specifications. (023)
Best,
Ingvar (024)
> But there are many
> other possible such relations, among them 'being made using the same
> apparatus', 'being a measurement made at the same time of day', etc..
> These are all mathematical equivalence relations, and all could count
> as 'similarity' relationships. What is that distinguishes your
> particular relationship form the many others?
>
>>
>> Best,
>> Ingvar
>>
>>
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