Re: comments on http://www.w3.org/TR/2006/NOTE-swbp-n-aryRelations-20060412/

>This email conveys some comments on the note "Defining N-ary Relations
>on the Semantic Web" (12 April 2006).  I realize that this publication
>is intended to represent finished work and that no revision is
>currently intended.  If you do ever revise the document, however, you
>may wish to consider these reactions of an interested reader.
>
>Thank you for addressing this topic, which is an important one to some
>prospective users of RDF.  On the whole, I found the paper useful and
>interesting; I do have some comments on details.
>
>1) I was surprised that the document appears nowhere to address what
>seems to me to be one of the pre-eminent issues with the use of
>Pattern 1: it involves ontological commitments that may be
>uncongenial.
>
>It may well be the considered opinion of the WG that the engineering
>arguments in favor of reifying relations as Pattern 1 does must
>outweigh the philosophical arguments that might be brought to bear
>against attributing existence to, or making individuals out of,
>events, actions, or anything else one might typically describe with an
>n-ary relation.

I would like to hear some such arguments that were at all convincing. 
I do not think that philosopher's views on how best to represent 
medical information are any more noteworthy than, say, the views of 
an aeronautical engineer. Unless of course the philosopher is also a 
medical expert.

>  But if so, that fact is worth recording.
>
>Since bad philosophy so frequently makes for bad engineering, I'm not
>sure whether the engineering convenience does outweigh the
>philosophical objections Quine or others might feel to treating
>diagnoses, or even purchases, as individuals.

In this particular case, the slogan about bad philosophy making for 
bad engineering must, I am afraid, be used in modus tollens against 
Quine, since his nominalistic views simply do not translate into 
feasible ontological engineering practice at all, let alone good 
ontological engineering. I speak as here as one who learned logic and 
set theory from Quine's own wonderfully clear writings, one who once 
was an avowed Quinean, and still with the shreds of regret clinging 
to my psyche, but the facts are simply overwhelming. And in any case, 
one may legitimately disagree with Quine's rather extreme nominalism 
without necessarily being a BAD philosopher.

In my view, what this remark illustrates is that it is now past time 
for philosophy to bear some responsibility for its engineering 
consequences, rather than to think of itself (and be thought of by 
its students and practitioners) as a source of pure insight. Some 
philosophical views, if they are taken to be engineering advice, are 
refutable. Such stark confrontation with the facts may seem alien to 
the business of philosophy, but accepting the possibility of 
rejection on pragmatic grounds is the price one pays for having the 
hubris to give advice in an empirical world. (By the way, Quine was 
wrong about gavagai, as well.)

In my experience so far, in most of the cases where a useful 
ontological decision has been ruled out on purely philosophical 
grounds, the philosophers have turned out to be mistaken (and of 
course, other philosophers turned out to be correct: one of the joys 
of philosophy is that one can find an authority for just about any 
position on just about any topic). A recent example is the insistence 
on a sharp distinction between continuants and occurrents, based 
ultimately on Brentano's search for the meaning of divinity and now, 
tragically, incorporated into a European ontology standard (Dolce), 
to the likely lasting harm of innumerable practical projects, which 
will waste hundreds of man-years trying to conform to ontological 
distinctions rooted in near-Medieval thinking.

>2) A third pattern may also merit mention, namely currying. An n-ary
>relation may be replaced by a binary relation between argument one and
>a relation of arity n - 1, which may itself be replaced by a binary
>relation between *its* first argument and ...  and so on.  An example
>is given in [1].

This is closely similar to the use of argument lists, of course: but 
Currying, unlike argument lists, requires the reification of n-ary 
relations in the first place, so hardly amounts to an elimination 
process in itself.

>[1]
>http://www.mulberrytech.com/Extreme/Proceedings/html/2004/Sperberg-McQueen01/EML2004Sperberg-McQueen01.html
>
>You may wish not to recommend this pattern, but it seems to me to be
>worth mentioning, if only because some readers will think of it and
>wonder whether it is to be preferred or not to the Pattern 1 and
>Pattern 2 identified in the document.  (I note that it does appear to
>avoid requiring anything more in the way of ontological commitment
>than the reification of statements.)

I think not, as I understand Currying. In fact, it cannot be stated 
without assuming that all n-ary relations exist, so is inherently 
second-order.

>3) The note numbers in the document seem to be garbled: in order, they
>appear to be "3", "3", "4", "5", "6".  At the end of the document,
>there are five notes.
>
>4) What on earth is the motivation of modeling a diagnosis by clumping
>Christine and her breast cancer into a single chimerical object?
>
>   :_Diagnosis_relation_1
>       a       :Diagnosis_Relation ;
>       :diagnosis_probability :HIGH;
>       :diagnosis_value :Breast_Tumor_Christine .
>
>Instead of modeling it as involving a patient, a disease, and a
>probability?
>
>   :_Diagnosis_relation_1
>       a       :Diagnosis_Relation ;
>       :diagnosis_probability :HIGH;
>       :diagnosis_patient :Christine;
>       :diagnosis_disease :Breast_Tumor .
>
>
>If there is some best-practices point being made by introducing the
>individual Breast_Tumor_Christine, you should know that it went clean
>over the head of this reader.  If there isn't, perhaps it would lower
>the astonishment factor for some readers if the example just relied on
>the individuals Christine and Breast_Tumor.

What kind of *individual* is Breast_Tumor? Do you refer to the 
particular malignancy in the unfortunate Christine, or do you mean to 
refer to the presence of a breast tumor as being a disease type, 
analogous to Diptheria or Mumps? The former seems to not be a 
specific enough name: the latter seems inadequate to the case.

>   Not everyone will be
>pleased, I suppose, to treat diseases as individuals.  But will anyone
>not a follower of Meinong really wish to treat Breast_Tumor_Christine
>as an individual?

Well, yes. One doesn't need to believe in a universe of mereological 
putty in order to wish to individuate a particular breast tumor. A 
tumor, you will recall, is an actual physical entity, as real and as 
palpable as Christine herself. And its physical characteristics, 
including its shape, rate of growth, biopsy results, etc.., are of 
considerable importance. It would probably be medically irresponsible 
to NOT treat it as an individual if one were an oncologist.

>  (The footnote numbered 2 suggests that Christine
>and her tumor were merged "for simplicity", or may be so read, but I
>have not yet been able to think of a way that a universe including
>Christine and Breast_Tumor_Christine is simpler than one including
>Christine and Breast_Tumor.)
>
>I am similarly puzzled by the restriction of diagnoses to single
>diseases and single probabilities; verisimilitude might be better
>served by allowing multiple disease/probability pairs.  (Or else say
>explicitly that the definition of diagnosis_value and
>diagnosis_probability as functions is a didactic simplification.)
>
>Am I right to think that the definitions given for Diagnosis_Relation
>do not restrict Christine to having diagnoses whose diagnosis_value
>involves Christine?  That is, the definitions given don't seem to rule
>out a graph of the form
>
>   :Christine
>       a       :Person ;
>       :has_diagnosis _:Diagnosis_Relation_1 .
>
>   :_Diagnosis_relation_1
>       a       :Diagnosis_Relation ;
>       :diagnosis_probability :HIGH;
>       :diagnosis_value :Breast_Tumor_Alison .

This is a general issue in Semantic Web formalisms. They do not 
restrict at all, so there is nothing to 'rule out', in the sense of 
forbid, the above or for that matter

  :_Diagnosis_relation_1
       a       :Diagnosis_Relation ;
       :diagnosis_probability :HIGH;
       :diagnosis_value :Vanilla_Custard .

Pat Hayes
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Received on Monday, 24 April 2006 15:59:22 UTC