More obscure analogies

[Tony Linde]

Maybe we should rename this group the 'VO Philosophy' IG? :)
 
<<My original comments were specifically about the word "event". An event is
not only an arbitrary notion - it is a whole constellation of arbitrary
notions.>>
 
Surely, from the sem.ig point of view, we need to focus on what the voevent
ontology will be *used* for and then look at the entities and relationships
we need to define for that. Let's keep things simple and focussed to start
with and then evolve (sexually and asexually) the ontologies as new
applications or needs arise.
 
Do we have any use cases for a voevent ontology?
 
Cheers,
Tony.


  _____  

From: owner-semantics at eso.org [mailto:owner-semantics at eso.org] On Behalf Of
Rob Seaman
Sent: 07 June 2005 07:46
To: semantics at ivoa.net
Cc: Rob Seaman
Subject: More obscure analogies


On Jun 6, 2005, at 4:28 PM, Bernard Vatant wrote:


Cool. I love recursive definitions :) That one is certainly operational -
fit for everyday life affairs. But to provide a scientific definition of
human kind as a species, forget it, it's easily broken ...


Actually, I think it is fairly close to what would be regarded as the
current "scientific definition". More to the point, it isn't clear that
"everyday" and "scientific" definitions are, or should be, different.
Certainly complexity of expression doesn't equal depth of understanding.


I would be happy to trace my ancestors back to, say, 200 millions years ago,
and meet them one by one - just to check the humanity breaking point


But evolution contains the context for addressing these issues, too. Our
most recent common ancestor with chimpanzees was something like seven
million years ago. See Richard Dawkins' fabulous "Ancestor's Tale".


... Not to mention my descendents 200 millions years from now


It may indeed be impossible to describe entities that do not yet exist.


"When in Earth history did humanity begin?" is a question exactly similar to
: "When in Universe history did galaxies appear"?


Well, no. The underlying "equations of state", if you will, are very
different. Galactic evolution is evolution in name only. You've already
pointed out the chicken and egg problem for biological entities. Life is a
rich binary tree of cousins - many branch points, many "buds". Galaxies were
always galaxies. Before that, they were only proto-galaxies. Our non-human
ancestors had their own identities - they were never "proto-humans". One
would be more correct to compare the first galaxies to the appearance of the
first eukaryotic cell, perhaps - but even then the complexity of the web of
life is both greater (in variety) and less (in the knowledge compression of
evolutionary genetics) than that of "mere" astronomy.


a species is still something very difficult to define, and hard to observe.
I won't elaborate on the details here, but I had an interesting breakfast
with a botanist a while ago, which definitely destroyed in my mind the
notion of any "objective" definition of what a species is ...


It may not be surprising that the taxonomy of Linnaeus may need tweeking
after 250 years. The notion of a species is quite different - perhaps
nonexistent - for entities that reproduce asexually. See
http://ucjeps.berkeley.edu/map2.html.



"Undecidable" was not adequate a word, I agree, if you read it in its strict
logical sense. I mean you can chose any arbitrary limit, like geographs do
for the classification of cities, by setting arbitrary population thresholds
...




But "city" is an arbitrary notion. "Human" and "Galaxy" have intrinsic
meaning, no matter how difficult to pin down. My original comments were
specifically about the word "event". An event is not only an arbitrary
notion - it is a whole constellation of arbitrary notions.

Rob Seaman
NOAO

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