Re: No universal things Re: comparing XML and RDF data models

On Jul 3, 2008, at 5:52 AM, Bernard Vatant wrote:
>
> I for one assume very strongly indeed that 'the description of the  
> thing causes the thing to exist', and my hunch is that Bijan will  
> follow me on this (at least I hope so). What we deal with in our  
> information systems are only descriptions (signs). A 'thing' exists  
> insofar as we have made a description which somehow cuts out the  
> world representation in some arbitrary way between 'this thing' and  
> the rest.

There are two things you are saying and they contradict. It is one  
thing to say that "the description of the thing causes the thing to  
exist". This evokes the idea that there is an empty vacuum, a thought  
comes in to your head, and presto the space is now occupied by the  
thing you thought of.

It is another thing to say that the world exists but that there is no  
objective way to decided where the boundary between things are. Rocks,  
in this view, don't pop in to empty space - it's just that it may be  
hard for us to see where the boundary of one (existing) rock ends, and  
the next begins.

Note that the word "thing" is used in two ways in the above two  
paragraphs. In the first it is meant as a mental structure. Certainly,  
if you think of something there is something about your your mind that  
enables that thought to be carried.

In the second paragraph it is used to denote some portion (albeit  
indeterminate) portion of material.

It is a common, and damaging, confusion in knowledge representation to  
unknowingly mix these these two sense up. Ideas pop in to reality  
while thinking. Rocks don't.

Let's call things in the first sense "concepts" and things in the  
second sense "individuals".

> The world is a continuum, it's not naturally divided into things  
> which would be given, and  which we could describe as accurately as  
> possible.

things = "individuals"

> Things emerge from descriptions, conversation about descriptions

things = "concepts"

> , and so do identity and difference.

There is a difference between "perceived difference" and "perceived  
identity" and "actual different" and "actual identity". All the  
biologists I know of try to get at the "actual difference" rather than  
the "perceived difference". Commonly there is initially no "perceived  
difference" but in experiments we are able to determine "actual  
difference".

The difference between an atom of gold and an atom of hydrogen has  
nothing to do with what you think. Rather the other way around.

> We might at some level of granularity agree we are describing the  
> 'same' thing, based on the mutual logical consistency of  
> descriptions, and a mutual agreement on which set of property/value  
> pairs we consider as "identifying".

It is more than consistency and agreement. It is easy to be  
consistent: Call everything "blah" and say all things are related by  
the relation "flah". If this is your conceptual universe, how do you  
arrive at an inconsistency? Similarly, you and I may identify gold  
atoms and hydrogen atoms as the same thing. That would make us idiots,  
not adepts in the process of identifying.

> Then further down the road, drilling down more precisely our  
> respective descriptions, we can come to a point were those  
> descriptions are no more consistent, and we then agree we were  
> speaking about different things indeed. This should not be an issue,  
> but the basis of day-to-day practice.

The point is that the consistency that we search for, at least in  
science, is not between ourselves, but between what we predict and  
what happens in reality. Science is about doing our best to remove the  
bias that our senses and preconception put in the way of us  
understanding reality, and instead understanding the mind-independent  
truth. Are scientists successful at it, always? No. However there is  
something to fail *at*, and that this is the case is in opposition to  
the idea that we construct all of reality in our heads.

> I had this viewpoint even before beginning to work in those  
> technologies, and was quite happy to find out that ten years or so  
> of work in very various industries and projects had brought me a  
> huge pile of examples to illustrate and confort it. Not only I don't  
> know what a universal thing is, but I'm pretty much convinced that  
> this is a void and useless concept.

Really? So the periodic table is a void and useless concept?

> It's been counter-productive in science for centuries. Physics had  
> to go over the notion of universal thing to understand that light is  
> neither a wave, nor a particle.

This is a separate issue. Physicists understand that there are  
*different* things than waves and particles, namely things that have  
properties of both. This is just as universal - just corrected from  
previous understanding in the light of new knowledge. And while you  
may lament the centuries that passed until this insight was achieved  
you fail to note the millions of people and tasks that are daily  
successfully accomplished not because people are good at agreeing at  
arbitrary ideas, but because the understanding that science has  
achieved make predictions possible. Those predictions are not enabled  
by agreements between people, they are enabled by agreement between  
what is thought and what is.

> Biology to go over the notion of taxa as rigid concepts based on  
> phenotypes to understand genetics etc.

There is much more to the evolution of biology, and to the difference  
between understanding based on taxa and understanding based on taxa,  
than a stubborn insistence of the notion of "universal thing". I hope  
you understand how simplistic this comes across.


> Many examples can be found in all science domains.
> My day-to-day experience in ontology building, listening to domain  
> experts, is indeed not that 'there are things that people are trying  
> to describe',

Things = "individuals". The results of that description effort: Things  
= "concepts".

> but that 'there are descriptions people take for granted they  
> represent things before you ask, but really don't know exactly what  
> those things are when you make them look closely'. When you play the  
> game, simply asking questions such as "in which way X is different  
> of Y", or "what does this mean exactly", you always bring domain  
> experts to acknowledge this.

What are they acknowledging exactly? What you are observing is not  
something about the nature of reality, it is something about the  
nature of how people think, what they bring to the forefront in  
consciousness, etc. Do you think you are teaching scientists something  
about science by asking them questions? Or revealing more clearly what  
they know?

> And all our job is not to figure out 'what the domain things really  
> are' and 'describe them properly', but to bring people to  
> acknowledge the arbitrary nature of their descriptions, the  
> fundamental impossibility to capture their referent in an exhaustive  
> way, hence the necessity of consensus at a certain level of  
> complexity and granularity, on which to build systems that work.

That systems (or at least, shall we say, biological experiments) work  
is not fundamentally due us agreeing about something. Biological  
experiments work when there is something out there - the cells that  
work in certain specific ways, for example, and we achieve a way of  
exposing that mechanism

> The world does not need to be consistent and logically organized,  
> but our systems need to be.

The world does not need to be anything. It just is. It is not the sort  
of thing for which the predicates "consistent" or "logically  
organized" apply. Those predicates apply to what you call  
descriptions, or others call concepts, or ideas. In order to do  
ontology in the life sciences I have found that understanding this  
distinction at the outset helps avoid a lot of churn and poor results.  
For one, it help avoid type errors such as the ones you are making here.


-Alan
http://sciencecommons.org/about/whoweare/ruttenberg/


>
>
> Bernard
>
> -- 
>
> *Bernard Vatant
> *Knowledge Engineering
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Received on Thursday, 3 July 2008 12:16:09 UTC