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Re: [ontolog-forum] Reality and semantics.

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Len Yabloko" <lenya@xxxxxxxxxxxxx>
Date: Mon, 22 Sep 2008 06:00:51 +0000
Message-id: <W6313810715246031222063251@webmail12>
Pat,     (01)

First - I want to thank you for the exposition. It is very satisfying to have 
people like you and John, who takes time to explain and support their position, 
in contrast to postings which express attitudes and very little substance. I 
also took time this weekend to carefully re-read the entire thread to see what 
engineer like myself can learn from it.    (02)

>My point (I just sent off a long exposition to the thread) was only  
>that logical semantics relates a logical representation to reality,  
>not to a representation or "model" (intuitive sense, as in 'model  
>airplane') or description of reality.  John's position is that this  
>never happens, that logical semantics cannot possibly relate logic to  
>reality, only to an intermediate abstraction which then must itself be  
>related to reality by some other means, hence the 'two-stage'  
>terminology.    (03)

The notion of "model" is one of those paradoxical notions that everyone is 
using every day without second thought, but if asked would not be able to 
explain in basic terms (another one ofcource is 'love', but that is entirely 
different topic). Yet I always thought that it is *not* one of those words with 
different meanings requiring us to qualify it every time we use it. I don't see 
that intuitive sense of it (as in 'model airplane') is so very different from 
formal. Here is the definition I found in your exposition:     (04)

"Put another way, the FOL semantic metatheory describes the real world as a 
relational structure; and for each world so described, it tells how to 
determine the truth-value (true or false) of any sentence in the FOL 
representation. It may be referred to as a model theory (the relational 
structure here being the 'model') or a logical semantics or a truth-functional 
semantics or a Tarskian semantics, after its inventor."    (05)

So according to you formal 'model' is a relational structure which describes 
the reality in a way that is suitable for reasoning about real things, which 
can be done using FOL, and thus can be (some times) execute by computers. Well 
- a 'model' of airplane is a structure equally suitable for reasoning about 
real airplane, as some times done by people and computers. The main difference 
is that logical model is used for different kind of reasoning than say - 
differential equation.    (06)

And here comes another one of these tricky words: 'semantics'. Ordinary use of 
that word would ascribe to differential equation semantics of differential 
calculus as a model theory (not *the* Model Theory created by Tarski). Again 
the main difference is the kind of reasoning. But do we have to qualify this 
time - that we are not talking about formal semantics, just ordinary one?    (07)

>> You seem to be implying that while you can represent knowledge using  
>> model-theoretic semantics - the same can not be said about actuality.
>Um, not quite. Knowledge is represented using logic (in the case under  
>discussion, i.e. a logic-based ontology), and the semantics is an  
>account of how this representation relates to the reality it describes  
>(more precisely, to some reality it could be describing.)    (08)

So is differential calculus an account of how equations relate to reality it 
could be describing? I think so.    (09)

>> To me the word 'represents' means the same as 'interfaces' - that is  
>> serves as a conduit for interaction and (limited) comprehension.
>Interesting. Im not sure I follow this, but I think I disagree :-)    (010)

I purposefully did not use the word 'represents' this time because it seems to 
be the point of disagreement between John and you. Your claim is that Tarskian 
semantics are sufficient to reason about the real world, be it limited in power 
by FOL, but by no means does it make it wrong about real things. And you claim 
that John implies that such reasoning is incorrect unless augmented with 
another non-Tarskian theory about possible worlds - each described by its own 
Tarskian model? Forgive my interpretation of you differences, but that is about 
as good as engineer can do, provided he is willing to get into semantics which 
most engineers don't (and seem to do as well as you do without any non-Tarkian 
or 'two-stage' semantics)    (011)

>>> BTW, of course reality can be comprehended. We do it all the time. We
>>> don't ever get complete comprehension, maybe, if that means what I
>>> suspect you mean by it. But I didn't say anything about being  
>>> complete
>>> (in this sense, ie comprehensive, all-knowing).  But its still the
>>> actual bridge that falls into the river when the cables break, not  
>>> our
>>> incomplete comprehension of it.
>> But what difference does it make for us in general and for your's  
>> and John's discussion?
>Well, if you had been on the bridge at the time, quite a lot. This  
>isn't meant to be a joke, by the way. I find it hard to understand how  
>anyone can say that reality isn't important, when just about all the  
>things that happen to us happen by virtue of impinging upon reality in  
>one way or another.    (012)

I did not notice anyone saying that reality isn't important, even after 
re-reading the entire thread couple of times. I think the argument arisen from 
interpretation of 'possible world' as abstraction that has no existence outside 
particular ontology or Tarskian model (seemingly equated by John?). Again 
forgive my interpretation! That claim somehow (I can't understand fully how) 
follows from John's 'metalevel reasoning' thesis. You on the other hand seem to 
say that all these possible worlds do exist, but only one of them is described 
by particular FOL ontology. That claim can be interpreted in two different 
ways:     (013)

1) All possible worlds exist side by side occupying the same physical universe, 
but exposing it from different prospectives given by semantic meta-theory (call 
it 'dark matter' theory because we have enough of it for few more worlds).    (014)

2) All possible worlds exist only in our imagination, but that is the only way 
we can reason about reality without being completely overwhelmed by it, so each 
world as real as it gets for all intents and purposes- just can't reason about 
all of it/them at once (call it 'multiple personality' theory because 
multiplicity originates when we begin to think).    (015)

>> The truth of any statement depends on initial assumptions and inputs  
>> obtained from some representation.
>No, really. The TRUTH depends on how well the representation  
>corresponds to reality. That is pretty much what truth means, in fact.  
>What you are talking about, I think, is how we come to know things,  
>which indeed does have to do with interfaces and transduction.    (016)

If I understood you correctly - you are telling me that statement about reality 
is truthful when semantics of language (used to make it) is fathefull to 
possible world. So if I make false statement about that world it will be 
provably and obviously (due to 'truth function') false. Thus we can't hide the 
truth anymore (from computers :-). But that is not what I meant by 'truth of 
statement' - I meant its meaning (if something said about world true or false).    (017)

>> The role of semantics is to make a sound connection from later to  
>> former. Moreover, semantics can not be fixed, but must allow for  
>> cycles of expansion and compression to accommodate growth and  
>> physical limits. Isn't that what you call two-stage semantics?
>No, thats not what I mean. In fact I cannot follow this stuff about  
>expansion and compression.    (018)

The stuff about expansion and compression is (IMHO) what makes one and only one 
real world to look like multiple worlds (ie. expansion), but allow interaction 
with one of your choice (compression).    (019)

--Len    (020)

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