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Re: [ontolog-forum] Presentism (was Re: Ontology of Rough Sets)

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Thu, 3 Feb 2011 04:02:13 -0600
Message-id: <EEBFCCF2-1D16-413C-A198-9D669B4B824E@xxxxxxx>

On Jan 27, 2011, at 2:38 PM, Chris Partridge wrote:

BTW the oddity I find with the Markosian description is this – “By contrast, on The 3D View, objects are to be thought of as three-dimensional things that are not made up of different temporal parts. On this view, an object at a time — Descartes in 1625, for example — is the same thing as the whole object — Descartes. Thus, according to The 3D View, the relation between Descartes in 1625 and Descartes in 1635 is the relation of identity: each one is just the same thing as Descartes.”
As a term, 3D or three-dimensional things seems to imply spatial dimensions, but ‘Descartes in 1625’ and ‘Descartes in 1635’ are identical, and he had a wider girth in 1635 (or was in a different part of the house/country), then spatially he does not seem to be identical – his spatial characteristics (his 3D characteristics?) are then clearly not identical. But Markosian says “on The 3D View, objects are to be thought of as three-dimensional things”. How can we think of them ‘three-dimensional things’ and also identical at different times? What sense does three-dimensional have here? Does it just mean capable of having spatial dimensions?

Your question, which to me has almost the force of a plea, is exactly my own reaction to the 'continuant' notion which Markosian is describing here. But this really is what some philosophers (Barry Smith and Peter Simons, to name but two) insist upon: ordinary physical objects, such as cups and saucers and animals such as you and me, are genuinely three-dimensional things which last through time (already I have a mental problem, but leave that aside) and change their physical properties (perhaps) but not their identity. You are the *very same person* as time passes, on this view, and yet you are three-dimensional: at any time you are present, you are *wholly* present: all your parts are present. (Of course, by 'parts' I mean 'parts at the time in question', since parthood, like all other time-dependent relations, has to be relativized to a time.) This perspective, I find, can be made intuitive and even comfortable, once one gets used to it; but it takes a certain mental discipline to keep reminding oneself that identity across times does not imply preservation of properties across times. I can grow fatter and still be the *very same* person, and this person can be wholly present now and also have been wholly present a while ago when I was thinner. Calling this 3D does not of course mean that I occupied the same, or even a congruent, chunk of 3D space as I did then; only that I did, and now also do, occupy a purely 3D space. And that space contains *all* of me now, just as that other space did back then, when there was less of me. 

But as I say, to stay comfortable with this perspective is a constant mental effort. And it has some very odd consequences. If for example we allow (as OBO does) something to be described either in this way or as a genuinely 4D entity, then we are obliged to distinguish the 4D 'thing' from the 3D one that lasts through time. OBO distinguishes in this way between a continuant and the occurrent which is that continuant's 'life'. So if Joe goes into an empty room and stays there for an hour, there were *two* things in the room during the hour: Joe, the continuant, *and* the hour-long slice of Joe's lifetime. ( I have checked this very example with Werner, and he says this is the right analysis.) But of course they are in the room with two different senses of 'in', which makes everything much clearer. 


I would have thought something like “on The 3D View, objects are to be thought of as having a three-dimensional spatial extent with no temporal extent that can be different at different times” would be less confusing.
From: Christopher Menzel [mailto:cmenzel@xxxxxxxx] 
Sent: 27 January 2011 19:32
To: [ontolog-forum]
Cc: mail@xxxxxxxxxxxxxxxxxx
Subject: Re: [ontolog-forum] Presentism (was Re: Ontology of Rough Sets)
On Jan 27, 2011, at 12:58 PM, Chris Partridge wrote:
Hi Chris,
Is the issue here *strict* presentism?
 (Where weak presentism would allow past and future objects to exist, but exist in different ways.)
No.  The qualification "strict" adds nothing; I should have just said "presentist".
I was under the impression that presentism and standard 3D accounts fitted naturally together (for example, Markosian makes this point in the Stanford article, though I find some of his comments on 3D a bit odd.).
I think Markosian's point is simply that one must be a 3D'ist if one is a presentist, pretty much by definition.  But one can certainly be a 3D'ist without being a presentist.  Presentism is a very problematic (though, I admit, rather metaphysically appealing, for whatever that's worth) form of 3D'ism — see for example the three difficulties Markosian mentions briefly at the end of the section on presentism in his article.

That one of the attractions of a 3D view is that it supports a presentist stance.
Otherwise, I cannot make sense of your comment – copied below.
CM> This is actually a rather radical metaphysical doctrine that encounters very serious semantic roadblocks not encountered by the standard 3D and 4D views.
It seems pretty clear to me that non-presentist 3D'ism is the "commonsense" view, at least, when it comes to the past — Socrates "exists in the past" and we unproblematically refer to him. For the presentist, this is strictly false, as there is no such ontological property as "past existence" and hence no such thing as Socrates to refer to.  But how, then, do we make any sense of such apparently unproblematic commonsense truths as "Socrates was a Greek philosopher"?
Presentism, by my lights, as an utter non-starter for the purposes of knowledge representation.  There might be tortured ways for the presentist to make sense of claims about past and future entities, but if we're interested in building usable knowledge bases for information systems, regardless of where we come down on the 3D-vs-4D issue, we simply need to be "ontologically promiscuous" (to borrow from the title of a lovely (and important) paper by Jerry Hobbs) about past and future objects and refer to them and quantify over them liberally and unabashedly.
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Christopher Menzel
Sent: 27 January 2011 18:31
To: [ontolog-forum] 
Subject: Re: [ontolog-forum] Presentism (was Re: Ontology of Rough Sets)
On Jan 27, 2011, at 7:00 AM, Ronald Stamper wrote:
The only things deemed to exist in a presentist ontology (metaphysical sense) exist now.  The present is no prison because we now have signs that stand for things we wish to know about in the past and future.  
Actually, for the strict presentist, that is flatly false, because there are no "things…in the past and future" for our signs to refer to and for us to know about, for only presently existing things exist and things only exist now.  This is actually a rather radical metaphysical doctrine that encounters very serious semantic roadblocks not encountered by the standard 3D and 4D views.

Presentism, I contend, provides a valuable discipline for engineers of information systems because that's the kind of world we deal with.
Seems to me that the world we deal with is the same regardless of one's metaphysical take on time. Be that as it may, might I suggest that the view you are actually arguing for is not presentism but rather the standard (and, I think most would agree, commonsense) 3-dimensionalist view that there is a distinguished, objective, ever changing present in virtue of which things are (at any present moment) genuinely presentpast, or future?
Chris Menzel

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