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## Re: [ontolog-forum] Two ontologies that are inconsistent but both needed

 To: "Cassidy, Patrick J." ontolog-forum@xxxxxxxxxxxxxxxx Pat Hayes Mon, 11 Jun 2007 15:21:10 -0500
 ```>Pat H - > Could you explain the logical factors that prevent one from equating >a zero-length time slice of a 4-D object to a 3-D object?    (01) You can equate it with a 3-d object: in fact, it is a 3-d object (at a particular moment). But you cannot equate it to a continuant.    (02) > It appears >that that is what you were saying: > >[PH] >> Just as 3-d entities have 2-d surface and sections, these things have > >> 3-d 'surfaces' and 'sections'. A 3-d section of one of them is an >> instantaneous snapshot of it, a freezing of it at a moment in time. >> (If that moment is understood to be 'the present', then at that >> present time, this section is very similar to a continuant, although >> it cannot actually be the continuant for essentially logical >> reasons.) > > . . . But I haven't seen the arguments for that.    (03) In a nutshell.    (04) A continuant is (according to various authorities): 1. 3-d, purely spatial, having no temporal extent, parts or aspects. 2. Exists at various times, and has no temporal location, because... 3 ... it endures through time while retaining its identity. That is, its the *same* continuant at one time as at another.    (05) A timeslice (3-d section of a 4-d spatiotemporal thing) is: 1. 3-d, with a spatial extent, but also with an associated time. 2. Exists at one time only, and is temporally located at that time. 3. Does not endure through time, and is not identical to any other timeslice.    (06) So for example, consider me (Pat) now. Lets say that I am a continuant. Wait a minute. Now consider Pat again. I'm still the same continuant. There is just one of me.    (07) Now do the same experiment talking about timeslices. The first slice is Pat-at-t, say, and the second slice is Pat-at-(t+1). These are not identical (they are at different times). Neither of them is identical to the continuant, because if one of them were then the other would also be, so they would be identical.    (08) That is the logical reason I was referring to. One could think of a timeslice as a continuant-at-a-time, were it not for the fact that this mode of expression is ruled out by the standard dogma, which insists that continuants cannot have temporal 'parts', since such a slice would be a temporal part of me. At this point one is typically directed to think of a slice of my life, the 'occurrent' version of me. Which is fine: my point is that this is what I have been all along. Anything I want to say about Pat can be said about the occurrent version of Pat, the Pat-life. This is the thing that has 3-d slices. I don't need the continuant Pat. I can have, purely for intuitive convenience, a 'thing' that is Pat and which is the same thing at different times, so writing things like    (09) (age Pat t)    (010) to mean the age of Pat at time t; and we can call this Pat a continuant if you like; but it is not a strict Simons/Smith continuant, since it can also be viewed as having temporal parts, so that I can also write    (011) (age (slice Pat t))    (012) i.e. speak about the t-episode of Pat.    (013) A continuant is something like a 'moving slice' of the 4-d Pat, which is the same slice as time goes on, retaining its identity as it moves [1]. This idea makes sense in the A-series view of time where one understands assertions to be made in a 'moving present', distinguished from assertions about the past and the future, a world where tenses make sense. Natural language is often organized this way, perhaps because it evolved mostly to convey information about the actual present circumstances. But it is a very poor way to try to state an ontology, for whatever one says or writes is immediately made wrong since after a very short time it is about the past rather than the present. If you want your words to be archived, it is better to use the B-series view (see http://en.wikipedia.org/wiki/B-Theory_of_time for this terminology) of a time-line, in which time is treated as a dimension and events and things are placed on it or in it by a date/time convention. Continuants are a vestige of the A-series way of talking which do not properly fit into a B-series metaphysics. The point being that there are no 'moving slices' in the 4-d world: the notion does not make sense.    (014) My complaint can be summarized thus. When writing ontologies we cannot manage without the B-series view. We cannot write ontologies in a 'present tense'. So our options are to use the B-series view, or to try to use both. I suggest that it is better to make a clean choice of the B-series as the single temporal framework than to try to mix the two notions together, as they (notoriously) do not mix. This may indeed have the consequence that certain very familiar modes of expression in natural language do not map directly into the ontology. But the engineering advantages of a clean, coherent, internally consistent temporal framework outweigh the resulting artificiality; particularly as one can get used to it quite quickly. Much of the basic thinking here was done by McTaggert in 1927, by the way, and it seems a shame to throw away all that good insight.    (015) Pat H.    (016) [1] Years ago when this issue came up in the SUO discussions, I tried to see how to map between the two modes of expression by finding a common description which both could agree on the formal theory of, but would interpret with a different metaphysics. I came up with the idea of a 'entity movie'. This is a temporally ordered *set* of 3-d things, which can be viewed by one player as simply being Pat, and by the other player as being the Pat-slices. The 4-d view is then got by thinking of this movie as the set of slices of a 4-d entity, and the continuant view is got by describing it as a series of views of a single continuant. I tried this idea out on several people, of various views, and they all agreed that it made a kind of sense from their perspective. So I set out to formalize the notion: and what I found is that this 'movie' might as well actually be the occurrent as far as the formalism is concerned. A 'frame' of the movie is defined by a name used to refer to one thing at different times, and a time-reference: (Pat + t). What is this '+', in the formalism? Well, you could write it like this    (017) (slice Pat t)    (018) where slice is a function (from things to their slices), or you could say that the 't' is an index used to make assertions about Pat, as for example    (019) (= (age Pat t) t)    (020) where 'age' is a fluent with a temporal parameter. So what it boils down to is a choice of where to put the temporal parameter: inside relations or inside functions. If I am a continuant I don't have slices, so 't' *must* go into the relational argument position. Or I can be allowed to have slices, and then it can be put anywhere.    (021) All that argument and debate and citing of authority, and it all boils down to this?? Yes. This is all it amounts to in the actual ontology: allowing slices or not. Not a matter worth spending any more time on, seems to me. Sure, allow them. Or don't. I don't really care: nothing depends on it; NOTHING. One can trivially, mechanically, translate from the continuant-anal formalism into the more relaxed one, without losing a gram of expressivity and making the axioms simpler.    (022) See why I get impatient with metaphysics and philosophy?    (023) :-)    (024) > >PatC > >Patrick Cassidy >CNTR-MITRE >260 Industrial Way West >Eatontown NJ 07724 >Eatontown: 732-578-6340 >Cell: 908-565-4053 >pcassidy@xxxxxxxxx > > >_________________________________________________________________ >Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  >Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  >Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx >Shared Files: http://ontolog.cim3.net/file/ >Community Wiki: http://ontolog.cim3.net/wiki/ >To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx >    (025) -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes    (026) _________________________________________________________________ Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/ Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/ Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx Shared Files: http://ontolog.cim3.net/file/ Community Wiki: http://ontolog.cim3.net/wiki/ To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (027) ```
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