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Date:         Mon, 9 Nov 1992 11:44:46 -0700
From:         "William T. Powers" <POWERS_W%FLC@VAXF.COLORADO.EDU>
Subject:      Marking and models

 [From Bill Powers (921109.1100)]

 Avery Andrews (921109) --

 Your comments on "marking" plus some by Hank Folson and Dag Forssell
 have brought my feeling of "something missing" into sharper focus.
 What's missing in linguistics is a model.

 When you talk about marking things in the knowledge base as said or
 not said, you're IMPLYING a model without saying what it is. Whenever
 you propose that something gets done in a certain way, you imply a
 model such that doing this sort of thing is consistent with the
 properties and constraints of the model. But if you never commit to a
 particular underlying model, then every time you come up with a new
 idea you're changing the constraints without knowing it, and perhaps
 invalidating some aspect of former implied models, also without
 knowing it. This is the general impression I have had about
 linguistics -- that the proposals may or may not be consistent with
 each other in terms of any one underlying model. Nobody can know,
 because the model is never elucidated.

 When I try to explain things like language, I always do it with an
 eye on the constraints of the HPCT model. I would never propose that
 perceptions are literally "marked" for communication, because there
 is no provision in the model for that sort of process. Perceptual
 signals can't carry anything but the signal; there's no room for a
 second channel to carry the marking, and there's nothing either to do
 the marking or to recognize it.

 Instead, I would accept that marking indicates some possible process
 and ask what operations ARE possible within the constraints of the
 model that would have an effect EQUIVALENT to marking. In this spirit
 I proposed that nonverbal perceptions are selected as reference
 signals for systems that produce utterances with those meanings, as
 per the diagram of a few days ago. The presence of a reference signal
 and an error is equivalent to marking the nonverbal experience as not
 said, although there is no explicit marking operation and nothing
 literally gets marked. The nonverbal experience remains not said --
 the error remains -- until some part of the utterance produces a
 meaning matching the unsaid reference signal, at which point the
 error signal disappears and the need to say that particular thing
 disappears.

 Now you can play around with all sorts of details in this design,
 such as how long a perception will persist after the "saying" so that
 the same thing doesn't have to get said again. There are obviously
 many details that could be proposed concerning how an error leads to
 finding a phrase or word that will supply the unsaid meaning, and how
 the words/phrases get transformed into nonverbal perceptions or
 meanings. I'm not claiming any particular merits for my sketchy
 propositions. But if we're to apply HPCT to linguistics, whatever we
 propose has to operate within the existing constraints of an explicit
 model. You have to find a way to do what you want done by some use of
 the principles already in the model.
 Only when you are absolutely sure that there is no way to get an
 equivalent effect within the constraints of the model is there any
 reason to start changing the model. And then, when you do make a
 change, you must be sure that it's the sort of change that opens up
 the possibilities rather than restricting them to a narrower range of
 phenomena. You don't want an ad-hoc solution that will screw up all
 the other explanations that the model can provide for other
 phenomena. You don't want to change the model so that perfectly
 satisfactory explanations of other phenomena are made clumsier and
 more complicated. You don't want the model to be more complicated
 than the phenomena it explains.

 The reason I asked about the nature of the knowledge base and how
 marking might be accomplished is that I was trying to get at your
 underlying model. What, literally, is the form of the knowledge base
 in a human being? What aspect of the model perceives this knowledge
 base, and in what form? How is a marking added, what physical form
 does a marking take, how is the marking recognized? I don't mean that
 I want a neural diagram; I'm just asking for a set of rules and
 definitions that pin the model down to some particular form, so we
 can see what its other implications are (other than serving the
 immediate purpose of explaining how we know something has been said).

 If the ONLY function of marking is to explain how we know something
 has been said, then the concept of marking is empty; it's a dormitive
 principle. It's just a long way of saying that we know something has
 been said by means of knowing that it's been said. My proposal, on
 the other hand, explains this knowing in terms of reference signals
 and error signals, which have a much broader applicability than just
 this one phenomenon. This is not an ad hoc explanation; it's a way of
 finding an explanation within a model that already has properties of
 general significance and wide application.

 Modeling involves thinking in two parallel modes. One mode is
 concerned with building the model itself -- with laying out its
 properties, its interacting elements, the fixed rules by which it
 operates in all situations. The other mode is concerned with
 phenomena: what do we observe happening, that the model must be able
 to do out of its own stated organization? The model itself changes
 far more slowly than our guesses about regularities in observed
 phenomena. As the model get more specific and more complex, it
 becomes capable of explaining more phenomena -- but by the same
 token, it takes longer to see how the model explains particular
 phenomena.

 Sometimes the model really does fail; we can't find a way to restate
 the phenomena that shows how it would grow out of the model. Then we
 have to search the model to see why it fails; what is missing, or
 what is incorrect. But most phenomena seem at first to be outside the
 model only because we're already interpreting them in terms of a
 different model. "Marking" is an example. Behind that interpretation
 are images of the way we would use a pencil-and-paper checklist. But
 that image is inadequate, because it implies operations and
 perceptions that are not in the model -- and that are not plausible
 additions to the model. We can accept that we somehow know what meanings that
 we want to communicate have and have not been
 communicated yet, without committing to the checklist model. The
 checklist model, to be made explicit, would bring in some very
 complex additions to the HPCT diagram as we try to explain how the
 creation and use of a checklist are brought about by the model. It
 would be much better to look for an equivalent process that will
 accomplish the same end -- not saying again what has already been
 said, and not failing to say what has not yet been said -- that uses
 the existing facilities of the HPCT model.
 -------------------------------------------------------------------
 Best,


 Bill P.
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU