[Martin Taylor 2015.07.24.10.55]
[From Rupert Young (2015.07.24 12.00)]
(Martin Taylor 2015.07.01.09.40]
I finally got around to reading Your messages and Rick's. The problem with constructing a proper reply at this point is that when I read what you wrote about perception a modelling, I agree with it. When I read what I wrote about those topics, I agree with it. When I read your critiques of what I wrote, I don't see why you think there is disagreement.
Well, I'm reluctant to get sucked backed into this vortex of despair. But I can't help myself.
I'm reminded of a recurrent question in my mind. When someone says to a child "Behave yourself" I ask myself "Who else would she behave?"
The term "model" comes from a different conceptual space, and has many possible denotations and a wider range of connotations. Powers liked to use it as a way of constructing something that performs like the thing modelled, which would be your "replica". But when you make a sculptural mould, that, too is a model. It is the inverse of the shaped moulded, and it enables replicas of the original to be made, replicas which could be modified to create possible variants of the original. I see the reorganized hierarchy as that kind of model, not of a physical shape, but of the workings of the world. It's a function of functions, and it is a model.
Let's try a simple example, of opening doors. You are likely to have a control system for the goal of force to apply (the perception of opposing muscle tensions) that will result in the door opening.
That doesn't sound very consistent with standard HPCT as I understand it. In my understanding, you have a reference to perceive the door opening, and you have probably reorganized to have two main ways to do it, by getting the door to swing and by sliding it. Both indeed do require the application of force, but so far as I am aware, the level of force provided as a reference to the muscles will depend on the current state of the perception of the rate of door opening -- not opening fast enough, increase the reference value or opening too fast, reduce the force.
You probably also need, at least, a higher system for controlling the perception of whether the door is actually opening (the perception of the rate of change of opening). The output from the higher level sets the reference for the lower level.
Yes, if you add "dynamically" before "sets the reference", but that seems inconsistent with what you said above.
That connection between the two may start off "loose" but will change through reorganisation according to what doors you are used to. So if you tend to come across 10 kg doors then the connection (gain perhaps) will reorganise such that the general error response of the system will minimise.
It's possible to be a bit more precise here. Since every reference value depends on many outputs from higher-level control units, and every perceptual input function receives many inputs from lower-level perceptual signals, we are dealing with context and associative memory. (I agree with Powers on this, at least, and to me it seems almost to be a requirement of HPCT, but I have no proof of it). What you are saying can be restated in this context as "If every door you have encountered has been a swinging door of 10 kg, with equally lubricated hinges, then perception of a closed door for which you have a reference 'open' will result in planning (by control in imagination) to apply the same force as always has been used to open a door". But even if this is so, when you come up against a lighter or heavier door, would you not expect normal control to kick in? What you imply seems to be the control of output, not the control of input that is fundamental to PCT.
This organisation, I think, would be what you are calling a model 'of the world'.
I think what we can say is that a structure has developed that is consistent with good control in the real world. But as there is nothing in system that actually models the world, such as mass of the door, it is not valid to call it a model 'of the world'. There is no direct correspondence between entities in the control system and entities in the world.
We are back to wordplay here. You define a model as an element-by-element replica of something. The system is definitely not that kind of "model". I have not (until reading your writings) usually limited "model" in this way, though my range of meaning for "model" certainly includes your more limited range. In my use of the word, what is described above is indeed a model. It's a model in the sense that the complementary strands of a DNA double helix are models of each other. It doesn't replicate the world, it mirrors the world -- perhaps "inverts" the world might be better than "mirrors", though neither really have the right connotations of dynamic complementarity.
An additional reason for demonstrating that it is not a model of the world is that it can handle situations which it has not come across before. For example, if you go on holiday to Brobdingnag where the doors are 20kg initially you wouldn't push against the door with sufficient force to open it, but after a while, due to error building up in your higher, rate of opening system, the reference for your "force-applied" perception will increase to the point where the door does open. So here the system handles a situation which was not part of the world it had met before, so how could the system be said to be modelling the 'world'?
I fail to see the issue, in two ways. Firstly, the model is correct in that pushing the 20kg doors does open them if you push hard enough. Secondly, the model is of the world encountered in its construction, not of Brobdingnag (coincidentally, I am reading Gulliver's Travels in the original for the first time, and am currently in Brobdingnag).
Also there seems to be a logical flaw in the whole concept of the HPCT-type control system being a model of the world, in that it could only model things which exist independently of the system itself; that is, it would be restricted to objective aspects of the world. This is plainly not the case, as has been discussed before; love, fear, justice, taste, honesty etc.
I don't follow that logic. Yes, I accept that no model can model itself entirely, since that would imply that the model that models itself also models itself modelling itself ... ad infinitum. But there's no reason why the model should not include any variables of the kind you mention. They are perceptions, after all. Subjectively, when you imagine certain situations, do you not also imagine experiencing perceptions such as those you mention? Is not your imagination a "replica-type" model of the world you are imagining?
I see the beauty and wonder, and power, of PCT being that it deals with subjective aspects (perceptions) which are most definitely not of the world, enabling living systems to control internal perspectives far beyond the limitations of the external world.
What are "the limitations of the external world"? External to what? Is one of the "limitations" that the world does not contain "jealousy" if you see the woman you want to be your girlfriend enjoying the company of another man? And yet you can imagine that you might perceive that emotion, can you not? So I ask again: "External to what?".
Why might imagination produce a replica-type model if the World Model is not a replica? Because the complementary nature of the Model produces a replica when it is used in imagination, just as it does when controlling in the world it models, and just as strand 2 of DNA provides the model for a replica of the strand 1 with which it was originally paired.
(Rick Marken (2015.05.18.0840)]
RM: Right now it seems more like a 'number of angels dancing on the head of a pin" kind of debate.Just trying to live up to the great tradition set by yourself and Martin
There are two questions here. One is what actually happens, and that's not a "dancing angels" issue. The other is what words are the best to communicate ideas about what is happening, because in the end we all (I presume) want to use the debate as a way of getting nearer to a complete theory of human (or biological or robotic) functioning.
If "Model" has a meaning to some people (including Rupert) that make it an unsuitable way to communicate the ideas, then it's not efficient to use the word, as it would convey the intended idea to only a subset of the readership, and that doesn't help advance the theory. But I don't know of a better word. Some, in the history of science have claimed that fuzzy words aren't useful at all, and only clean-edged well-defined mathematics ensures proper communication. (In the 1970s, I had a friend who claimed the programming language APL was the only language in which scientific ideas should be discussed). I don't buy the mathematics idea, for reasons I won't go into here, but people who espouse that position do have a point.
I thought of "mold" as a replacement for "model", but to me that has a static connotation, and the World Model as I conceive it is highly dynamic process that produces either the desired effects in the real world or dynamic replicas in imagination of the real or any fantasy world. Unless someone comes up with a better word, I intend to continue using the word "model" and hope that readers will understand the context in which I use it.
Martin