# The Beauty of PCT (was Re: CEV and RREV)
**URL:** http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239
**Category:** CSG2019
**Created:** [April 23, 2019, 4:04pm UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239 "2019-04-23T16:04:24Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@MartinT](http://discourse.iapct.org/u/MartinT)
#### Post date: [April 23, 2019, 4:04pm UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239/1 "2019-04-23T16:04:24Z")
[Martin Taylor 2019.04.23.11.28]
> **···**
>
> > Â
>
> > ```
> > No, neither, but the RREV is that something
> >
> > ```
> >
> > which I would call “picture� or “object of perception� which
> > makes it possible and very probable that creatures with
> > similar visual perceptual functions and contextual knowledge
> > as us will see either the wife or the mother in law, but not a
> > tree, a car, an elephant or something else. It could very well
> > be Adelbert’s office like Martin suggests, but I like somewhat
> > simpler speculations
>
> ```
> The beauty of PCT is that, unlike control-of-output (CoO) versions
>
> ```
>
> of control, PCT doesn’t care how a perception in the mind is
> created. All that matters is that the difference between the
> perception and its reference is reduced, on average, by the output
> to lower-levels reference inputs (or whatever the output
> influences). All else must be consistent with that, but otherwise
> there is no constraint on how the feedback path between the output
> and the perception is implemented. CoO theories of organic control
> do care about the implementation, because they require that the
> output be calculated using knowledge of what happens in the
> feedback path to create the desired effects on the perception.
>
> ```
> The gnomic bureaucracy I have been using as a possible model of
>
> ```
>
> what is in Real Reality was chosen for two reasons 1) as a
> ridiculous but impossible to refute example to illustrate that for
> PCT it doesn’t matter at all how much we know about the workings
> of Real Reality, and 2) to illustrate that so long as evolution
> and reorganization have teamed to keep our intrinsic variables in
> good enough conditions to keep us alive, the CEVs that we perceive
> to be in our external environment must be closely related to
> structures of relationships in Real Reality, whether those be
> implemented through inter-departmental memos circulated among the
> gnomic authorities and minions or by real structures that
> correspond directly to the tables and chairs, trees, elephants,
> and stars, of the CEVs that we perceive to be “out there”.
>
> ```
> Â It's the beauty of PCT that no knowledge of Real Reality is
>
> ```
>
> needed beyond the consistencies of relationships provided our
> sensors by whatever happens to be hidden there. Those
> consistencies determine which perceptual functions survive over
> changing times and which are modified out of recognition as more
> and more data arrive over the lifetime of an individual, a
> species, or a planet. The Perceptual Functions approximate some of
> the consistencies and produce higher and higher levels of
> perception to take advantage of them. We perceive them in
> consciousness (as I presume most sufficiently complex mobile
> organisms also do) to exist as entities of different kinds (chairs
> and chair legs, distances and differences, locations and speeds,
> …) set in among other such entities.
>
> ```
> Science produces ever more such Perceptual Functions, and
>
> ```
>
> sometimes those ones puzzle us. Our unaided sensory systems never
> create a pattern that we perceive as a wave and as a particle, or
> one in which the state is unresolved until the state of another
> “wavicle” elsewhere is observed. Why should it? Science uses
> sensors sensitive to properties of Real Reality for which we have
> no sensors. I think it was Einstein who said that the Universe is
> not only stranger than we imagine, it is stringer than we can
> imagine. But the beauty of PCT is that this doesn’t matter. What
> matters is what works. No theory of control that is not a theory
> of control of input can make this claim. The genius of Powers was
> to see how this applies to life itself.
>
> ```
> Martin
>
> ```
---
### Author:  [@rsmarken](http://discourse.iapct.org/u/rsmarken)
#### Post date: [April 26, 2019, 6:02pm UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239/2 "2019-04-26T18:02:43Z")
[Rick Marken 2019-04-26\_11:02:09]
> [Martin Taylor 2019.04.23.11.28]
>
> ```
> MT: The beauty of PCT is that, unlike control-of-output (CoO) versions
>
> ```
>
> of control, PCT doesn’t care how a perception in the mind is
> created.
RM: I think when you say that PCT doesn’t care “how a perception is created” you must mean that a control system doesn’t care about how physical variables (including one’s own outputs) affect the state of the perceptual variable it is controlling. That is, indeed, what distinguishes a control of output from a control of perception system; the control of output system has to use knowledge of how physical variables affect the state of a controlled variable because they use this knowledge as the basis for calculating the outputs that are used to control the variable. But this “beautiful” aspect of control of input is true of all negative feedback control systems, not just PCT. What I think is beautiful about PCT is that it explains the controlling done by living systems, something no other theory of behavior does.Â
> ```
> MT: All that matters is that the difference between the
>
> ```
>
> perception and its reference is reduced, on average, by the output
> to lower-levels reference inputs (or whatever the output
> influences). All else must be consistent with that, but otherwise
> there is no constraint on how the feedback path between the output
> and the perception is implemented. CoO theories of organic control
> do care about the implementation, because they require that the
> output be calculated using knowledge of what happens in the
> feedback path to create the desired effects on the perception.
 RM: Right.
> ```
> MT:Â It's the beauty of PCT that no knowledge of Real Reality is
>
> ```
>
> needed beyond the consistencies of relationships provided our
> sensors by whatever happens to be hidden there.
RM: To a large extent this is true. But I can think of many cases of human controlling that does require knowledge of real reality, For example, consider launching a satellite in to low earth orbit. This requires very accurate knowledge of real reality in the for of models provided by the physical sciences.Â
BestÂ
Rick
> **···**
>
> > ```
> > Science produces ever more such Perceptual Functions, and
> >
> > ```
> >
> > sometimes those ones puzzle us. Our unaided sensory systems never
> > create a pattern that we perceive as a wave and as a particle, or
> > one in which the state is unresolved until the state of another
> > “wavicle” elsewhere is observed. Why should it? Science uses
> > sensors sensitive to properties of Real Reality for which we have
> > no sensors. I think it was Einstein who said that the Universe is
> > not only stranger than we imagine, it is stringer than we can
> > imagine. But the beauty of PCT is that this doesn’t matter. What
> > matters is what works. No theory of control that is not a theory
> > of control of input can make this claim. The genius of Powers was
> > to see how this applies to life itself.
> >
> > ```
> > Martin
> >
> > ```
>
> –
> Richard S. MarkenÂ
>
> "Perfection is achieved not when you have nothing more to add, but when you
> have nothing left to take away.�
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de Saint-Exupery
---
### Author:  [@MartinT](http://discourse.iapct.org/u/MartinT)
#### Post date: [April 26, 2019, 9:21pm UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239/3 "2019-04-26T21:21:30Z")
[Martin Taylor 2019.04.26.14.27]
> [Rick Marken 2019-04-26\_11:02:09]
>
> > [Martin Taylor 2019.04.23.11.28]
> >
> > ```
> > MT: The beauty of PCT is that, unlike control-of-output
> >
> > ```
> >
> > (CoO) versions of control, PCT doesn’t care how a
> > perception in the mind is created.
>
> ```
> RM: I think when you say that PCT doesn't care "how a
>
> ```
>
> perception is created" you must mean that a control system
> doesn’t care about how physical variables (including one’s
> own outputs) affect the state of the perceptual variable it
> is controlling. That is, indeed, what distinguishes a
> control of output from a control of perception system; the
> control of output system has to use knowledge of how
> physical variables affect the state of a controlled variable
> because they use this knowledge as the basis for calculating
> the outputs that are used to control the variable.
```
That captures what I wanted to get across.
```
> ```
> But this "beautiful" aspect of control of input is true
>
> ```
>
> of all negative feedback control systems, not just PCT.
```
True, but nevertheless, few people unacquainted with PCT realize
```
this, and many researchers in the field continue to publish peer
reviewed papers in which they explain how much better is their way
of computing the required output than other ways of doing the same
thing. Few papers get published to say that you really don’t need
that computation if you allow your system to reorganize and find its
own way.
> ```
> What I think is beautiful about PCT is that it explains
>
> ```
>
> the controlling done by living systems, something no other
> theory of behavior does.
```
I'm always reluctant to accept absolute statements like that. If you
```
had finished the sentence “no other theory of which I am aware does”
I would quite agree with you (apart from the implied restriction to
living systems).
>
> > ```
> > MT:
> >
> > ```
> >
> > All that matters is that the difference between the
> > perception and its reference is reduced, on average, by
> > the output to lower-levels reference inputs (or whatever
> > the output influences). All else must be consistent with
> > that, but otherwise there is no constraint on how the
> > feedback path between the output and the perception is
> > implemented. CoO theories of organic control do care
> > about the implementation, because they require that the
> > output be calculated using knowledge of what happens in
> > the feedback path to create the desired effects on the
> > perception.
>
> Â RM: Right.
>
> > ```
> > MT:Â
> >
> > ```
> >
> > It’s the beauty of PCT that no knowledge of Real Reality
> > is needed beyond the consistencies of relationships
> > provided our sensors by whatever happens to be hidden
> > there.
>
> ```
> RM: To a large extent this is true. But I can think of
>
> ```
>
> many cases of human controlling that does require knowledge
> of real reality, For example, consider launching a satellite
> in to low earth orbit. This requires very accurate
> knowledge of real reality in the for of models provided by
> the physical sciences.
```
Yes. But I'm not clear whether this is supposed to contradict
```
anything I said. The phrasing suggests it is, but the content says
it isn’t.
```
All these models and procedures rely on perceptions built by the
```
consistent relationships among the influences from Real Reality that
we can sense. We call the most consistent sets of relationships
“Laws of Nature” which almost always work. We know that our current
“Laws of Nature” don’t work all the time, because the laws of
General Relativity (which are needed for satellite operations) are
inconsistent with Quantum Chromodynamics laws (which are needed for
nuclear operations). Still, the relationships provided by Real
Reality from which we extract the Laws of Nature that we now have
seem to be better chosen than those that produced older Laws of
Nature such as the phlogiston law of heat or the Ptolemaic laws of
planetary motion.
```
You talk about "accurate knowledge of real reality" when there's no
```
way for us ever to know what in Real Reality produces the
relationships from which we are able to choose. I doubt that anyone
will ever be able to disprove my goblin bureaucracy suggestion, just
as I doubt that anyone will ever believe it to be correct. The CEVs
of our perceptions are of structures that produce perceived
relationships that match the relationships given us by Real Reality
as closely as the evolution/reorganization of our perceptual
functions allows. Maybe there’s something in RR that looks like
them, but we would never know. All we know is that there is
something in RR that behaves much as our CEVs do.
```
Martin
```
> **···**
>
> >
>
> > BestÂ
>
> >
>
> > Rick
>
> >
>
> > > ```
> > > Science produces ever more such Perceptual Functions,
> > >
> > > ```
> > >
> > > and sometimes those ones puzzle us. Our unaided sensory
> > > systems never create a pattern that we perceive as a
> > > wave and as a particle, or one in which the state is
> > > unresolved until the state of another “wavicle”
> > > elsewhere is observed. Why should it? Science uses
> > > sensors sensitive to properties of Real Reality for
> > > which we have no sensors. I think it was Einstein who
> > > said that the Universe is not only stranger than we
> > > imagine, it is stringer than we can imagine. But the
> > > beauty of PCT is that this doesn’t matter. What matters
> > > is what works. No theory of control that is not a theory
> > > of control of input can make this claim. The genius of
> > > Powers was to see how this applies to life itself.
> > >
> > > ```
> > > Martin
> > >
> > > ```
>
> >
>
> > –
> > Richard S. MarkenÂ
>
> > ```
> > "Perfection
> >
> > ```
> >
> > is achieved not when you have
> > nothing more to add, but when you
> > have
> > nothing left to take away.�
> > Â Â Â Â
> > Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de
> > Saint-Exupery
---
### Author:  [@rsmarken](http://discourse.iapct.org/u/rsmarken)
#### Post date: [April 27, 2019, 7:50pm UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239/4 "2019-04-27T19:50:15Z")
[Rick Marken 2019-04-27\_12:45:23]
> [Martin Taylor 2019.04.26.14.27]
>
> ```
> MT: All these [scientific] models and procedures rely on perceptions built by the
>
> ```
>
> consistent relationships among the influences from Real Reality that
> we can sense.
RM: OK.Â
Â
> ```
> MT: We call the most consistent sets of relationships
>
> ```
>
> “Laws of Nature” which almost always work.
 RM: I think the phrase “Laws of Nature” in an unfortunate one because it implies that what is observed is the way reality really works. In fact, “Law of Nature” refers to observations that fit current physical models accurately. So it was a “law of nature” that light travels in straight lines because that model fit all observations. Then another model came along and predicted that the path of light is bent by gravity. This new “law of nature” is really a new, more successful model of nature.Â
> ```
> MT: We know that our current
>
> ```
>
> “Laws of Nature” don’t work all the time, because the laws of
> General Relativity (which are needed for satellite operations) are
> inconsistent with Quantum Chromodynamics laws (which are needed for
> nuclear operations).
RM: Right. It’s not the laws of nature that don’t work all the time; it’s the models of nature being eventually replaced by better models. This is because the models are simply our best current guess about the nature of reality. Science progresses to the extent that the models get better and better as approximations to that reality; each new iteration of these models should explain what the previous models explained and some new, previously unexplained observations. This is why “the environment” or "real reality"Â in PCT is _our best current_ physical science models of the nature of reality.Â
> ```
> MT: Still, the relationships provided by Real
>
> ```
>
> Reality from which we extract the Laws of Nature that we now have
> seem to be better chosen than those that produced older Laws of
> Nature such as the phlogiston law of heat or the Ptolemaic laws of
> planetary motion.
RM: Right. But sometimes the “old”, somewhat imperfect models will serve as the models of reality for practical purposes. We still use Newton’s model to fly satellites; as far as I l know we only use Einstein’s model to accurately synchronize the clocks on the fast moving satellites with those on the relatively slow moving earth.
> ```
> MT: You talk about "accurate knowledge of real reality" when there's no
>
> ```
>
> way for us ever to know what in Real Reality produces the
> relationships from which we are able to choose.
RM: I’m talking about scientific accuracy, not cosmic accuracy (or epistemological accuracy or whatever you want to call it). Scientific accuracy just means how well our theories account for the observations (perceptions) predicted by those theories.Â
Â
> ```
> MT: I doubt that anyone
>
> ```
>
> will ever be able to disprove my goblin bureaucracy suggestion
RM: You can’t disprove a theory that makes no predictions. And the predictions of the theory must be clearly derivable from the assumptions of the theory. I see no way of deriving testable predictions from your description of the goblin theory.Â
Â
> ```
> MT: The CEVs
>
> ```
>
> of our perceptions are of structures that produce perceived
> relationships that match the relationships given us by Real Reality
RM: So now CEVs are “of our perceptions” rather than being perceptions themselves? This seems to take us back to the idea that CEVs are entities in the environment that we perceive. Indeed, you say they are “structures that produce relationships that match the relationships given us by real reality”. Why not just go with the PCT idea that what you call CEV’s are perceptions that are a function of real reality, where real reality is defined by our current best models of physical reality.Â
> ```
> MT: Maybe there's something in RR that looks like
>
> ```
>
> them, but we would never know. All we know is that there is
> something in RR that behaves much as our CEVs do.
RM:Â Yes, we know that variable aspects of RR that are our perceptions vary as as expected from our models of RR. So, for example, I can control the position of a table (a variable aspect of my environment) only by applying the forces Newton says I have to apply in order to produce that perception.
RM: Also, note that what we control are _variables_. A table is not a variable; it is the state of a variable that could be called “type of furniture”. You might control for a particular value of that variable when you are furnishing a room; putting the table in this room, the bed in that room and the couch in the other room. I don’t think it’s necessary to assume that there is a variable in the real world – an RREV – that corresponds to “type of furniture”. This “type of furniture” variable is certainly a _function_ of variables in the real world but it exists only as a perceptual variable. At least, that’s the way it works in PCT.Â
RM: But since this idea of an RREV seems to be popular with everyone but me, I suppose I’ll just have to get used to it. But I would like to know how the notion of an RREV fits into research on living control systems. How, for example, is the RREV relevant to the work on object interception? How does the concept of an RREV relate to the perceptual variables that I found to be pretty accurate predictors of the behavior seen in object interception tasks?
 Best
Rick
> **···**
>
> > ```
> > Martin
> >
> > ```
> >
> > >
>
> > > BestÂ
>
> > >
>
> > > Rick
>
> > >
>
> > > > ```
> > > > Science produces ever more such Perceptual Functions,
> > > >
> > > > ```
> > > >
> > > > and sometimes those ones puzzle us. Our unaided sensory
> > > > systems never create a pattern that we perceive as a
> > > > wave and as a particle, or one in which the state is
> > > > unresolved until the state of another “wavicle”
> > > > elsewhere is observed. Why should it? Science uses
> > > > sensors sensitive to properties of Real Reality for
> > > > which we have no sensors. I think it was Einstein who
> > > > said that the Universe is not only stranger than we
> > > > imagine, it is stringer than we can imagine. But the
> > > > beauty of PCT is that this doesn’t matter. What matters
> > > > is what works. No theory of control that is not a theory
> > > > of control of input can make this claim. The genius of
> > > > Powers was to see how this applies to life itself.
> > > >
> > > > ```
> > > > Martin
> > > >
> > > > ```
>
> > >
>
> > > –
> > > Richard S. MarkenÂ
>
> > > ```
> > > "Perfection
> > >
> > > ```
> > >
> > > is achieved not when you have
> > > nothing more to add, but when you
> > > have
> > > nothing left to take away.�
> > > Â Â Â Â
> > > Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de
> > > Saint-Exupery
>
> >
>
> –
> Richard S. MarkenÂ
>
> "Perfection is achieved not when you have nothing more to add, but when you
> have nothing left to take away.�
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de Saint-Exupery
---
### Author:  [@MartinT](http://discourse.iapct.org/u/MartinT)
#### Post date: [April 27, 2019, 9:30pm UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239/5 "2019-04-27T21:30:43Z")
[2019.04.27.16.35]
```
So far, you seem to agree with me completely. That's good.
```
> **···**
>
> Up to where I mark with \*\*\*\*\*, you
> either restate of agree with what I said, so I’ll ignore that
> part.
>
> > [Rick Marken 2019-04-27\_12:45:23]
>
> >
>
> > > [Martin Taylor 2019.04.26.14.27]
> > >
> > > ```
> > > MT: All these [scientific] models and procedures rely on
> > >
> > > ```
> > >
> > > perceptions built by the consistent relationships among
> > > the influences from Real Reality that we can sense.
>
> >
>
> > RM: OK.Â
>
> > Â
>
> > > ```
> > > MT: We call the most consistent sets
> > >
> > > ```
> > >
> > > of relationships “Laws of Nature” which almost always
> > > work.
>
> >
>
> > ```
> > Â RM: I think the phrase "Laws of Nature" in an
> >
> > ```
> >
> > unfortunate one because it implies that what is observed is
> > the way reality really works. In fact, “Law of Nature”
> > refers to observations that fit current physical models
> > accurately. So it was a “law of nature” that light travels
> > in straight lines because that model fit all observations.Â
> > Then another model came along and predicted that the path of
> > light is bent by gravity. This new “law of nature” is really
> > a new, more successful model of nature.Â
>
> >
>
> > > ```
> > > MT: We know that our current "Laws of
> > >
> > > ```
> > >
> > > Nature" don’t work all the time, because the laws of
> > > General Relativity (which are needed for satellite
> > > operations) are inconsistent with Quantum Chromodynamics
> > > laws (which are needed for nuclear operations).
>
> >
>
> > ```
> > RM: Right. It's not the laws of nature that don't work
> >
> > ```
> >
> > all the time; it’s the models of nature being eventually
> > replaced by better models. This is because the models are
> > simply our best current guess about the nature of reality.
> > Science progresses to the extent that the models get better
> > and better as approximations to that reality; each new
> > iteration of these models should explain what the previous
> > models explained and some new, previously unexplained
> > observations. This is why “the environment” or "real
> > reality"Â in PCT is _our best current_ physical
> > science models of the nature of reality.Â
>
> >
>
> > > ```
> > > MT: Still, the relationships provided
> > >
> > > ```
> > >
> > > by Real Reality from which we extract the Laws of Nature
> > > that we now have seem to be better chosen than those that
> > > produced older Laws of Nature such as the phlogiston law
> > > of heat or the Ptolemaic laws of planetary motion.
>
> >
>
> > ```
> > RM: Right. But sometimes the "old", somewhat imperfect
> >
> > ```
> >
> > models will serve as the models of reality for practical
> > purposes. We still use Newton’s model to fly satellites; as
> > far as I l know we only use Einstein’s model to accurately
> > synchronize the clocks on the fast moving satellites with
> > those on the relatively slow moving earth.
>
> >
>
> > > ```
> > > MT: You talk about "accurate
> > >
> > > ```
> > >
> > > knowledge of real reality" when there’s no way for us ever
> > > to know what in Real Reality produces the relationships
> > > from which we are able to choose.
>
> >
>
> > ```
> > RM: I'm talking about scientific accuracy, not cosmic
> >
> > ```
> >
> > accuracy (or epistemological accuracy or whatever you want
> > to call it). Scientific accuracy just means how well our
> > theories account for the observations (perceptions)
> > predicted by those theories.Â
>
> > Â
>
> > > ```
> > > MT: I doubt that anyone will ever be
> > >
> > > ```
> > >
> > > able to disprove my goblin bureaucracy suggestion
>
> >
>
> > ```
> > RM: You can't disprove a theory that makes no
> >
> > ```
> >
> > predictions. And the predictions of the theory must be
> > clearly derivable from the assumptions of the theory. I see
> > no way of deriving testable predictions from your
> > description of the goblin theory.
>
> > Â
>
> > > ```
> > > MT: The CEVs of our perceptions are
> > >
> > > ```
> > >
> > > of structures that produce perceived relationships that
> > > match the relationships given us by Real Reality
>
> >
>
> > ```
> > RM: So now CEVs are "of our perceptions" rather than
> >
> > ```
> >
> > being perceptions themselves? This seems to take us back to
> > the idea that CEVs are entities in the environment that we
> > perceive. Indeed, you say they are “structures that produce
> > relationships that match the relationships given us by real
> > reality”. Why not just go with the PCT idea that what you
> > call CEV’s are perceptions that are a function of real
> > reality,
>
> -
>
> ```
> just go with the PCT idea that what you call CEV's are
>
> ```
>
> perceptions that are a function of real reality\*
>
> -
>
> ```
> You can't disprove a theory that makes no
>
> ```
>
> predictions. And the predictions of the theory must be clearly
> derivable from the assumptions of the theory. I see no way of
> deriving testable predictions from your description of the goblin
> theory\*
>
> > ```
> > where real reality is defined by our current best models
> >
> > ```
> >
> > of physical reality.
>
> >
>
> > > ```
> > > MT: Maybe there's something in RR
> > >
> > > ```
> > >
> > > that looks like them, but we would never know. All we know
> > > is that there is something in RR that behaves much as our
> > > CEVs do.
>
> >
>
> > ```
> > RM:Â Yes, we know that variable aspects of RR that are
> >
> > ```
> >
> > our perceptions vary as as expected from our models of RR.
> > So, for example, I can control the position of a table (a
> > variable aspect of my environment) only by applying the
> > forces Newton says I have to apply in order to produce that
> > perception.
>
> >
>
> > RM: Also, note that what we control are _variables_ .
> > A table is not a variable;
>
> > ```
> > it is the state of a variable that could be called "type
> >
> > ```
> >
> > of furniture".
>
> > ```
> > You might control for a particular value of that
> >
> > ```
> >
> > variable when you are furnishing a room; putting the table
> > in this room, the bed in that room and the couch in the
> > other room. I don’t think it’s necessary to assume that
> > there is a variable in the real world – an RREV – that
> > corresponds to “type of furniture”. This “type of furniture”
> > variable is certainly a _function_ of variables in the
> > real world but it exists only as a perceptual variable.
>
> -
>
> ```
> At least,
>
> ```
>
> that’s the way it works in PCT\*
>
> > At least, that’s the way it works in PCT.Â
>
> >
>
> > ```
> > RM: But since this idea of an RREV seems to be popular
> >
> > ```
> >
> > with everyone but me, I suppose I’ll just have to get used
> > to it. But I would like to know how the notion of an RREV
> > fits into research on living control systems. How, for
> > example, is the RREV relevant to the work on object
> > interception? How does the concept of an RREV relate to the
> > perceptual variables that I found to be pretty accurate
> > predictors of the behavior seen in object interception
> > tasks?
>
> >
>
> > Â Best
>
> >
>
> > Rick
>
> > > ```
> > > Martin
> > >
> > > ```
> > >
> > > >
>
> > > > BestÂ
>
> > > >
>
> > > > Rick
>
> > > >
>
> > > > > ```
> > > > > Science produces ever more such Perceptual
> > > > >
> > > > > ```
> > > > >
> > > > > Functions, and sometimes those ones puzzle us.
> > > > > Our unaided sensory systems never create a
> > > > > pattern that we perceive as a wave and as a
> > > > > particle, or one in which the state is
> > > > > unresolved until the state of another
> > > > > “wavicle” elsewhere is observed. Why should
> > > > > it? Science uses sensors sensitive to
> > > > > properties of Real Reality for which we have
> > > > > no sensors. I think it was Einstein who said
> > > > > that the Universe is not only stranger than we
> > > > > imagine, it is stringer than we can imagine.
> > > > > But the beauty of PCT is that this doesn’t
> > > > > matter. What matters is what works. No theory
> > > > > of control that is not a theory of control of
> > > > > input can make this claim. The genius of
> > > > > Powers was to see how this applies to life
> > > > > itself.
> > > > >
> > > > > ```
> > > > > Martin
> > > > >
> > > > > ```
>
> > > >
>
> > > > –
> > > > Richard S.
> > > > MarkenÂ
>
> > > > ```
> > > > "Perfection
> > > >
> > > > ```
> > > >
> > > > is achieved not when you
> > > > have nothing more to add,
> > > > but when you
> > > > have
> > > > nothing left to take
> > > > away.�
> > > > Â
> > > > Â Â Â Â Â Â Â Â Â Â Â Â Â
> > > > Â Â --Antoine de
> > > > Saint-Exupery
>
> > >
>
> >
>
> > –
> > Richard S. MarkenÂ
>
> > ```
> > "Perfection
> >
> > ```
> >
> > is achieved not when you have
> > nothing more to add, but when you
> > have
> > nothing left to take away.�
> > Â Â Â Â
> > Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de
> > Saint-Exupery
---
### Author:  [@rsmarken](http://discourse.iapct.org/u/rsmarken)
#### Post date: [April 28, 2019, 5:15am UTC](http://discourse.iapct.org/t/the-beauty-of-pct-was-re-cev-and-rrev/11239/6 "2019-04-28T05:15:31Z")
[Rick Marken 2019-04-27\_22:10:05]
> > Â
> > > ```
> > > MT: The CEVs of our perceptions are
> > >
> > > ```
> > >
> > > of structures that produce perceived relationships that
> > > match the relationships given us by Real Reality
> >
> > ```
> > RM: So now CEVs are "of our perceptions" rather than
> >
> > ```
> >
> > being perceptions themselves?..
> ```
> MT: This is a neat debating trick you seem to favour -- taking
>
> ```
>
> statements out of the context of the ongoing thread.
RM: I’m not debating you. I’m just trying to figure out what this CEV and RREV stuff is about.Â
> ```
> Â MT: As you have to know, having been a thread participant, I do
>
> ```
>
> “\* just go with the PCT idea that what you call CEV’s are
> perceptions that are a function of real reality\*,”
RM: OK, great. So CEVs are exactly the same as controlled quantities.Â
> ```
> MT: But I do NOT go along with this. Real Reality is not defined by
>
> ```
>
> anything since we can know nothing of it other than the
> relationships it induces among our sensory inputs and our actions.
 RM: OK, so that is different than the PCT view, which is that reality is taken to be the models of the physical sciences.Â
> ```
> MT: Our current "best models of physical reality" can be derived from
>
> ```
>
> the data provided by the goblin bureaucracy exactly as well as they
> can by any other of the several that have been seriously proposed.
> Those same data are all you have to work with, and you simply cannot
> “define” real reality as being any one of them rather than any
> other.
RM: This doesn’t make sense to me; nor does it correspond to anything in PCT. Â
> ```
> MT: I remain puzzled why for so many years you treat functions of
>
> ```
>
> variables as though they were not variables themselves in the same
> sense of the word.
RM: And I remain puzzled why you think that. I’ve always said that perception is a variable – the perceptual signal – that is a function of other variables. You can’t build PCT models without knowing that.
Â
> ```
> MT: As far as perceptions are concerned, the only
>
> ```
>
> functions of interest are the perceptual functions, which produce
> functions of their inputs that we call Perceptions. \* At least,
> that’s the way it works in PCT\*.
RM: Yes, that is indeed the way it works in PCT.Â
> > ```
> > RM: But since this idea of an RREV seems to be popular
> >
> > ```
> >
> > with everyone but me, I suppose I’ll just have to get used
> > to it. But I would like to know how the notion of an RREV
> > fits into research on living control systems. How, for
> > example, is the RREV relevant to the work on object
> > interception? How does the concept of an RREV relate to the
> > perceptual variables that I found to be pretty accurate
> > predictors of the behavior seen in object interception
> > tasks?
> ```
> MT: I'm not sure what you are asking. Are you asking how predictions
>
> ```
>
> based on an unknowable RREV can improve on predictions based on our
> perceptions, the answer is that it can’t.
RM: OK, great. So it’s useless for research purposes, as I suspected.Â
> ```
> MT: The fact that control
>
> ```
>
> works and often works very well is testament to the ability of
> evolution and reorganization to provide functions that fit parts of
> Real Reality quite closely.
RM: How do you know that perceptions fit parts of real reality quite closely? In order to know this you must know what real reality is. So can you tell how close someone’s perceptions are to real reality?
> ```
> MT: If they didn't, you wouldn't be able to
>
> ```
>
> control very well using the derived perceptions.
RM: Ah, so how well one controls a perceptual variable is a measure of how well that perceptual variable corresponds to real reality? Is that right?
Â
> ```
> MT: What the notion of
>
> ```
>
> an RREV can do is allow you an escape hatch if your predictions
> based on perceptions/CEVs doesn’t fit your experiments. And that, I
> think, would by itself be enough to demonstrate the importance of
> the concept for scientific research of any kind, PCT included.
 RM: This sounds interesting. Could you explain it in more detail.
Â
> ```
> MT: As I pointed out several times, the fact that you may have created a
>
> ```
>
> perception/CEV from sensory data does NOT mean that there exists a
> corresponding RREV out there in Real Reality. What it does mean is
> that you cannot control that perception by acting on the RREV.
RM: Could you give me an example of that. So if I am perceiving something that I can’t control it’s because the perception doesn’t correspond to an RREV? Couldn’t it be because I have no means of influencing that perception? Or that I have not yet developed the skill to control that perception? How do I know when my inability to control a perception is because the perceptual variable doesn’t correspond to an RREV?
> ```
> MT: You
>
> ```
>
> would have to act on its elements in ways that maintain the sensory
> relationships that led to the perception in the first place. Just
> imagine trying to create a picture by individually colouring each
> pixel, rather than by sweeping a paintbrush over many pixels all
> together! Sometimes, when your CEV seems to be “out there” in the
> consciously perceived environment, there is a corresponding RREV,
> sometimes there isn’t. The famous “taste of lemonade” is an example
> of when there probably isn’t.
 RM: But if the taste of lemonade doesn’t correspond to an RREV then I shouldn’t be able to control for it. But I can? I’m so confused!
> ```
> MT: If thinking of the RREV doesn't help you get some ideas clearer in
>
> ```
>
> your head, don’t use the concept.Â
RM: Yes, I think that would go a long way to eliminating my confusion.Â
Â
> ```
> MT: Nobody is pressuring you to use
>
> ```
>
> it, though I am and have been trying to illustrate to you how and
> when it might be useful.
RM: Well, thanks for trying.
Â
> ```
> MT: It helps me shed light on a few murky
>
> ```
>
> issues, and it may help one or two others if not you, so I think it
> is worth thinking through.
RM: When I think it trough it just makes things murkier. I guess I’m just the scarecrow to your wizard;-)
 BestÂ
Rick
> **···**
>
> > ```
> > Martin
> >
> > ```
> >
> > >
>
> > > Â Best
>
> > >
>
> > > Rick
>
> > > > ```
> > > > Martin
> > > >
> > > > ```
> > > >
> > > > >
>
> > > > > BestÂ
>
> > > > >
>
> > > > > Rick
>
> > > > >
>
> > > > > > ```
> > > > > > Science produces ever more such Perceptual
> > > > > >
> > > > > > ```
> > > > > >
> > > > > > Functions, and sometimes those ones puzzle us.
> > > > > > Our unaided sensory systems never create a
> > > > > > pattern that we perceive as a wave and as a
> > > > > > particle, or one in which the state is
> > > > > > unresolved until the state of another
> > > > > > “wavicle” elsewhere is observed. Why should
> > > > > > it? Science uses sensors sensitive to
> > > > > > properties of Real Reality for which we have
> > > > > > no sensors. I think it was Einstein who said
> > > > > > that the Universe is not only stranger than we
> > > > > > imagine, it is stringer than we can imagine.
> > > > > > But the beauty of PCT is that this doesn’t
> > > > > > matter. What matters is what works. No theory
> > > > > > of control that is not a theory of control of
> > > > > > input can make this claim. The genius of
> > > > > > Powers was to see how this applies to life
> > > > > > itself.
> > > > > >
> > > > > > ```
> > > > > > Martin
> > > > > >
> > > > > > ```
>
> > > > >
>
> > > > > –
> > > > > Richard S.
> > > > > MarkenÂ
>
> > > > > ```
> > > > > "Perfection
> > > > >
> > > > > ```
> > > > >
> > > > > is achieved not when you
> > > > > have nothing more to add,
> > > > > but when you
> > > > > have
> > > > > nothing left to take
> > > > > away.�
> > > > > Â
> > > > > Â Â Â Â Â Â Â Â Â Â Â Â Â
> > > > > Â Â --Antoine de
> > > > > Saint-Exupery
>
> > > >
>
> > >
>
> > > –
> > > Richard S. MarkenÂ
>
> > > ```
> > > "Perfection
> > >
> > > ```
> > >
> > > is achieved not when you have
> > > nothing more to add, but when you
> > > have
> > > nothing left to take away.�
> > > Â Â Â Â
> > > Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de
> > > Saint-Exupery
>
> >
>
> –
> Richard S. MarkenÂ
>
> "Perfection is achieved not when you have nothing more to add, but when you
> have nothing left to take away.�
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â --Antoine de Saint-Exupery