Dear Pat,

I think we are getting to the core!

You say:
"Yes and no. I agree that the language of science is an extension and
refinement of everyday language. However, I do not agree that everyday
language is #entirely# [HPS: I did not say *entirely*: language does many
things besides describing experiments and their results]  concerned with, 
or can be translated into a language which is entirely concerned with, 
'visual appearances' which are 'associated' with words, or that it does 
not involve understanding of a theory.  Everyday language is absolutely 
thick with implicit theory: in fact, my own professional life has been 
devoted to uncovering some tiny parts of this theory. See Aaron's recent 
response which expresses this point better than I now have time to do here."

I absolutely agree that everyday language (and in fact everyday thought
and experience) is absolutely thick with implicit theory. But it is important
to make the distinctions that are neccessary to move ahead in a particular
case. The question is how much of modern biological theory is needed to
allow the young-boy gardener to recognize and report that the thing he 
plucked from the rose bush is a `leaf', and that the light reflected off 
of it landed on a spot lying between `8' and `9' on the dial, and to 
thereby introduce a fact pertaining to a biological system into
the biological data base. 

According to the principles of classical
physics the fact that this spot of light lies between `8' and `9'
is ENTAILED by the complete classical physical description of nature, which
thus entails a particular biological datum. This example illustrates
the way that the original data base upon which biology is based was
created: although there is certainly a complex intertwining of the
developing biological theory and the growing data base, *some* of that
biological data base depends only on theories already woven into
the web of our language before the development of modern biological theories.

Entailment requires definitions: that is your point. The word `leaf'
is used in biology but is not part of the language of physics: it is not
found in physics text books. So how can there be entailment from PAF 
(classical particle and fields) physics to biology? That is your question, 
which I understand very well, and which I claim to be answering.

My answer is, and has been, that physics is tied into experiment by means
of a suitably refined extension of ordinary everyday language: that without
that language physics is nothing: it has no connection to experiments or
empirical observations. That language has at its base the ordinary words
that a child learns to use to describe the objects in his normal life, and to
communicate about them to others. This language becomes refined by our
theoretical ideas in a kind of step by step way. Certainly one is using the
ideas of physics (e.g., that light normally moves in straight lines, to a good
approximation; that rigid object retain their shapes under transportation, 
to a good approximation) to interprete the experiments, and revisions of the
`meanings of what we see' come about as the theory evolves. But this whole
process is an evolutionary one, and at various stages one has a contemporary
conception of how one's observations are tied into the PAF description.
And certain basic facts pertaining to biological systems, such as the fact
represented by the boy-gardener's report that he took a `leaf' from a `rose
bush' and measured its length to be `definitely more that one inch and 
definitely less that 2 inches' can be regarded as being part of the classical
physics description because `leaf' and `rose bush', in the context of his
report, and  the meaning of `measuring an object' is part of what is 
specified by the ordinary language (suitably refined) that classical physics 
uses to tie the formal mathematical apparatus involving PAF to experiments
and empirical observation. 

Because the PAF description is expressible in terms of spacetime forms, 
the primary linkage of PAF to properties of objects identified in the 
everyday language is to properties that are expressible in terms of 
recognizable (to trained observers) spacetime forms: the operative 
correspondences are matchings between the empirical and theoretical 
(PAF) spacetime forms. Because of this tie-in of the classical physics 
formalism to ordinary language one can say that certain complete 
classical physical descriptions ENTAIL the results of measurements, 
even though the objects that are being measured (e.g., a leaf) are 
defined only to a degree that allows the experimenters to be able to 
report what they have done to them, and what they have then seen.
 
Using this data about this leaf, and a lot of similar data, the community of
biologists can start to build biological theories that rest ultimately on this
kind of data. Hence they are tied into a web of scientific knowledge
that can be regarded as having the PAF description as its base: all the 
physical facts about the physical and biological objects can be imagined 
to tie into spacetime through PAF. The empirical observations, which are
basically experiences of spacetime forms, can be construed to be experiences
"of" various physical and biological objects built out of PAFs. 

I call a "physical fact" about a physical or biological system a fact whose
truth is entailed by the classical principles and the classical 
physics description of that system. The essential thing about any physical 
fact about any system is that it is nothing but a conventional labelling or 
naming of some property of the  PAFs that make up that system: if it 
were any thing more then it would not be entailed by those principles and
that description.

One's experiences are  "associated" with his or her brain: 
illusions, drugs,  etc. convince us of that.
 
But they are not physical facts because they are not mere conventional
labels for properties of PAFs: an experience has a actual texture or 
feel that is not a mere convention. By contrast, for example, the 
"temperature" of a gas is nothing but a conventional name for a property
of the PAFs: that property of the PAFs is all there is to the temperature 
of the system. Of course, an observer who comes in contact with the 
system may feel the hotness or coldness, but that feeling is part of his 
or her system.

The point here is that an observing brain adds something to the
full nature of things that is not present in the accounts of the PAFs
of the object it is observing. This is clear in case the brain is observing
an object outside of itself, since the itself experience is some aspect 
of the brain, not of the object being observed. But if one tries to
identify the experience as a physical property of the observing brain then
there is, according to the classical-physics conception of nature,
the collection of PAFs that constitute the brain, and there are all the
properties that are defined simply as configurations of these  properties.
But a feel is not identically the same thing as 






Now all of the 

But then there are two sorts of experiences to consider.

There is the experience by the observer "of" his brain, and the related
PAF description of his brain. The observer's experience "of" his brain
is supposed, according to the classical conception, to be an experience "of"
certain properties of the PAFs in his brain.




This kind of direct spacetime matching is not available when the 
comparison is between a theoretical (PAF) description of a brain activity 
and an empirical sensation of "sorrowness". In the
former cases the PAF description and what is directly experienced
are similar spacetime forms, but sorrowness is not experienced by normal
people as a certain particular spacetime form.

So the connection of the physical PAF description postulated by
classical physical theory to the empirical experiences of objects
 

>To illustrate this I took "The case of the green leaf", which you had
>raised as an example of your argument.
>
>But you now agree that the complete classical physics description
>(which by the way obviates any need to "predict", because it
>gives the entire physical history of the world) does entail
>that the child would see that the light reflected off of the leaf
>(that he picked off of the apple tree) does end up at the location
>entailed by the complete classical physics description of nature.

Only if, as I said, the notion of 'leaf' were somehow unpacked into the PAF
language in which classical physics is couched.

.... You said: "this conception is only feasible
>because we know how leaves are made up of smaller pieces of stuff".
>But the classical conception by itself already asserts that the leaf
>is made up of smaller parts, and also that the complete classical physics
>description says every about the full history of all of these parts;

OK: my point about vitalism was off the mark, and I apologise for the
error. So, classical conception ITSELF claims that all of science is
reducible, in principle, to it. (In fact I think it only claims
supervenience, not reducibility.)

>and also everything about these parts interact with everything else,
>including light. So it can certainly do the job that you said the
>biological theory of the leaf could do.

NO: it claims that this job can be done, in principle. But it cannot in
fact DO it until the relvant details can be given. Without the detailed
unpacking of 'leaf' into biochemistry, classical (or any other) physics
can't predict anything about the behavior of the leaf. (Biology can,
however.)

On the other hand, the details of
>biological theory is far from complete, even now, and is certainly not
>known to be completely causal. So the complete classical physical
>description *can* do the required job, but the biological theory
>probably cannot.

Let me press you on this point. If I understand what you are here saying,
you claim that classical physics would be able to predict where light
shines when it falls on a leaf even if we have no idea how to translate
'leaf' into PAF language. How can it possibly do that? Suppose I tell you
only that it was a deciduous leaf, but give you no further information
about its shape, size or location: can PAF now tell me where it will
reflect light? Surely not. In order to do this, it must be given an exact,
detailed specification of where every particle and field which make up the
leaf are located at some time. But this IS the biochemical account of the
structure of the leaf which you say is unnecessary.

I think we are getting confused about two different claims.
(1) classical physics claims to  predict everything
(2) classical physics claims that all facts are determined by its facts,
which it can fully predict.
I am willing to agreee with claim 2, but this is not the same as agreeing
with claim 1. If classical physics were this crazy we could reject it out
of hand, since it could be trivially shown to be logically false.

>The key point here is that (following Bohr) I define the biological
>terms used to describe the observations on the biological
>system in terms of the names that trained technicians use to describe
>to others what they have done and what seen.

??? You are DEFINING biological vocabulary in terms of the
observation-reports of 'trained technicians' ?  But now you are totally at
odds with your earlier claim that the vocabulary of science is based in
'ordinary language'; and moreover you are at odds with almost all
biologists, I suspect. It is one thing to insist that all the empirical
evidence for the existence of things must be ultimately reducible to such
spatiotemporal observer-reports; but that is not the same as claiming that
the vocabulary used to refer to the world is defined in such terms.

I challenge you to show how such definitions could be produced for even a
tiny part of any science, even particle physics. Is the concept of 'lepton'
defined in terms of the names that trained technicians use to describe to
others what they have done and what seen? (Where can such a definition be
found?)



Since the topic under
>discussion is `what is entailed by the complete classical physics
>description,' I describe the biological system (leaf or cell) by
>following this physics description up to the point where the trained
>observer sees the recognizable form, leaf or cell, and I use this
>recognition to define the biological object in question, in the context
>of physical biology. These physics-based facts, "recognized" by trained
>observers, are communicated by word and symbol into the realm of
>experiences of biologists, who may or may not form other opinions or
>other theories about them. These other opinions and theories *are* more
>disconnected from the classical physics foundation, because they may
>make no reference at all to the particles and fields of the classical
>physical theory.

Then you have admitted my point: most of the language of most of science is
'disconnected' from the language of physics, and is NOT entailed by it,
because it doesn't refer to particles and fields. This is what I have been
arguing ever since our email discussion began. There are explanatory gaps
everywhere!

>The point of all this is to show how the physical facts that are the
>basis of the physical sciences are entailed by the complete
>classical physics description of nature, without encountering any
>gap of the kind encountered in trying to tie consciousness to brain
>activity.

??WHAT?? But you have just admitted, in your previous sentence, that there
is such a gap! (What ARE you talking about? You seem to blatantly
contradict yourself here. We must not be communicating, I guess. Sigh.)

>The lack of a large gap in the physical cases is a consequence
>(as spelled out in earlier letters) of the following fact: in those cases
>what are being compared---in making the connection of `the physical world'
>(as it is conceived of in classical physical theory) to `our
>relevant experiences of that physical world' ---are essentially `conceptions
>of the world constructed from generalizations of our visual experiences'
>to `our direct visual experiences themselves'.
>
>There is no comparable common denominator for comparing the classical
>conceptualization of an active brain (as a complex spacetime activity
>in  one' skull)  with the sensations of redness and sadness, or
>perplexity and hunger.

As this point seems central to you thinking, I am trying to understand it.
What you seem to be referring to here is the 'privacy' argument: that
introspective observations differ from other observations in not being
publicly accessible. Is that right? Because if this is the center of your
point, then (1) we should shift to arguing about it directly, as I believe
I can give a reasonable answer to it; but (2) more to the point for this
discussion, it seems to be just as true even if we have a
quantum-theoretical view of the world.

But let me ask you to confirm that this is the basis for your claimed gap
which exists for psychology but not biology, or if I have again
misunderstood you.

>I turn now to your questions.
>
.....>
>Yes! You talk here about "translations". But the issue is entailment!
>One may or may not be able to dream up some translation between
>languages. But that does not allow the facts in one description to
>ENTAIL the facts of the other description.

It may not be sufficient to produce entailment, but it is necessary.

The question is only what can
>be logically deduced simply from the the facts of the classical physics
>description. I thought that you had already granted that there was no way
>to *logically deduce* from the physical description of the brain in terms
>of particles and fields the fact that "redness" or "intolerance" is
>actually experienced, and experienced in just the way that it is
>experienced.

Yes, and in this strict sense of 'entail', most of science is not entailed
by classical physics, including all of neurobiology.

>
>I(HPS) said:
>>Now an important point must be made here. If there is a gap
>>in the normal classical laws of physics that allows the
>>particle-and-fields to do whatever they actually do without
>>experience being present then zombies would be possible, within
>>the framework of the classical theory, regardless of whether or
>>not `other gaps' exist.
>
>PH said:
>"Let me give you some other examples of LOGICAL possibilites within the
>framework of classical theory which become  impossible only when a
>sufficiently detailed 'connecting theory' is provided.
>
>1. Squareoids. A squareoid is a planetery system in which some of the
>planets move in square orbits rather than elliptical ones.
>2. Bombzies. A bombzie is somthing of the opposit of a zombie: it has a
>fully-fledged rich internal life of conscious experience, but it's neurones
>never fire at all.
>3. Flying pigs made of concrete and butterfly wings.
>
>Get the idea? All you need to do is to reject enough knowledge and almost
>anything becomes 'possible'."
>
>We are speaking within the framework of classical physics, and its laws and
>principles. Squareiods would not be possible unless there were some sources
>of forces that would actually cause the planets to move in such orbits.

Henry, please watch my lips, and I will try to explain the point once
again. (Believe me, you STILL have not understood what I have been saying.)

Your reply here clearly indicates that (as working scientists often do) you
are simply taking for granted all the information we have about the world
which enables us to relate things like planets to the predictive machinery
provided by classical physics. You just 'know' that planets have
gravitational mass, are opaque and roughly spherical, have centers of
gravity, etc.; but all of this knowledge is part of what might be called a
'theory of planets'. If one were to reject this theory, a squareoid might
be quite consistent with Newtonian gravitation. (For example, suppose we
claim that some planets might have zero mass, but be invisibly attached to
flat transparent square sheets which are themselves in orbit; or some other
unlikely fantasy.) We know this extra stuff so well now, and it seems so
obvious, that we might almost be inclined to hardly call it knowledge: but
it is all needed in order to make a deductive inferential connection
between the laws of classical physics and the macroscopic observations that
they predict.

....
>HPS:
>>No further theory of the brain is needed to establish
>>this elemental fact that, according to the classical physics
>>conceptualization, (the description of) each brain is included in
>>the classical physics theoretical desription of the the universe.
>>This fact has been true for three hundred years, long before
>>this century's great advances in understanding the brain.
>
>PH:
>Rubbish!  Did physics include a theory of brains before biology did? (If
>this is true, then all Nobel prizes given to biologists should be
>immediately rescinded.) How can something be 'included in the classical
>physics theoretical desription' before it even exists?
>
>I did not say "theory of brains", I said description of brains.

How can a description of brains (in PAF language) be provided, other than
by a theory of brains?

>HPS:
>>The essential REASON for the difference is that this latter
>>gap is specifically linked to consciousness. It arises from the
>>character of classical physical theory. That theory ties together
>>everything that is built out of particles and fields into one
>>highly coherent unified structure. But these laws and principles of
>>classical physics do not bring consciouness into this tight structure
>
>PH:
>"They do not at present, but they might as we learn more. On what grounds do
>you insist that this can never happen?"
>
>PH:
>"Look, isnt it obvious to you that you are here begging the question? How do
>you know they enter so differently into the web of knowledge? Suppose that
>by the end of the next millenium we come to understand how mentality is
>physically realised. Then it WILL be completely entailed. Or, it may be
>impossible to do this. But right now, we can't argue one way or the other.
>You havnt pointed to any PRINCIPLED DIFFERENCE between 'experiental
>content' and any other aspect of reality, other than a firm conviction you
>seem to have that such a difference must exist (on what I am increasingly
>coming to think must essentially be religious grounds, since your belief is
>so unshakeable and so unjustified.)
>
>"You insist that physics might completely account for the neural goings-on
>in our heads, without ever mentioning the experiences we have. But maybe it
>can't, in fact: maybe our expereinces ARE aspects of the neural activity in
>our brains. I know you find this unpalateable, but what grounds do you
>offer for your faith in the permanence of the 'explanatory gap'?"
>
>I do not find this at all unpalateable: it is exactly what I believe
>to be the case. I am seeking a way to make this compatible with
>our fundamental  science, and eliminate the `explanatory gap'.
>
>I the issue here is whether these advances can be achieved rationally within
>the very rigid framework provided by the classical-physics conception
>of the nature of matter.
>
>You said: "Suppose that by the end of the next millenium we come to
>understand how mentality is physically realised. Then it WILL be
>completely entailed."
>
>`Entailed by the complete classical physical description plus the
>laws and principles of classical physics?'

In the second, looser, sense of entailment, yes: but then we have to say,
plus the (newly acquired, in my scenario) understanding of the true meaning
of mental terms, of course. But like other definitions which reflect
understanding, these come for free.

>...experiences, though they can be regarded as transformations of such
>things, or translations of them into some other language, are not conceivable
>as NOTHING BUT a swarm of such separate individual entities and localized
>fields.

You have still given no argument in support of this claim, which you
reiterate again and again. What is the NATURE of this 'principled
difference'? Why cannot experiences be conceived as nothing but such a
'swarm' when things so apparently un-swarm-like as such as planets, leaves
and brains can be?

There is no way that a collection of such independent entities can
>rigorously ENTAIL, using only the principles of classical mechanics, the
>existence of a feeling of sarrowness, and the quality and tone of that
>feeling. For the principles of classical physics simply do not give us any
>grip that would allow us to pass from the concepts that classical mechanics
>deals with to such a qualitatively different sort of thing.

Maybe this 'qualitatively different' gets at the nub of the disagreement.
You obviously feel this difference very acutely, as many people do.
However, such intuitive feelings need to be backed up by something more
coherent if they are to be offered as arguments. It is still somewhat
remarkable that living things, which also are a qualitatively very
different sort of thing than stones, should be constructed from little
pieces of matter.

>SOME added principle would be needed to bring  consciousness into classical
>physical theory. But since the theory is logically complete without this
>added principle, that principle is not part of the basic physical theory:
>it would be an ad hoc appendage. Without it zombies would be possible.

Henry, your wheels are spinning: you keep reiterating your own slogans.
Classical theory is not LOGICALLY complete; it is in some sense causally
complete. To reach entailments expressed in anything other than its basic
PAF language one must add 'principles' to it, be they considered to be
bridging laws, aspects of definitions, or parts of meanings.  If these are
ad hoc appendages, then most of science consists of such ad hoc appendages,
so the implied criticism is not very forceful.

Pat Hayes

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phayes@ai.uwf.edu                Institute for Human and Machine Cognition
(904)474 2091                     University of West Florida
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