Dear Pat, 

Thank you for your patient reply. I think I had understood your
position before, but it probably helps to have it spelled out in the detail 
you did. Now I must try to make you understand why I believe I have
answered your challenges. 

I'll try not to repeat. But a key point  is Bohr's
central point that the language of classical physics  
is a refinement of everyday language, which we use to tell each other 
what we have done and what we have learned. When I tell the 
technician to put that mirror at the place marked by X and a second 
mirror ten feet north of the first, I am using everyday language. 
Children learn what "dogs", and "cats" and "mirrors" are, and also 
what "ten feet" means. This all comes about through pointing, 
examples, and training, and is part of what it means to learn a
language. This same common language is used by all the physical sciences
to describe how to set up an experiment and how to describe the results.
Of course, as the sciences evolve the languages evolve with them, so that
today a technician knows what ten gauge copper wire means. But he has 
learned this in much the way he learned as a child what a spoon is. This 
common language of the physical sciences allows the scientists and 
technicians to set up experiments that conform to specifications and 
allows the observers to report the results. It involves ever more 
technically refined language. But the metalurgical specification of the 
materials from which a wire is made might be used by biologists and 
chemists and physiologists etc.

You accuse Bohr of "conceptual myopia", but in this matter he was
seeing things in a broad way,  in the sense of encompassing all of 
science when he emphasized, in connection with experiments, the use 
of  "everyday language suitably refined" to "tell each other what 
we have done and what we have learned".

You speak of "scratching my nose" as  an example of the kind of problem
that arises. We learn as children what a "nose" is and what it means 
to "scratch" a nose. This is not part of a disconnected language of biology:
any aborigines know what a "nose" is, and what the word for it is in his 
language.

You cite the fact "leaves are green" as a fact *not* entailed by 
the classical physics theoretical description and principles. 
That may be true. Green might mean a psychological rather than spacetime
form, and quantum theory is needed. If by "green" we mean only
that the light from the leaf lands at a certain point after passing 
through a prism, then that fact is certainly specified by the complete 
classical description, because the complete classical description says
exactly where all the energy is located. No extra vocabulary is involved
in the description of the observed fact: i.e.,where the light lands.
The fact specified by the classical physics description, namely that
the light from the leaf "lights up a patch on the screen centered 
on a certain number, say 752, which is also labelled by the word "Green", 
is specified by the complete classical physics description, and the
technician can announce to the scientific community that "the patch
labeled `green' lighted up", in write this in his log book. 

In fact, one of the key episodes in the history of science revolved about
this sort of fact, namely Newton's announcing of his results of experiments
with sunlight and prisms; the retort of some philosopher that
those results were absurd and impossible; and the confirmation of
Newton's claim by countless scientists.

If classical physics did describe the world then it would certainly
have to account for the fact that the light from the leaf (or from every
green leaf) is in fact green not red (i.e., gets deflected 
in the manner that characterizes green light, not red light). 
And the fact that the light lands where it does is something that can be
reported in common everyday language by a child.

I have spelled this out in detail because I am baffled by your remarks
about the possibility of "red chlorophyll". This is certainly a place
where some futher explanation is needed: I simply have no idea
what all your remarks at this point are supposed to show. No extra
"theory" is involved here. And nothing depends on what "I know" now
or did not know about plant biology. If the classical theory were 
correct it would necessarily, by itself, entail where the light reflected 
off of any leaf would go if it were passed through a prism. This is simply
because if the classical conception of nature were correct, then
the complete classical physics description would specify where every 
bit of energy and matter is at every instant of time, and that would
specify in particular where the light that is deflected throught the 
prism would land on the screen. 

I quite agree that once we know how experience is connected to the
brain we will find zombies a ridiculuos idea: that is MY point!
That is why the classical physics framework is unsatisfactory: it 
leads to this ridiculous idea. It leads to this ridiculous idea 
because the description provided by the classical physics description
describes nothing but the dispositions of the particles and fields:
the empirical connection of the "physical facts" specified by this 
classical physics description to the general realm of our experience 
is made by observers communicating `what they have done and what they 
have learned' to the community by means of everyday language, 
refined to take into account our expanding theoretical ideas 
about the world.
 
But this empirically effected transfer of the facts
represented in particle-and-fields description to the realm of experience
of communicating scientists is not explained by the classical physical
theory itself: there is this "expanatory gap". You admit that this gap 
exists, but claim that a similar gap exists for the physical sciences.

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. So this issue of `other possible gaps' is 
a red herring.

You admit that the gap in question is present. So you should admit
that Zombies are possible within the logical framework provided
by the classical laws and concepts. Raising the issue of other
possible gaps obfuscates this main point.

But are there other explanatory gaps? Well, that depends
on what you want to explain. 

Insofar as the classical conception is valid, there is a whole 
world of physical facts specified by (entailed by) the dispositions 
of the particles and fields at all times. This includes the changes 
and developments and evolutions of all physical systems. There is also 
all of our empirical ability to recognize various named spacetime 
configurations, and our ability to communicate to the scientific community
what we have done in the way of setting up spacetime congigurations
and what we have learned in terms of the appearance of recognizable
named spacetime forms. All of these communications constitute a certain 
body of scientific knowledge that belongs to the scientific community,
but that does not involve a gap of the kind mentioned above.

I said: "So if our brains are included in the classical physics
theoretical description of the physical world..."

You objected: "But this begs the question! HOW can the concept of
`brain' be included in a description in theoretical physics?
(Where in physics is there any reference to `brains'?) To do this,
one must provide an ACCOUNT of brains in sufficient detail to be able to
translate brain-language into particle-and-field language. That translation
constitutes the `bridging laws' we keep referring to, and it/they
are NOT entailed by physics.... There is no `classical description
of our brains' because the word `brain' is not part of the vocabulary
of physics. ( Like you, I feel a sense of frustration. This point seem so
obvious I cannot find a simpler way to express it, yet it seems not to get
across.)"

This point may lie at the root of our inability to communicate, so I 
shall pay attention to it.

The `bridging principle' that *I* keep referring
to is the one needed to bring consciousness in, not brains:
I say that the complete classical physics theoretical description 
includes by definition the description of the location and velocity 
of every particle in the universe, and the value and  rate of change 
of every field at every spacetime point. So the complete classical
description includes, in particular, the description of the dispositions 
of all the particles and fields in anyone's skull, and this conglomerate 
consists chiefly of that person's brain.   

So it is true *by definition* that, according to the classical physics
conceptualization of nature, the classical physics theoretical
description of the universe includes the description of all the particle and
fields in anyone's brain, and this description of all the particles
and fields in a brain is what is called the description of that brain.

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.

Similarly, Newton was able to make predictions about the orbit of the
earth, without having a theory of plate tectonics

You say:

" I still see NO REASON you have given to justify your firm belief
that subjectivity differs from any other phenomenon, other that confidence
in our future ignorance."

This is one of your principal and oft-repeated assertions. So I must
spell out my answer.

You tie your assertion to your "red chlorophyll" discussion, and the
idea of "other theories", and the possibilities of future advances in our 
knowledge. 

I certainly recognize that our everyday language evolves and becomes
more refined, and is a giant web of interconnecting links tied into
our realms of experience. And we can use these refinements to refine
the experiments that we are able to specify and report upon. But I think
it is a mistake to think that this common language can be usefully
separated into disjoint parts: this language by means of which we
communicate to each other what experiments we have set up and what
results we have observed is an inseparable whole, based on 
everyday language. So I see no `other theories" or "changing
theories" problem.

In the classical conceptualization the physical sciences are tied 
together two ends. At one end there is the common physical foundation
in the particles-and-fields that are supposed to be the physical 
ingredients from which everything physical is built: at the other end 
there is the linkage to the community of scientific thinkers, via
their sense experiences and their refined common language.

But I fail to see in any of this any gap of the kind that you admit
is present in the case of consciousness. 

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
that includes everything else.

You always reply that these laws and principles also do not bring in 
such things such as brains, cells, cell walls. etc. etc..  

But *the complete physical description* that these principles claim 
exists does, if the theory is correct,  describe all the brains that 
are present in the universe, and all the cells and all the cell walls. 
And by our experiments we can learn about the spacetime structure that 
exist and are, if the classical  conception is valid,  entailed by the
complete physical description. No big gap is encountered.

But if one  asks about the *experiential content* of the  universe 
that is entailed by `the complete physical theoretical description' 
then the answer is "nothing at all", really. There is no entailment of 
consciousness. So the two kinds of properties, physical and 
experiential, enter very differently, due to the very different ways 
that they enter into the `complete classical physical description', 
namely completely entailed in the case of the physical and 
not entailed at all in the case of the experiential.

In this connection I say later:
"the classical physics description would---to the extent that it is 
true---give a complete physical description of all the physical facts
about biological systems."
 
You counter with:
"Not without some account of how concepts such as `cell wall', etc.
are connected to the language of physics. I'm still unclear whether you
allow such accounts to be part of physics, or to be bridging laws that 
are somehow entailed by physics (which I think I can prove is logically
impossible, given your own definition of `entailment' in terms of
deduction.) or to be part of biology not but not of physics. If the latter
then your claim in the last sentence above is manifestly false."

So here we are at the heart of the matter!
How do I answer?

I am saying that---if the classical conception is correct---then the 
complete classical physical description would give a complete description
of every physical fact and object that exists in the universe, and hence 
every `cell' and `cell wall', etc. to the extent that it is 
something physical. 

Now---according to the classical conceptualization--nature herself just
does her thing, which is simply to unfold in accordance with the 
deterministic physical laws: in the process she makes what biologist 
call "cells", but she herself has no need to "define" exactly what 
a "cell" is, nor which of the sciences should concern itself with
such things.

Focus now on some clear  example of a cell. According to the classical
conceptualization it is---and has--some structure, which can be specified 
at the level of particles and fields. It will evolve and eventually
disintegrate: the point at which it ceases to be a cell will depend on the 
exact definition of cell one chooses to use. In view of this ambiguity
one sees that the physicist's description of it in terms of its
evolving microscopic structure, and its interactions with its 
surroundings, is more informative than its limited specification in 
terms of certain arbitrary conventional terms: given the complete physical 
description one can see how all sort of possible higher-level (hence 
less informative) definitions would apply: one has the base information
from which the special conventional definitions must draw. Consequently,
the biologist's definitions can be regarded as basically secondary
and derivative. They are useful to biologist and hence certainly 
are not to be ignored. But they are less informative in principle,
and unsuitable for the basic ontology. 


You say: If you find it obvious that `physical biology' can account
for our overt behaviour then... [PROVE IT]

Proof:
What I claim is obvious is that if the principles of classical
mechanics were valid then the complete physical description in terms of
particles and fields that these principles claim exists would
completely specify our overt behaviours. This result is rigorous and obvious
and trivially true because the complete physical description in terms of
particles and fields specifies, according to the assumed principles, 
exactly where every particle and bit of energy is at every instant of time
from the beginning of time to the end of time, and the assumed 
principles also assert that all physical objects are made up
exclusively of these particles and bits of energy. But the behaviour
of any system that is built exclusively out of tiny localized parts is
determined by the changing locations and motions of these parts.

You say in response to my claim: 
"I disagree, see above. This has been my central point ever 
since the beginning of this debate."

Well, this certainly pinpoints a basic disagreement!

It seems to me that you are simply wrong on this point
about which there is no room for rational dispute.

Best regards, Henry