From stapp@thsrv.lbl.gov Fri Apr 14 15:39:57 2000 Date: Fri, 20 Aug 1999 14:45:29 -0700 (PDT) From: Henry Stapp To: pat hayes Cc: Bruce Rosenblum , A.sloman@bham.ac.uk, bdj10@cam.ac.uk, brings@rpi.edu, chalmers@paradox.ucsc.edu, ghrosenb@ai.uga.edu, hameroff@u.arizona.edu, hpstapp@lbl.gov, Jeffrey M. Schwartz , keith@imprint.co.uk, klein@adage.berkeley.edu, patrickw@monash.edu.au Subject: Re: Definition of "classical physics" Dear Pat, Your reply explains your position clearly. Let me explain why I demur. On Mon, 16 Aug 1999, pat hayes wrote: > Hi Henry > > >In spite of the divisions of science along departmental lines, the idea > >of the unity of science is still an ideal that motives much of science. > >The idea is that, even though the behavior of gigantic systems cannot > >be computed in detail, the behaviour of the entire physical universe, and > >everything in it, is fixed by the basic facts and principles of > >physics: no behaviour of any physical system should be incompatible > >with that notion. > > That isnt what I mean by the 'unity of science', which is that the various > sciences should be compatible with each other and (ultimately) be connected > by explanatory bridges. Thus for example "calorifics" - the science of heat > and the gas laws - existed for some time, and was highly successful, before > people were sure that heat could be identified with energy of particle > movement. But that 'bridge' isnt part either of particle physics or of > 'calorifics', narrowly understood. > Your notion of 'unity of science' seems to me more like 'reducibility of > science to physics', which is what I've come to expect from physicists, who > almost to a man seem to think that they are closer to God than the rest of > science. > It is not about being closer to God. It is about rational explanation of physical properties. Thermodynamics and Statistical Mechanics are the theories by which the phenomena of "calorics" are treated in contemporary science. They are taught in the physics departments of our universities, and are regarded by most scientists as part of physics. I doubt if anyone who works in these fields would deny that, insofar as classical physical theory is correct, the complete description of the locations of all the particles at all times and the values of all the fields over all spacetime, (plus the laws of physics, if they could add anything) would fix all the physical facts of "calorics": i.e., the facts about thermometer readings, pressure readings, volume measurements, and all other facts of "calorics", other than some facts about experiential states of the observers. As regards the theoretical connection between dynamics and thermodynamics/(statistical mechanics) it is true that some sort of statistical assumption is needed---an assumption that essentially that equal volumes of phase space have equal a priori probability---is needed, but this assumption can be made extremely plausible on physical grounds, and is a physical assumption, because it is, effectively, about the physical properties of large collections of similarly prepared physical systems: it is about geometric properties that are "logically" reducible to statements (about possible worlds) specified in terms of basic geometric properties, namely the spacetime dispositions of particles and fields. Hence this statistical assumption is not analogous to the "bridging property" that is needed to connect physical (i.e., geometric) properties to felt experiential properties, such as pain, sorrow, and "yellowness". > >....supervenience.... > >if the location of every particle at every instant of time, and the value > >of every field at every spacetime point, and every law of physics, is > >fixed then every physical aspect of the universe is fixed. > > The idea of supervenience is that A supervenes on B if determining the > facts of B thereby determines those of A. In this sense, indeed, there is a > widespread assumption that everything supervenes on the facts of physics, > if a sufficiently large chunk of the universe is taken into account. > Iguanas are ultimately made of quarks and maybe a few leptons, just like > everything else, so if all the quarks and leptons are fixed then so are the > iguanas. However, supervenience does not mean reducibility (which was, > indeed, the original point of introducing the concept) so your next > sentence here is wrong; the population density of iguanas is not *defined* > in terms of spacetime distributions of particles. If it were, iguana > ecology would be reducible to physics, not just supervenient on it. > > > This includes > >the population density of iguanas in Hawaii, which, according to classical > >physical theory, is defined in terms of spacetime distributions of the > >material particles and fields. By "define" I mean here "suffiently characterized": characterized in enough detail to do the job. From the physics perspective an "iguana" can be "defined" to be any physical system that has the physical properties that biologists would specify as sufficient requirements for something to be called an "iguana". This would probably start with some conditions on the shape of the system, its evolution from earlier systems, its skeletal structure, the structure of organs and skin, etc. Then the distribution of "iguanas" in Hawaii, in space and time, would be determined by the description of the physical universe over a hunk of spacetime: the iguana distribution would be completely fixed by the physical description. and reducible to it, in the sense that the physical description of the world together with the sufficient physical characterizations of meanings of words being used to label the classes of objects under consideration (e.g., iguanas) in terms of their physical properties completely fixes the iguana distribution, and entails it in the sense that if fixing the physical description in this hunk of spacetime to be P fixes the iguana distribution to be D, then P entails D in the usual logical sense that for every physically possible world W either P is false in W or D is true in W. > > Notice that supervenience doesnt say anything at all about what can be > inferred from what. It doesn't mean that it is possible to infer anything > about the supervening topic given the facts of the supervened. One could > totally specify the positions of every particle and every field (or > whatever) in the entire universe, and still know nothing about iguanas (or > about most anything except particles and fields). Even though the actual > iguanas would be superveniently locked in place, as it were, by the > locatings of their ultimate components, there would be no way for you to > know this *unless you already had a physical theory of iguanas*. You would > have no way to decipher God's notebook, if all it mentioned was particles > and fields, and if you knew nothing about iguanas. (This is really just > another way to say that ecology isn't logically reducible to physics.) So > your next two sentences, even if correct, constitute a non-sequiteur: > The reason why aerodynamics and marine engineering are reducible to classical physics is that these theories deal with properties that are localizable in spacetime regions, and these properties, e.g., pressures, densities, velocities etc. are, to the extent that classical physical theory is valid, logically related to the basic physical properties of the particles and fields, and many properties of these macroscopic quantities are then derivable from the basic physical Laws. Many of the facts of chemistry are also explanable in terms of the concepts and principles of classical physical theory in this same sense that the chemical properties, such as concentrations of different chemical species, and temperatures etc. are expressed logically in terms of the basic concepts of classical physical theory, and certain features of the interconnections are explanable in terms of the basic physical laws. The same goes for biology: much of it can be explained in terms of the precepts of classical physical theory. One must again identify some key macroscopic but localizable biological features and identify them with the properties of the classical model that would, if the classical model were correct, produce those biological properties such as shape, density, ionic concentrations, etc.. Whether or not a system is an "iguana in Hawaii" can be specified in terms of such properties that are logically expressible in terms of the basic properties of the classical physical theory. In this way the facts of the matter of the distribution of iguanas in Hawaii is reduced to the physical description of nature, as it is given by classical physical theory. > > But the conscious thoughts of human observers > >are not logically reducible to spacetime dispositions of bits of matter: > >the concept of a conscious thought includes more than just the > >idea of spacetime arrangements. > > They also contain another non-sequiteur. You say that the *concept* of a > conscious thought includes more than the idea of spacetime arrangements. > Well, so does the *concept* of an iguana, of course: No non-sequiteur here! Our conscious thoughts are not logically reducible to spacetime dispositions of bits of matter. But SOME of our concepts are constructs that DO arise from the aspects of our perceptual experience that pertain to spacetime structure: a certain part of our experience "of the world around us" comes to us in terms of LOCATIONS of properties in space, and of their motions. Classical physical theory is constructed upon microscopic idealizations of those geometric concepts, and it is this close logical connection between the concepts of classical physical theory and the geometric aspects of our experiences that provide the logical basis of our identifications of geometric aspects of the objects of our perceptions with the geometric features of the classical model. For example, shapes and motions at the perceptual and theoretical levels can be correlated because the basic theoretical ideas are simply conceptual idealizations of their perceptual counterparts. But other aspects of our conscious experiences are not used in the construction of the concepts of classical physical theory. For example, "yellowness" is not a geometric concept, and it does not enter into basic concepts of classical physical theory. We may discover some empirical connections between certain geometric aspects of the classical model and the occurrence of a perceptual "yellowness", but this is, from a logical point of view, a connection that is different in kind from the connection between the geometric features of our perceptual experiences and the concepts of classical physical theory that are microscopic idealizations of these perceptual concepts. The idealizations---relative to our perceptions--- of "points" and "lines" that form the basis of (say Euclidean) geometry are clearly the basis of classical physical theory. > that iguanas (living > things, more generally) are supervenient on physics is a very recent > opinion, and still probably a minority view among educated American adults, > so one can hardly claim that the very *concept* of iguanas somehow involves > a physicalist theory of life I do not claim that. The concept of "iguanas", and of EVERY object of the world that we see about us, has many aspects beyond the very special geometric features that are logically linked to the classical model of the physical world. That is exactly the problem: classical physical theory is logically linked to only a small part of our conceptual and perceptual world. So classical physical theory deals with only a small part of reality. But, in sharp contrast, according to orthodox quantum theory, every conscious thought, in its totality, is supposed to be represented by an associated reduction of a quantum brain state: othodox quantum theory demands, rationally, a linkage between each subjective knowing and a corresponding functional aspect of brain dynamics, rather than a correspondence only via geometric properties of perceived objects. "Yellowness" and "pain" are just as real as features of a knowing as a perception of a location, and all experiencial features should enter in basically the same way. Of course, this is what the classical-physics-based theory would LIKE to do. But that theory does not have "felt aspects" among its primitive elements, and has no dynamical role for such things. Hhence it has no way no way to get such things into the theory except by ad hoc external fiat based on the observed empirical correlations. But then there is no EXPLANATION of these connections in terms of the basic concepts of the theory. Orthodox quantum theory starts, basically, with the mind-brain connection formulated in a way that explaines ALL the physics data, as a starter. Quantum theory cannot explain why "yellowness" feels just the way it does, and not some other way. But this theory does not need to reduce a feeling/knowing to something else: a feeling/knowing is not regarded as REALLY something else; e.g., some arrangement of moving bits of matter. Yet the theory has a natural dynamical place for various feels/knowings: it has a built-in way for feelings/knowings to DO something, and to DO something not done by the Schroedinger process (evolution via the Schroedinger equation), which is the quantum analog of the dynamical equations of motion of classical physical theory. > (this has as a consequence, for example, that > the bulk of the competent native speakers of English don't understand the > vocabulary of their own language.) Not so! The point at issue is that within the classical-physics conceptualization of nature only a small fraction of the perceptual and conceptual elements of our thoughts are logically reducible to the classical physics concepts. So I am not claiming that ALL concepts are captured by classical physical theory: just the opposite. The problem is rather that almost everything is left out of the conceptual structure upon which classical physical theory is based: only the "geometric" aspects are included. That works very well for a very limited class of phenomena, but it does not adequately cover even all of physics. > But in any case, so what? Our concept of > conscious thought may be referentially successful - it may indeed identify > real conscious thoughts - without being factually accurate. Maybe our > concept is just flat wrong. Most people believe that their personality will > survive after they die. I'm quite certain they are wrong, but still I can > understand what they mean by 'soul'. > This appears to be off the point: what was being talked about was my assertion that: > >the concept of a conscious thought includes more than just the > >idea of spacetime arrangements. I was stressing that the nongeometric features of nature are logically outside of classical physical theory, and that this lacuna severely curtails, as a matter of principle, the explanatory power of that theory. > > Nor do the explicit laws of classical > >physics make this bridge from spacetime structure to the concept of > >conscious thought. > > Indeed, just as the laws of classical (or quantum) physics don't make any > bridge to all other concepts not mentioned in the theory. The point is that there IS a logical link between classical physical theory and the space-time aspects of our perceptual experience, because the the former is based on geometry, which is an idealization of the latter. And this logical link does provide very useful connections between classical physical theory and important aspects of our perceptions of the world about us. But other aspects of our perceptions are left out, along with much of the conceptual activity that constitutes a person's stream of consciouness. > If the supervened > theory provided the 'bridge', the supervening theory would be reducible to > it, and there would be no need for the concept of supervenience. > There is no really essential need to speak of supervenience, except perhaps to make contact with philosophers. This is because the key idea is "logical" supervenience, and logical supervenience does give logical entailment: If D logically supervenes on P then D is entailed by P (by virtue of the meanings of the concepts P and D.) Entailment holds in the usual sense: if P is a classical-physics description of an appropriate hunk of spacetime, and D is the population density of iguanas in Hawaii that is fixed (true) if P is fixed (true), then whenever P is true also D is true. > > One does not have to understand all the intricacies > >of consciousness to see that felt features of human consciousness, such > >as "yellowness" or "sorrow", have conceptual dimensions beyond the physics > >aspects of spacetime location of bits of matter. Maybe some sort of > >connection will eventually be discovered, but as conceptually given there > >is more to the felt qualities of human experience than locations and > >velocities of the bits of matter that constitute the subject matter of > >physics. > > What are you saying here? Of course what might be called the content of the > experience of seeing yellow (etc.) isn't reducible to terms of locations > and velocities of bits of matter. So what? The content of the experience is > more likely to be related to the richness of the internal vocabulary of > the mental system which represents our awareness. But of course this need > bear no simple relationship to the way that this system is physically > implemented. ( To make a simple analogy, the fact that one only has an HB > pencil doesnt mean that one is unable to write *about* color.) > Your analogy is a nonanalogy. To identify an HB pencil in the sense that is relevant to classical physical theory it is sufficient to specify various features about shape and physical constitution in terms of physical properties of the localizable components (atoms and how they are arranged). One does not need to say how some person might want to use it: that goes beyond the purely physical properties of being an HB pencil. But I think your comment goes deeper. You are stressing the richness and complexity of our concepts, the breadth of our conscious life, and also its functional character. Our ideas are largely about how we can DO things with other ideas and things, and our ideas of things are more closely connected to how we can USE those things, than about what those things ARE, constituently. This is precisely why quantum theory is so much better as a foundation for thinking about consciousness than classical physical theory. That latter theory insists that the basic realities are bits of localized matter, and that everything must, to be understood fundamentally, be understood in terms of this highly restrictive idea. But our concepts are not bits of localized matter, and are not amenable to being captured, and put into such a small cage. In quantum theory, on the other hand, our thoughts/ideas/knowings enter fundamentally as functional entities characterized by what they do. Recall that Bohr stressed how our descriptions of the physical facts were the objects by means of which we communicated to our colleagues what we have done and what we have learned. Ideas enter the dynamics as vehicles of communications between different subjective realms of ideas, or perhaps between earlier and later phases of the same realm. and more generally BY WHAT BRAIN ACTIONS THEY INITIATE. Ideas are closely linked to the complex quantum systems that implement their functional essences. They are not reducible to a classical-physics conceptualization of that brain because that conceptualization, by setting Planck's constant to zero, eliminates the causal openings through which our subjective ideas and thoughts, which are basic functional entities within quantum theory, interface with the objective aspects of nature. It seems to me that our disagreements stem from the fact that you basically adhere to the functional conception of ideas that quantum theory is based on and implements, while insisting on a classical-physics foundation that does not naturally support it, because it rests on a primitive and empirically inadequate notion of what IS, rather than on an empirically adequate conception of nature that links, in a mathematically specified way, a different idea of what objectively IS to our intuitive idea of what a subjective thought DOES. > > None of the "analogies" that have been advanced to try to > >support the idea that maybe someday, in the distant future, we shall > >understand our felt conscious experiences well enough to see that these > >internal subjective feelings are "logically reducible" to spacetime > >arrangements of bits of matter stands up to scrutiny: it is clear > >from the outset that a young child's subjective feeling of pain > >is not conceptually reducible to motions of bits of matter in his brain, > >for he has that concept of pain before he knows what lies inside his > >skull. > > Yes, of course. Nobody is suggesting that the content of child's thoughts > or experiences are reducible to physics. But then we don't need to feel > that this forces us into quantum theory. The nonreducibility means that the facts of consciousness are EXTRA FACTS, that are not logically a part of classical physical theory: they are, logically, dangling appendages. Of course, that does not FORCE one to go to quantum theory: one can try to make sense of the obscure concept of "emergence". (There is no problem with the idea that new ideas may be useful for dealing with complex classical systems, or that new ways of organizing the variables may allow the main features of dynamical structure to be expressed in simpler terms. But those features do not, within the framework of (the dynamically complete) classical physical theory, lead from the fact of the benefits of a rearranged physical description to the fact that this rearranged physical description should be (accompanied by) something not described within the theory, namely a "feeling": that "feeling" is an extra fact that is not entailed by the physical facts as the later are conceived of in classical physical theory. Going the "emergence" route seems obviously far less satisfactory than simply accepting the empirically established fact that the concepts of classical physical theory are fundamentally false, and that the completely adequate (so far as is known) replacement, orthodox quantum theory, is, logically, so very satisfactory with regard to these matters that are so troublesome within the classical-physics conceptualization. > The mere existence of fiction on a > (physical) printed page, with every ink-mark fully accounted for in > classical terms, is enough to show that one can give a classical physical > account of something which has itself no classical physical interpretation. The meaning of an object to a conscious observer is certainly not exhausted by the geometric/physical aspects of either the object, or the percept of the object: that is just what I have been saying. Our concepts are far richer: they extend beyond geometry. > (Look, the key point here is that mental content - including conscious > mental content - almost certainly involves some kind of mental process of > representation. If it does, then it follows basically from Church's thesis > that the content of the representation isnt reducible to the syntax of the > representation. Thats enough to account for your intuition of > nonreducibility of subjective experience to classical physics.) > We agree that our concepts are not exhausted by their geometric aspects: Church's thesis is not needed to prove this basic verity.. > >Bruce's physicist friends understand these matters well enough, > >and understand also that classical physics is about spacetime arrangements > >of bits of matter, to be able to see that felt conscious experiences have > >a conceptual dimension that is not conceptually entailed by the laws of > >the classical physical theory that they know and understand. > > > > > >> In spite of Henry's fulminations to the contrary, this observation applies > >> just as much to quantum physics as it does to classical physics. > > > >Let it first be made clear that the quantum theory in question is > >orthodox quantum theory .... > > (OK.) . > > >But consciousness is part of the universe, so it seems totally > >wrong-headed to try to root consciousness back out of physics, rather than > >to build on the fact that consciousness came in naturally from > >physics-based demands, and in a dynamically specified way. > > Consciousness is indeed part of the universe, but there are some simple > observations one can make about it which strongly suggest that it is a very > special aspect of the universe, one found only under extremely rare > circumstances. As far as we know, it arises only in certain complex > biological systems which exist only in a thin film on the surface of a > small rock near one star. By the usual measures of physical processes it is > almost unbelievably slow. It has existed only for a few hundred thousand > years at best, and it ceases to exist when the brains which exhibit it are > placed under quite moderate amounts of physical stress. It requires > extraordinarily special and idiosyncratic physical conditions (temperature, > presence of oxygen and water, many intricate molecules which are not found > anywhere else in the known physical universe, etc.) None of the conditions > which are necessary for consciousness bear any relation to any known > physical constant. Under all these circumstances it seems wrong-headed to > expect that one will be able to "root" an account of consciousness in > physics. One is more likely to be able to root, say, a theory of French > rococo furniture in physics. At least furniture stays being furniture when > it is frozen to absolute zero. > We know about consciousness because we have it, but it is unreasonable to think that it had no precursors: human consciousness must have evolved from more primitive forms. I believe that approximate self-replication is the core functional element. > >Your claim that " this observation applies > > just as much to quantum physics as it does to classical physics." > > > >is a pronouncement that is utterly contrary to the facts of the matter. > > I knew you were going to say that. OK, let me challenge you. Cite me one - > just ONE - prediction about conscious experience - phenomenology - which > can be derived from quantum physics, and which is precise enough to be > empirically testable. You keep making these claims, but I've never seen > anything to back them up. Let us recall the context. I said: > >Bruce's physicist friends understand these matters well enough, > >and understand also that classical physics is about spacetime arrangements > >of bits of matter, to be able to see that felt conscious experiences have > >a conceptual dimension that is not conceptually entailed by the laws of > >the classical physical theory that they know and understand. Your reply was: > >> In spite of Henry's fulminations to the contrary, this observation applies > >> just as much to quantum physics as it does to classical physics. I said; > >is a pronouncement that is utterly contrary to the facts of the matter. So the point at issue here is whether the fact that classical theory deals with only a small part of our conceptual realm, namely the only the geometric aspects, carries over to quantum theory? No! In orthodox quantum theory all conscious experiences are treated basically the same: Every conscious experience is associated with a reduction of the state of an associated brain. The nongeometric aspects of experiences are treated on a par with the geometric aspects. > > > >I am the only one who works actively on this basic key problem, so it is > >to my book and papers that you must turn. ... > > Well, I confess I don't have time to read all that, so will just refer you > back to my challenge. i.e., your above challenge pertaining to predictions about conscious experience According the Copehagen interpretation all predictions are about conscious experiences---phenomenology--- and the orthodox theory conforms to that same principle: that is how the orthodox theory is able to show that it reproduces all the predictions of the Copenhagen theory. So ALL the predictions of physics, both quantum and classical, are, according to quantum theory, about our conscious experiences: that was the big advance that was the essential basis of the successful re-formulation of physics in 1927 that constitutes quantum theory. > But I am pretty sure that a paper which used > psychological terminology would get published in Physical Letters, and a > paper on quantum theory wouldnt get published in Psychological Review, and > in both cases for very good reasons. > Well, two papers of mine about quantum theory and consciousness have been published in The Journal of Mind and Behaviour (Vol 18, 1997). The second one might be a good place to begin to find out how quantum theory can be tied into phenomena: it was written for an audience of psychologists. > best wishes > > Pat Hayes > > --------------------------------------------------------------------- > IHMC, University of West Florida (850)434 8903 home > 11000 University Parkway (850)474 2091 office > Pensacola, FL 32514 (850)474 3023 fax > phayes@ai.uwf.edu > http://www.coginst.uwf.edu/~phayes > From stapp@thsrv.lbl.gov Mon May 1 08:34:51 2000 Date: Thu, 2 Dec 1999 10:53:11 -0800 (PST) From: stapp@thsrv.lbl.gov Reply-To: hpstapp@lbl.gov To: pat hayes Cc: hpstapp@lbl.gov, Aaron Sloman , bdj10@cam.ac.uk, brucero@cats.ucsc.edu, chalmers@paradox.ucsc.edu, ghrosenb@ai.uga.edu, hameroff@u.arizona.edu, Jeffrey M. Schwartz , keith@imprint.co.uk, klein@adage.berkeley.edu, patrickw@monash.edu.au Subject: Re: Reply to Henry's reply [Part 4] (Back to logic vs causality (and Dave)) On Wed, 1 Dec 1999, pat hayes wrote: > > > [HPS, replying to Aaron] > > >There seems to be some deep difference here in our understanding > >of the ontology postulated by CPT. This difference keeps coming > >in throughout your text, so it needs to be brought out in the open. > > > >The CPT ontology is dualistic: there are just TWO kinds of existing > >entities. The first are the physical ones, which are built out of > >micro-local entities that obey micro-local laws that we call the causal > >properties of these entities. From these basic microcausal properties > >follow the causal properties of all aggregates of these microlocal > >entities, and hence the causal structure of the entire physical world. > >The second part of the CPT ontology consists of experiences: of the > >various ideas, percepts, feeling, and emotions that combine to form our > >streams of consciousness. Since the physical part is "causally > >complete", and the experiential part is evidently in step with > >the physical, it can be assumed that the physical somehow "causes" > >the experiential to be what it is. > > This dualist view of the ontology of CPT is news to me. I don't > recall anything about consciousness, experiences or qualia in any of > the classical physics I was taught. I've been assuming throughout > these discussions that CPT referred to the usual classical ontology > of the physical sciences, ie Henry's 'physical ones'. > > Pat Hayes Dear Pat. We may have, at last, discovered the origin of our differences. Most dictionaries define "matter" by distinguishing it from mind and identifying it as the subject matter of physics. This distinction between mind and matter goes back at least to the time of the greeks, and was made into a basic ontological distinction by Descartes. Newton worked within the intellectual framework set up by Descartes: he stressed his intellectual indebtedness to Descartes, as well as certain differences on specific details, but never on the this basic thesis. John Locke, working in the climate created by Newton's great work, and its overpowering influence in England, spelled out the common sense idea of the difference between mind and matter that prevails still today, with physical bodies made up of tiny localized particles, an idea used often by Newton---e.g., to calculate the center of gravity of an object. That particular idea also goes back to the time of the Greeks, and is also cited in dictionaries as an idea of what matter is. In the Principia Newton's concern was generally with "bodies", and in the preparation of that worh he made repeated efforts to define what bodies were. One of his trials reads: DEFINITION I I call `body' every tangible thing that resists things touching it, and whose [action] resistance, if it be great enough, can be felt. For it is in this sense that ordinary people always take the word `body'. And of this kind are metals, stones, sand, clay, mud, earth, salts, woods, bones, meats, water, oil, milk, blood, air, wind, smoke, exhhalation, flame, and whatever can be comprehended under the four elements, or can flow [arise or emanate] from these by evaporation and return to them by condensation. I add the celestial bodies... [Introduction to Newton's Principia, I. Bernard Cohen, Harvard U.P., 1971, p.39] Although Newton finally gave up in his efforts to formulate a good definition of what he was theorizing about, it is clear that he was trying to distinguish mind from matter: in his long list we do not find sorrow, pain, or our feelings themselves. Nor do we find in contemporary physics text books any effort to deal with pain or sorrow or the `feeling' of resistance when we touch material bodies. College students know that they will not learn about such things in courses in classical physics, even though classical physics was supposed to give a complete-in-principle account of the physical part of nature. The idea that you seem to be defending, identity theory of mind, was not argued for until the late 50's and in the 60's [J.J.C. Smart (and D. M. Armstrong)] and is, I believe, not held by any philosophers of mind active today: it had the virtue of simplicity, to the point of being simplistic, but had serious flaws, which philophers sought to avoid or evade in various ways. I have noted in recent communications that this identity theory is not the position held by Aaron, who focusses on the idea of trying to understanding connection between different ontologies, rather than simply collapsing mind to matter. Henry