Dear Pat, March 26, 1997 It is encouraging that my previous letter has clarified my thinking for you enormously. But your tendency not to pay close attention to *my actual words*, but substitute your own with substantially different meanings, has caused you to miss some essential points. (<....> my highlight) Your first question was how classical physics can tie its PAF equations to its macroscopic #predictions#. There is a major misunderstanding there. In elaborating on your point you said: "Of course it requires very little biological theory to make such an observation. My point was different: that it requires rather a lot of such theory to tie this observation to the PAF language of classical physics. "There is a subtle point here. The 'classical conception' claims that its equations are in principle complete, so that it the outcome of every physical experiment. But it can actually MAKE such a only if it is provided with a sufficiently detailed description of the experimental conditions. The outcome of the experiment may in some sense be foregone, but to actually make the connection between the PAF account and the refined-ordinary-language observations (of color or of pointer positions), . THIS is where the 'connecting theory' or 'meanings-for-free' play an essential role." ". The classical picture may assert that such a decomposition must exist: but that is not enough to , only to express confidence that one could if one knew enough of the details. Other sciences, or 'meanings', or SOMETHING, must provide these details." You have not paid close attention to my words. When speaking of entailment from classical physics I always specified that the entailment was from the plus the Bohrian theory of experiment. I have repeatedly emphasized that this `complete classical physical description' is . Thus no is needed for entailment from this base. You yourself explicitly admit, above, that entailment does follow from this complete base. The point is that the classical conception asserts that this `complete classical physical description' does exist. The equations merely place conditions on this reality: they play no role in my argument. It is only the assertion of the existence of this definite classical description that I use or need. I am not trying here to DO or to USE science to solve a practical problem: the issues are logical and conceptual. And the only entailment I need in this context is from this broad base. So in the situation involving the green leaf the premise is that there exists, as classical physics avers, a complete classical physical description of the world (a physical-world history), and that in this real world a boy gardener engages in an activity which he describes to himself and others as plucking a `leaf' from a `rose bush', putting it into a certain device, and reporting that he "sees a spot lying between `8' and `9'". Of course, there can be mistakes in scienfific observation, and these have to be weeded out by a tedious process, but if we discount the possibility of a mistake in this simple case we can say, given the precepts of classical physics, including the Bohrian account of "experiments", that the actual world history is in fact one in which some physical structure that has a shape that the boy gardener `sees as leaf shaped', (and which, in this world history, was plucked from a structure of PAFs that appeared to the boy gardener to be `shaped like a rose bush'), seemed to the boy to be placed by him in a device, whereupon a certain spot of light was then seen by the boy to appear on the dial at a location "lying between `8' and `9'". In this specific situation the world history in terms of PAFs entails a certain fact about a `leaf', where this `leaf' is characterized preciesely by what this boy recognizes and reports as a `leaf'. This datum may eventually become integrated into a more comprehensive biological theory involving cell biology. But at this stage it is a putative biological datum that was entailed by the complete classical physical description of reality plus the Bohrian account of experiment, which in this case specifies the meaning of `leaf' to be what the boy recognized as a `leaf' (by virtue of his training as a gardener), and reported as a `leaf'. *Entailment* from the complete classical physical description plus the Bohrian theory of experiment into the world of human experience means the process of injecting articulated facts into the realm of human discourse by means of the capacities of human observers to experience macroscopic properties that: (1), are carried by the PAFs, and (2), they have learned to recognize and report about. You say: "Of course it requires very little biological theory to make such an observation. My point was different: that it requires rather a lot of such theory to tie this observation to the PAF language of classical physics." You have not explained why more biological theory is needed to account for this entailment, from this huge base, of the fact in question. `Seeing a cell wall disintergating' is exactly analogous, in the case that I described, where the observer was a boy who was taught nothing about "cells" and "cell walls" but how the recognize them under the microscope, and report what he saw. You say: "Second, you have now made clear that you want to make a very sharp distinction between two classes of observations, allowing only one kind into classical physics; but I can see no reason to make this distinction, which seems based on a very simplistic notion of 'direct' perception." My distinction was based upon the fact that classical physical theory is built on the notion of forms in spacetime, and that these notions are generalizations extracted from the character of "certain" of our experiences, #primarily# our visual experiences, although we do also have some experience of the spacetime location of the source of a sound, and also the location of something we touch. But we only the stars in the heavens, and astronomy was important in the creation of classical physics. Also, our idea of spacetime points probably arises mainly, for most of us, as a generalization of aspects of our visual experiences. You say: "This 'proposed 'tie-in' is unacceptable, for several reasons. First, the PAF description is in terms of spacetime forms, but that doesnt mean that it specifies *all* spacetime forms." I have repeatedly emphasized that I am not trying to encompass *all* of everything, merely all of what can reasonably be called classical physical science. But the complete classical physical description does, according to classical physics, specify *all physically existing* spacetime forms. You continue: " In our example, even if it completely accounts for all the particle trajectories of the the pieces of a leaf, that alone doesnt tell us where the leaf is until one has also identified that part of the total plenum as *being* the leaf, and classical physics makes no claims to be able make *that* identification." As regards the identification of the `leaf', the central point of my account, repeatedly stressed, is that it is the *trained observers* who singles out some part of the total plenum as the `leaf' upon which he is going to perform a certain experiment. You then say: "Second, as Aaron has emphasised, most of ordinary language (even refined ordinary language used by trained observers) does not refer simply to properties that are expressible in terms of spacetime forms: this picture of language and how it operates is just plain wrong. So how is the rest of observational language to be tied to PAF?" My repeatedly emphasized point is that I am *not* trying to encompass all of language: I am trying to separate off classical physical science, which, because of the interconnectedness of language, is not an easy task. You say: "Let me ask you directly, as you often seem to wriggle on this point. Does it include any part of (1) psychology, (2) linguistics or (3) medicine? Or is all this (and any other science which sets out to empirically investigate human thought or experience) to be regarded as 'mere opinion'?" I do not exclude them by definition, and some parts of these disciplines could satisfy my criteria for belonging to the classical physical sciences. A lot of medicine certainly does. Of course, most of human thinking is not about the physical sciences, and I anticipate that much of psychology will not fulfill the criteria I have set for being part of what I define to be `classical physical science'. You ask: "What singles out 'matching of spacetime forms' as the crucial kind of observation? Is this supposed to be an empirical claim about the way that experiments are conducted? It seems entirly ad-hoc and arbitrary, since the complete physical description predicts many other observable aspects of the world." The basic premise of the discussion is that the classical conception of the physical world is correct. But this classical conception is based on the conception or notion of *forms existing in spacetime*. This notion, or idea, is a generalization of "certain" aspects of our sense experiences. By "certain" I mean to stress that when one `hears a sound' the experience may have a quality of "coming from some location". But it also has a quality of "pitch" that can be separated off from "location": we can experience that two sounds coming from different locations have, nevertheless, a certain aspect that can be recognized as being the "same", namely the "pitch", or the "timbre". The classical conception of physical reality says that the complete classical physical description of some physical object, like a horn, can be specified without associating with the horn itself a quality that is like the pitch we experience, perhaps refined. But the theory does associated with the horn something like the location that we experience the horn to be at. This experience of an object's "being at some location at some time" is much more vivid when we are "seeing it" than when we are merely hearing it. But in any case, this experiencing of an object's being at a certain location can be conceptually disjoined from the experiencing of the qualities of pitch, timbre, and color. The classical conception of the physical world says that the complete classical physical description is in terms of locations, and quantitative properies located at spacetime points: the physical description of the physical object is asserted by classical physics to be complete without including in the description properties like what we feel when we experience "pitch" , "timbre", or "color". The that restrict the allowable possible forms that a possible physical world can have, and that renders each such possible world dynamically complete, deals exclusively with these spacetime forms. By virtue of this fact---that classical physical theory conceives the physical world to be built out of spacetime forms that are, by nature, generalizations of our experiencings of spacetime forms---we can correlate structures existing in physical world to our experiences of the world by experiencing between the spacetime forms specified by and spacetime forms occurring in our . The thing that makes this kind of mapping special, within the context of classical physics, is that this is THE ONLY WAY of correlating the complete classical physical description of nature to our empirical experiences without introducing bridging principles that relate the structures that the physical world is asserted to be built out of---namely spacetime structures---to other kinds of empirical experiences. For example, one cannot *deduce* from the complete classical physical description of nature which `color' will be experienced when some observer looks at the leaf; for the complete classical physical description is, by assumption, built exclusively out of properties like the properies we experience when we experience spacetime forms, not including properties like the properties we experience when we experience colors. You say: "Its so easy to think of counterexamples (Newtons light refraction experiments, Fermi's first nuclear-critical event (detected by loudspeakers), etc.) that I wonder what makes you claim it is true." In these experiments one cannot *deduce* just from the complete classical physical description of nature that Newton experienced a band of red here and a band of blue there. The connection between the frequencies of the light vibrations and the experienced colors is not entailed by that putative complete physical description of nature, which contains no specifications about experienced colors. On the other hand, the fact that in this description of nature a `leaf-shaped' object was plucked from a `rose-bush-shaped' object is a fact that IS represented in this description, and this fact can be directly experienced by the boy who is doing the plucking because the theoretical and empirical experiences are , and he has been trained to recognized and give names to various experiences of this kind. He may also be trained to recognize and give a name "GREEN leaf" to a leaf that he sees as a leaf that is colored green. But in that case there is no possibility of a matching of his actual empirical experience against the facts specified by the `complete classical physical description of nature' because that description does not contain anything of the some kind as his actual experience of greeness, although it does contain information about certain vibrational frequencies near the leaf. You say: "Im afraid I just disagree with you...When I say that a leaf is green, I am not referring to anything in my head, but to the COLOR OF THE LEAF. ... but the claim made by this report (1B) is about the world, not my experience. That claim would be expressed by your (2B). Color is a surface reflectance property... That they ARE green, however, is a fact about them, not about experience." What is under discussion here is a comparison between two things. When you say the leaf is green something about the world. That is fine. But there is also something else here that is relevant to this discussion about the connection between physical and phenomenal facts. There is a fact about experience that you say is represented by a different sentence, 2B. If by `something about the world' you mean something about the world as that world is conceived to be represented in classical mechanics than that property of the world would be about the frequency of some vibrations. The corresponding phenomenal fact, the actual `experience of greenness' experienced by the boy gardener, and referred to by sentence 2B, does not have within it a specification of vibration frequency: in the case of greenness the phenomenal and physical facts do not have the quality of sameness-in-kind that the phenomenal and phyical facts about spacetime form can have: one cannot experience the same sort of felt congruence that one can experience between one's empirical experience of a certain spacetime form and one's theoretical picture of a spacetime form specified by the complete classical physical description of nature. You say some things about failure of observations to be veridical, under certain conditions. But that is not the point here: let us focus on simple ideal cases where the problems of illusions and delusions and mistakes have somehow been weeded out. These are the most pertinent cases. But precisely in these cases there is a big DIFFERENCE IN PRINCIPLE between spacetime forms and a quality such as greenness: the *nature of the connections* between corresponding physical and phenomenal facts is completely different. And the origin of this PRINCIPLED DIFFERENCE is a matter of principle, within the context of an assumed-to-be-correct classical physics: that physical theory builds its picture of the physical world precisely on structures in spacetime, and it exclude from this image of the physical world properties that can be identiable as the same properties (perhaps idealized) that we immediately experience when we experience the greenness of a leaf. Phenomenally experienced greenness and phenomenally experienced spacetime form are DIFFERENT IN PRINCIPLE in the context of their connections to the concepts used by classical physicists to build their theoretical model of the physical world. You say: "In any case, if I read you properly here, your 'principled' difference simply amounts to the fact that science has singled out one kind of observation as being more, well, *scientific*, than other kinds. Even if your account were correct, this difference would be a matter for historians to ponder, not a 'principled distinction'." Yes and No! I certainly agree that historians will be amazed that scientists tried for so long to cling to an already-proved-false conception of nature that was so obviously ill-suited when they had at hand one that was so well suited to the problem. It is that `science' has singled out this ill-suited philosophy. Science has moved past that primitive and false conception to one beautifully suited one to the problem. The `principled difference' exists only in the context of the outmoded and manifestly incorrect classical philosophy, which gives no adequate status to almost all of our experience. You say: "All this is wrong. We don't 'directly perceive' anything about the world," Your words do not match or mean the same as the words of mine that you are reacting to. I did not say "We directly perceive". That terminology raises the ghost-on-the-machine spectre. I said:" although in both cases the empirical experience is >(presumeably) an aspect of brain activity," You continue: "and our experiences are not 'likenesses' of the world. (Think: what would the point be of maintaining an internal likeness of what you see? All you could do with it would be to look at it, and you are doing that already.)" I am not suggesting that there is some "me" who is looking at my experience. "The experienced "I" is an aspect of a certain cohesive realm of experience." Nor am I suggesting that our experiences of the world are `likenesses' of the world: just the opposite! Certain aspects of our experiences of the world---namely those pertaining to spacetime form---are `like' (not the actual physical world itself, but rather) aspects of the (clearly false) classical image of the world, precisely because classical physics created this (basically false) classical image of the physical world out of certain generalizations of those particular (i.e., spacetime) aspects of `our experiences of the world', and essentially ignored all other kinds of experiences. You say: "You may fail to appreciate how much internal work is needed ....with our sense of the stable physical world. Our spatiotemporal experience is not nearly as 'directly' attached to nature as we feel it to be. (Many aspects of the design of instruments (mirrors behind pointers, vernier gauges) are devoted to overcoming these errors.) Our experience of position and shape is no more 'transparent' in its access to the world than our experience of color (or indeed of touch, scent or taste.)" True! So is it not foolish to tie our physical science to a conception of the physical world so biasedly based on this one aspect of our experience of the world, as if it is somehow sacred? You say: "If this really is the classical conception (which I doubt), then I agree that the classical conception is wrong. However, there is no need to turn to quantum mechanics, only to have a slightly more sophisticated notion of what constitutes an observation (one that is more in accord with the realities of science, and which I suspect Bohr might have endorsed.)" I do not think one can rationally deny the fact that the classical physics conception of physical reality is based on structures in space and time, and that this structure does not include among its properties any property that is identifiable with the *phenomenal* experience of, say, greenness. So the issue is not what counts as an observation (certainly experiencing green and experiencing location are similar in terms of phenomena, but the classical conception of nature does not treat these phenomena symmetrically), but which kinds of observations can be be regarded as experiencings of features of nature that, according to the *assumed* physical theory, are features of the physical reality. You say: "On the matter of 'seeing though' our experience to the outside, there is an important point (which goes well beyond our little quarrel!). Even if one concedes this distinction as being important, notice that it obviously must be modified if the 'forms' predicted by physics are in fact INSIDE the observer's own head, which is the case for subjective experience-reports. In this case the 'outside world' has become part of the observing system itself. This is not to endorse the idea that we can "see" into our own heads, of course; but it is the case that physical events there produce experiences which we can describe to others, just as external positions and forms reflect light which, hitting our eyes, produces experiences of the world which allow us to make reports. The cases seem quite parallel to me, and I see no reason to suppose (and every reason to deny) that the complete physical story determines my experiences in one case but not the other." Yes indeed! This is THE problem with the classical conception! The lopsided treatment that essentially ignores most experience. You say:(first quoting me) ">Although science can evolve in many ways, it remains physical, at least in my >definition, only insofar as the interface between theory and experiment >remains >Bohrian, with the `physical' in `technical physical interpretation' >meaning that the PRINCIPLED DISTINCTION between physical >and phenomenal described above be retained If you make this a matter of DEFINITION, as you here seem to, then this entire discussion is a complete waste of time, all your claims are vacuous tautologies, and none of your substantive conclusions have any content. I hope you don't really mean to make this claim." I want to separate from all of human knowledge a particular small part that I would like to call `classical physical science'. It should, at least in principle, be about those aspects of nature that can be conceived to be built up out of the PAFs of the complete classical physical description of nature, and to have no properties that are not at least in principle entailed by this complete classical physical description of nature taken together with the linkage into human experience provided by the precept that--- because the conceptualization of the physical world provided by classical physics is erected on our notions of spacetime form extracted from certain sense experiences---we can empirically experience spacetime forms that can be taken to be identifiable with spacetime aspects of the complete classical physical description: moreover these spacetime forms can, because of this identification and the precepts of the theory, be considered to belong to both the physical and phenomenal worlds. They can be linked into our other thoughts and theories, and in fact become associated with words and other symbols, so that something like a `leaf' can come to be defined through interactions of the community of communicating observers with the classically described world of which the observers and a plenum of spacetime forms are parts. Certain facts about the plenum of spacetime forms that constitute the physical world, in this classical conception, can by means of this interplay, be become known, articulated facts in the minds of the community of communicating observers. Classical physical science builds itself, according to this definition, always by this interplay between the world of physical and phenomenal facts through the mediation of these facts that can be conceived to belong to both. People can spin theories about aspects of the physical world that can be conceived to be defined in terms of the properties of the PAFs, and can test those theories by comparing how the spacetime forms entailed by the complete classical physical description matches against the spacetime forms empirically experienced. The linkage down to the level of PAFs needn't be explained in detail, but the higher-level properties should at least in principle be entailed by the PAF-level description. The bottom line is that because the classical model world is built exclusively upon idealizations and generalization of our sense experiences about spacetime structures it is only these special kinds of empirical experiences that can be conceived to be experiencings of the putative physical world itself. That constitutes a PRINCIPLED DIFFERENCE between these kinds of experiences and, for example, a phenomenal experience of greenness. This difference biases the whole picture in the way I have outlined above, and it prevents these latter sorts of empirical experiences from being entailed by the classical physical model in the way that empirical experiences of spacetime forms can. I hope this message will finally succeed. Best regards, Henry