From: SMTP%"hpstapp@lbl.gov" 3-MAR-1997 03:26:28.07 To: STAPP CC: Subj: bridging principles---revised Message-ID: <331AB65A.387C@lbl.gov> Date: Mon, 03 Mar 1997 03:30:34 -0800 From: "Henry P. Stapp" X-Mailer: Mozilla 3.0 (Win95; I) MIME-Version: 1.0 To: hpstapp@lbl.gov CC: ghrosenb@phil.indiana.edu Subject: bridging principles---revised Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Dear Pat, I really do appreciate your taking the time to respond to my efforts. I cannot feel comfortable about my understanding of these matters if I cannot pin down the basis of my inability to communicate with you. Although I am sure neither of us wants to get sucked into another interminable dialog, still I would like to enlarge my comprehension by trying to respond to your points. About ‘deductive reduction’, I had also originally thought that it was equivalent to entailment, but expressed from the other end, i.e., from top down rather than bottom up. But then I thought I saw that Aaron meant something different here, namely the fact that e.g. a computer program does not reveal how it is to be implemented at the physical level, nor do the rules of chess say anything about their physical implementation. So these ‘architectures’ are somehow floating in another realm of reality: they are not bound into any particular implementation. But the ‘entailment’ that I am talking is another sort of connection: it IS ‘deductive implication’ , within some logical framework that must of course be specified. In the present context it refers to deductive implication from the description of some system in terms of the concepts of , say classical physical theory, to the facts about this system as they are represented or described within some other level or kind of description. My example was the way that facts of a meteorological description of the hurricane (e.g. pressures, temperature, wind velocities, humidities etc.) are entailed by the facts of the physical description, owning to the fact that the behaviors of the devices that measure the meteorological properties are entailed by the facts and principles of the physical description, at least in principle. And the underlying basis of this entailment is the fact that both descriptions are in terms of mathematically describable properties that can be assigned to smallish space-time regions, and the properties defined in somewhat larger regions are specified by the micro-physical properties. Regarding ‘possible worlds’ versus ‘formal systems’ in the context of the meaning of entailment it must be mentioned that the notion of ‘laws of nature’ enter into our idea and characterization of ‘possible worlds’, and the entailments can depend on what these laws are. The present discussion revolves around the distinction between the ‘true laws’, whatever they might be, and the putative laws of nature proposed in classical physical theory, and the deficiency that I claim for the latter for dealing with the connection between brains and the experiences associated with them. About my description of what I think is the orthodox classical viewpoint you exclaim: "This is physics?? If so then physics had better get its act together. Its not neuroscience or psychology, both of which assume that experiences have causal effects on the physical world". I agree completely that physics had better get its act together, in the sense that this orthodox classical conception is not the right kind of physics to serve as a foundation for psychology or neuroscience, if these disciplines want to examine the connection of brains to the experiences associated with them. Indeed, that is exactly the point that I have been making. I now have your reply to Gregg . At the end of you seem to make your position very clear: "Of course the physical facts do not entail the phenomenal facts without additional bridging laws. My point is only that it applies just as forcibly to *any* facts that are not couched in the particle-field language of physics." This seems to be the nub of the matter: you do not disagree with my claim (and that of many others, of course) that extra bridging principles are needed to make the jump to phenomena, but claim that what is needed here is not significantly different in kind from what is needed, analogously, in the non-phenomenal cases. I have never said that the needed bridging principles are "invalid", as you claimed. Indeed I have repeatedly said that introducing them is OK, and that this is what is normally done, but have emphasized that this would mean that the phenomenal facts are then not entailed by the physical ones (and the basic physical laws and principles), and that zombies are therefore logically possible within the framework of classical physical theory. I regard that as a defect of the classical theory: I think we should look for a physical theory in which thoughts are integral and causally effective. Thus the nub of our disagreement is that I claim that the "physical" sciences of e.g., meteorology, thermodynamics, stellar mechanics, astrophysics, biology, etc. do not need bridging principles of the kind needed for those sciences that try to deal with our experiences themselves as part of what is being studied! The subject matter of those other (i.e., physics-based) sciences are "physical" things in the sense that they are described within the mathematical portion of the theory in terms of physical properties that are defined in principle in terms of micro-physical properties. Of course, this mathematical description must be tied to other aspects of our experience. In particular, this mathematical part of the theory must be imbedded in a more general conceptual framework that allows us to ties it to those experiences that we call our experiences of the physical world, and which we believe are coming to us with the aid of our senses. I have described in some detail in our earlier correspondence how Einstein and Bohr agreed that the readings on measuring devices are the right place to make this connection because they are objective in the sense that all the people who are looking at them can agree about what the readings are, and the "bridging principle" that connects the direct experience of seeing a displayed number to the associated theoretical property is simply the demand that the spacetime form of the displayed symbol as experienced by the observer be congruent to the spacetime form of the displayed symbol as specified by the mathematical theory. I am trying to counter here your claim that I am just spouting out intuitive feelings or prejudices, by reminding you of the reasons I have put forth for claiming that there is *a huge difference in kind* between, on the one hand, the "bridging principles" that span the gigantic gap between descriptions of brain activity, as described within the framework of classical physical theory, and the descriptions of corresponding experiential realities, and, on the other hand, the analogous "bridging principle" needed for the `physical theories’: this latter "bridging principle" simply requires the congruency of a person’s experiential and theoretical descriptions of certain spacetime forms. Perhaps I can move this discussion forward by responding to your challenge to me, in your letter to Gregg, to show the big difference in the physical and phenomenal cases. Actually, I have just done this, essentially. But let me fill in some details. First, we must be clear about the distinctions between various aspects of our experiences that pertain to the notion of the ‘physical objects’ or ‘physical systems’ to which some of our experiences seem to refer. We might consider a biology class with fifteen students and a professor. The professor is lecturing about the anatomy of frogs and, according to the orthodox classical picture of nature, there are (if none of the students has doused off) sixteen evolving realms of experience, one for each person in the classroom. Then they go to the lab and find five frogs: each frog is dissected by three students. We should have no difficulty with the classical notion that there are five physical objects, the five frogs, that are the objects to which some of the experiences of the sixteen person’s refer. The organs of the frogs are removed and measured, and certain of the concepts that the students had formed in the lecture, for example that each normal frog has a brain, two eyes, a heart etc., become linked up to experiences derived from examining frogs: the immediate visual and tactile experiences that arise from examining the frogs and touching and seeing these organs become linked to the concepts that were formed in the experiential realms of the students while they were listening to the lecture. In another laboratory tissues are examined under a microscope, and pictures with calibration marks document the cellular structure of the organs. In another laboratory the properly trained and educated student exclaims: Look! The cell has divided! The classical conception of nature has evolved over the past 400 years with the participation of tens of thousands of scientists, some of whom have developed these microscopes, with their calibrations. In the realms of experience of these communicating scientists and technicians a conceptual picture of the things like frogs and microscopes etc. has evolved, with the aid of hints and checks provided by a hosts of interfaces between the evolving classical conception and experiences identified in that conception as experiences of various physical objects and systems such as these frogs and microscopes. This classical conceptual picture has developed to the point where all of those physical objects are conceived to belong to a physical world built out of particle and fields of various kinds, and the evolving state of this conglomerate of stuffs will, according to this conception, determine/entail what ‘symbols’ will experienced by, for example, the students who examine the calibrated photos of the frogs. The theoretical picture of the world will specify the presence or absence of developed grains of silver iodide on the calibrated photos. The locations these grains relative to the calibration marks on the photo as specified by the theory, on the one hand, and as experienced by the student, on the other, should agree: this congruency of the theoretical and observed symbols constitutes the bridge that ties the general conceptual/theoretical description of "what seems to out there" with our experiences coming via our senses. More general kinds of symbols are eventually allowed, but they are by nature just generalizations of displayed number/symbols, or the presence of observable physical irregularities at points labeled by symbols. As you yourself have emphasized, the encompassing theoretical/conceptual picture is one big web-like structure. It include concepts from engineering (the properties of the microscope, for example) and chemistry and biology etc. in one big unified package that is all required to hang together on the foundation provided by the highly constrained basic micro-physical theory, with its precise mathematical laws. The reason that the whole picture hangs together so well is that it is based, in effect, on a conceptual separation of our picture of nature into two parts: one part, the outer world, is conceptualized in terms of the idea of physical objects and systems, which are conceived to be built out of the basic micro-physical elements of classical physical theory, and this conceptualization is followed up to the calibrated photos; a second part that consists "our experiences", and these experiences include both the conceptualizations mentioned above, and some associated experiences, such as the visual and tactile experiences of the students in the lab, which are conceived to be caused by the physical objects and systems, and that provide us with some information about those objects and systems. One can try to push this boundary that plays a key role in the formation and structure of this classical conceptualization into the brain of the observer. This is not too difficult if one goes only up to the receptors, such as the retina, etc. But if one tries to push this boundary deep within the brain then the classical "bridging principle" no longer works, because there is no longer a *congruence* of the spacetime forms that the classical conceptualization provides with elements of our experiences. If one is experiencing the visually displayed number/symbol "8", then the brain activity---if one goes deep within the brain structures to the aspects of brain activity that corresponds to our experience of this "8"---seems to lose the congruency (even up to a scale change) to the spacetime form that we seem to experience; e.g. the two loops of equal size touching at one point. But, in any case, the real problems are with the more general kinds of experiences such as pains, anxieties, anger, or the concept of the architecture of a tower of computer programs. For such cases the connection between the experience itself and the spacetime configurations specified by the classical conceptualization of the corresponding brain state is not one of congruency. This lack of congruency in these cases where one is interested in the representations in someone’s brain of his experiences brings on the need for "bridging principles" that are highly non-trivial and depend on the detailed properties of brains. This makes these latter bridging principles *different in principle* from the simple congruency bridging principle that suffices for the physical sciences. I will not go here into the great superiority in this context of the quantum mechanical conception of nature over the classical one. But the main point is that in QM the connection between the geometrical and experiential aspects of nature lies at the dynamical heart of the theory, rather than being something that needs to be added on via a supra-physical "bridging principle". Best regards, Henry