Pat Hayes (28 Aug 13:41:34 -0500) has responded. His first point is that thermodynamics does not seem to be included in my definition of classical physics. Most physics curriculae have a course in statistical mechanics that derives the principles of thermodynamics from classical mechanics and plausible statistical assumptions about normally occurring physical systems. Thermodynamics is included in this sense. HPS[Previous Posting]: "But can one deduce from these laws and definitions whether or not the (angry) cloud feels like you feel when you feel angry? The answer is no!" PH[Aug 28]: "Of course: lacking a satisfactory physical account of what 'feeling anger' means, we cannot make a link to any kind of physics. But this doesnt argue that no such link could ever be possible, only that we have don't yet have it. (There may be other arguments why it is impossible, but this isn't one.) What we do have, however, as Aaron Sloman points out very elegantly, is plenty of examples of cases where complex properties which seem to have no satisfactory physical account can in fact, given enough ingenuity, be realised in devices which can be accounted for using classical physics." But the examples that Aaron gives are all similar in this basic feature: the complex properties are always completely expressible in terms of behaviours of systems, including tendencies of systems to behave in various ways. Now I certainly believe that, in actual fact, a person's behaviour is closely tied to what he is feeling, or experiencing, and that some appropriate kind of physics can provide a rationally coherent account of this connection. But the principles of classical mechanics give no toe-hold for passing from the behaviour of a system, no matter how complex this behaviour is, to what the system is feeling, or experiencing. One can postulate such a connection, or determine empirically the existence of such a connection. But even such behaviours as those that reveal that a chess-playing computer `understands' the rules of chess, and `knows' where on the board the `white king' is located, do not allow one to deduce, given the principles of classical mechanics, that this machine is having even the faintest glimmering of the experiences that we feel when we feel that we understand or know something. It is completely compatible with the principles of classical mechanics for the chess-playing machine to have absolutely no feelings or experiencings at all. Passing to machines of greater complexity does not change this absolute zero to nonzero: By "behaviour" I mean here that which can be expressed in terms of the concepts of classical physics. The point is that classical physics deals with things that can be built out of the basic elements of classical physics, namely the particles and local fields. Particles have the feature that they are completely described in terms of a description that can be regarded as a view from the outside: the description is a description of what a huge collection of tiny marbles would "look like" to an outside observer that was able to comprehend where each of these particles was located, and in fact its entire spacetime trajectory. And the fields are basically of the same kind: they describe what can be imagined to be a bunch of wavelike structures of the kind that we see when we look at the ocean from an oceanside cliff: we are looking at the the wave from a point outside the wave. Of course, the wave may have structures, and these structures may have substructures, but the entire mathematical structure provided by classical mechanics can be regarded as a description of a view-from-a-distance of a system of particles and waves. The actual reality of the situation may be that certain of these structures have an aspect that is akin to what a person that we are observing from a distance himself feels or experiences. And these feelings and experiencings might be in one-to-one correspondence with certain of the structures that the classical physics "view-from-the-outside" provides. But___ HPS[Previous post]: "There is no logical principle there (in the priciples of classical physics) that entails anything about what the actually experientially felt realities are." PH[Aug 28]: "Not by itself: but perhaps, given an adequate account of how consciousness can be physically realised, such a connnection could, in principle, be made." Pat is suggesting that "given an adequate account of how consciousness can be physically realized" the principles of classical mechanics could entail the existence of the experientially felt realities. But how does one arrive at such an `adequate account'? Does one: (1), postulate the sameness of certain classically describable activities and certain felt experiences, or (2), derive this connection from the principles of classical mechanics. Pat admits that one cannot derive this sameness from the principles of classical mechanics: he admits that option (2) is not open. But if option (2) is blocked and one must postulate the connection, rather than derive it, then one can, logically, deny this postulate. But then the existence of consciousness cannot actually be derived from the classical principles: consciousness *could be* absent without violating the dynamically complete classical principle, and hence consciousness *would be* epiphenomenal. Pat gives an explanation of how he seeks to evade this logical problem. He says: "Exactly the same observations apply to any complex thing. Nothing in physics enables us to infer the functional role of a leaf in the life of a tree; but once we have a proper account of leaves and photsynthesis (etc.), then physics *together with these* allows us, in principle, to infer what the leaf does from its physical description." It is certainly true that one cannot deduce from the principles of classical physics (without boundary conditions) exactly which physical structures will actually come into being. So one must put in some kind of boundary condition that specifies what the physical structures are, before the principles of classical mechanics can be applied. Similarly, one must have the appropriate physical structures, namely human brains, in place before one can try to consider, within the framework of classical physics, the experiences that human beings have. Only after a classical-physics representation of a brain is given can one consider how various functional features of our thought processes could be implemented in this classical-physics representation of a brain. Similarly, in the consideration of processing by computers one must eventually descend to the level of implementation in some particular machine before the principles of classical mechanics actually come directly into play. But which machines actually come into existence in not determined by the general principles of classical physics: boundary conditions are needed to fix that. It is certainly true that the principles of classical physics do not specify which systems actually exist in nature: some extra boundary-value-type information is needed to fix that. But all of that is beside the point. It is only after the particular physical system that is supposedly implementing some property is specified that the question arises as to the relationship of that physical system, as it is represented in the physical theory (i.e., classical mechanics), to various other things arises. If the classical-mechanics model of the physical system is adequate then it must account for the functional behaviour that is observed "from the outside". Let us suppose that it does so. Then we arrive at the question of what the system is experiencing or feeling. This brings us back to the logical problem: the fact that boundary conditions are needed to specify what the physical system is does not allow this logical problem to be evaded. Insofar as the property being implemented is a functional behaviour (i.e., something that is explanable in terms of the concepts of classical physics) then we seem to be exactly in the situation that I am referring to of not being able to deduce from the classical principles anything about how the system that is doing the implementing "feels": about what its experiences are, or are like. Going back to Pat's quotation, substituting now the actual situation at hand, we have: "Nothing in physics enables us to infer the functional role of consciousness in the life of a brain; but once we have a proper account of consciousness and brains, then physics *together with these* allows us, in principle, to infer what the consciousness does from its physical description." The significance of this assertion is not easy to ascertain, but it seems to be begging the question. I said: HPS[Previous Post]: " There is a logical disjunction between (1), the set of all assertions about physical behaviours that are strictly deducible from the mathematical laws of motion plus the mathematical definitions of physical properties (in terms of the basic physical quantities) and (2), the set of empirical facts about our experiences." Pat replied: PH[Aug 28] "This is a claim, but you have not given a shed of evidence for it or even an argument supporting it. In order to make a connection between your notion of 'classical' and this, you would need to demonstrate that awareness somehow goes beyond the local, continuous fields which classical physics discusses. But note that consciousness, as far as we know, is only realised in things containing about 10|46 atoms, which leaves a hell of a lot of room for complex behavior to emerge from local simplicity." The point is this: The classical-physics description is generally conceived by physicists to be a description from the outside: a description of what would be "seen" by an infinitely sharp-eyed external observer. This is at least a logically coherent possibility. From this point of view any behaviour of a brain, no matter how complex, is just what its mathematical description says it is: nothing more. It is a complex behaviour of particles and fields. The principles of classical mechanics, by themselves, entail nothing beyond this. You may consult any mathematician or physicist and he will not be able to claim that he could *prove*, on the basis of these principles alone, that there is a *feeling* or an *experience* associated with some complex activity of some system. This is because in order to prove such a thing one needs to have within the principles that are accepted some sort of criterion for the existence of a *feeling* or an *experience*, and the principles of classical mechanics contain no such criteria. One must not confuse what can be deduced from a set of mathematical postulates, and what the real actual world is like. It could be (if we ignore the conflicts with the empirical data) that the actual world is exactly like what some classical description says it is, and that certain behaviours of certain brains *are* the various experience that we feel. But the existence and nature of these latter *identities* are not derivable from the classical principles themselves. Some extra postulates would be needed to make the principles complete in the sense that one would be able to deduce from the principles whether a "pain in one's foot" is present or not. And since the original principles are consistent and dynamically complete without these extra postulates one could consider also a conceivable classical world completed with the postulate that there are no feelings or experiences (we are already disregarding the conflict with experience). In this sense our experiences are epiphenomenal: the description in terms of the basic classical variables would be not be changed if the actual world were one in which there were no experiences at all---i.e., one that conformed to the postulates of classical mechanics plus a postulate that there were no experienced feelings, rather than one that conformed to the postulates of classical mechanics plus a postulate that certain physical activities described in terms of the basic physical physical variables were accompanied by, or were the same as, certain felt experiences. Note that in deriving thermodymanics from classical mechanics one does need a statistical assumption that is essentially a boundary condition that specifies a class of normally occurring systems, but then the behaviours that characterize thermodynamics, in terms of relationships between readings on pressure gauges and thermometers, etc., are supposed to follow from the principles of classical mechanics (together with some quantum principles to account for behaviors of materials in thermometers, etc.). So this example does not allow one to draw a valid analogy between thermodynamic variables and felt experiences: that false analogy seems to have generated an enormous amount of invalid thinking on this issue. Henry P.Stapp