[Note: Also a crude rough draft that eventually needs more refinement than this.]
When we say that scientific analysis of a given physical phenomena “explains” it, what is it that we mean? Let’s take the analysis of the behavior of “water” in terms of chemistry as a paradigmatic example. When we speak of the behavior of “water”, we have in mind such phenomena as the fact that an object of sufficient density placed on the surface of water, for example, will “sink.” Now, to give a scientific “explanation” of this phenomena is to say that molecules of H2O bond together quite loosely, so that when collections of molecules more tightly bound come into contact with it, these more tightly bound molecules are capable of slipping through the gaps of space between molecules of H2O. 
Now, how then are the properties of H2O to be explained? Once again, the behavior of H2O must be “explained” in terms of the structural properties of the composing entities one level down: in this case, atoms. And how are the properties of atoms to be explained? Once again, … you get the picture. Physical explanations work, in essence, by ‘zooming in’ on any given phenomena and going one level of reality ‘down’. Eventually, however, it stands to reason that we’re going to have to find the “rock bottom”—the unit which is, finally, indivisible into anything other than itself. For some time, we thought that these would be atoms—“atoms” were given the name, in fact, precisely because they were believed, at first, to be indivisible. However, we later discovered that they were divisible into the particles we call protons, neutrons, and electrons—and with the advent of quantum physics, we discovered that these were even further divisible into the categories of particles known as fermions (a category which includes quarks) and bosons. Currently, fermions and bosons are regarded as “elementary particles,” which means that we don’t know yet whether they represent “rock bottom” or are composed of any more basic particles or not—but for now, until we find something more basic, we can only assume that they are, in fact, rock bottom.
But suppose, as we investigated the properties of water, it had turned out that atoms themselves were simply the “rock bottom”—that atoms themselves had in fact been the ultimate, most indivisible thing in existence. Would that be ‘weird?’ Suppose it turned out that it was H2O. Would we feel like there was some mystery left over that we simply hadn’t, and couldn’t yet, explain about the world? How long would that continue to ‘bug us’ before we would give up and accept that H2O is ‘as far down as it goes?’ We can go even further with this thought experiment: what if it had turned out that the “rock bottom” thing was simply water itself? To say that water itself was the “rock bottom” thing underlying the behavior of water would simply be to say that no matter how much you try to divide water up, all you would get are still yet more units of water. Suppose that had been what we discovered. Would we be unsatisfied? Would we feel that something was fundamentally missing in our ability to use scientific investigation to understand the roots of the properties of water? I think it’s obvious that we would. We would be missing the only kind of “explanation” that science as we know it allows! We would just have to take the way water acts completely for granted, and there would be nothing else left for us to say about it to elucidate anything about “why” it behaves as it does. That would leave us in a particular kind of state of ignorance.
Yet the point we have to realize is that a world in which our ultimate “explanation” of the behavior of water simply did in fact have to stop with water itself is ultimately no different from the world we are in. The notion that the fact that water divides into units of something other than “water” (molecules), and that these units (molecules) divide into units of something other than “molecules” (atoms), and that these units (atoms) divide into units of something other than “atoms” (protons, neutrons, electrons)—and so forth—makes any of it less ultimately inexplicable is simply an illusion. We don’t understand the ultimate nature of our world any more than we would have if water itself had simply turned out to be the most indivisible thing composing “water”—and at least so far as scientific investigation can take us, we never will. Science can explain the relationship between the properties that a given physical entity has and the properties of the component entities that make that first entity up—but whatever the ultimate properties are, they can’t, by definition, be “explained” in this same way. And this is just as true whether the most basic entities are quarks, atoms, or even “water” itself. In the world where the most indivisible units of water turn out to be water, “Why does ‘water’ do what it does?’ remains a mystery. In the world where it turns out to be the case that water divides into more primitive units, which we call molecules, “Why does ‘water’ do what it does?” acquires an answer—but only at the expense of leaving us with the question, “Why do molecules do what they do?” which now remains every bit as unanswerable as the question “Why does ‘water’ do what it does?” was in the last world. And in the world where it turns out to be the case that molecules are divisible into more primitive units, which we call atoms, “Why do molecules do what they do?” acquires an answer—but only at the expense of leaving us with the question, “Why do atoms do what they do?” which now remains every bit as unanswerable as the question “Why do molecules do what they do?” was in the last world, and as “Why does ‘water’ do what it does?” was in the world before it.
The point here is much deeper than the mere fact that we can keep asking “why?” indefinitely. The point is that we naively assume that scientific explanation gets us further into “understanding” reality than it actually does. The ultimate situation we are in with regards to understanding reality in any of these scenarios ends up staying essentially exactly the same. If something turns out to be composed of divisible parts that have different properties from the composed whole, then we can “explain” how the properties of the pieces at the lower level necessarily result in the properties that we see at the higher level (e.g., we can learn that the properties of H2O molecules dispose them towards forming weak molecular bonds, and we can explain that these bonds necessarily result in a substance that things can “sink into” as groups of other molecule slip between these gaps even though nothing “sinks into” individual molecules of H2O). And we satisfy ourselves that this counts as some meaningful clarification of the nature of reality itself.
But what we fail to take account of is that if we postulate that all “explanation” must be of the properties of some whole in terms of the differing properties of some underlying compositional parts, then we eventually reach the “rock bottom” behind which there is no underlying compositional part—no matter what. And no matter when we reach this point, the situation is ultimately no different than it would have been had water itself simply been the thing that could not be divided into any more basic units than “water.” I expect that most of us generally feel that if we had been in the world in which “water” was not divisible into anything more basic than “water”—where these most basic parts were clear, wet, allowed other objects to “sink” into them, etc.—and looked, felt, and behaved exactly like the “water” we observe—so that the only thing left for “science” to do was to catalogue the behavioral properties of the same “water” anyone can see with his naked eye, and there was no room for “science” to clarify anything else—that this would be a world in which we “understood” less about the physical reality around us.
But why should the fact that water just so happens to divide into parts with different properties from water itself render our “understanding” of the nature of physical reality any deeper? We still can’t explain the behavior of those parts. If we think that what explanation consists of is reducing the terms of one event seen at one level of “zoom” into the underlying terms of another level, then eventually we reach the level that is supposed to be the one explaining all the rest—and once we get to that one, we‘re simply going to have no idea why it behaves the way that it does.
Scientific accounts can allow us to explain a in terms of b, and b in terms of c, and c in terms of d, … but once we get down to z, we have to stop there and take the behavior of z for granted and accept that z must necessarily remain absolutely unaccounted for. This is really not fundamentally any different from the situation in which a is explained in terms of b, and b in terms of c, and c in terms of d … but at d, we have to stop there and take the behavior of d for granted and accept that d must necessarily remain absolutely unaccounted for. And it isn’t really fundamentally any different from situation in which we simply have to take the behavior of a for granted and accept that a must necessarily remain absolutely unaccounted for. The only real differences between these scenarios are “How big are the most indivisible pieces of reality?”, or “How many times can we zoom in and find parts that individually have different properties from the thing we’re zooming in on?” But no matter how big the indivisible pieces are, and no matter how many times we can zoom in, the best answer “science” can give about the ultimate nature of physical reality is:
John R. Ross, in his 1967 Constraints on Variables in Syntax, tells a version of a story in which: “After a lecture on cosmology and the structure of the solar system, William James was accosted by a little old lady. “Your theory that the sun is the centre of the solar system, and the earth is a ball which rotates around it has a very convincing ring to it, Mr. James, but it’s wrong. I’ve got a better theory,” said the little old lady. “And what is that, madam?” Inquired James politely. “That we live on a crust of earth which is on the back of a giant turtle.” Not wishing to demolish this absurd little theory by bringing to bear the masses of scientific evidence he had at his command, James decided to gently dissuade his opponent by making her see some of the inadequacies of her position. “If your theory is correct, madam,” he asked, “what does this turtle stand on?” “You’re a very clever man, Mr. James, and that’s a very good question,” replied the little old lady, “but I have an answer to it. And it is this: The first turtle stands on the back of a second, far larger, turtle, who stands directly under him.” “But what does this second turtle stand on?” persisted James patiently. To this the little old lady crowed triumphantly. “It’s no use, Mr. James—it’s turtles all the way down.””
Scientific “explanation” of the nature of the physical world is “turtles all the way down”—right up until we suddenly reach the bottom turtle, and find that this one—the one on which all of the others are resting—is simply floating in mid–air, bearing the weight of all the others with the help and support of nothing. This is, quite plainly, no less mysterious than the case in which the only thing we ever had to begin with was a single levitating turtle. In fact, finding more turtles resting on that bottom turtle doesn’t make the question of the levitating turtle less mysterious—it makes it more so, because it not only keeps the question of how the turtle is levitating intact, it adds the question of how all these other turtles could be resting on a levitating turtle with nothing holding up the whole lot of them..
Now, the philosophical position I’ve been striving to give comprehensive defense to throughout this series has been that consciousness—the first–person subjective stream of qualitative experience and intentionalistic thought which we all experience the world exclusively in and through—can neither be eliminated, nor called “identical to” anything other than itself, nor “built into” the physical world along the lines of panpsychism, nor considered causally “epiphenomenal” with respect to the external world. This process of elimination entails that consciousness is therefore both something as fundamentally different from other physical phenomena as gravitational forces are from strong nuclear forces, and yet something which nonetheless somehow causally interacts with at least some of those other forces.
In physics, gravity and the strong nuclear force are called “fundamental forces” because they appear not to be reducible either to each other or to any other more basic kinds of force. In other words, when we come to these four kinds of forces, we have to accept that this is simply the point where we must be resigned to say: “shit do what it do”—because there is simply in principle nothing else that can be said. And as we saw above, even if two or more of these kinds of force are reducible to something else, then this can only be in terms of some other kind of force which will now have to be the “basic” one which we cannot in principle provide any account of, beyond simply cataloging what it does and then taking this catalog for granted as a primitive observation about how the world operates. In other words, no matter what the details are, at least something has to be “basic” in the sense that it is both irreducible and ultimately inexplicable (because there is nothing more basic which it can be explained in terms of—that is, “reduced to”).
Furthermore, given our current state of knowledge, we think that there are at least three or four such “basic” kinds of irreducible forces operating in the world. Even if this state of knowledge should eventually be overturned, and all four of these forces united into description in terms of some other singular underlying force, this still suffices to show that it is not inconceivable that there should be more than one “basic” kind of irreducible force, which are different in fundamental ways and yet still causally interact with each other within the same singular universe.
Now, the “interaction problem”—the question of how a “nonphysical” mind could interact with a “physical” world—is often taken to be the most disastrous, fatal problem for this kind of position. There are more subtle and complicated forms of the “interaction problem” which I may discuss later, but in its most basic form the “interaction problem” aims to reject dualism by simply expressing incredulity that things that seem to be defined by such different kinds of properties could possibly interact with each other, in principle.
Part of the problem here is simply linguistic: when we discovered that electromagnetic forces were not reducible into terms of atomic interactions, but instead a whole new fundamental category of kinds of things in the world all their own right alongside atomic forces themselves, up to that point in history our definition of what it meant to be “physical” was encompassed by the properties we had noted by observing interactions between atomic particles. When we included electromagnetism into our account, however, we didn’t call electromagnetic forces “nonphysical”—even though it is plain to see that there is in fact a sense of the word “physical” in which electromagnetic forces are “nonphysical!”—rather, we expanded our definition of what it means for a thing to be “physical.” Why shouldn’t we do something similar here? The very word “dualism” itself reinforces the notion that this is off–limits, of course, suggesting as it does a “du–ality”—an etymological root which implies a specifically two–fold distinction—between “things” which are “physical” and “things” which are “non–physical.” But why think of this in terms of “du–ality?” Why not think of it in terms of plurality? In other words, why not think of it as the phenomena of consciousness and consciousness’ capacity to interact with other parts of the world standing right alongside the phenomena of gravity and gravitational forces, right along side atoms and strong and weak nuclear forces, and so on, all as equally irreducible categories of ‘kinds of things the world turns out to contain’ in their own right? Why not think of a multitude of phenomena existing and interacting within the world, each containing different fundamental properties, some overlapping and some not?
The problem with providing a clear definition of what it means for a thing to be “physical” without creating a straw notion of physicalism is often taken as a hurdle against attempts to refute the philosophical position of physicalism—but it is just as much a hurdle against attempts to establish it as a true position over and against alternative positions which could reasonably be called “dualistic”: a definition of physical must suffice to rule out the possibility of dualism turning out to be true in a non–question begging way every bit as much as it must suffice to rule out the possibility of physicalism turning out to be true, and physicalists rarely if ever perform better at this task than dualists. If the physicalist asks the dualist how to define “the physical” such that consciousness couldn’t be a “physical” process without begging the question, then the dualist has every right to turn exactly the same question around and ask the physicalist how to define “physical” such that irreducible consciousness couldn’t possibly qualify as “physical” and therefore be allowed to exist, in the way that the dualist believes that it does, without begging the question.
But it should be clear to see, in any case, how thinking of the phenomena of consciousness in this way renders the “problem” posed by standard forms of the “interaction problem” moot. When it comes to any “basic” irreducible force or phenomena in the world, the question of “how” it does what it does is always, in principle, necessarily mysterious. How does the gravitational force cause objects to gravitate towards large bodies in space? If your answer is that large bodies in space create curvature in the fabric of spacetime, then the question simply becomes: How does a large body in space cause the fabric of spacetime to curve? Again, the point is not merely that we can keep asking “Why?” forever. The point is that there necessarily must be some actual point at which the only question left to ask literally has no conceivable answer other than “that’s just how we observe that phenomena in the world behave”—at which point the Why–asking must stop because it cannot, in principle receive an answer—and the only open empirical question left is just simply, “When have we reached that point?”—“Is this the inexplicable rock bottom, or does rock bottom lie somewhere further?” And we reach this point necessarily any time we talk about the most basic actions and behaviors and properties of the most basic kinds of forces and entities in the world—whatever they may turn out to be.
In other words, the kind of account which the physicalist demands the dualist give to justify the claim that interaction between consciousness and the physical world could occur is one that no one can give for any phenomena in the world whatsoever—yet, if consciousness is indeed itself just such a “basic” phenomena, this is exactly the situation that should be expected. As James Moreland writes, “One can ask how turning the key starts a car because there is an intermediate electrical system between the key and the car’s running engine that is the means by which turning the key causes the engine to start. The “how” question is a request to describe that intermediate mechanism. But the interaction between [consciousness] and [the brain] may be … direct and immediate. [And if] there is no intervening mechanism, [then] a “how” question describing that mechanism does not even arise.”
The problem with this “intuitive” version of the “interaction problem,” I think, quite simply results from the fact that we can’t take a third–person view on someone else’s consciousness and visualize their subjective intentions playing a causal role in their ensuing physical behavior, in the way that we can at least visualize one billiard ball bouncing into another from the third–person point of view. Yet, I think Descartes himself adequately addressed this version of the problem all the way back in 1912: “At no place do you bring an objection to my arguments; you only set forth the doubts which you think follow from my conclusions, though they arise merely from your wishing to subject to the scrutiny of the imagination matters which, by their own nature, do not fall under it.” In other words, we can’t visualize conscious streams of experience existing in any way from the third–person point of view. And the key issue underlying this fact is one that is universal to all positions in philosophy of mind whatsoever—it is, in fact, exactly what makes consciousness seem mysterious in general, no matter what metaphysical view we take towards its ultimate nature: namely, physical properties as such and conscious experiences as such seem wildly unrelated no matter what “theory” we suppose for understanding their relationship.
If the world, at root, is a causally closed process of physical properties following patterns of inert cause and effect on other physical properties, then why the hell should experiences even squirt out of that epiphenomenally? How the hell does anyone ever get the idea in their heads that that in any way doesn’t face an “interaction problem?” It just postulates that the interaction goes in a single direction: from the physical to the experiential. But either interactions between the physical and the experiential can happen, or they can’t. If they can’t, then epiphenomenalism is ruled out as a conceivably true option every bit as much as dualism. And if they can, then there is no reason in principle why dualism couldn’t be true. So anyone who thinks it is even conceivable that epiphenomenalism could be true—and many physicalists are willing to grant that it could be, as a last resort—has no valid recourse to this “intuitive” version of the “interaction problem.” Whether we can only walk across it from left–to–right or we can walk in either direction we choose, a bridge is a bridge. And if we can walk across a bridge from left–to–right, then there can’t be any reason in principle why we couldn’t conceivably walk across it from right–to–left. It’s as if the physicalist who considers the possibility that epiphenomenalism might be true is an atheist who finally goes so far as to say, “Alright, God exists. But God can look into our world from His—we can’t ever travel over to His, in principle! So there still can’t possibly be a Heaven or a Hell!” Would anyone ever consider calling this “Atheism, Or Something Near Enough?” Wouldn’t we think it was demonstrating something about the inherent weakness of atheism itself if atheists were, in any significant numbers, finding themselves compelled to retreat to this kind of position?
What we’re actually dealing with here is simple bafflement upon trying to imagine the two phenomena interacting. But is the idea of your subjective experience of the qualitative taste of a strawberry in and of itself playing a causal role in your later description of what the strawberry tasted like any more difficult or bizarre to imagine than the idea of a series of blind physical particles moving in space literally composing a subjective experience of the qualitative taste of a strawberry? I don’t think so. The intuitive weirdness of interaction can’t be any reason to weigh the scales against dualism if every picture of how consciousness and the physical relate we could possibly imagine is overwhelmingly weird to intuition. We especially can’t do so if we arrived at the hypothesis of dualism by a process of elimination composed of a series of arguments in which we found deductive reasons to reject alternative attempts—which is how I do it. (So even if my reasoning in those steps turns out to be flawed at some point, those are the steps around which the whole issue pivots—and the “interaction problem” simply contributes nothing new that is important to the question.)
When I observe the properties of gravity, I take it for granted as a brute fact that a given equation describes the relationship between the mass of an object and the gravitational force it exerts—and how gravity causes an object to move remains inexplicable in principle. If I later discover that this works by objects influencing the curvature of space in proportion to their mass, then I take it for granted as a brute fact that an object of a given mass influences the curvature of space in a given degree—how an object of a given mass causes space to curve remains inexplicable in principle. It is, again, not simply that we can keep asking “Why?” indefinitely and eventually have to stop simply in order to move on to doing something with our knowledge—it is that knowledge itself necessarily reaches a brute stopping point in principle as soon as it arrives at the most basic behaviors and properties of the most basic entities that there are, and it simply remains an empirical detail to be fleshed out what these are.
Supposing I suggest that the first–person subjective phenomena of consciousness itself is one of them, and supposing I suggest that it is a brute fact about consciousness that it possesses the property of intentionality—of being intrinsically “reflective of” or capable of “representing to itself” or “directing itself towards” an external world—and that as one of the “basic” actions of consciousness, subjectively created and experienced intentions can influence my objective physical behavior—then so long as I do not try to visualize this in terms that would only be appropriate for mechanical interactions between blind physical particles in the first place, there is simply no real conceptual problem here—the fact that intentions influence behavior should be treated as a basic data of first–person awareness in just exactly the same way that the mass of a physical object creates gravitational forces by influencing the curvature of the surrounding space should, and I no more need “an account” of how the former happens in order to be fully justified in believing that it does than I do in the case of the latter.
And herein lies one significant dialectic difference between interactionism and “identity theories,” etc.: the fact that there is a relationship between physical states and experiences—from the looks of things, in both directions—is a direct datum of experience. The claim that the physical brain composed of parts which are non–qualitative, non–experiential, and non–intentionalistic generates or is identical to consciousness itself (qualitative experience and intentionalistic thought) is not. So first, we do not have the same prima facie justification for believing that the production of consciousness by the brain happens (or that consciousness is “identical to” the physical brain) that we have for the fact of interaction in the first place. But second, the physicalist does not have the option of making these “brute fact” posits in the same way that the dualist does—the very definition of the physicalist claim is that the physicalist himself rules this option out: quite simply, consciousness is not a “basic” entity within the physicalist’s scheme—and it therefore cannot be said to possess “basic” properties. So the physicalist actually holds a burden of “explaining” the appearance of consciousness in a way that the dualist does not—because according to physicalism, consciousness is a secondary, derivative phenomena—which therefore according to the physicalist scheme itself must in fact have an explanation in some other terms—hence the Hard Problem. Thus, there is simply no special burden on the dualist to provide an account of interaction—just as there is no special burden on someone who proposes that gravitational forces are the curvature of spacetime to explain how an object’s mass ‘causes’ spacetime to curve. There is a burden to motivate dualism—just as there is a burden to motivate the claim that gravity does in fact work by causing curvatures in the fabric of spacetime—and I think that this burden can be met (as it can for gravity).
Notice that this is exactly why the gravitational force itself is currently considered to be a “basic” fundamental force in the universe, and why science places the burden squarely on whomever wants to propose a “theory of everything” that reduces gravity to some other more basic force: the claim that gravity is reducible needs to be demonstrated before we can be justified to believe it. And until then, there is simply no a priori reason to suppose that it has to be—no a priori reason that gravity can’t just be the “basic” phenomena itself—so we can’t assume that a “theory of everything” will necessarily succeed until someone actually spells out the details of how the forces we know and currently consider fundamental reduce to some other. This is the most reasonable way to think—yet it is a rule that we violate flagrantly when it comes to consciousness, usually with appeals to some notion of “parsimony.” But—rightly—no one reasons in the same way when it comes to gravity. No one says that it is more “parsimonious” to assume that a “theory of everything” that reduces gravitational forces to some other more basic force must be true. Certainly, no one does so even because the notion of discrete matter interacting with space interacting with time is too weird to accept. The burden is squarely upon the “reductionist” to actually perform the work of demonstrating how gravity “reduces.” And until then, we rightly assume that it doesn’t (pending further notice of an actual proof of how it does.)
When the physicalist supposes that consciousness is not in fact a basic phenomena, and instead of being analogous to the brute existence of the gravity as a basic, fundamental force is instead analogous to the behavioral properties of water, which exist solely in virtue of the very different behavioral properties of molecules of H2O (which water could be described equally as either “identical with,” “emergent from,” or “reducing to”), thus does in fact create a burden of providing an explanation of “how” consciousness appears in the course of this process—because the physicalist himself is the one making the supposition that consciousness appears through some intermediary process. The mechanism of its appearance must therefore be explained—because the physicalist himself, if he is not an outright eliminativist (or panpsychist), is the one supposing that there is a mechanism mediating the process whereby ingredients which are not conscious go through some process to somehow become conscious which should, therefore, be explicable. Immediately, it is not clear how these unspecified mechanisms (which somehow produce something radically unlike themselves in kind, per any definition of the physical and the experiential besides that of the panpsychist who supposes that consciousness utterly pervades the physical world or that of the eliminativist who supposes that no one actually has any subjective experiences or intrinsically intentional states at all) are supposed to be more “parsimonious” than the posit that consciousness itself is simply fundamental—just as it is clear that a “theory of everything” is not a priori more “parsimonious” than the posit that gravity itself is simply fundamental. Especially so when we have no idea what the supposed mechanisms are, how they work, or how they could even conceivably relate the terms of items so radically different (per everyone but the panpsychist or the eliminatist’s definition).
But this opens up an even further, an even stronger argumentative possibility that does not exist against the posit that consciousness itself is a “basic” phenomena in the world: namely, that we might pose a successful argument to defeat the claim that such a mechanism could ever in principle succeed to do what is claimed for it, for all the reasons summarized here and explained in more detail in essays (IV)—(VII) of this series—in short, because if the physicalist posits that all that the world contains at root is mechanism, then this supposition is incapable in principle of predicting anything other than further mechanisms—and a description of the qualitative nature of subjective experience and the intentionalistic nature of conscious thought simply can’t be built up to through descriptions of the mechanisms that happen to accompany experience and thought (a summary this brief can’t come anywhere close to doing the argument justice), any more than there is some special way of drawing lines on a flat two–dimensional canvas that can build up to a fully–fleshed three–dimensional object. In just the same way that the very nature of a three–dimensional object includes a category—the third dimension—that can’t be “reached” in principle through the two dimensions provided by the canvas’ surface, so consciousness includes categories (subjectivity and intentionality) that can’t be “reached” in principle through the mechanisms provided by the physicalist’s ‘objective’ blind mechanical processes. But comparatively, there is no reason in principle why interaction between consciousness and the physical world cannot occur—the question asks something that commits a category error within the very question, essentially similar to asking how an object’s velocity at one moment causes it to keep moving through space in the next moment—and draws its intuitive force simply by asking us to imagine interaction in an inappropriate way: from the third–person perspective, which is exactly where the dualist suggests that consciousness cannot be seen in the first place.
Relocating the act of imagining to the first person perspective, there is no intuitive problem: I set an intention to move my hands, and they move. This is just as direct a piece of data in my immediate awareness as any data about any external phenomena like gravity could ever possibly be. Justifying the claim that conscious experiences and physical particles are “identical” would take a lot more than simply insisting that we can’t visualize that sort of interaction taking place from the third–person stance—when the whole core of the dualist insight to begin with is precisely to see that the entire phenomena of consciousness can’t be found “from the third–person stance” in the first place. If the inability to visualize a process is enough to defeat a position in philosophy of mind, then my arguments against physicalist views become even stronger, because so far as it is they’re based on positive arguments that we can’t visualize mind–brain “identity” because the claim is incoherent for principled reasons. If all it takes for a successful argument is difficulty with visualization, then these other arguments go well beyond the burden required of them, and physicalist views would be all the more disqualified at exactly the same time by the same stroke.
The second part of this post will discuss a refined version of the argument against the possibility of interaction which presents a much greater threat—and indeed, may be the one and only real empirical threat that dualism has ever actually faced. In his discussion of his view of the problem interactionism poses, Dennett devotes just two sentences to this aspect of it, though I consider it by far the most significant: “A fundamental principle of physics is that any change in the trajectory of any physical entity is an acceleration requiring the expenditure of energy, and where is this energy to come from? It is this principle of the conservation of energy that accounts for the physical impossibility of “perpetual motion machines,” and the same principle is apparently violated by dualism.” This line of argument actually attempts to take specific principles which seem well justified by our scientific observations of the world and argue that interactionism seems to require that we haphazardly violate them. A premise like this could actually provide well motivated grounds for offering specific empirical reasons why a “naturalistic” approach to understanding the nature of human consciousness and the relationship between the “mind” and the brain cannot be “dualistic” which go beyond mere verbal sleight–of–hand through question–begging definitions of terms like “natural” and “physical.”
We’ll see in a future post how this much more troubling version of the argument fares.
_______ ~.::[༒]::.~ _______
 This is a simplified example, since only one illustration is needed for the purpose of demonstrating the underlying point we’re discussing here.
 See here for an overview of scientific attempts to achieve this. There is no currently plausible grand unified theory—grand unified theories attempt to unite electromagnetic with strong and weak nuclear forces, while leaving out gravity—the goal of a “theory of everything” which incorporates gravity into the analysis presently seems even more implausible to achieve. It may eventually happen; but again, there is simply no a priori reason to assume that it necessarily must.
 The materialist–turned–epiphenomenalist Jaegwon Kim’s book is titled “Physicalism, Or Something Near Enough.”