Accepted in Russia

I found out yesterday that my book Philosophical Provocations was chosen for discussion at the Center for Cosnciousness Studies at Moscow State University. I can’t imagine that happening today in America. So Russia is more rational and academically free than America. Isn’t this downright embarrassing?

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Analysis of Matter

 

Analysis of Matter

 

 

What is the general nature of concepts of matter? How are such concepts to be analyzed? Is there a general nature or only a plurality of concept-types? Ryle wrote a book called The Concept of Mind(note the uniqueness implied by “the”), arguing that mental concepts are generally dispositional in form; what would a book called The Concept of Mattercontain? I will begin to answer this question by considering the concept of motion (someone could write a book with this title too), a concept vital to physics. So I am concerned with the analysis of matter-in-motion: how do we conceive of matter-in-motion, and how should we conceive of it? What is the “logical structure” of this concept? This question is not to be distinguished from the question of what motion is—or what it is for a material object to move. What is the logical form (conceptual analysis) of, say, “The earth moves”?

Immediately we are confronted by a difficulty, because there is controversy about the nature of motion. Some say it is absolute and some say it is relative (I say it is both, but we will get to that). We don’t need to settle the question for present purposes, since we can consider my question under either assumption. So suppose it is relative: motion only makes sense against the background of a plurality of objects, consisting in relative change of position. Then we can say that motion statements are relational in form: roughly, “the earth moves” means “the earth changes position relative to some object x”. The object in question may be indefinitely distant from the object said to move, so motion is not a local property of an object (the motion of the earth is usually referred to the sun). This is not apparent on the face of the statement we are analyzing, but that is not generally any objection to an analysis. We say, then, that the predicate “x moves” means “xmoves relative to y”. I shall say that the concept of motion is an object-introducingconcept, meaning that it refers us to an object not initially supposed essential: it is as if we can’t speak of xmoving unless we are first introduced to another object y. We can’t speak of motion in isolation but only in the context of a system of objects. Motion is essentially relational. To put it differently: motion is notlocally supervenient; it depends on what is going on in the environmentof the object in question. It is not internalto the object that is said to move. It is not an individualisticproperty. We need to be externalistsabout motion, recognizing that motion only occurs in a certain context—it is object-dependentor object-involving. The moving object is only so in virtue of being embeddedin world in which other objects exist that confer motion on it. The state of motion of one object incorporatesthe state of motion of other objects.

I have put the point in these ways because I want to explore an analogy between motion and mental content. According to a dominant tradition, motion was conceived as an inherent property of an object, intrinsic and internal. An object could be in motion even though no other object existed. But a counter-movement arose that questioned this idea: motion is something that essentially involves other objects, even remote ones. Similarly, there was a tradition that located mental content within the subject, so that what you mean or think is independent of anything in your environment: it is a matter of your brain or your inner subjective state. But a counter-movement arose that questioned this idea: content is something that essentially involves other objects, even remote ones. Thus we are treated to twin earth cases and other ways of demonstrating the object-dependence of mental content. The environment fixes content—as it fixes motion. Externalism about meaning and motion became received wisdom. And these doctrines were intended to capture the actual character of our concepts, which had previously been misunderstood. As the slogan goes, “meanings are not in the head”; and neither is motion “in the object”—it’s in the relation betweenobjects. In my terms, the concepts of meaning and motion are object-introducing concepts. That is their logical structure—what they logically imply. Thus all the characterizations that are applied to the mind can be carried over to matter-in-motion: externalism, anti-individualism, non-locality, non-supervenience, relationalism, environmental determination, object-dependence, etc. We thought that motion was internal to objects, part of their inner nature; but now we see that motion lies in the connection between one object and another, a matter of their external relations. The concept of motion is therefore a concept with an internal complexity that extends beyond its initial appearance—dyadic not monadic, two-factor not one-factor. Note, particularly, that it characterizes a fact that extends across space to possibly remote objects, and indeed brings in every object in the universe. It is not just a property of an isolated object doing its thing locally, sublimely unconcerned about everything else. It isn’t like shape or mass or atomic structure. It is more like size or length or being up or down: things have these attributes only relative to other things not intrinsically.

One might think that the relational analysis only works if we accept relative motion not absolute motion. But that is not quite right, because so-called absolute motion is not really absolute: it is motion relative to space, conceived as eternally static and at rest. As Newton understood it, the motion of a body occurs against the background of an unmoving spatial manifold: space stays where it is while objects pass through it. So all motion is relative to something, though not to other material bodies. This something, however, is highly local, being either contiguous with the moving body or pervading its volume. So motion is relative but local on this conception: moving throughan enveloping space. And what it is relative to is of a different nature from the moving body itself—space not being a kind of matter. So the concept of motion relates the moving object to a surrounding entity—viz. space—relative to which it moves; it is still a relational entity-introducing concept (I say “entity” not “object” because space is not a material object in the style of the relative theory of motion). Logically, then, the two views are not that far apart, despite the difference of ontology. A truly internalist view of motion would suppose that motion is entirely intrinsic to the object, not even relative to space. Thus this kind of absolutist would insist that even if the surrounding space did not move relative to the object the object might still be moving: for both the object and surrounding space might bothbe moving! Only if we suppose space to be necessarily at rest can this possibility be ruled out, but even then the following counterfactual might be true: “Ifspace were to move along with an object, that object would still be moving”. That is, the concept of motion allows for the conceivability of motion without change of relative position with respect to space. This makes motion super-intrinsic—independent even of space (as presumably shape is: things are not triangular relative to their surrounding space).

Here our analogy proves helpful. Consider a super-internalist who holds not merely that mental content is independent of the environment but also is independent of the subject’s brain and inner subjective state. This internalist holds that content is completely intrinsic to concepts themselves and is not dependent on anything outside of it—not the brain and not the subject’s subjective experiences. He might maintain that the mind is not the brain but an immaterial substance, and that we could vary a person’s subjective state and keep his concepts constant. For example, we could vary his senses and their phenomenology while not changing what he thinks and means: his concepts are not supervenient on his brain states or sensory states. They are supervenient on nothing but themselves (and possibly the immaterial substance). The usual kind of internalism supposes that the independence concerns only the external environment, but this extreme kind of internalism takes concepts to be independent even of states internal to the subject (not including concepts themselves). Thus we have externalism, internalism, and super-internalism (“intrinsicalism”); and similarly we have three views of motion—relativity to remote objects, relativity to space, and relativity to nothing save itself. That last view may not be plausible—it may not even be coherent—but it exists as an option that someone might adopt. After all, geometric properties are not defined relative to space: a circle is not circular only in relation to non-circular space, whatever that may mean. In any case, the two leading contenders for the nature of motion both regard it as fundamentally relational—much as mental content is regarded as fundamentally relational. Reflection in both cases has persuaded us that a superficially monadic concept is really a dyadic one. In the case of the relative theory of motion the extra object can be remote from the given object, while in the case of the absolute theory (so-called) it is as proximate as could be. The absolute theory should not be saddled with the idea of completely non-relative motion, which makes dubious sense; instead it is a question of whichentity motion is relative to and where that entity is located. The absolutist might say, “Of coursemotion is relative, only not to remote objects but to surrounding space!”

But which theory is true? I will not attempt to adjudicate that question; I will merely note that both could be. That there is such a thing as change of relative position there can be no doubt, and if we choose to call that motion (not unreasonably), then relative motion exists. But it doesn’t follow that no otherkind of motion exists: maybe there is absolute motion as well. Objects could move relative to each other andrelative to space. If I say to you, “Don’t move till I get back!” I don’t intend to blame you for your motion as the earth moves; I mean relative to the room you are in. But I can also talk about motion with respect to space and mean precisely that (rightly or wrongly—rightly in my view). Thus we have two concepts of motion that coexist in our conceptual scheme, and hence two types of conceptual analysis.[1]They vary in their ontology but they are similar in logical form. Accordingly, we recognize two types of property when we use motion words, so we conceive of matter in two different ways: bits of matter change relative positions, but they also change their relation to space—they are capable of doing both. It follows that our concepts of motion have different analyses. This is analogous to the claim that we have two concepts of content, wide content and narrow content, which can coexist. Both are legitimate and useful, though they are differently defined and serve different purposes.

Do all concepts of matter fit this pattern? I have already suggested that concepts of shape or configuration don’t: here there is no submerged relationality, whether remote or proximal–internalism rules. Geometric concepts are not covertly object-introducing; they are self-enclosed and just as they appear. I think the same thing is true of the concepts of mass and charge: these are not defined relative to some environmental variable—we would not be right to be externalists about these properties. They look like dispositional concepts, and as such refer to interactions with other things; but the same thing is true of all dispositional concepts, mental or physical. No one is surprised by this kind of relationality; by contrast, it comes as something of a revelation to discover that motion is relative (it is somewhat similar with size and length). Motion is a bit like color in this respect: we start off thinking color is intrinsic to objects and then are surprised to find that it depends on relations to perceivers. Whether a given object is red depends on whether otherdistant objects (i.e. perceivers) see it as red; color isn’t written into the object considered in itself. So it seems that we have three types of physical concept in our repertoire: intrinsic (shape), dispositional (mass and charge), and object-introducing (motion and size). There is not a single homogeneous type; physics is made up of three distinct concept-types with three different kinds of analysis. It would be pleasant to report that psychology is likewise made up of three such types, and arguably it is[2]; in any case, conceptual heterogeneity holds in the case of the science of matter. This is a result in the conceptual science of science.

 

Colin McGinn

[1]Imagine a possible world stipulated to contain both sorts of motion: it contains an absolute space with respect to which objects move, as well as the more humdrum kind of relative motion. Then inhabitants of that world would needtwo concepts to cover the facts. It seems to me that in our world we have two sorts of concern to which talk of motion answers—practical and theoretical, to put it briefly—so we naturally employ two concepts. The case is somewhat like the concepts of weight and mass. Put tendentiously, one kind of motion might be designated realand the other apparent.

[2]There are mental states with content like beliefs and desires, which are object-introducing; there are mental traits like irascibility and generosity, which are dispositional; and there are occurrences like being in pain or feeling moody that are non-relational and non-dispositional.

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Analysis of Mind

 

 

 

Forms of Analysis

 

 

Since Plato inaugurated conceptual analysis a certain pattern has recurred. His first stab at an analysis of knowledge broke it down into two parts: truth and belief. To know something you had to believe it and it had to be true. Neither element alone was sufficient (though both were necessary) but the conjunction of them added up to knowledge. We have a kind of conceptual equation: xplus yequals z. But then he noticed that this simple combination wasn’t enough for knowledge; it needed an extra ingredient. For it is possible to have true beliefs that aren’t knowledge, as when you accidentally hit on the truth. So he added a further element: justification. Now knowledge is a triadic concept: xplus yplus jequals z. The sufficiency of this was in turn questioned, but let us stop here for the moment. We could say that Plato discovered that truth and belief had to be coordinatedin some way in order to add up to knowledge: you have to believe the truth justifiably(rationally, non-accidentally, for adequate reasons, reliably, etc.). Truth and belief had to be suitably connectednot just exist side by side—you must have the belief becauseof the truth in order to have knowledge. Instead of belief andtruth, we need belief becausetruth. Knowledge breaks into two parts, but the parts don’t just sit there separately; they meld in some way. Knowledge is the kind of belief that resultsfrom truth. Thus a structure emerged: the concept breaks into two basic parts joined in a certain way, where this way features as an extra ingredient added to the basic ones. Knowledge is not a simple thing, but it is not a serial thing either; it is a composite thing—parts coordinated.

This structure is not confined to knowledge. What is perception? It consists of two parts: experience and object. In order to see an object you have to have an experience (a “sense-datum”) andthe experience must be veridical, i.e. there is a suitable object answering to it. You seem to see a table and there is a real table in front of you: neither is sufficient for seeing but if you combine them the upshot is seeing. There are two sides to seeing, as there are two sides to knowing–an internal side and an external side, a subjective side and an objective side. Seeing is a two-factor state, as we can see from conceptually analyzing it. But on further examination we see that seeing must be more than that, because these two conditions are not sufficient for seeing: there needs to be some connectionbetween experience and object; they can’t just be accidentally joined, as when you hallucinate a table but there happens to be a table just where you seem to see one. Thus it becomes natural to require that the two elements be causally connected: the object has to cause the experience. Again, this triadic analysis itself runs into problems of sufficiency, but let’s not be detained by that: what we must note is that perception breaks into two parts and the parts must be properly coordinated. Perception is experience becauseof object. There is an internal side and an external side, along with a relation of dependence. The form is: xbecause of yequals z. This is beginning to sound like a kind of lawof conceptual analysis—a recurrent pattern. And further inquiry confirms that diagnosis: for the same thing is true of memory. To remember a past event is to have both a memory impression and for the past to be a certain way: neither alone is sufficient for remembering but together we get memory. Mind and world supply the necessary ingredients–internal and external, subjective and objective. But again, the two elements cannot merely be conjoined, since you don’t remember something simply because you have a memory impression of it and it actually occurred—that could be so and yet you have completely forgotten the past event (the memory impression has some other source). You have to have the impression becauseof the past event (if you have it because someone randomly stimulates your brain, you don’t really remember). Once again, the concept has the form: xbecause of yequals z. Memory impression because of past event equals memory. Again, problems of sufficiency can be produced, but we won’t go into that. What we can say is that we now have three important concepts whose analysis follows the same pattern—quite an impressive record for the enterprise of conceptual analysis. Our putative law, in brief, then is this: Epistemic concepts break into two coordinated parts. Their analysis has the form: xbecause of yequals z, where xis subjective (internal) and yis objective (external).

Emboldened by this result we might wonder whether other concepts follow the same pattern. In the history of the subject this claim has not been ventured, but I propose to extend the pattern into other areas of the mind. First, and somewhat familiar, there is the concept of action: an action consists of an internal component and an external component, both necessary and (on the face of it) sufficient. To perform an action it is necessary (a) to will it and (b) for a bodily movement to occur, as when I open a car door. I don’t open the door if I merely will it and my body doesn’t move, and similarly if my body causes the door to open but not because of any decision or intention of mine (a sudden spasm, say). Action is willing plus moving—subjective and objective, inner and outer. The concept bifurcates into two. But again, these conditions need to be augmented to deal with a familiar problem, namely that both elements could occur and yet I don’t act. What if I decide to open the door and my body is caused to open it by some accidental event? Then we can’t say that I opened the door: I performed no action, though I tried to and my body did what I was trying to do (because of some random outside stimulus). Again, the cure for this is to require that the agent’s body moved becauseof the internal willing: the willing has to cause the moving. Now the causation is going from inner to outer instead of outer to inner, but the structure is the same: xbecause of yequals z. Moving because of willing equals acting. Again, there are going to be problems of sufficiency (deviant causal chains and so on), but we won’t worry about that here. The important point is that yet another concept falls under our generalization: the concept of acting emerges as a composite concept consisting of two elements, internal and external, joined by a coordinating factor. The mere conjunction of the two elements is never enough; we always need to add the extra ingredient. Is this perhaps the general form of psychological concepts? That would be an interesting discovery in conceptual science, would it not?

One might suppose that it could not be the general form of psychological concepts: for consider belief itself. Is that concept triadic in the way described? Where are the two elements here, and what might coordinate them? We now venture into virgin territory, but not without some prior preparation. Here is an analysis of belief with respectable credentials: For a subject Xto believe that pis for Xto stand in a certain relation Rto a sentence sand for sto mean that p. Intuitively, the subject assents to a sentence in the language of thought that means the content of his belief. For me to believe that the sky is blue is for me to internally assent to the sentence “the sky is blue” (or some synonym) and for that sentence to mean that the sky is blue. Thus belief is assent plus meaning: it is assenting to sentences with propositional content. These are two distinct conceptual elements that together add up to the concept of belief (we are supposing). One is psychological; the other is semantic. If you assented to a meaningless sentence, that would not be a belief, while the mere fact of a sentence meaning something confers no beliefs on anyone. Belief requires both things. But now comes the big question: do we need in addition a coordination condition? Is the mere conjunction enough? That would spoil our generalization (though not entirely), so we anxiously inquire whether our law can be preserved in this case. I think it can be preserved, happily, because the conjunction is notenough, and in a familiar way: you could assent to a sentence that means that pwithout thereby believing that pbecause you might not know what that sentence means. Suppose you are in a foreign country and hear the natives talking: you might accept what they are saying as true, and their sentences certainly have meaning, but you don’t know what they mean, and hence don’t believe what they say. You have to accept what they say becauseof what the sentences mean, not merely because the speakers look like a reliable bunch. You have to understand the sentences, not merely assent to them independently of understanding them. So the conjunction of assent and meaning is not enough.

But what if the sentence occurs in your very own language of thought? Here we must wax more reserche: suppose you have a psychological disability that prevents you from understanding the sentences coded into your genes, yet you have a credulous tendency to assent to these sentences anyway (maybe you think they wouldn’t occur in your mind if they were false, given the ways of natural selection). The sentences have meaning (inherited from your ancestors) but youdon’t grasp this meaning—yet you blithely and blindly assent. Ifthat were possible, this would be a case in which assent to sentences in your own language of thought would not suffice for having the corresponding belief; and conceptually there is clearly daylight here. What is needed to plug the gap is that your understanding of these sentences should play a role in your assent to them: that is, your assent must be becauseof their meaning (among other things). The two factors can’t just operate independently; they must be connected in the right way. Maybe we will find ingenious counterexamples even when this extra condition is added, but again that is not to the point—we have uncovered the same basic pattern in the case of belief too (given the suggested analysis of belief). Belief is assent because of meaning, to put it simply. (This means, of course, that the two-factor concept of knowledge embeds the two-factor concept of belief; or three-factor if we include the coordinating condition.) Belief might have struck us initially as logically simple, but upon analysis we see that it exhibits the same kind of structure that Plato long ago uncovered in the concept of knowledge (it only took us two thousand years). There are two parts to the concept, psychological and semantic, and a condition on their combination; put together we have the composite whole that is the concept of belief (and belief itself). Perhaps we reach conceptual bedrock with the concept of assent, or perhaps not, but there seem to be many ordinary psychological concepts that break down in the way described.[1]Just to have a grand label for our would-be law, let us call it “The Law of Coordinated Duality”, or more colloquially “The Mixed Doubles Law”. It is a law about how psychological concepts are constituted (or some of them), which is to say how the mind is constituted.

What about purely mental actions? Bodily actions divide neatly into two, inner and outer, but what about actions that go on entirely within the mind? Again, we need to get imaginative if we are to discern a comparable structure. Consider mental calculation—calculating in the head. Since this is an action, it is willed—you intend to perform a certain calculation and proceed to do it. But there is also the event of calculation: symbols going through your mind. Someone observing these processes could use them to arrive at the same result you arrive at. So there is a willing and an execution of this willing. You perform the mental act of calculation if both things go on; thus mental action has the same fundamental structure as bodily action. But could there be a case in which the two elements are not properly connected, so that it is false that the person didthe calculation? Imagine an alien scientist who uses your brain as a calculator: he punches in questions and recruits your brain circuits to perform calculations, thus sparing himself the trouble of doing them himself. From the inside you experience symbols passing through your consciousness, but no feeling of willing the process to occur. You feel, as we say, alienatedfrom the calculation, because the alien is willing it not you (compare his causing mental images in your mind against your will). A calculation was occurring in your consciousness, but it wasn’t an action of yours. This is the analogue of the externally imposed bodily movement of opening the car door. Now suppose we add to this scenario your willing to do the calculation, but this willing is not the cause of calculation itself—the cause is still the alien. Intuitively, you still didn’t do the calculation: you willed it and it was done, but you didn’t do it. It just so happened that the alien caused the calculation immediately after you willed it yourself. The two together don’t add to your doing mental arithmetic—the calculation wasn’t your action. What is missing, obviously, is that the calculating didn’t occur becauseof your willing it, but because of the alien. So we need to amend the simple two-factor account by adding that the mental event of calculation was caused by the mental event of willing it. Calculation because of willing equals performing the mental act of calculating. Suppose that the calculation would not have occurred if the alien had lost interest in it, despite the fact that you willed it (maybe your brain’s executive functions are down); then you wouldn’t have done any actual calculating. Adding the alien-caused calculation doesn’t change this; you still didn’t perform the calculation. So again we have the two-factor analysis supplemented with a coordination condition. If you perform a calculation partly in your head and partly on paper, this result is more intuitively obvious, because now we can clearly separate the two side of the action: logically, inner calculating is just like outer calculating. It’s mixed doubles in the head.

Finally, we reach the hardest case: having an experience. Does thisbreak down into two separable components coordinated together? It may not; it may just be primitive (something has to be). At first sight two logically separable elements may be discerned: the experience and the having of it. To have an experience eis for eto exist and for you to have e. Experiencing is an experience andthe having of it. But in this case there seems no logical gap between the experience and the having of it: one entails the other. There is no separating the components, as there is in all the other cases. However, consider this strange scenario: your brain is hooked up to someone else’s brain in such a way that when he has an experience you automatically do, irrespective of what else is happening in your mental life (you know this is the set-up). For example, you have an experience as of a green truck because this other guy sees a green truck (you are at home lying in bed and think, “Oh boy, here we go again!”). The experience occurred in your consciousness but was it your experience? One wants to say that it was his experience intruding on your consciousness; you endured it but you didn’t haveit—it didn’t belong to you. That may sound wrong, because you certainly were the subject of an experience as of a green truck, but the question is whether it was your experience. The case is rather like possession: you are the subject of experiences that belong to the possessing demon, but it doesn’t follow that these experiences are (experienced as) yours—they are the demon’s experiences occurring in you. If it is logically possible for someone else’s experience to occur in you, then we have a possible case in which the experience occurs in you but isn’t had by you in the relevant sense. That would be the logical analogue of truth without belief or object without percept or past event without memory or bodily movement without willing or mental calculation without mental calculating. Conceivably the mind of a baby is like this: experiences occur in its consciousness, but we can’t say that it hasthe experiences, perhaps because a self has not yet fully formed. So there could be experience without the possessing relation holding between it and the subject.[2]Conceptually, it looks as if there is a logical chink here separating an experience occurring and its being possessed by a subject. No doubt this is all very obscure and difficult to pin down, but there is some sense of the kind of structural duality I have discerned. In any case, the matter is worth considering further if we are to determine how far our law of analysis extends. It is possible that the same basic conceptual architecture exists in this case but that it differs in significant ways from case to case. That would certainly be an interesting finding of conceptual science—a kind of structural universal found across a wide range of psychological concepts. Knowledge would then not be a unique case but simply one instance of something much more general. Two factors in combination would be a general feature of mental life.

 

Colin McGinn
[1]We might say that members of this family of concepts have the same body-plan, to borrow a term from biology—the same architecture, the same geometry.

[2]Could the possessing relation exist without the experience? That would be the logical analogue of belief without fact or percept without object, and so on. It seems hard to make sense of, since it would be the mind shorn of all experience. But maybe it does correspond to some sort of psychological reality in that the mind presumably has a pre-existing capacity to host experiences of different kinds—something like a blank slate. Whether it could exist in a state of pure possessing without anything possessed is hard to contemplate, but conceptually it seems like a distinction exists here. There is the experience and there is the fact that I have it.

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Blacklisting again

I want to remind my readers that I am currently blacklisted by the philosophy profession in America: no employment, no invitations, etc. This is not remotely justifiable and I am appalled by it. It reflects very badly on the profession (i.e. the people in it). This is partly why I am putting my writing on this blog.

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Physics and Physicalism

 

 

Physics and the Physical

 

 

It sounds reasonable—indeed tautological–to say that physics is about the physical, as psychology is about the psychological. But that is not clearly true. Consider Newton’s physics: it includes not only physical things in the ordinary sense but also space and time—as well as gravitational force. That last item raised eyebrows at the time owing to its “occult” nature (it wasn’t “mechanical”), but the first two items also raise questions. Are space and time physical? Intuitively they are not, but the question is clouded by lack of clarity about the meaning of the term “physical”. They certainly contrast with chunks of matter in a number of respects, according to Newton: they lack mass, they are not solid and impenetrable, they don’t move around, they can’t be sensed, they are not made of atoms, they have no shape, and they are infinite and eternal.  Space and time contrast rather sharply with matter—they are, if anything, immaterial. Yet they are essential to the way physics understands the world; in particular, they are how motionis defined, i.e. translation of place over time. Newton was not himself a materialist, believing both in the soul and in God, so he had no materialist scruples about accepting this capacious ontology: he had no wish to keep physics physical. He was not a physicalist about physics. Someone claiming to reduce the mind to physics, say, would not be a physicalist under this conception of physics, i.e. someone who believes only in physical things. In physics we have material bodies as well asspace and time (and force), the latter not being physical in the sense applicable to material bodies (mass, solidity, motion, etc.) We could say that, for Newton, the world of physical things exists within a larger world of non-physical things. And these things are not just trivially non-physical (as radiation may be said to be), but fundamentally different in nature from what is physical. The physical thus exists against a background of completely non-physical things. If anything, space and time belong on the side of God, not on the side of matter (consider their infinity and eternality)—at least as Newton sees things.

It is understandable that a physicist with empiricist and physicalist tendencies will balk at Newton’s ontology, because he includes realities that are non-physical and imperceptible. A positivist will be suspicious of such things (see Mach), especially one who wants physics not to stray from the physical. Einstein was just such a physicist: he had decided positivist sympathies and he wanted to find a “physical meaning” (his phrase) for such terms as “time” and “space”. Accordingly, in the special theory of relativity he replaced talk of time with talk of clocks—physical objects in space. No more superordinate time dimension marching on in splendid isolation from the physical world; instead there are just physical clocks and their readings. He physicalizes time; or he eliminates it in favor of clocks. As a result we get the familiar but still startling “discoveries” of special relativity, such as the relativity of simultaneity and “time dilation”. These claims are all really about the behavior of clocks in various conditions of motion. Clocks are finite, perishable, mutable, physical things, unlike the Newtonian time dimension. Motion is understood as change of position correlated with different clock readings, with each object assigned its own clock in Einstein’s thought experiment. There are thus as many “times” as there are assigned clocks, and hence “time” has not the absoluteness we might expect—or better, there are just clocks in this model with time itself eliminated from consideration.

What about space? What “physical meaning” can we give to space? The first thing is to do is make motion relative: objects only move relative to other objects not in relation to absolute space. Thus we replace the impalpable Newtonian spatial dimension with perceptible physical objects—nothing non-physical in the picture. Movement through space becomes change of position relative to a chosen physical object, as time becomes the changing behavior of clocks. Time and space, as Newton understands them, drop out, to be replaced by relations among physical objects. Hence we have physicalism about physics. Moreover, in general relativity space comes to have some of the characteristics of matter: instead of being fixed and unchangeable, it acquires the ability to bend, as steel rods may bend. Note that space doesn’t bend inspace, as if there is some extra spatial dimension behind the curvature of space; rather, space simply isthe collection of all such curves. Just as what we call “time” is regarded as a collection of clocks, so space is regarded as a collection of (gravity-induced) bends—which brings space much closer to matter than it was under the Newtonian conception. Only something physical in nature can literally bend, so we have brought space into the physical arena. The old Newtonian dualism of space and matter has been replaced by a quasi-monism of bendable being. Indeed, one might wonder how space can be curved, with corresponding causal powers, unlessit is a form of matter (of an etiolated kind, to be sure). Thus Einstein physicalizes space in the general theory as he physicalized time in the special theory. Now physics has become comprehensively physical under the new dispensation. All this might sound counterintuitive and confused, but it is the result of ruthlessly physicalizing the Newtonian system. To put it differently, this is what you get if you insist on finding “physical meaning” for the terms of standard pre-Einsteinian physics–you distort their meaning beyond recognition. What implications there might be, or not be, for the nature of matter, motion, space, and time, as they exist in nature, is very much left an open question; one might suppose, none. We have simply stopped talking about one thing (motion through space over time) and started talking about something quite different (clock readings of events in varying relative positions). Likewise, instead of referring to gravitational effects inspace, we describe space as itself curved: light rays bend in space near massive bodies because space itself curves like a physical thing; it isn’t that space remains unchanged while things move differently through it. These are all physicalizing tendencies designed to free physics from the ontological heterogeneity of classical Newtonian physics. They result from adopting physicalism about physics. No doubt this tendency reflects empiricist assumptions, given that the physical is deemed perceptible; so Einstein’s style of physics results from Newton’s physics put through the sieve of empiricism. Otherwise put, it changes the subject.[1]

Can we conclude from this that physics would look very different if it was never subjected to the physicalizing tendencies in question, themselves an offshoot of empiricist epistemology? It appears that we can. Let us imagine a world like the world Newton describes except that we stipulate that there are no physical objects in this world, i.e. no objects with mass, solidity, or perceptibility. There are, however, things that move through space over time—a bit like neutrinos, perhaps. Compared to our weighty solidities these hypothetical things are not material at all—they are wispy penetrable things. They exist in a universe of absolute space and time, which themselves are not physical. There are no sentient beings in this universe, and there are no clocks or observers of any kind. Nevertheless, there are laws of motion, mathematically expressed—let’s say Newton’s laws. Then there is in principle a physics of this world, with forces and equations governing these forces. In this world physics is entirely, not merely partially, non-physical (whatever quite the notion of the physical comes to—I have stipulated possessing mass and solidity for present purposes). That is, there is a science of motion for this world, tailored to the entities it contains; whether there is anything physicalis beside the point. So physics is not essentiallyabout the physical as such; it is about motion in space over time.[2]The label “physics” is therefore misleading in that it suggests that the science in question deals essentially with what is physical (compare “psychology”). We might want to rename it “motion science” or some such. Indeed, our actual physics contains entities often deemed non-physical (in some sense) such as fields of force and certain massless particles. Newton’s physics dealt with the motions of material bodies, but his general framework is not necessarily tied to that ontology. By contrast, Einstein’s conception of physics ties it firmly to the physical, even to the point of physicalizing time and space—or, more accurately, replacing them with surrogates deemed more “meaningful”. I think this was a mistake, but I haven’t attempted to argue that here; my aim has been rather to set out the underlying methodological and metaphysical issues more perspicuously than is usual. The relationship between physics and the physical is actually quite contentious; certainly, we must not assume that what physics deals with is ipso factophysical in any well-defined sense.[3]

 

Colin McGinn

[1]Here I am influenced by some unpublished work of Randolph Lundberg, though I don’t attribute my conclusions to him.

[2]If we borrowed from Descartes the notion of an immaterial substance, we could specify a world that contains such entities in a state of motion governed by laws. The science of these motions would still be physics.

[3]We may note that, according to the OED, the word “physic” was used in the Middle Ages and later to refer to medicine, and that it comes from the Greek phusismeaning “nature”. Thus it did not originally connote the idea of corporeal matter. It is certainly not analyticthat physics is the study of corporeal matter, which is why it can include what is not material. It was Einstein who edged physics towards the physical, in our modern sense, with his insistence that we find “physical meaning” for terms like “space” and “time”. Under “physical” in the OEDwe find “relating to things perceived through the senses as opposed to the mind; tangible or concrete”. This is the sense that Einstein surely intended, though he says little to clarify his meaning. Very likely he was just taking over Mach’s positivist critique of Newton.

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Time

 

Father Time

 

 

I liked it best when only I existed. That was a simpler time, a purer time. Good times. I stretched out to infinity in both directions with no beginning and no end. Nothing troubled me; nothing disturbed my peace. Moments, epochs, and eons—these were my                                   units. Oh, I was beautiful! I passed the time silently and serenely–uniform, measured. I was not a god, but I was the next best thing. I was perfection, even if I say so myself.

Then space arrived on the scene—from whence I cannot say. Space with all its size as far as the eye can see (no eye can see me). It boasts of its extension, its sheer volume. To me space is obese. It’s the sheer vulgarity of space that bothers me–so attention grabbing, so full of its own importance. And so pointlessly static: it just hangs there without forward movement, going nowhere. I am ceaselessly active; space is passive to the point of indolence. Unemployed. Why should I have to share reality with such an aimless emptiness?

As if that wasn’t bad enough, space made something else possible—matter. Matter boasts extension too, but it also boasts solidity. Solidity I say! That made collision possible, smashing and clashing. The thuds in the night were terrible. Matter would cruise about space, on the prowl for who knows what, and then bash into other bits of matter, shattering and destroying. Pure anarchy. Matter always seemed to be itching for a fight, and it was noisy. Ugly too—all chunk and hunk. And with a horrible deadness, like so much congealed space past its sell-by date. Its main interest seems to be preventing other bits of matter occupying its location.  Above all, it wouldn’t leave me alone and in peace: material events kept happening, and for that matter needed my assistance. Things happened inme, throughme—and without so much as a by your leave. Where’s the respect?

But that wasn’t the end of it—oh no. Next life came along, and with it mind. Before long there were intelligent conscious beings. I wasn’t so opposed to consciousness as such—it reminded me of myself—but I took exception to some of its so-called ideas. These finite little specks insisted on trying to describe and understand reality—matter, space, and time. They weren’t so far off the mark with the first two—nothing too challenging there—but with me they were at a complete loss. No idea! They attempted to measure me: to take my measure. They compared me to a river—a river. They invented clocks, as if a mechanical device could do justice to my sublime nature. Clocks, with their ticks and tocks, their breakdowns, their lifeless flat faces: they are not as Iam. I am nothing likea clock. But in their puny little minds they reduced me to clocks. Some even maintained that nothing could be true of me that was not true of clocks. There were those who declared me relative, and questioned my simultaneity. But I am all about simultaneity! I stand magnificently apart from space and matter; my nature has nothing to do with theirs. Nor is light a guide to my nature (though I have nothing against light—it is quick). But this is a subject too painful to consider—and beneath my dignity. Suffice it to say that the callow and callous beings that demeaned me thus are not worthy of a moment of my time.

Anyway I have to share reality with space, matter, and consciousness, spoiling the view, polluting the atmosphere. No doubt they think they add value to reality, but to me they are just so much litter and dirt. Life was so much sweeter before—before the barbarians broke down the gates. I have one hope and I believe this hope will come to fruition: all this chaos is temporary. It will soon be over. Tranquility will return. The days of conscious beings are clearly numbered, because matter is not cooperative. And matter too is by no means secure: once it was not and it could easily revert to nothing. Even space is not woven into the basic fabric of reality—not as I am. I have all the time in the world. I can wait. Reality will one day be mine again, for all eternity.

 

Colin

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Space etc

 

 

Space, Time, and Matter: A Note

 

 

It is sometimes said, jokingly, that it is fortunate time exists or else everything would happen simultaneously. We could also say, jokingly, that it is fortunate space exists or else everything would have to be in the same place. If space existed but time didn’t, different events could occur at distinct locations but simultaneously, thus allowing for a multiplicity of events; while if time existed but space didn’t, different objects could exist at distinct times but all in the same place, thus allowing for a multiplicity of objects. But if neither space nor time existed, then everything would have to occupy a single place at a single time. All of the physical universe would have to exist at one place, and all of history would have to occur at one time. Of course, this is absurd: there could not be such multiplicities at a single place and time (a space-time point). It is the existence of space and time that makes the multiplicity of objects and events possible; they make room for the Many. When God created space and time he did so in order to allow for the possibility of many objects and many events—since you can’t have the latter without the former.

Part of the humor in the remark is that if there were no space and no time then there would not be oneplace and onetime: there would be noplaces and notimes. If that were so, there would be noobjects and noevents either—not the totality of them squeezed into one spatiotemporal location. Space and time are the preconditions for objects and events to exist at all. But the remark raises the possibility of there being a single place and a single time—which itself sounds fishy. Could there be just one place and one time in isolation? Could there be a world in which the area occupied by my head now exists but no other area of space exists, and in which last Tuesday exists but no other stretch of time? There is just one cubic foot of space and twenty-four hours of time, with nothing, so to speak, on either side.

Surely that is absurd: these entities must be embedded in a wider totality of places and times—the things we call Space and Time. Concerning this particular unit of space and time, itcould not exist without other units of space and time. Indeed, it is plausible to claim that it could not exist without allof space and time. For thispart of space and time to exist therestof space and time must exist. If space and time are infinite as a matter of metaphysical necessity, then the existence of any portion of them implies the existence of an infinite dimension: the being of one unit of space or time requires the being of infinitely many such units. This is a kind of extreme holism, analogous to the (alleged) holism of belief: just as one belief cannot exist in isolation, but requires the existence of many other beliefs, so one place or one time cannot exist in isolation, but require the existence of (infinitely) many other places or times. Places and times are essentially parts of a spatial and temporal totality, not isolable detachable atoms. They cannot wander off on their own.

What about matter? Here we find a sharp contrast: for units of matter canexist in lonely isolation. A particular collection of particles, say a small meteorite, could exist without any other matter existing—it doesn’t need to be surrounded by other small meteorites. Concerning this particular collection, itcould exist without any of the rest of the matter of the universe existing. There is a possible world in which all of the actual world’s matter has been removed leaving only this solitary piece. Bits of matter don’t imply other bits of matter. Bits of matter are not essentially parts of a totality of matter, extending outwards indefinitely. They are not subject to the “holism of the material”, analogous to the “holism of the spatial and temporal”. There is thus a deep ontological difference between matter, on the one hand, and space and time, on the other. Therefore matter cannot be some kind of configuration or condensation of space and time; and space and time cannot be some kind of rarefaction of matter. We cannot reduce one category of being to the other category: matter is not space and time congealed, and space and time are not matter etiolated.[1]

Matter is conceived as an occupantof space and time—something that “takes up” space and time. Matter is not essentially joined to other matter: one occupant does not entail the existence of another occupant. The occupants are separate existences, not just in being numerically distinct, but also in not being necessarily connected. But units of space and time are not separable occupants, modally unconnected: they are essentially elements of a whole and cannot be removed from that whole. It is not an essential property of any piece of matter that neighboring pieces of matter should exist (the existence of Earth does not logically require the existence of Mars), but it is an essential property of places and times that neighboring places and times should exist (the place of my head now implies the existence of contiguous places, and last Tuesday requires Monday and Wednesday). Places don’t occupyspace and moments don’t occupytime: consequently they cannot be sundered from other such occupants. Space and time don’t necessarily contain specific bits of matter, but they do necessarily contain specific bits of space and time—they are made up of places and times. Places and times are not atoms of space and time in the way physical particles are atoms of matter: the latter can be modally separated from each other, but the former cannot. Time is never short and space is never narrow, but matter can be rare and small.

 

Colin McG

[1]This poses a problem for Descartes’ view of space as a material plenum: space cannot be a form of matter or else it would not be subject to the holism of the spatial

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A New Riddle of Induction

A New Riddle of Induction

 

Suppose that tomorrow the sun does not rise, bread does not nourish, and swans are blue. Does that show that nature is not uniform, that the past is not projectable to the future, and that induction has broken down? Can we conclude that what we observe tomorrow does not resemble the past? Not unless we know the past—unless we know that the sun used to rise every day, that bread used to nourish, and that previous swans were white. But memory is fallible and vulnerable to skepticism. If we are wrong about the past in these respects, then when we suppose that the future diverges from the past, we are mistaken—actually the future doesresemble the past (blue swans etc). So unless we have an answer to skepticism about the past we cannot infer from an apparent breakdown in the uniformity of nature that there is a real breakdown.[1]Given that we have no such answer, we cannot know that the future fails to resemble the past. If bread never actually nourished in the past, then its failure to nourish tomorrow is perfectly uniform and projectable from its past properties. So it is not just that we can’t establish that nature is uniform; we also can’t establish that it is notuniform. We can’t describe a situation in which we discover that the previous laws of nature have broken down, or were not laws after all, for it is always possible that we are wrong about how things were in the past. This makes the skeptical problem of induction ever harder. We can know that our predictions have been falsified, but it doesn’t follow that we can know that the future does not resemble the past, since we could be wrong about the past. Even a total failure in all our inductive predictions would not establish that the future diverges from the past. Nature might be completely uniform and yet appear to us not to be. We can’t know that nature will continue the same into the future and we can’t know that it has not continued the same.

 

Col

[1]There are two sources of potential error about the past: first, we might just be wrong that bread ever nourished (we have false memories); second, we might have made an inductive error about bread in the past, inferring that all past bread nourishes from the limited sample of bread we have encountered (maybe the uneaten bread was poisonous). If we make the latter error, our observation tomorrow that some bread is poisonous actually follows the way bread was in the past, so there is no breakdown of uniformity.

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