The Atlas of Reality
Page 82
Someone who rejects Physicalism, like Trenton Merricks, is an Anti-Physicalist or Emergentist. Emergentists have two possible responses to the empirical case for Physicalism. First, Emergentists could point out that our knowledge of how fundamental particles act when they are situated in complex organisms or in the brains and bodies of persons is still very partial, to say the least. Even when dealing with relatively simple bodies like crystals or fluids, some solid-state physicists have expressed skepticism about Physicalism, supposing that composite material bodies sometimes exercise emergent powers that are more than the sum of the powers of the constituent particles. A fortiori, we might think that it is still more reasonable to suppose that organic bodies and bodies of persons possess emergent active powers. Bertrand Russell at one point in the early twentieth century took seriously the possibility that electrons and other particles might move differently when under the influence of thought or will within the human brain, and nothing we have discovered since makes that possibility any less serious today.
Alternatively, Emergentists might accept that the uniformity of behavior that we have observed gives us reason to believe that fundamental particles always behave in essentially the same way, following the same regularities whether inside or outside a living body. We'll take up this second option in the next section.
22.6.3 Mock Physicalism and the absorption of powers
To make good on the second option just noted, Emergentists might concede that it would be unreasonable to suppose that our best theory of micro-physics is empirically inadequate. A theory is empirically inadequate if its predictions are at variance with any possible observation or experiment, unless we have a good explanation, in terms of the theory itself, for the unreliability of the conflicting observation or empirical result.
Methodological Physicalism. Reject any theory that is inconsistent with the empirical adequacy of our best theory of fundamental micro-particles and fields.
Can one accept Methodological Physicalism while rejecting Physicalism proper? If our micro-physical theory is empirically adequate, even with respect to the behavior of human brains and human bodies, shouldn't we admit that it contains all of the metaphysically fundamental truths? Not necessarily, especially if the Cartesian argument or the appeal to our practices gives us reason to suppose that we ourselves must be fundamental but macroscopic entities. We could suppose that when some particles compose a human body, the fundamental active powers of the particles are absorbed by the human being as a whole. As a result, the particles then behave in accordance with the ordinary laws of physics, but they do not obey those laws! They act as they do because of the exercise of new active and immanent powers of the whole human being, not as a result of their ordinary micro-physical powers, which they have utterly lost. The particles satisfy the descriptions of their behavior given by physics, but they do not obey the laws of physics.
To say that the microscopic parts of an organism satisfy descriptions in the language of physics is to stretch somewhat the usual meaning of ‘satisfaction’. Strictly speaking, the atomic particles of an organism do not have the same physical natures as do the corresponding particles in the inorganic world. Instead, they have natures qua functional parts of the organism, natures that may perfectly mimic the behavior of the natures of the corresponding free particles, given the parameters of the organic body in which they occur.
The resulting picture is one that we could call ‘Mock Physicalism’. It is immune from empirical refutation by empirical observation, but it rejects the further claim that the micro-physical level is metaphysically fundamental. Instead, within persons and other organisms, it is the organic and personal level that is fundamental and the micro-physical level that is derived and reducible.
22.7 Finding an Intelligible Principle of Composition
In this chapter so far, we have examined the question of whether there are any fundamental composite entities, and if so, of what kind. In this last section, we want to turn to the question of what sorts of composite entities exist at all, whether fundamental or derived. We might call this the Broad version of van Inwagen's Special Composition. The first question to ask is whether there is any principle of composition at all. We will return to our earlier discussion of heaps, since we will need to determine when a heap exists as a derived entity.
22.7.1 Is there a principle of composition?
First, we have to consider whether there is a principle of composition, a finite answer to the Broad version of van Inwagen's Special Composition Question. If there is, the answer to the Special Composition Question is intelligible. If not, then the Special Composition Question has a brutal answer:
22.8T Intelligible Composition. There is a finite set of necessary and sufficient conditions C, such that for any set of simples S, the members of S compose something if and only if they jointly satisfy C.
22.8A Brutal Composition. There is no such finite set of conditions.
A metaphysical theory incorporating Brutal Composition (Markosian 1998) would be in some sense much more complex than one satisfying Intelligible Composition, since the Brutal theories have to include separate axioms for the existence of each composite thing or for an infinite number of families of composite things, while Intelligible theories could instead list a finite number of axioms specifying which kinds of sets of simples compose something composite. So long as there are more things in the world than there are conditions in the Intelligible Composition set, the Intelligible theory will be simpler. Presumably that would be so.
So, let's assume that there is an intelligible answer to the Broad version of the Special Composition Question. What are some possible answers? One extreme answer would be to deny that some things ever compose anything, whether fundamental or derived:
26.8T.1T Mereological Nihilism. No non-empty set of things ever composes anything (whether fundamental or not).
26.8T.1A Mereological Aliquidism. Some non-empty sets of things do compose something: there is some other principle of composition besides Mereological Nihilism.
Mereological Nihilists can appeal to Ockham's Razor in defense of their principle, although, since Mereological Nihilism rules out not only fundamental composite things but also non-fundamental composite things, the force of Ockham's Razor is much reduced, as we saw in Section 3.9. A slightly less radical view would admit organisms as composite entities:
26.8T.1A.1 Extreme Organicism. A set of entities composes something if and only if they participate in a single life.
Extreme Organicism is defended by Peter van Inwagen (1990a). It entails that there exist no heaps and no artifacts:
26.9T Extreme Anti-Heapism. No heaps exist.
26.10T Extreme Anti-Artifactualism. No composite material artifacts exist.
The opposite extreme from Mereological Nihilism is Mereological Universalism:
26.8T.2 Mereological Universalism. Any non-empty set of material things composes something.
Mereological Universalism will be true if organisms, artifacts, and arbitrary heaps exist. Since we have discussed the existence of organisms, we will now turn to heaps and to artifacts.
22.7.2 Do heaps exist?
If heaps exist at all, when do things compose a heap? One simple answer is simply to deny that heaps exist at all. On this view, the only composite things that exist at all are the fundamental composite things, like organisms (or perhaps artifacts).
22.9T Extreme Anti-Heapism. No heaps exist.
We certainly talk as though we believed in the existence of heaps of many kinds. We talk about rocks, clouds, lakes, planets, stars, and so on. We say things like ‘There are many mountains in Colorado’ or ‘Nine planets rotate around the sun.’ Statements like these involve bound variables, which were Quine's proposed criterion of ontological commitment. These statements imply that some things are mountains and some things are planets. Prima facie, our acceptance of these common-sense statements commits us to believing in the existence of such heaps.
Common s
ense, then, tells us that many heaps exist. Therefore, Extreme Anti-Heapism might seem initially rather implausible. Extreme Anti-Heapists have a number of strategies for explaining away this apparent conflict with common sense:
Paraphrase. We don't really mean it when we say heaps exist. What we really mean could be put more precisely by saying that there are simples arranged heap-wise. That is, (1) is simply a loose and popular way of saying (2):
(1) Some mountains are tall.
(2) Some atoms (metaphysical simples) arranged in a mountainish way are collectively tall.
Useful fiction. We mean it when we say that heaps exist, but we do so in an intentionally fictional mode of speech. On this view, (1) is true only when understood as something like (3):
(3) According to the useful fiction of Heapism: some mountains are tall.
(3) is a good deal like (4):
(4) According to the Conan Doyle stories: a great detective once lived on Baker Street in London.
(4) is obviously true even if in fact no great detective ever lived on Baker Street. Similarly, (3) could be true even if in fact there are no mountains. We merely pretend that things like mountains exist because it would be so tedious and inconvenient to be talking all the time about simples arranged mountain-wise.
Quasi-truth. A statement about heaps is quasi-true (according to Sider 2001) if it is something that would have been true if heaps had existed. It seems plausible that (1) is quasi-true. If there were heaps, mountains would probably be among them, and some of these mountain-heaps would be tall. All of this could be true even if, in fact, there are no heaps and thus no mountains. It seems reasonable that we would assert quasi-truths, in part because they are so much easier to say and to understand than the corresponding real truths, like (2) or even (3). In addition, it would be understandable if we were even to believe the quasi-truths to be really true. Most people are not aware of the complex subtleties of metaphysics, and many who are couldn't care less about them. Such people might well believe false metaphysical theories and thus come to believe many quasi-truths. Since quasi-truths are close enough to the truth for nearly all practical purposes, such errors would be unlikely to be corrected.
Thus, there are a number of strategies available to Extreme Anti-Heapists to argue that we aren't really or seriously committed to the existence of such heaps (e.g., paraphrase, useful fiction, quasi-truth). And here is some additional evidence that confirms Extreme Anti-Heapism. If we ask ourselves whether one and the same rock or lake or cloud has persisted through time or whether it has been destroyed and replaced by a new one, we often feel that the question has no deep or principled answer. If a small stream has been dammed into a lake, has one and the same body of water survived and been changed or have we destroyed the stream and created a new lake? If a small chip has been struck from a stone, has the stone survived the deletion or has it been destroyed and replaced by a new, smaller stone? When we consider questions like these, we are inclined to think that there is no real fact of the matter—that we should feel free to legislate or stipulate any answer that is practically useful under the circumstances. This attitude can be easily explained if, strictly speaking, there simply are no heaps. (The attitude can also be explained by Mereological Universalism, but that's no aid to common sense!) If talk of heaps is not literally true or is a merely useful fiction or only quasi-true, it would make sense for us to be free to alter our way of talking about heaps without concern that we might be losing our grip on any truth about the world.5
In Material Beings (1990a), Peter van Inwagen proposes a large number of possible answers to the Special Composition Question that are compatible with the existence of heaps. He finds serious difficulties with or objections to each.
The first is the simplest principle of all: Mereological Universalism. Mereological Universalists believe that the members of any non-empty set of things, no matter how diverse or scattered, no matter how loosely related to one another, jointly compose some further thing, namely, their mereological sum.
22.8T.1A.2 Mereological Universalism. For every non-empty set S, the members of that set compose something. (Equivalent to Arbitrary Sums MA6.)
On the plus side, Mereological Universalism is a very simple principle. In addition, if Universalism were true, there would be no vagueness or indeterminacy in the world. We would never have to worry whether some things really met the conditions necessary for composition, since there are no such conditions beyond mere existence.
On the minus side, Universalism seems to multiply entities needlessly, contrary to Ockham's Razor (PMeth 1). Second, Universalism is contrary to our ordinary way of identifying and counting things. Suppose we found four wooden rocking chairs in a room and were asked, ‘How many wooden things are in the room?’ We would be unlikely to answer that there were an astronomical number of wooden things, one corresponding to every possible combination of woody bits contained by the four chairs. We don't ordinarily believe in scattered or arbitrarily gerrymandered objects.
A third objection to Universalism involves the Problem of the Many. Suppose we have a wooden chair, Chair Maximus. If we carved off a few small wood chips, the resulting object would still be a wooden chair, Chair Minus. According to Universalism, Chair Minus is there all along, even before we carve off the chips. If Chair Minus is there, isn't it already a chair? It doesn't seem to be missing anything required to be a chair.6 So, we are forced to say that we really have two chairs, Chair Maximus and Chair Minus. In fact, we have billions and trillions of chairs, one corresponding to each possible way of subtracting some of the matter of Chair Maximus in such a way as to leave a chair in existence. This is the problem of the many.
The problem of the many obviously applies to heaps, likes stones or mountains. But the problem of the many can also be developed in more disturbing cases. Consider a person Susan and Susan Minus, where Susan Minus would be there if some trivial bits of Susan's matter, like a hair follicle or a skin cell, were deleted. Universalism presses us toward the bizarre conclusion that wherever Susan is there are billions and trillions of other people, the various Susan Minuses. Or, if you prefer to identify Susan with an immaterial mind or soul, we are pressed toward the conclusion that she has trillions of overlapping but distinct human bodies.
The fourth major drawback to Universalism concerns the question of how composite things persist through time, a subject we will take up in Chapters 24 and 25. This is in fact van Inwagen's principal objection to heaps. For the time being, let's set aside Universalism.
The next principle is one that van Inwagen calls ‘Fastenation’. On this view, a composite entity is brought into being whenever a number of things are fastened tightly together.
Def D22.8 Fastened. The x's are fastened to each other if and only if they are so arranged that there are very few ways of separating them without breaking or distorting some of them. (van Inwagen 1990a: 56)
22.8T.1A.3 Fastenation. The x's compose something if and only if they are fastened to each other.
In the Physics, Aristotle considers an even weaker and broader principle that we could call ‘Locomotive Unification’. Some things are locomotively unified if and only if they tend to move together as a unit. Aristotle suggested that things have a certain kind of oneness, and so count together as a single composite thing, if they have locomotive unity.
Def D22.9 Locomotively Unified. The x's are locomotively unified if and only if they are joined together in such a way that the vast majority of ways of moving one of the x's (i.e., causing its acceleration in some direction) would move the others in the same direction.
22.8T.1A.4 Locomotive Unification. The x's compose something if and only if they are locomotively unified.
However, neither Fastenation nor Locomotive Unification are plausible principles of composition, since they lead to implausible results in imaginable cases. Suppose two people are shaking hands. They do not compose a third thing, since they are not fastened together or locomotively unified. Suppose, h
owever, that while they are shaking hands, their hands lock together as a result of muscular paralysis. Now they are fastened together, and we are supposed to believe that this fact about paralysis is sufficient to bring into existence a new thing (van Inwagen 1990a: 58). Similar cases pose problems for Locomotive Unification.
The next two principles van Inwagen considers are Cohesion and Fusion.
Def D22.10 Cohere. The x's cohere together if and only if they are so arranged that it is impossible to separate them without breaking some of them (van Inwagen 1990a: 58).
22.8T.1A.5 Cohesion. The x's compose something if and only if they cohere together.
Def D22.11 Fuse. The x's are fused together if and only if they cohere together in a way that leaves no discernible boundary.
22.8T.1A.6 Fusion. The x's compose something if and only if they are fused together.
Van Inwagen argues that even if the hands of the two people discussed above were glued together, satisfying Cohesion, this wouldn't be sufficient to bring into existence a new composite thing having the two people as its parts. Even if a mad scientist were to fuse two people together, say, two identical twins, into a case of artificial Siamese twins, this would not produce a new, composite thing containing the two twins as parts. We still have only the two individual twins, even when there is no discernible boundary between them. If the two people do compose some third thing, it is not because of their cohesion or fusion.
So far, van Inwagen's objections to the bonding principles have relied on our common-sense intuition that when two people or two living organisms of any kind are bonded together, we do not thereby produce a new composite thing. Van Inwagen next considers some principles that sidestep these objections by ensuring that the only things that can compose anything are metaphysical atoms: