领域：学术论文 · 人文科学

The failure of consciousness to logically supervene on the physical tells us that no reductive explanation of consciousness can succeed. Given any account of the physical processes purported to underlie consciousness, there will always be a further question: Why are these processes accompanied by conscious experience? For most other phenomena, such a question is easily answered: the physical facts about those processes entail the existence of the phenomena. For a phenomenon such as life, for example, the physical facts imply that certain functions will be performed, and the performance of those functions is all we need to explain in order to explain life. But no such answer will suffice for consciousness. Physical explanation is well suited to the explanation of structure and of function. Structural properties and functional properties can be straightforwardly entailed by a low-level physical story, and so are clearly apt for reductive explanation. And almost all the high-level phenomena that we need to explain ultimately come down to structure or function: think of the explanation of waterfalls, planets, digestion, reproduction, language. But the explanation of consciousness is not just a matter of explaining structure and function. Once we have explained all the physical structure in the vicinity of the brain, and we have explained how all the various brain functions are performed, there is a further sort of explanandum: consciousness itself. Why should all this structure and function give rise to experience? The story about the physical processes does not say. We can put this in terms of the thought experiments given earlier. Any story about physical processes applies equally to me and to my zombie twin. It follows that nothing in that story says why, in my case, consciousness arises. Similarly, any story about physical processes applies equally to my inverted twin, who sees blue where I see red: it follows that nothing in that story says why my experience is of one variety rather than another. The very fact that it is logically possible that the physical facts could be the same while the facts about consciousness are different shows us that as Levine (1983) has put it, there is an explanatory gap between the physical level and conscious experience. If this is right, the fact that consciousness accompanies a given physical process is a further fact, not explainable simply by telling the story about the physical facts. In a sense, the accompaniment must be taken as brute. We might try to systematize and explain these brute facts in terms of some simple underlying pattern, but there will always remain an element here that is logically independent of the physical story. Perhaps we might get some kind of explanation by combining the underlying physical facts with certain further bridging principles that link the physical facts with consciousness, but this explanation will not be a reductive one. The very need for explicit bridging principles shows us that consciousness is not being explained reductively, but is being explained on its own terms. Of course nothing I have said implies that physical facts are irrelevant to the explanation of consciousness. We can still expect physical accounts to play a significant role in a theory of consciousness, giving information about the physical basis of consciousness, for example, and perhaps yielding a detailed correspondence between various aspects of physical processing and aspects of conscious experience. Such accounts may be especially useful in helping to understand the structure of consciousness: the patterns of similarity and difference between experiences, the geometric structure of phenomenal fields, and so on. I say much more about these and other things that physical explanation can tell us about experience in a nonreductive frame- work in Chapter 6. But a physical account, alone, is not enough. At this point, a number of objections naturally arise.Objection 1: Are we setting the standards too high? Some might argue that explanation of any high-level phenomena will postulate "bridge laws" in addition to a low-level account, and that it is only with the aid of these bridge laws that the details of the high-level phenomena are derived. However, as the discussion in the last chapter suggests (and as is carefully argued by Horgan [1978]), in such cases the bridge laws are not further facts about the world. Rather, the connecting principles themselves are logically supervenient on the low-level facts. The extreme case of such a bridging principle is a supervenience conditional, which we have seen is usually a conceptual truth. Other more "localized" bridging principles, such as the link between molecular motion and heat, can at least be derived from the physical facts. For consciousness, by contrast, such bridging principles must be taken as primitive. It is interesting to see how a typical high-level property—such as life, say—evades the arguments put forward in the case of consciousness. First, it is straightforwardly inconceivable that there could be a physical replica of a living creature that was not itself alive. Perhaps a problem might arise due to context-dependent properties (would a replica that forms randomly in a swamp be alive, or be human?), but fixing environmental facts eliminates even that possibility. Second, there is no "inverted life" possibility analogous to the inverted spectrum. Third, when one knows all the physical facts about an organism (and possibly about its environment), one has enough material to know all the biological facts. Fourth, there is no epistemic asymmetry with life; facts about life in others are as accessible, in principle, as facts about life in ourselves. Fifth, the concept of life is plausibly analyzable in functional terms: to be alive is roughly to possess certain capacities to adapt, reproduce, and metabolize. As a general point, most high-level phenomena come down to matters of physical structure and function, and we have good reason to believe that structural and functional properties are logically supervenient on the physical. Objection 2: Couldn't a vitalist have said the same thing about life? All this notwithstanding, a common reaction to the sort of argument I have given is to reply that a vitalist about life might have said the same things. For example, a vitalist might have claimed that it is logically possible that a physical replica of me might not be alive, in order to establish that life cannot be reductively explained. And a vitalist might have argued that life is a further fact, not explained by any account of the physical facts. But the vitalist would have been wrong. By analogy, might not the opponent of reductive explanation for consciousness also be wrong? I think this reaction misplaces the source of vitalist objections. Vitalism was mostly driven by doubt about whether physical mechanisms could perform all the complex functions associated with life: adaptive behavior, reproduction, and the like. At the time, very little was known about the enormous sophistication of biochemical mechanisms, so this sort of doubt was quite natural. But implicit in these very doubts is the conceptual point that when it comes to explaining life, it is the performance of various functions that needs to be explained. Indeed, it is notable that as physical explanation of the relevant functions gradually appeared, vitalist doubts mostly melted away. With consciousness, by contrast, the problem persists even when the various functions are explained. Presented with a full physical account showing how physical processes perform the relevant functions, a reasonable vitalist would concede that life has been explained. There is not even conceptual room for the performance of these functions without life. Perhaps some ultrastrong vitalist would deny even this, claiming that something is left out by a functional account of life—the vital spirit, perhaps. But the obvious rejoinder is that unlike experience, the vital spirit is not something we have independent reason to believe in. Insofar as there was ever any reason to believe in it, it was as an explanatory construct—"We must have such a thing in order to be able to do such amazing stuff." But as an explanatory construct, the vital spirit can be eliminated when we find a better explanation of how the functions are performed. Conscious experience, by contrast, forces itself on one as an explanandum and cannot be eliminated so easily. One reason a vitalist might think something is left out of a functional explanation of life is precisely that nothing in a physical account explains why there is something it is like to be alive. Perhaps some element of belief in a "vital spirit" was tied to the phenomena of one's inner life. Many have perceived a link between the concepts of life and experience, and even today it seems reasonable to say that one of the things that needs to be explained about life is the fact that many living creatures are conscious. But the existence of this sort of vitalist doubt is of no comfort to the proponent of reductive explanation of consciousness, as it is a doubt that has never been overturned. Objection 3: Is conceivability a guide to possibility? Philosophers are often suspicious of arguments that give a key role to conceivability, frequently responding that conceivability does not suffice for possibility. This is a subtle issue that I have discussed earlier and will dis cuss again: but here, the subtleties are not especially relevant. When it comes to matters of explanation, it is clear that conceivability is central. If on reflection we find it conceivable that all these physical processes could take place in the absence of consciousness, then no reductive explanation of consciousness will be satisfactory: the further question of why we exist and not zombies will always arise. Even if conceivability is tied to the limits of human capacity, explanation is tied to the limits of human capacity in a similar way. Another way to put the point is to note that reductive explanation of a phenomenon in terms of the physical requires an a priori implication from the physical facts to the relevant high-level facts (logical supervenience according to primary intension, as I put it earlier). If such a connection does not hold, then we will always be able to raise the further question of why the physical processes give rise to consciousness. We have seen that in almost all domains, the right sort of connection holds, making reductive explanation possible; but it does not seem to hold for conscious experience. One can question whether ontological views such as materialism turn on these a priori links—I discuss that matter in the next chapter—but when it comes to reductive explanation, such links are crucial. Objection 4: Isn't this a collection of circular intuitions? It might be further objected that the arguments I have given consist, at bottom, in a collection of intuitions. There is certainly a sense in which all these arguments are based on intuition, but I have tried to make clear just how natural and plain these intuitions are, and how forced it is to deny them. The main intuition at work is that there is something to be explained—some phenomenon associated with first-person experience that presents a problem not presented by observation of cognition from the third-person point of view. Given the premise that some explanandum is forced on us by first- person experience that is not forced on us by third-person observation, most of the arguments above fall out. It follows immediately, for example, that what needs to be explained cannot be analyzed as the playing of some functional role, for the latter phenomenon is revealed to us by third-person observation and is much more straightforward. The "intuition" at work here is the very raison d'etre of the problem of consciousness. The only consistent way to get around the intuitions is to deny the problem and the phenomenon altogether. One can always, at least when speaking "philosophically," deny the intuitions altogether, and deny that there is anything (apart from the performance of various functions) that needs explaining. But if one takes consciousness seriously, the conclusions for which I am arguing must follow.Objection 5: Doesn't all explanation have to stop somewhere? A final objection is that no explanation gives one something for nothing: all explanation has to stop somewhere. In explaining the motion of the planets, for example, one takes the laws of gravity and the existence of mass for granted. Perhaps we should simply take something for granted in this case, too? I am sympathetic with this point; I think we do have to take something for granted in explaining consciousness. But in doing so we inevitably move beyond a reductive explanation. Indeed, this sort of analogy lends support to the nonreductive position I am advocating. We take the laws of physics for granted because they are fundamental laws. If we take a link between physical processes and conscious experience for granted, this suggests that the link should be taken as fundamental in the same way. I return to this point in the next chapter.

翻译考点：
考点1：“consciousness/conscious”译为“意识/有意识的”

考点2：“logically supervene”译为“逻辑（地）随附”，逻辑随附（logical supervene）是相对自然随附（natura supervence）而言的固定用法，Chalmers 在The Conscious Mind（即本文节选）中将随附性分为两类，一是全局/局部随附；二是逻辑/自然随附。不应拆分进行翻译

考点3：“conscious experience”译为“意识经验”，“experience”直译可为“经验；体验”，虽然其含义包含个体独特体验的成分，但在哲学文本中，“experience”通常译为“经验”

考点4：“low-level physical story”译为“低阶物理描述”，心灵哲学术语是借鉴语言哲学、数理逻辑的专业术语来的，“low-level”固定译法为“低阶”

考点5：“zombie twin”译为“孪生僵尸”

考点6：“inverted twin”译为“颠倒孪生体”

考点7：“explanatory gap”译为“解释鸿沟”

考点8：“brute facts”译为“原始事实”

考点9：“bridging principles”译为“桥接原则”

考点10：“physical processing”译为“物理加工”，涉及过程状态的描述，一般将之视为“意识加工（conscious processing）”对应的结构，即“物理加工”

考点11：“phenomenal fields”译为“现象（性质）领域”，“phenomenal”是指“现象性质的”，现象性质是指某种独特的内在的非物理的心理体验（如看到某种颜色、感到疼痛等），而不是指某种公共现象，不应翻译为“现象场”，后文“phenomenal fields”翻译为“现象性质”同理

考点12：“conceptual truth”译为“概念真理”

考点13：“epistemic asymmetry”译为“认知反对称（性）”，“asymmetry"一般沿用逻辑学术语译为“反对称（性）”

考点14：“functional terms”译为“功能（性）词项”

考点15：“vitalist”译为“活力论者”，“vitalism”通常译为“活力论”，对应译为“活力论者”。

考点16：“vital spirit”译为“生命精神”或“活力灵魂”等

考点17：“conceivability/possibility”译为“可设想性/可能性”

考点18：“reflection”译为“反思”

考点19：“why we exist and not zombies will always arise”译为“为何是我们存在，而不是僵尸存在，这一问题总是会出现”

考点20：“a priori implication”译为“先天蕴涵”，目前“a priori”在分析哲学文本中有时也可译为“先验”，如在讨论先验/后验必然性的时候，但需要与传统哲学文本的“transcendental（超验）”区别开来，尤其不应对同一个英文词给出两个争议极大的汉译。

考点21：“primary intension”译为“首要(初始)内涵”，源于Chalmers的二维语义学，一般译为“首要(初始)内涵”

考点22：“no explanation gives one something for nothing”译为“没有哪个解释是无中生有的”

考点23：“nonreductive position ”译为“非还原立场”