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 | |  The Modal Argument | |
The Modal ArgumentThere is an argument, which has roots in Descartes (Meditation VI), which is a modal argument for dualism. One might put it as follows:[list="margin-top: 0.5em; color: rgb(26, 26, 26); font-family: serif; font-size: 16.5px; line-height: 21px; background-color: rgb(255, 255, 255);"] [*]It is imaginable that one's mind might exist without one's body. therefore [*]It is conceivable that one's mind might exist without one's body. therefore [*]It is possible one's mind might exist without one's body. therefore [*]One's mind is a different entity from one's body. [/list] The rationale of the argument is a move from imaginability to real possibility. I include (2) because the notion of conceivability has one foot in the psychological camp, like imaginability, and one in the camp of pure logical possibility and therefore helps in the transition from one to the other.This argument should be distinguished from a similar ‘conceivability’ argument, often known as the ‘zombie hypothesis’, which claims the imaginability and possibility of my body (or, in some forms, a body physically just like it) existing without there being any conscious states associated with it. (See, for example, Chalmers (1996), 94–9.) This latter argument, if sound, would show that conscious states were something over and above physical states. It is a different argument because the hypothesis that the unaltered body could exist without the mind is not the same as the suggestion that the mind might continue to exist without the body, nor are they trivially equivalent. The zombie argument establishes only property dualism and a property dualist might think disembodied existence inconceivable—for example, if he thought the identity of a mind through time depended on its relation to a body (e.g., Penelhum 1970).Before Kripke (1972/80), the first challenge to such an argument would have concerned the move from (3) to (4). When philosophers generally believed in contingent identity, that move seemed to them invalid. But nowadays that inference is generally accepted and the issue concerns the relation between imaginability and possibility. No-one would nowadays identify the two (except, perhaps, for certain quasi-realists and anti-realists), but the view that imaginability is a solid test for possibility has been strongly defended. W. D. Hart ((1994), 266), for example, argues that no clear example has been produced such that “one can imagine that p (and tell less imaginative folk a story that enables them to imagine that p) plus a good argument that it is impossible that p. No such counterexamples have been forthcoming…” This claim is at least contentious. There seem to be good arguments that time-travel is incoherent, but every episode of Star-Trek or Doctor Who shows how one can imagine what it might be like were it possible.It is worth relating the appeal to possibility in this argument to that involved in the more modest, anti-physicalist, zombie argument. The possibility of this hypothesis is also challenged, but all that is necessary for a zombie to be possible is that all and only the things that the physical sciences say about the body be true of such a creature. As the concepts involved in such sciences—e.g., neuron, cell, muscle—seem to make no reference, explicit or implicit, to their association with consciousness, and are defined in purely physical terms in the relevant science texts, there is a very powerful prima facie case for thinking that something could meet the condition of being just like them and lack any connection with consciousness. There is no parallel clear, uncontroversial and regimented account of mental concepts as a whole that fails to invoke, explicitly or implicitly, physical (e.g., behavioural) states.For an analytical behaviourist the appeal to imaginability made in the argument fails, not because imagination is not a reliable guide to possibility, but because we cannot imagine such a thing, as it is a priori impossible. The impossibility of disembodiment is rather like that of time travel, because it is demonstrable a priori, though only by arguments that are controversial. The argument can only get under way for those philosophers who accept that the issue cannot be settled a priori, so the possibility of the disembodiment that we can imagine is still prima facie open.A major rationale of those who think that imagination is not a safe indication of possibility, even when such possibility is not eliminable a priori, is that we can imagine that a posteriori necessities might be false—for example, that Hesperus might not be identical to Phosphorus. But if Kripke is correct, that is not a real possibility. Another way of putting this point is that there are many epistemic possibilities which are imaginable because they are epistemic possibilities, but which are not real possibilities. Richard Swinburne (1997, New Appendix C), whilst accepting this argument in general, has interesting reasons for thinking that it cannot apply in the mind-body case. He argues that in cases that involve a posteriori necessities, such as those identities that need discovering, it is because we identify those entities only by their ‘stereotypes’ (that is, by their superficial features observable by the layman) that we can be wrong about their essences. In the case of our experience of ourselves this is not true.Now it is true that the essence of Hesperus cannot be discovered by a mere thought experiment. That is because what makes Hesperus Hesperus is not the stereotype, but what underlies it. But it does not follow that no one can ever have access to the essence of a substance, but must always rely for identification on a fallible stereotype. One might think that for the person him or herself, while what makes that person that person underlies what is observable to others, it does not underlie what is experienceable by that person, but is given directly in their own self-awareness.This is a very appealing Cartesian intuition: my identity as the thinking thing that I am is revealed to me in consciousness, it is not something beyond the veil of consciousness. Now it could be replied to this that though I do access myself as a conscious subject, so classifying myself is rather like considering myself qua cyclist. Just as I might never have been a cyclist, I might never have been conscious, if things had gone wrong in my very early life. I am the organism, the animal, which might not have developed to the point of consciousness, and that essence as animal is not revealed to me just by introspection.But there are vital differences between these cases. A cyclist is explicitly presented as a human being (or creature of some other animal species) cycling: there is no temptation to think of a cyclist as a basic kind of thing in its own right. Consciousness is not presented as a property of something, but as the subject itself. Swinburne's claim that when we refer to ourselves we are referring to something we think we are directly aware of and not to ‘something we know not what’ that underlies our experience seemingly ‘of ourselves’ has powerful intuitive appeal and could only be overthrown by very forceful arguments. Yet, even if we are not referring primarily to a substrate, but to what is revealed in consciousness, could it not still be the case that there is a necessity stronger than causal connecting this consciousness to something physical? To consider this further we must investigate what the limits are of the possible analogy between cases of the water-H2O kind, and the mind-body relation.We start from the analogy between the water stereotype—how water presents itself—and how consciousness is given first-personally to the subject. It is plausible to claim that something like water could exist without being H2O, but hardly that it could exist without some underlying nature. There is, however, no reason to deny that this underlying nature could be homogenous with its manifest nature: that is, it would seem to be possible that there is a world in which the water-like stuff is an element, as the ancients thought, and is water-like all the way down. The claim of the proponents of the dualist argument is that this latter kind of situation can be known to be true a priori in the case of the mind: that is, one can tell by introspection that it is not more-than-causally dependent on something of a radically different nature, such as a brain or body. What grounds might one have for thinking that one could tell that a priori?The only general argument that seem to be available for this would be the principle that, for any two levels of discourse, A and B, they are more-than-causally connected only if one entails the other a priori. And the argument for accepting this principle would be that the relatively uncontroversial cases of a posteriori necessary connections are in fact cases in which one can argue a priori from facts about the microstructure to the manifest facts. In the case of water, for example, it would be claimed that it follows a priori that if there were something with the properties attributed to H2O by chemistry on a micro level, then that thing would possess waterish properties on a macro level. What is established a posteriori is that it is in fact H2O that underlies and explains the waterish properties round here, not something else: the sufficiency of the base—were it to obtain—to explain the phenomena, can be deduced a priori from the supposed nature of the base. This is, in effect, the argument that Chalmers uses to defend the zombie hypothesis. The suggestion is that the whole category of a posteriori more-than-causally necessary connections (often identified as a separate category of metaphysical necessity) comes to no more than this. If we accept that this is the correct account of a posteriori necessities, and also deny the analytically reductionist theories that would be necessary for a priori connections between mind and body, as conceived, for example, by the behaviourist or the functionalist, does it follow that we can tell a priori that consciousness is not more-than-causally dependent on the body?It is helpful in considering this question to employ a distinction like Berkeley's between ideasand notions. Ideas are the objects of our mental acts, and they capture transparently—‘by way of image or likeness' (Principles, sect. 27)—that of which they are the ideas. The self and its faculties are not the objects of our mental acts, but are captured only obliquely in the performance of its acts, and of these Berkeley says we have notions, meaning by this that what we capture of the nature of the dynamic agent does not seem to have the same transparency as what we capture as the normal objects of the agent's mental acts. It is not necessary to become involved in Berkeley's metaphysics in general to feel the force of the claim that the contents and internal objects of our mental acts are grasped with a lucidity that exceeds that of our grasp of the agent and the acts per se. Because of this, notions of the self perhaps have a ‘thickness’ and are permanently contestable: there seems always to be room for more dispute as to what is involved in that concept. (Though we shall see later, in 5.2.2, that there is a ‘non-thick’ way of taking the Berkeleyan concept of a notion.). Because ‘thickness’ always leaves room for dispute, this is one of those cases in philosophy in which one is at the mercy of the arguments philosophers happen to think up. The conceivability argument creates a prima facie case for thinking that mind has no more than causal ontological dependence on the body. Let us assume that one rejects analytical (behaviourist or functionalist) accounts of mental predicates. Then the above arguments show that any necessary dependence of mind on body does not follow the model that applies in other scientific cases. This does not show that there may not be other reasons for believing in such dependence, for so many of the concepts in the area are still contested. For example, it might be argued that identity through time requires the kind of spatial existence that only body can give: or that the causal continuity required by a stream of consciousness cannot be a property of mere phenomena. All these might be put forward as ways of filling out those aspects of our understanding of the self that are only obliquely, not transparently, presented in self-awareness. The dualist must respond to any claim as it arises: the conceivability argument does not pre-empt them. | |
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