Given the theory of event identity which I have just outlined, it follows that my having a red image in my visual field at noon cannot be the same event as some brain-event such as my C-fibres firing at noon. The substances and times (me and noon) involved are the same, but the properties are, as we saw earlier, different. Both descriptions seem to be intrinsic descriptions. The events are described in terms of what they are in themselves, not in terms of what they are in virtue of their surroundings. My having my C-fibres fire is not a matter of the event having certain causes or effects or certain conventions being operative in any society. The same goes, I suggest, for my having a red image. Yet ‘having C-fibres fire’ is not a part of ‘having a red image’ or conversely. I conclude that the two events are different events and neither is part of the other.
The identity theorist may attempt to deny this conclusion by claiming that to describe an event as a sensation, the instantiation of a sensory property, and more generally to describe an event in apparently mental terms, is to give an extrinsic description of it, to describe it in terms of its causes or effects. This claim was first made by J. J. C. Smart in 195939giving his ‘topic-neutral’ account of the sensory, and in more recent years it has been the hallmark of the form
of identity theory known as functionalism. Functionalism is the doctrine that apparent mental events are the particular events which they are (this sensation, that belief, or that desire) in virtue of the causes which normally bring them about and the effects which normally follow them, i.e. in my terminology, sensory or other apparently mental properties are properties of having a certain pattern of causes and/or effects. Thus, according to Smart: ‘When a person says, “I see a yellowish-orange after-image”, he is saying something like this: “There is something going on which is like what is going on when I have my eyes open, am awake, and there is an orange illuminated in good light in front of me, that is, when I really see an orange” ’.40To have an orange image is to have instantiated in you whatever
property is caused to be instantiated in people when they look at oranges. Again, according to the functionalist, to be in pain is to have instantiated in you whatever property is normally caused to be instantiated by
39 ‘Sensations and Brain Processes’, Philosophical Review, 1959, 68, 141–56 . Reprinted in many collections including Borst, op. cit. 40 Borst, p. 60.
bodily damage and gives rise to inclinations to withdraw the damaged part from the cause of the damage, cry out, etc. (Inclinations are to be understood in terms of what the subject would do, unless other properties are instantiated in him—such as courage, of which a similar functionalist account can be given.)41
So, say Smart and the functionalists, in describing an event in sensory terms, we describe it in terms of its causes and effects (or normal causes and effects), and so in my terminology we give it an extrinsic description. Science tells us which event it is which has, or has normally, those causes and effects—it is a brain-event. There is a kind of brain- event normally caused in us when we look at oranges; we therefore call such an event an orange image; when one such event occurs after the subject looks hard at and then away from some bright object, it is (in virtue of its normal causes and actual circumstances) an orange after-image. There is an event caused in me by sticking a pin in me, which leads to my crying out. It is a pain because of its causes and effects, and science could tell us which event it is which has those causes and effects—a particular brain-event.
The functionalist draws our attention to the fact that bodily malfunction may cause to be instantiated in different kinds of organism different brain or other bodily properties, which in turn cause the subject to cry out. The same stimulus and response may be connected by a different intervening bodily process. Pains may be events of different kinds of different organisms; they may be brain-events of this kind in humans, and of that kind in cats, and very different electrochemical events in Martians. But, say the functionalists, they are always going to be brain- or other bodily events—we have good reason to believe that science will so discover.
However, functionalism is totally unsatisfactory. One major difficulty is that an attempt to identify sensations as those events which have such and such causes and effects ignore the point that
41 For functionalism see, e.g. H. Putnam, ‘Minds and Machines’, ‘The Mental Life of Some Machines’, and ‘The Nature of Mental States’, in his Mind, Language and Reality,
Philosophical Papers, vol. 2, Cambridge University Press, 1975 . He writes: ‘I propose the hypothesis that pain, or the state of being in pain, is a functional state of a whole organism’ (p. 433), and he concludes that such identification ‘is to be tentatively accepted as a theory which leads to both fruitful predictions and fruitful questions, and which serves to discourage fruitless and empirically senseless questions, where by “empirically senseless” I mean “senseless” not merely from the standpoint of verification but from the standpoint of what there in fact is. ’ (p. 440).
‘the cause of x’ (where x is an individual event) hardly ever picks out a particular event (unless further guidance is provided explicitly or by the context), for the reason that x will normally have been brought into being by a chain of events, each of which is a cause of x. What causes the present position of the planets? Their position and that of the sun one minute ago; and so does their position and that of the sun two minutes ago (by causing their position and that of the sun one minute ago). And so on. A similar point goes for ‘the effect of x’. There is no one effect in me of my looking at an orange object; there is a chain of effects caused in me. There is no one effect of sticking a pin in me which causes me to cry out; there is a whole chain of events between the two. To which of such events are we referring by the words ‘orange image’ and ‘pain’? The answer is obvious. It is the sensory event, the experience. If we cannot distinguish a sensation from other effects of stimuli and causes of responses in us in some non-functionalist way (i.e. in virtue of their having some intrinsic description), we cannot give a functionalist account of sensations.
However, functionalism is still wrong in its major assumption. Sensations are not sensations of a certain kind in virtue of being the causes or effects of certain responses or stimuli, even if we specify them as the sensory causes or effects. Although we pick out and learn to talk about sensations of different kinds by describing them as the sensory causes or effects of certain public stimuli and responses (in the way analysed in the last chapter), we do not mean by a sensation of a certain kind the sensory cause or effect of stimuli and responses. For sensory properties are not causal properties. In referring to the sensory property of ‘having that taste caused by tea’, we are normally describing the property (and in so doing, picking it out by some non-essential characteristic), we are not naming the property. Having a red image may be having that sensory property which is in fact instantiated in a man when he looks at ripe tomatoes, etc.; it is not having whatever sensory property is instantiated in a man when he looks at ripe tomatoes, etc. For in another world ripe tomatoes might be yellow, and so might ripe strawberries, etc. We may identify having a red image by its being the property which is in fact caused in us when we look at certain things, but note that it is a contingent matter that it is so instantiated on these occasions.
fire at noon are both events described intrinsically. The properties involved are different, and intrinsic descriptions of the one do not entail intrinsic descriptions of the other. Hence the events are different. Certainly the one may be the cause of the other—my C-fibres firing may be the cause of my having a red image; and in that case the former may be redescribed as the event which caused my red-imaging. My C-fibres firing may cause red-imaging, but it is not red- imaging itself.
For the sake of completeness, I must discuss very briefly a theory of event-identity different from the one which I have put forward, which is now very popular. It is a theory similar to the ‘causal potentiality’ and ‘causal liability’ theories of property identity. This theory states that two events are the same if, and only if, they have the same causes and effects.42
This theory is different from the similar-looking theory of property identity, for events are actual particular occurrences and properties are universals which may be instantiated in many different circumstances. Indeed, unlike the similar property theory, it seems to me true—if taken in a very restricted sense. Suppose that there are two events E1and E2,
both of which have C as their cause and F as their sole effect. Now clearly E1and E2can be distinct events if they have
the same cause. Likewise they can still be distinct if by each causing F is meant only that each in the circumstances was sufficient for the occurrence of F, for F might then be over-determined—each event separately might have caused it (and would therefore also have done so in the absence of the other). This theory is plausible only if overdetermination is ruled out. But to say the latter is to say that there is only one event which is a sufficient cause for the occurrence of F. We have already said that E1 and E2 are both sufficient causes of F—so necessarily they must be the same event.
However, this theory is of no use as a criterion for determining whether or not two events E1and E2are identical, for it
is circular. It can only be applied, given a prior assumption that E1 and E2 are identical, or alternatively that they are
distinct. For suppose that E1 and E2 both occur caused by C, and are followed by F. Then, by
42 See for example D. Davidson ‘The Individuation of Events’ in (ed.) N. Rescher, Essays in Honor of Carl G. Hempel, Reidel, Dordrecht, 1969, p. 231 . For Davidson's argument
the suggested criterion, they are identical if each is sufficient for F and there is no overdetermination. But if E1and E2
are each sufficient for F, necessarily there will be overdetermination if E1and E2are distinct events but not if they are
the same event. So we need a further criterion for determining whether they are the same event, e.g. the one which I have put forward.43
It might be thought that my arguments prove too much. Is not much of science marked by discovery of identities which the arguments of this chapter would rule out? Not so. Science has discovered many identities of substances—water with H2O, light with electromagnetic radiation, etc.; but the arguments of this chapter do not
concern substance identity. Science has also discovered some property identities—e.g. a gas having a certain temperature with it consisting of molecules having a certain mean kinetic energy; and some event-identities—e.g. a certain flash of lightning with a certain electrical discharge. But these are not ruled out by my arguments. Consider the property identity. What does one mean when one says of a gas that it has such and such a temperature? Perhaps, today, one is not saying anything more than that its molecules have a certain mean kinetic energy. In that case, the cited identity is a necessary one, on the strongest criterion of property identity. Maybe two centuries ago, one was saying that it had a certain quantity of calorific fluid. But according to modern science that property cannot be identical with its consisting of molecules having a certain mean kinetic energy, for the reason that that property is never instantiated, as there is no calorific fluid. Maybe four centuries ago, one was saying that the gas felt to be a certain degree of heat. But that property is not identical at all with it consisting of molecules having a certain mean kinetic energy. The former property is a matter of the effect of the gas on human observers. The instantiation of one property may cause the instantiation of the other property but they are not the same property. But in making the claim in fairly recent years that ‘temperature is mean kinetic energy’, what I think scientists were saying is that the something, they knew not what but called
43 In Holistic Explanation, Clarendon Press, Oxford, 1979, pp. 134 f. , Christopher Peacocke in effect appeals to this theory to attempt to show the identity of mental and brain-
events. He seems to me, however, to beg a crucial factual question in assuming that each of his events is sufficient for the effect, and also the crucial logical issue in assuming as well the absence of overdetermination.
‘temperature’ which was measured by thermometers and in general accounted for the thermodynamic behaviour of gases, was in fact mean kinetic energy. That is, ‘temperature’ was not a name, but the definite description of a property. Temperature meant ‘the property which has the property of causing the thermodynamic behaviour of gases’. To equate that with mean kinetic energy is to put ‘temperature is mean kinetic energy’ in the same category as ‘blue is the colour of the sky’ (in the sense in which the latter is true). As we have seen, my arguments do not rule out such identities. But no such analysis can be given of having a red after-image or of having one's C-fibres fire. For one does
not mean by my having a red after-image my having some property which causes me to have some sensation.44
Similar points apply to the event-identity—‘this flash of lightning is such-and-such an electrical discharge’. What is meant by ‘lightning’? If the event of lightning is the event of the sky suddenly appearing bright, then this event is a different event from the electrical discharge. The former is the effect which the electrical discharge has on observers. There is no identity here. But if lightning is not the event of the sky lightning up but ‘the event (whatever it is) which causes the sky to light up’, then the lightning is indeed an electrical discharge of a certain kind. But again we cannot construe ‘my having a red after-image is my C-fibres firing’ on these lines, because we do not mean by ‘my having a red after-image’ the event which causes a certain sensation, but the sensation itself.
The possibility of normal scientific identification of public properties and events gives no encouragement to the philosopher seeking to identify apparent mental properties and events with brain properties and events.
We reached this conclusion by an analysis of our normal criteria for the identity of properties and events, which have the consequence that no scientific discoveries about causes and correlations could upset the distinction between a man's experiences and what goes on in his brain. It may be objected that these criteria are those of an out-of-date world-view and that we need
44 Kripke has a somewhat similar argument with respect to the similar sentence ‘heat is the motion of molecules’. See his ‘Identity and Necessity’ in (ed.) M. K. Munitz, Identity and Individuation, New York University Press, 1971, pp. 158–61 .
different criteria of property and event-identity for a new scientific age. But the whole function of science is to explain what happens, and all that these criteria seek to do is to distinguish as different events the different things that happen. They do not dictate to science how it shall explain, but only attempt to distinguish from each other the different things which need explaining. And science needs to explain both why certain things happen in the brain and why people have certain experiences. If it was able only to explain one of these things, there would be something occurring in the world which it had failed to explain. It is natural to call that something an event, and to use our ordinary criteria for event- identity and difference which bring out the evident fact that there are two separate things happening which require scientific explanation. Science must start from the data of experience, and these include sensations. And if it finds some of these too difficult to explain in terms of current theories, it should openly acknowledge this fact; not pretend that what it cannot explain does not exist.
Hard materialism claimed that apparent mental events such as sensations were really physical events. The behaviourist variant of hard materialism claimed that sensations were really just matters of public behaviour. I argued in the last chapter that behaviourism was false. In this chapter I have examined the alternative, mind/brain identity theory, variant of hard materialism which claims that sensations are brain-events; and developed a theory of event-identity which has the consequence that mind/brain identity theory is false. Both variants of hard materialism fail; and no one has ever suggested anything else physical beside public behaviour and brain-events which might constitute a man's sensations. Hard materialism fails, since there really are some events, viz. sensations, which are not physical events. That sensations are mental events, events about which the subject is necessarily in a better position to know than is anyone else, is indeed initially very plausible, as we saw in Chapter 1. For whatever ways an outsider has of finding out about my sensations I could use too (I could examine the evidence of stimulus and response), and yet I have a further way—by my experience of the sensation. Only under pressure of behaviourist or identity theory arguments is anyone likely to abandon this position, and we have now seen that those arguments do not work. Having argued for the mental nature of
sensations at some length in these two chapters and reached the conclusion that sensations are mental events, there will not be the same need for such lengthy arguments to show the mental nature of thoughts, purposings, desires, and beliefs. Brief arguments about these will, however, be given.