An Introduction to the Philosophy of Mind - Mental states

3 Mental states In the previous chapter, we focused on two important meta- physical questions in the philosophy of mind. One was the question of whether persons or subjects of experience are identical with their physical bodies, or certain parts of those bodies, such as their brains. The other was the question of whether the mental states of persons, such as thoughts and feelings, are identical with certain physical states of their bodies, such as states of neuronal activity in their brains. Many materialists would endorse positive answers to both of these questions, although later in this chapter we shall encounter a species of materialism which denies that mental states, as we ordinarily conceive of them, really exist at all. But before we examine that position, it is worth remarking that, so long as one is a realist about mental states – that is, so long as one considers that states of thinking and feeling really do exist – one can, for many purposes, afford to remain neutral with regard to the question of whether or not mental states are identical with physical states. There are many issues in the philosophy of mind which we can usefully discuss without presuming to be able to resolve that question. And this is just as well, knowing as we now do how thorny a ques- tion it is. One of these issues is that of how we can best characterise and classify the various different kinds of mental state which, if we are realists, we believe to exist. So far we have been talking about mental states quite generally, with- out differentiating between them in any significant fashion. But in a detailed description of the mental lives of persons we need to be able to distinguish, in principled ways, between 39 An introduction to the philosophy of mind40 sensations, perceptions, beliefs, desires, intentions, fears, and many other kinds of mental state: and providing a satisfact- ory account of these distinctions is no easy matter. It is to the difficulties besetting that task that we shall turn in this chapter. PROPOSITIONAL ATTITUDE STATES Let us begin by considering those mental states that philo- sophers like to call propositional attitude states. For brevity, I shall refer to them as ‘attitudinal states’. These include beliefs, desires, intentions, hopes and fears, to name but a few. A common feature of such states is that we may ascribe them to subjects of experience by using statements of the form ‘S φs that p’. Here ‘S’ denotes a particular subject or person, ‘p’ stands for some proposition – for example, the proposition that it is raining – and ‘φ’ represents any so- called verb of propositional attitude, such as ‘believe’, ‘hope’ or ‘fear’. Such verbs are called ‘verbs of propositional atti- tude’ because each of them is considered to express a particu- lar attitude which a subject may have towards a proposition. (What propositions are and how subjects can have ‘attitudes’ towards them are matters which we shall take up more fully in the next chapter.) Thus, the following sentences can all be used to ascribe attitudinal states to subjects: ‘John believes that it is raining’, ‘Mary hopes that she has an umbrella’, and ‘Ann fears that she will get wet’. In each case, the ‘that’ clause expresses the propositional content of the atti- tudinal state which is being ascribed. A number of questions immediately arise concerning attitudinal states and our knowledge of them. For instance: what, exactly, makes a belief, say, different from a hope or a fear? One and the same subject may simultaneously possess two different attitudinal states with the same propositional content: for example, Ann may both fear that she will get wet and believe that she will get wet. What does this difference of ‘attitude’ to one and the same proposition amount to? Again, how do we know what attitudinal states another person possesses – indeed, how do we know what attitudinal states we ourselves possess? Notice Mental states 41 here that knowledge itself is an attitudinal state, so that knowledge of someone’s attitudinal states appears to be a ‘second-order’ attitudinal state – as in the case of John’s knowing that Ann fears that she will get wet, or John’s know- ing that he himself believes that it is raining. We may be inclined to think that there is no special prob- lem about identifying our own attitudinal states, at least at the times at which we possess them. Surely, if I have any beliefs, desires, hopes or fears right now, then I, at least, must know what they are, even if no one else does. Descartes certainly seems to have assumed that this is so. But how do I know? Perhaps it will be suggested that I know by a process of ‘reflection’ or ‘introspection’, which somehow reveals to me what I am thinking and feeling. After all, if someone asks me whether I believe or desire such-and-such, I am usually able to reply fairly spontaneously, so it seems that I must have some sort of direct access to my own attitudinal states. On the other hand, perhaps the feeling of having such a direct or ‘privileged’ access to one’s own attitudinal states is just an illusion. Perhaps I find out what I believe, for example, by hearing myself express my beliefs in words, whether out loud to other people or just sotto voce to myself. This would make my knowledge of my own beliefs no differ- ent in principle from my knowledge of other people’s beliefs, which I commonly discover by hearing them express them. Of course, sometimes I can form a good idea of someone’s beliefs on the basis of their non-verbal behaviour, as when I judge that John believes that it is raining when I see him open his umbrella. But perhaps the same is true, at times, with regard to my knowledge of my own beliefs – as when I surprise myself by the fact that I have taken a certain turning at a road junction and realise that I must believe that it will take me to my desired destination. (We shall explore the nature of self-knowledge more fully in chapter 10.) BEHAVIOURISM AND ITS PROBLEMS There are some philosophers who are extremely sceptical about the reliability – or, indeed, the very existence – of An introduction to the philosophy of mind42 introspection as a source of knowledge about our own mental states. At its most extreme, this scepticism finds expression in the doctrine known as behaviourism. Behaviourists hold that the only sort of evidence that we can have concerning any- one’s mental states, including our own, lies in people’s out- wardly observable behaviour, both verbal and non-verbal. ‘Scientific’ behaviourists take this view because they think that a science of mental states – which is what scientific psy- chology in part claims to be – ought only to rely upon object- ive empirical evidence which can be corroborated by many independent observers, whereas introspection is necessarily a private and subjective affair. But more radical behaviour- ists – those who are sometimes called ‘logical’ behaviourists – would go even further than this. They maintain that what it is to ascribe a mental state to a person is nothing more nor less than to ascribe to that person some appropriate behavi- oural disposition. 1 A ‘behavioural disposition’, in the sense understood here, is a person’s tendency or propensity to behave in a certain way in certain specified circumstances. Thus, for instance, a logical behaviourist might suggest that to ascribe to John a belief that it is raining is simply to ascribe to him a disposition to do such things as: take an umbrella with him if he leaves the house, turn on the wind- screen wipers if he is driving the car, assert that it is raining if he is asked what the weather is like – and so on. The list must, of course, be an open-ended one, since there is no limit to the ways in which someone might evince the belief in ques- tion. This sort of account is intended to apply not only to what we have been calling ‘attitudinal’ states, but also to what we might call sensational states, such as pain and nausea. To be in pain – for example, to feel a sharp twinge in one’s big toe – is not to have some attitude towards a proposition: pains do not have ‘propositional content’. But the logical behaviourist will once again contend that to ascribe to John 1 A sophisticated version of logical behaviourism is developed by Gilbert Ryle in his The Concept of Mind (London: Hutchinson, 1949). See especially p. 129, for Ryle’s account of belief. Mental states 43 a feeling of pain in his big toe is simply to ascribe to him a disposition to do such things as: wince and groan if the toe is touched, hobble along if he has to walk, assert that his toe hurts if he is asked how it feels – and so on. The list is, once again, an open-ended one. Now, the very fact that such lists of behaviour are necessar- ily open-ended ones presents a problem for logical behaviour- ism. Take the list of activities associated with John’s belief that it is raining. What can possibly be meant by saying that John has a disposition to do ‘such things’ as are on this list? What unifies the items on the list, other than the fact that they are the sorts of things that one might reasonably expect a person to do who believes that it is raining? It seems that one must already understand what it means to ascribe to some- one a belief that it is raining in order to be able to generate the items on the list, so that the list cannot be used to explain what it means to ascribe to someone such a belief. Even set- ting aside this difficulty, however, there is another and still more serious problem which besets the logical behaviourist’s account. Take again John’s belief that it is raining. The prob- lem is that someone may perfectly well possess this belief and yet fail to do any of the things on the associated list in the appropriate circumstances. Thus John may believe that it is raining and yet leave his umbrella at home when he goes out, fail to switch on the windscreen wipers when he is driv- ing, deny that it is raining when he is asked about the weather, and so on. This is because how a person who pos- sesses a certain belief behaves in given circumstances does not depend solely upon what that belief is, but also upon what other attitudinal states that person may happen to possess at the same time, such as his or her desires. John may, for instance, be unusual in that he likes to get wet in the rain and so never takes an umbrella with him when he believes that it is raining. Indeed, whatever behaviour the logical beha- viourist attempts to represent as being characteristic of someone who believes that it is raining, it is possible to envis- age a person who holds that belief and yet is not disposed to behave in that way, if only because such a person might have An introduction to the philosophy of mind44 a very strong desire to deceive others into thinking that he or she does not hold that belief. The same is true with regard to a person’s sensational states: one may feel a pain in one’s big toe and yet suppress the kinds of behaviour which the logical behaviourist says are definitive of feeling such a pain, because one is determined to be stoical about it or does not want to appear weak. So we see that there can in fact be no such thing as behaviour that is uniquely characteristic of someone who possesses an attitudinal state with a given propositional content or a sensational state of a certain type. And consequently it is impossible to explain what it means for someone to possess such a state in terms of his or her sup- posed behavioural dispositions. ‘Logical’ behaviourism is clearly doomed to failure. However, the failure of logical behaviourism still leaves untouched the weaker form of behaviourism mentioned earl- ier, which is espoused by ‘scientific’ behaviourists. This merely maintains that the only evidence on whose basis attitudinal and other mental states can be ascribed to subjects is behavioural evidence, that is, publicly available evidence of how people behave in various circumstances. We could perhaps call this ‘epistemic’ behaviourism, because it concerns our knowledge of mental states rather than the nature of those states them- selves. Logical behaviourism entails epistemic behaviourism, but not vice versa – which is why I have described epistemic behaviourism as being the weaker doctrine. However, epi- stemic behaviourism, unlike logical behaviourism, does not offer us any account of what mental states are, so it needs to be supplemented by such an account – an account which must, of course, be consistent with what the epistemic behaviourist has to say concerning our evidence for the existence of mental states. Is a satisfactory account of this sort available? Many contem- porary philosophers of mind would say that it is, in the form of a doctrine known as functionalism. FUNCTIONALISM Functionalism acknowledges the fact that it is impossible to identify types of mental state with types of behavioural dis- Mental states 45 position, but it still wishes to characterise mental states by reference to behaviour, albeit only indirectly. It tries to achieve this by characterising mental states in terms of the causal roles they are thought to play in determining how a subject behaves in different circumstances. 2 (Another term for ‘causal role’ in this sense is ‘functional role’: hence the name ‘functionalism’.) According to functionalism, three dif- ferent kinds of causal relationship can be involved in the make-up of a mental state’s causal role. (Here, it should be emphasised, we are primarily talking about types of mental state, although by implication also about particular instances, or tokens, of those types: I shall say more about the type/token distinction in due course.) First, there are charac- teristic ways in which states of a subject’s environment can cause that subject to have a certain type of mental state, as when injury to one’s leg causes one to feel pain in it, or when light falling upon one’s eyes causes one to experience a visual sensation. Secondly, there are characteristic ways in which a certain type of mental state can interact causally with other mental states of the same subject, as when a feeling of pain in one’s leg causes one to believe that the leg has been injured, or when a visual experience causes one to believe that one is seeing something. And third, there are character- istic ways in which a certain type of mental state can contrib- ute causally to the bodily behaviour of its subject, as when a belief that one’s leg has been injured, together with a desire to relieve the consequent pain, can cause one to rub the affec- ted part of the leg or withdraw the leg from harm’s way. Thus, to a first approximation, the functionalist might say that the causal role of a feeling of pain in one’s leg is to signal the occurrence of a physical injury to the leg, cause one to believe that such an injury has occurred, and thereby help to bring it about that one acts in such a way as to repair the damage done and avoid any further injury of a similar kind. 2 One of the founders of functionalism was Hilary Putnam: see his ‘The Nature of Mental States’ (1967), reprinted in W.G. Lycan (ed.), Mind and Cognition: A Reader (Oxford: Blackwell, 1990). An introduction to the philosophy of mind46 We see, then, that functionalism is committed to regarding mental states as really existing states of subjects which can properly be referred to in causal explanations of the overt behaviour of the persons whose states they are. But it reco- gnises that how a person behaves in given circumstances can never be accounted for simply in terms of the fact that he or she possesses a mental state of this or that type, since an adequate explanation of behaviour will always need to take into account the causal interactions which can occur between different mental states of the same subject. Consequently, functionalists acknowledge that the behavioural evidence for ascribing mental states to a subject is always open to many alternative interpretations and that often the best that we can hope to do, in the light of a given subject’s circumstances and pattern of behaviour, is to assign a reasonably high degree of probability to the hypothesis that that subject pos- sesses a certain combination of mental states of various types, on the grounds that such a combination of mental states would most plausibly explain the subject’s behaviour in these circumstances. Suppose, for example, that John exhibits the following behaviour when, on a particular occasion, it starts to rain as he is walking to work: he unfolds his umbrella and puts it up. Part of an explanation of this behaviour might be that John believes that it is raining. However, it will be reason- able to ascribe this belief to John in partial explanation of his behaviour only if it is also reasonable to ascribe to John certain other mental states which are suitably causally related to that supposed belief of his – for instance, a sensation of wetness on his skin, a desire to remain dry, a memory that he has brought his umbrella with him, and a hope that putting up an umbrella in these circumstances will help to keep him dry. However, in the light of John’s behaviour in other cir- cumstances, it might well be the most likely hypothesis in the present case that his current behaviour is indeed the result of his possessing this particular combination of mental states. In many respects, mental states as characterised by func- tionalism are rather like ‘software’ states of a computer, which may likewise be characterised in terms of their rela- Mental states 47 tions to the computer’s ‘inputs’, other software states of the computer, and the computer’s ‘outputs’. By a ‘software’ state of a computer, I mean, for instance, its storing of a particular piece of information – which, on the proposed analogy, may be likened to a subject’s possession of a certain belief. Such a software state may be contrasted with a ‘hardware’ state of the computer, such as an electromagnetic state of certain of its circuits, which might correspondingly be likened to a neural state of a person’s brain. The computer’s ‘inputs’ are, for example, keystrokes on its keyboard, while its ‘outputs’ are, for example, patterns displayed on its video screen: and these again might be likened, respectively, to stimulations of a subject’s sensory organs and movements of his or her body. Indeed, for many functionalists, this is more than just an analogy, since they think of the human brain as being, in effect, a biological computer fashioned through eons of evolu- tion by processes of natural selection. According to this view, just as the biological function of the heart is to circulate blood through the body and thereby keep it oxygenated and nourished, so the biological function of the brain is to gather information from the body’s environment, ‘process’ that information in accordance with certain ‘programmes’ which have been ‘installed’ in it either by genetic evolution or else through processes of learning, and finally to use that informa- tion to guide the body’s movements about its environment. How seriously or literally we can take this as an account of what the brain really does is a matter we shall discuss more fully in chapter 8. But as a model for the functionalist’s con- ception of mental states the analogy with software states of a computer is certainly an apt one. Indeed, as a matter of historical fact, it would appear that the computational model provided an important source of inspiration for functionalism. 3 3 See again Putnam, ‘The Nature of Mental States’, and also Alan M. Turing, ‘Com- puting Machinery and Intelligence’, Mind 59 (1950), pp. 433–60, reprinted in Margaret A. Boden (ed.), The Philosophy of Artificial Intelligence (Oxford: Oxford University Press, 1990). An introduction to the philosophy of mind48 FUNCTIONALISM AND PSYCHOPHYSICAL IDENTITY THEORIES It is important to appreciate that functionalism is noncom- mittal on the question of whether mental states can be identi- fied with physical states of a subject’s brain – and this is often held to be one of its advantages. Identity theories, in this context, fall into two classes: those which maintain that every type of mental state can be identified with some type of phys- ical state (type–type identity theories) and those which main- tain only that every token mental state can be identified with some token physical state (token–token identity theories). The type/token distinction, which is of perfectly general applica- tion, can be illustrated by the following example. If it is asked how many letters I write when I write the word ‘tree’, the correct answer is either three or four, depending on whether one is concerned with letter-types or letter-tokens, because what I write includes one token of each of the letter-types ‘t’ and ‘r’, but two tokens of the letter-type ‘e’. Now, in contem- porary philosophy of mind, type–type identity theories have been called into question on the grounds that types of mental state are, plausibly, ‘multiply realisable’. For instance, it is urged that it is implausible to suggest that pain of a certain type is identical with a certain type of neuronal activity, because it seems conceivable that creatures with very differ- ent types of neural organisation might nonetheless be cap- able of experiencing pains of exactly the same type. The com- puter analogy once again seems apt, for in a similar way it is possible for two computers to be in the same ‘software’ state even while possessing very different ‘hardware’ states – for example, they might be running the same programme but implementing it on very different computing machinery. But rejection of any type–type theory of mental and physical states is consistent with acceptance of a token–token theory, that is, a theory according to which any token mental state, such as a pain that I am now feeling in my left big toe, is identical with some token physical state, such as a certain state of neuronal activity now going on in my brain. Such a [...]... helpful introductory essay, ‘What is Functionalism?’ I should perhaps emphasise that functionalism is a family of views rather than a single doctrine, some of its proponents regarding it more as an account of our concepts of mental states than as a theory of the nature of mental states themselves 52 An introduction to the philosophy of mind ing an adequate account of the character of mental states, leaves... asymmetry between ‘first-person’ and ‘third-person’ knowledge of mental states – the knowledge of such states which one has in virtue of being a subject of such states oneself and the knowledge of such states which one has in virtue of being an observer of other subjects of such states This makes mental states quite different from any of the other kinds of state known to empirical science, all of which are studied... Foundations of Psychology, Minnesota Studies in the Philosophy of Science, Volume 9 (Minneapolis: University of 60 An introduction to the philosophy of mind that, since functionalism contends that all that is required for certain states of an object to qualify as mental states of certain types is that those states should stand in appropriate causal relations to each other and to states of certain other types... that they are all played with in accordance with the rules Mental states 51 governing the movements of the bishop Alternatively, however, one might think of identifying the type to which our particular chessman belongs in terms of the type of material object which plays the role of the bishop in the chess set of which this chessman is a member Analogously, then, if we conceive the type to which a token... 66 An introduction to the philosophy of mind chapter 9 But there is, in any case, another reason for contending that ‘folk psychology’ is not any sort of theory of human behaviour This is that – or so many philosophers and psychologists would now maintain – when we form expectations of how people will behave on the basis of the beliefs and desires which we attribute to them, we are not ‘predicting’ their... For a well-known exposition of verificationism, see A J Ayer, Language, Truth and Logic, 2nd edn (London: Victor Gollancz, 1946) 56 An introduction to the philosophy of mind different people exactly what is involved in the case of a single person in the intrapersonal case Another possible response for the functionalist is to argue that, when we look into the details of the hypothetical case of interpersonal... would-be scientific theory Very arguably, when we ascribe beliefs and desires to people and attempt to understand their behaviour in terms of their possession of such mental states, we are not doing anything at all analogous to what scientists do when they explain the movements of massive bodies by reference to the forces acting upon them For one thing, explanations framed in terms of beliefs and desires... the important work of Jaegwon Kim in this area, collected in his Supervenience and Mind: Selected Philosophical Essays (Cambridge: Cambridge University Press, 1993) The topic of supervenience is too complex and large, however, for me to do it justice in the present book 50 An introduction to the philosophy of mind suitable pattern of causal relationships, as may the states of a bundle of human neurones,... engrained in us, probably having an evolutionary basis in our hominid ancestors’ need to cooperate and compete effectively with other members of a closely knit group As such, these patterns of thinking are not to be viewed as a proto-scientific theory of human behaviour but, rather, as part of what it is to be a human being capable of engaging meaningfully with other human beings They are not dispensable intellectual... characterise mental states in terms of the patterns of causal relations which they need to bear to other states, both mental and physical, in order to qualify as mental states of this or that type: it consequently leaves entirely open the question of what, if any, intrinsic properties mental states must have (An intrinsic property is one which something has independently of how it is related to other things: . of any type–type theory of mental and physical states is consistent with acceptance of a token–token theory, that is, a theory according to which any token. the nature of mental states themselves. An introduction to the philosophy of mind5 2 ing an adequate account of the character of mental states, leaves