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IS CONSCIOUSNESS A BRAIN PROCESS?
By U. T. PLACE
Institute of Experimental Psychology, University of Oxford
The thesis that consciousness is a process in the brain is put forward as a reasonable scientific hypothesis, not to be dismissed on logical grounds alone. The conditions under which two sets of observations are treated as observations of the same process, rather than as observations of two independent correlated processes, are discussed. It is suggested that we can identify consciousness with a given pattern of brain activity, if we can explain the subject's introspective observations by reference to the brain processes with which they are correlated. It is argued that the problem of providing a physiological explanation of introspective observations is made to seem more difficult than it really is by the 'phenomenological fallacy', the mistaken idea that descriptions of the appearances of things are descrip~ tions of the actual state of affairs 'in a mysterious internal environment.
I. INTRODUCTION The view that there exists a separate class of events, mental events, which cannot be described in terms of the concepts employed by the physical sciences no longer commands the universal and unquestioning acceptance amongst philosophers and psychologist.s which it once did. Modern physicalism, however, unlike the materialism of the seven- teenth and eighteenth centuries, is behaviouristic. Consciousness on this view is either a special type of behaviour, 'sampling' or 'running-back-and-forth' behaviour as Tolman (1932,p. 206) has it, or a disposition to behave in a certain way, an itch for example being f a temporary propensity to scratch. In the case of cognitive concepts like 'knowing', 'believing', 'understanding', 'remembering' and volitional concepts like 'wanting' and 'intending', there can be little doubt, I think, that an analysis in terms of dispositions to behave (Wittgenstein, 1953; Ryle, 1949) is fundamentally sound. On the other hand,
there would seem to be an intractable residue of concepts clustering around the notions of
consciousness, experience, sensation and mental imagery, where some sort of inner process story is unavoidable (Place, 1954). It is possible, of course, that a satisfactory behaviouristic account of this conceptual residuum will ultimately be found. For our present purposes, however, I shall assume that this cannot be done and that statements
about pains and twinges, about how things look, sound and feel, about things dreamed of
or pictured in the mind's eye, are statements referring to events and processes which are in some sense private or internal to the individual of whom they are predicated. The ques:. tion I wish to raise is whether in making this assumption we are inevitably committed to a dualist position in which sensations and mental images form a separate category of pro- cesses over and above the physical and physiological processes with, which they are known to be correlated. I shall argue that an acceptance of inner processes does not entail dualism and that the thesis that consciousness is a process in the brain cannot be dismissed on logical grounds.
II. THE 'IS' OF DEFINITION AND THE 'IS' OF COMPOSITION
I want to stress from the outset that in defending the thesis that consciousness is a process in the brain, I am not trying to argue that when we describe our dreams, fantasies and sensations we are talking about processes in our brains. That is, I am not claiming that
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statements about sensations and mental images are reducible to or analysable into state- ments about brain processes, in the way in which 'cognition statements' are analysable into statements about behaviour. To say that statements about consciousness are state- ments about brain processes is manifestly false. This is shown (a) by the fact that you can describe your sensations and mental imagery without knowing anything about your brain processes or even that such things exist, (b) by the fact that statements about one's consciousness and statements about one's brain processes are verified in entirely different ways and (c) by the fact that there is nothing self-contradictory about the statement
,X has a pain but there is nothing going on in his brain'. What I do want to assert, however,
is that the statement 'consciousness is a process in the brain', although not necessarily
true, is not necessarily false. 'Consciousness is a process in the brain', on my view is neither
self-contradictory nor self-evident; it is a reasonable scientific hypothesis, in the way that the statement' lightning is a motion of electric charges' is a reasonable scientific hypothesis. The all but universally accepted view that an assertion of identity between conscious- ness and brain processes can be ruled out on logical grounds alone, derives, I suspect, from a failure to distinguish between what we may call the' is' of definition and the' is' of composition. The distinction I have in mind here is the difference between the function
of the word 'is' in statements like' a square is an equilateral rectangle', 'red is a colour',
'to understand an instruction is to be able to act appropriately under the appropriate
circumstances', and its function in statements like' his table is an old packing case', 'her hat is a bundle of straw tied together with string', 'a cloud is a mass of water droplets or other particles in suspension'. These two types of 'is' statement have one thing in com-
mon. In both cases it makes sense to add the qualification' and nothing else'. In this they
differ from those statements in which the' is' is an 'is' of predication; the statements , Toby is 80 years old and nothing else', ' her hat is red and nothing else' or 'giraffes are tall and nothing else', for example, are nonsense. This logical feature may be described by saying that in both cases both the grammatical subject and the grammatical predicate are expressions which provide an adequate characterization of the state of affairs to which they both refer. In another respect, however, the two groups of statements are strikingly different. Statements like' a square is an equilateral rectangle' are necessary statements which are true by definition. Statements like' his table is an old packing case', on the other hand, are contingent statements which have to be verified by observation. In the case of state- ments like' a square is an equilateral -rectangle' or·'.red is a colour " there is a relationship between the meaning of the expression forming the grammatical predicate and the meaning of the expression forming the grammatical subject, such that whenever the subject expression is applicable the predicate must also be applicable. If you can describe something as red then you must also be able to describe it as coloured. In the case of statements like 'his table is an old packing case', on the other hand, there is no such relationship between the meanings of the expressions' his table' and 'old packing case'; it merely so happens that in this case both expressions are applicable to and at the same time provide an adequate characterization of the same object. Those who contend that the statement' consciousness is a brain process' is logically untenable base their claim, I suspect, on the mistaken assumption that if the meanings of two statements or expres- sions are quite unconnected, they cannot both provide an adequate characterization of the same object or state of affairs: if something is a state of consciousness, it cannot be a
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posed of tiny particles in suspension. There is no contradiction involved in supposing that clouds consist of a dense mass of fibrous tissue; indeed, such a consistency seems' to b'e implied by many of the functions performed by clouds in fairy stories and mythology. It is clear from this that the terms 'cloud' and 'mass of tiny particles in suspension' mean quite different things. Yet we do not conclude from this that there must be two things, the mass of particles in suspension and the cloud. The reason for this, I suggest, is that although the characteristics of being a cloud and being a mass of tiny particles in suspen- sion are invariably associated, we never make the observations necessary to verify the statement 'that is a cloud' and those necessary to verify the statement 'this is a mass of tiny particles in suspension' at one and the same time. We can observe the micro-structure of a cloud only when we are enveloped by it, a condition which effectively prevents us from observing those characteristics which from a distance lead us to describe it as a cloud. Indeed, so disparate are these two experiences that we use different words to describe them. That 'which is a cloud when we observe it from a distance becomes a fog or mist when we are enveloped by it.
IV. WHEN ARE TWO SETS OF OBSERVATIO~S OBSERVATIONS OF THE SAME EVENT~ The example of the cloud and the mass of tiny particles in suspension was chosen because it is one of the few cases of a general proposition involving what I have called the 'is'· of composition which does not involve us in scientific technicalities. It is useful because it brings out the connexion between the ordinary everyday cases of the' is' of composition like the table/packing case example and the more technical cases like 'lightning is a motion of electric charges' where the analogy with the consciousness/brain process case is most marked. The limitation of the cloud/tiny particles in suspension case is that it does not bring out sufficiently clearly the crucial problem of how the identity of the states of affairs referred to by the two expressions is established. In the cloud case the fact that something is a cloud and the fact that something is a mass of tiny particles in suspension are both verified by the normal processes of visual observation. It is arguable, moreoever, that the identity of the entities referred to by the two expressions is established by the con- tinuity between the two sets of observations as the observer moves towards or away from the cloud. In the case of brain processes and consciousness there is no such continuity be- tween the two sets of observations involved. A closer introspective scrutiny will never reveal the passage of nerve impulses over a thousand synapses in the way that a closer scrutiny of a cloud will reveal a mass' of tiny particles in suspension. The operations re- quired to verify statements about consciousness and statements about brain processes are fundamentally different. To find a parallel for this feature we must examine other cases where an identity is asserted between something whose occurrence is verified by the ordinary processes of observation and something whose occurrence is established by special scientific procedures. For this purpose I have chosen the case where we say that lightning is a motion of electric charges. As in the case of consciousness, however closely we scrutinize the lightning we shall never be able to observe the electric charges, and just as the operations for deter- mining the nature of one's state of consciousness are radically different from those involved in determining the nature of one's brain processes, so the operations for determining the occurrence of lightning are radically different from those involved in determining the occurrence of a motion of electric charges. What is it, therefore, that leads us to say that
48 I s consciousness a brain process?
the two sets of observations are observations of the same event1 It cannot be merely the fact that the two sets of observations are systematically correlated such that whenever there is lightning there is always a motion of electric charges. There are innumerable cases of such correlations where we have no temptation to say that the two sets of observations are observations of the same event. There is a systematic correlation, for example, be- tween the movement of the tides and the stages of the moon, but this does not lead us to say that records of tidal levels are records of the moon's stages or vice versa. We speak rather of a causal connexion between two independent events or processes. The answer here seems to be that we treat the two sets of observations as observations of the same event~ in those cases where the technical scientific observations set in the context of the appropriate body of scientific theory provide an immediate explanation of the observations made by the man in the street. Thus we conclude that lightning is nothing more than a motion of electric charges, because we know that a motion of electric charges through the atmosphere, such as occurs when lightning is reported, gives rise to the type of visual stimulation which would lead' an observer to report a flash of lightning. ' In the moon/tide case, on the other hand, there is no such direct causal connexion between the stages of the moon and the observations made by the man who measures the height of the tide. The causal connexion is between the moon and the tides, not between the moon and the measurement of the tides.
V. THE PHYSIOLOGICAL EXPLANATION OF INTROSPECTION AND
THE PHENOMENOLOGIOAL FALLACY If this account is correct, it should follow that in order to establish the identity of con- sciousness ,and certain processes in the brain, it would be necessary to show that the introspective observations reported by the subject can be accounted for in terms of pro- •
cesses which are known to have occurred in his brain. In the light of this suggestion it is
extremely interesting to find that when a physiologist as distinct from a philosopher finds it difficult to see how consciousness could be a process in the brain, what worries him is not any supposed self-contradiction involved in such an assumption, but the apparent impossibility of accounting for the reports given by the subject of his conscious processes in terms of the known properties of the central nervous system. Sir Charles Sherrington has posed the problem as follows: 'The chain of events stretching from the sun's radia- tion entering the eye to, on the one hand, the contraction of the pupillary muscles, and on the other, to the electrical disturbances in the brain-cortex are all straightforward steps in a sequence of physical" causation", such as, thanks to science, are intelligible. But in the second serial chain there follows on, or attends, the stage of brain-cortex reaction an event or set of events quite inexplicable to us, which both as to themselves and as to the causal tie between them and what preceded them science does not help us; a set of events seemingly incommensurable with any of the events leading up to it. The self" sees" the
sun; it senses a two-dimensional disc of brightness, located in the" sky", this last a field
of lesser brightness, and overhead shaped as a rather flattened dome, coping the self and a hundred other visual things as well. Of hint that this is within the head there is none. Vision is saturated with this strange property called "projection", the unargued inference that what it sees is at a "distance" from the seeing "self". Enough has been said to stress that in the sequence of events a step is reached where a physical situation in the
50 I s consciousness a brain process?
Once we rid ourselves of the phenomenological fallacy we realize that the problem of explaining introspective observations in terms of brain processes is far from insuperable. We realize that there is nothing that the introspecting subject says about his conscious experiences which is inconsistent with anything the physiologist might want to say about the brain processes which cause him to describe the environment and his consciousness of that environment in the way he does. When the subject describes his experience by saying that a light which is in fact stationary, appears to move, all the physiologist or physiological psychologist has to do in order to explain the subject's introspective obser- vations, is to show that the brain process which is causing the subject to describe his experience in this ~ay, is the sort of process which normally occurs when he is observing an actual moving object and which therefore normally causes him to report the movement of an object in his environment. Once the mechanism whereby the individual describes what is going on in his environment has been worked out, all that is required to explain the individual's capacity to make introspective observations is an explanation of his ability to discriminate between those cases where his normal habits of verbal description are appropriate to the stimulus situation and those cases where they are not and an explana- tion of how and why, in those cases where the appropriateness of his normal descriptive habits is in doubt, he learns to i~sue his ordinary descriptive protocols preceded by a quali- ficatory phrase like' it appears', 'seems', 'looks', 'feels', etc.
I am greatly indebted to my fellow-participants in a series of informal discussions on this topic which took place in the Department of Philosophy, University of Adelaide, in particular to Mr O. B. Martin for his persistent and searching criticism of my earlier attempts to defend the thesis that consciousness is a brain process, to Prof. D. A. T. Gasking, of the University of Melbourne, for clarifying many of the logical issues involved
and to Prof. J. J. O. Smart for moral support and encouragement in what often seemed a
lost cause.
REFERENCES
PLACE, U. T. (1954). The concept of heed. Brit. J. Psychol. 45, 243~55. RYLE, G. (1949). The Concept of Mind. London: Hutchinson. SHERRINGTON, SIR CHARLES (1947). Foreword to the 1947 edition of The Integrative Action of the N erVOU Sy8tem. Cambridge University Press. TOLMAN, E. C. (1932). Purp08ive Behaviour in Animals and Men. Berkeley and Los Angeles: University of California Press. WITTGENSTEIN, L. (1953). Philosophical Investigations. Oxford: Blackwell.
( Manuscript received 30 November 1954)
