Logical Positivism, and Ryle in particular, prepared the way for the modern theories of mind that reject the existence of a spiritual substance called Mind or Soul. The universe is entirely “material”, hence all mental phenomena are reducible to matter. The brain is at the centre of all modern day debates about the Mind or Soul, from theories that stress identity between the mind and the brain, to theories that claim that all mental states are caused entirely by physical states in the brain as a result of constant stimuli from the external or internal world. As science advances we become more aware of the possibilities of the extremely complicated biological system that is our brain. Some modern philosophers have stressed the analogy between the functioning of the human brain and the functioning of digital computers; some would say that the brain is just a very sophisticated computer and the mind is just a computer program, that is, the mind is to the brain what the program is to the computer hardware. Most people who hold this view think we have not yet designed programs which are minds; but they believe that it is only a matter of time until computer scientists and workers in artificial intelligence design the appropriate hardware and programs which will be equivalent of human brains and minds. M. Minski, one of such philosophers, believes that “the next generation of computers will be so intelligent that we will be lucky if they are willing to keep us around the house as household pets”!
The belief that a human being is made up of two completely different “substances”, soul and body, spirit and matter, has been a very constant and widespread belief in the history of the human race. Belief in the immortality of the soul is to be found everywhere right from the beginning of human evolution, and all major religions have always subscribed to some forms of life after death. For Socrates and Plato, the pre-existent immortal soul is forced into the prison of the body from which it will be released again with death, to live blissfully in heaven or to be re-incarnated for another chance of bettering itself. For the Hindu sacred book, The Upanishad, the body is like a garment that is discarded at death, leaving the soul free to join God if it has achieved perfection or to be re-incarnated in another body. Belief in immortality of the soul is a constant in human history.
Modern philosophers, however, credit Descartes for producing the most systematic theory of man as a being made up of two different “substances”, the Mind and the Body. In the Meditations, Descartes proves systematically that whereas we can have absolute certainty that we exist as minds, we may well doubt that we have a body and we can prove that we do have a body only after proving that God exists. For Descartes the essential man is mind; his body is not essential to him. Whether I got a body or not, I am totally myself when I perceive myself as a thinking being. Indeed, when my body dies, I am still myself. Given this view of two separate substances, the thinking substance and the bodily substance, how do the two substances interact? This is the famous Cartesian Dualism. We are made up of two opposite things: the mind (spiritual, indivisible, un-extended, immortal, thinking) and the body (material, divisible, extended, mortal, un-thinking): how can these two opposite substances go together in any individual? Descartes’ solution was to say that mind and body “interact” in a most intimate manner, communicating with one another through the pineal gland in the brain. The body sends messages to the mind and the mind to the body and the two interact continuously: the mind is not like “a pilot in a ship”: on the contrary, if the body is hurt the mind feels pain, if the stomach is empty the mind feels hunger, etc. There is a most profound interaction between mind and body.
However, the problem is there: how can two opposite substances work together? How can a spiritual substance cause motions in a material substance? In science we know that matter moves matter, we have no instance of spirit moving matter, of minds causing physical events and vice-versa. Even the princess Elisabeth of Bohemia asked Descartes to explain this mysterious interaction between spirit and matter: “How can the soul of man, being only a thinking substance, determine his bodily spirits to perform voluntary actions?” Leibniz himself wrote, “I find no way to explain how the body causes anything to take place in the soul, or vice versa; Descartes gave up the struggle over this problem, as far as we can know from his writings”.
One criticism sometimes levelled at dualism is that it does not explain what the mind really is. To say that it is a spiritual substance that thinks does not provide science with any means for proper investigation since science deals only with the physical world. Moreover, at what precise stage in the course of evolution did minds appear? Or are we to say that every physical thing also has a mind of some sort? According to a theory called “panpsychism” even stones have very primitive minds, the human mind being a combination or merging of simple minds to create a more complex one. And how do we prove that we have one mind and not many minds?
Materialism or Physicalism rejects Cartesian Dualism. The general idea is that there is no place in the scientific view of the universe for spiritual substances like minds (or angels, or devils); where do spiritual minds come from? Man evolved from apes, which evolved from reptiles, fish, primordial soup, ball of gas. Initially, according to the Big Bang Theory there was only gas; how does one account for the emergence of spiritual minds? The modern scientific view is that humans are no different from everything else in the universe, we are material beings, subject to the laws of science, entirely predictable once we know all the scientific laws that apply to us.
We all know how easy it is to destroy and tear apart a theory, although Cartesian Dualism is still strong and has produced respectable answers to the many questions raised by its opponents. Materialism or Physicalism, on the other hand, has failed miserably so far to come up with any other acceptable theory. John Searle, a highly respected modern philosopher, wrote recently in an article entitled, “What’s wrong with the philosophy of mind?” an assessment of materialistic theories over the past fifty years:
“Seen in perspective, the last fifty years of the philosophy of mind present a very curious spectacle. The most striking feature is how much of mainstream philosophy of mind seems obviously false. I believe there is no other area of contemporary philosophy where so much is said that is so implausible; obvious fact about the mental, such as that we all really do have subjective conscious mental states and that these are not eliminable in favour of anything else, are routinely denied by many, perhaps most, of the advanced thinkers in the subject”.
In materialist theories the mental is not distinct from the physical; indeed, all mental states, properties, processes, and operations are in principle identical with physical states, properties, processes, and operations. Some materialists, known as behaviourists, maintain that all talk of mental causes can be eliminated from the language of psychology in favour of talk of environmental stimuli and behavioural responses. Other materialists, the identity theorists, contend that there are mental causes and that they are identical with neurophysiological events in the brain.
For the MIND/BRAIN Identity theorists, the mind is simply the brain, is identical with the brain. A thought about the definition of a triangle is identical to a neurophysiological event in a part of the brain; a few inches away in another part of the brain there may be a thought of a white Christmas which is again the firing of neurons, electrical discharges, etc. There is no Mind, a spiritual substance, that does the thinking, but thinking is purely the neurophysiological events taking place in parts of the brain.
There is difficulty in understanding how the mind and the brain are identical: identity between two things implies that whatever is said of one thing it applies perfectly to the other. Prince Charles is soon to marry Camilla and the Prince of Wales is soon to marry Camilla is an example of identity since Prince Charles and the Prince of Wales is the identical person. But, how can the mind be identical with the brain? How can mental events like beliefs, feelings, thoughts, intentions, consciousness be identical with the firing of neurons, mixing of chemicals, electrical discharges? Mental language and neurophysiological language are miles apart and cannot be saying the same, identical things. Also, if mind and brain is the same thing, why do we have two languages, the mental and the neurophysiological language? How can we possibly verify that my thought of two plus two equal four is identical to neuron firings?
Some theorists claim that the identity of mind/brain is not to be taken as a necessary identity but only as a contingent identity. For example the word “water” and the formula “H2O” are different, yet they refer to the same substance. We use the term “water” in everyday contexts, and “H2O” in scientific ones. Similarly a flash of lightning is also an electrical discharge of a certain kind. Whether we use “flash of lightning” or “electrical discharge” to describe the same event depends on the particular context.
The problem, however, is that there cannot be contingent identity: we may use two words that refer to the same, identical person or event, but the identity if it refers to the same person or event is always necessary. In the case of mind/brain, we simply do not have any way of establishing that the thought of a white Christmas is identical with neuron firings and chemical secretions in a part of the brain.
Eliminative Materialists, like Paul and Patricia Churchlands, make the claim that all mental language will one day disappear and the only language of the future will be neurophysiological language, with an entirely different logic. They say that our present mental language stands to the language of science of the brain like primitive talk about demon possession stands to our talk about epileptic fits. They also claim that it will be possible to “photograph” thoughts and perceptions!
Mind/Brain identity theorists can be “Type-Type Identity” theorists or “Token-Token Identity” theorists: the former claim that particular types of thoughts are always identical with particular states in the brain, the latter allows for more flexibility about the manner and the location in the brain of the neurophysiological events which are the particular types of thoughts.
Philosophical behaviourism is primarily concerned with the semantics of our common mental vocabulary. It seeks to explain the “meaning” of mental terms like “belief”, “hope”, “intention”, etc. without having to treat them as referring to some mental substance. The goal is to translate terms that purport to refer to mental activity into terms that speak only of behaviour or propensities to behave in a certain way. The clear starting point is that there is no substance called Mind, there is no ghost in the machine, there is only the body and any talk about mental activities (thinking, believing, perceiving, being aware, seeing colours, having pain, etc.) is to be translated into talk about behaviour or propensities to behave.
Since there is no mind in the body we are purely creatures subjected to a variety of stimuli and producing automatically a variety of responses. You are kicked (stimulus), you cry (response), there is no I that feels the pain, feeling pain simply means having tears, screaming, hopping around, etc. For behaviourism to be right it has to be successful in translating all mental language into behavioural language, without loss of meaning. Have they succeeded? After the initial enthusiasm, supported by the Logical Positivists, Wittgenstein, and Ayer the view today is that behaviourism fails to take into account fundamental meanings of mental language, like my own feeling of the pain, or the “raw feels” or “qualia” which are known only to myself and no other. Also behaviourism seems unable to explain consciousness, intentionality, subjectivity, and mental causation.
This modern, popular view is a reaction to the inadequacy of behaviourism. For a behaviourist there is a perceptual input (stimulus) followed immediately by a behavioural output (response); there is nothing else in between. Functionalism says that there is something in between, a mental state or functional state; and so they talk about input – functional state – output. Theoretically the functional state could very well be a mental/spiritual state, so you could be a functionalist and hold the view that the mind is spiritual; the only point you need to make clear is that your functional mind is caused into a functional state by a variety of inputs and itself causes a variety of behavioural outputs.
The punch you receive –input – causes a functional state in your mind; such functional state links up with other functional states present at the same time in your mind and then causes a variety of forms of behaviour. Input, processing, output.
In matter of fact nearly all functionalists are also materialists, since they believe that all causes and effects are physical causes and effects. They believe that all functional states are brain states. All functionalists hold that a particular kind of mental state may be realised in a number of different ways; for example, on a functionalist view, being in pain is being in a functional state. Being in pain is being in a state which results from certain sensory inputs and causes pain-behaviour. This account holds true for any being capable of being in pain: humans, cats, dogs, Martians, and perhaps, one day, computers. However, the way in which the state of being in pain is realised may differ radically according to the make up of these beings. Pain may be realised by the firing of C-fibres in a human central nervous system, but they way they fire in dogs, Martians may be physiologically different.
The functionalist philosopher Alan Turing devised the Turing test to establish whether computers are intelligent: a man and a woman in separate desks in one room must answer questions posed by an interrogator in a separate room. The interrogator has to decide first whether the man or the woman has given the answer; at a second stage, the woman is replaced by a computer, and the interrogator has to decide whether the man or the computer has provided the answer. If answers are even better, then we must conclude that computers are intelligent. The Turing Machine also supports the view that computers can fulfil certain specific functions which we know our brains can fulfil; after all computers have a hard disc (brain), have software (functions) and outputs (behaviour). We are extremely sophisticated computers, our brain is capable of a great variety of functions (pain, pleasure, volitions, abstract thinking, planning, etc.). For J. Searle, instead, computers, no matter how sophisticated, will never be able to think, unless they are given the same biological structure of a human being – but then we will be talking of clones not computers. His parable of the Chinese Room explains what he means when he says that computers, by definition, have only syntax but not semantics, act “formally” without any “understanding”. If you are put in a room in which you find several baskets full of Chinese symbols and you do not understand a word of Chinese, if you are given instructions to join together symbols, to take certain symbols when other symbols are shown, etc., you still would not “understand” a word of Chinese, even if, by obeying the rules given to you, you should provide absolutely correct answers in Chinese! A Chinese, who knows the symbols and understands them, who has syntax and meaning, has a full understanding. Similarly a computer, any computer no matter how sophisticated, simply works on programs which are only manipulation of symbols, which operate formally but without any understanding. Hence computers will never be “intelligent”, in the sense of understanding what they are doing.
This materialist theory of mind is associated with the influential philosopher John Searle. He seems to move away from the crude materialism of other philosophers in the sense that he is prepared to accept the irreducibility of the mental to the physical, and he acknowledges the validity of mental phenomena like consciousness, intentionality, subjectivity, and mental causation. Yet, he claims that all mental states are caused by brain states and is not prepared to accept the possibility that there may be a substantive mind or soul that cannot be caused by processes going on in the brain.
Searle begins by saying that we think of ourselves as conscious, free, mindful, rational agents in a world that science tells us consists entirely of mindless, meaningless physical particles. How can it be the case that the world contains nothing but unconscious physical particles, and yet that it also contains consciousness? How can a mechanical universe contain intentionalistic human beings, that is, beings that can represent the world to themselves?
Since Descartes, the mind-body problem has taken the following form: how can we account for the relationships between two apparently completely different kinds of things? On the one hand, there are mental things such as our thoughts and feelings; we think of them as subjective, conscious, and immaterial. On the other hand, there are physical things; we think of them as having mass, as extended in space, and as causally interacting with other physical things.
Given the success of the physical sciences the temptation is to downgrade the status of mental entities. Most of the recent fashionable materialist conceptions of the mind – such as mind/brain identity theories, behaviourism, functionalism – end up by denying, implicitly or explicitly, that there are such things as minds as we ordinarily think of them. That is, they deny that we do really intrinsically have subjective, conscious, mental states and that they are as real and as irreducible as anything else in the universe.
There are four features of mental phenomena which have made them seem impossible to fit into our “scientific” conception of the world as made up of material things:
These four features are what make the mind-body problem seem so difficult. Yet, they are all features of our mental lives. Any satisfactory account of the mind and of mind-body relations must take account of all four features (see J. Searle, Minds, Brains, and Science).
It is to Searle’s credit that he manages to present the mind-body problem so clearly and accurately. His solution, however, is still far from a satisfactory explanation.
Searle claims that all mental phenomena, whether conscious or unconscious, visual or auditory, pains, tickles, thoughts, indeed, all of our mental life, are caused by processes going on in the brain.
Take the example of pains. Pain signal are transmitted from sensory nerve endings to the spinal cord by at least two types of fibres, Delta A fibres, and C fibres. These terminate on the neurons of the cord. The signals go up the spine, enter the brain, go through the thalamus, ending in the somato-sensory cortex or in the hypothalamus. Our sensations of pains are caused by a series of events that begin at free nerve endings and end in the thalamus and in other regions of the brain. If events outside the central nervous system occurred, but nothing happened in the brain, there would be no mental events (surgical anaesthesia works on this fact: the outside stimulus is prevented from having the relevant effects on the central nervous system).
Now what are pains? Searle claims that pains and other mental phenomena just are features of the brain (and perhaps the rest of the central nervous system). But how can it be both the case that brains cause minds and yet minds just are features of the brain?
A common distinction in physics is between micro and macro properties of systems, the small and the large scale. The desk, the glass of water are composed of micro-particles. The micro-particles have features at the level of molecules and atoms as well as at the deeper level of sub-atomic particles (quarks, gluons). But each object also has certain properties such as the solidity of the desk, the liquidity of the water, and the transparency of the glass, which are surface or global features of the physical systems. Many such surface properties can be causally explained by the behaviour of elements at the micro-level.
Just as the liquidity of the water is caused by the behaviour of elements at the micro-level, and yet at the same time it is a feature realised in the systems of micro-elements, so in exactly that sense of “caused by” and “realised in” mental phenomena are caused by processes going on in the brain at the neuronal level, and at the same time they are realised in the very system that consists of neuron. And just as we need the micro/macro distinction for any physical system, so for the same reason we need the micro/macro distinction for the brain. Nothing is more common in nature than for surface features of a phenomenon to be both caused by and realised in a micro-structure.
The conclusion, for Searle, is quite simple: there is no substantive mind, no soul. There is the brain, and the brain can be considered at the micro-level of neurons, synapses, chemicals, that is, at the physical, neurological level, and it can also be considered at the macro level of mental thoughts and perceptions. The physical and the mental are not separate properties of the brain, but the mental is linked causally with the physical and vice versa, without any possibility of reducing the one to the other.
Searle, therefore, seems to safeguard consciousness, subjectivity, intentionality, and mental causation by recognising the irreducibility of such features to the physical and by accepting them as objective realities of the universe. But is his micro/macro distinction taken from the physical world sufficient to explain the origin and the nature of the mental? On his account, the mind is the macro feature of the brain, like liquidity is the macro feature of water, and transparency of glass. The mind would emerge from the workings and biological arrangement of the micro structures of the brain: but this emergence seems even more mysterious and difficult to justify than the view that the mind is a different substance from the body. It is also difficult to understand how the “subject”, and therefore consciousness and intentionality, can emerge from the workings of the billions of neurons in the brain.
Modern philosophy rarely speaks of the “soul”. For Descartes the soul became the “mind”: the mind is the thinking substance, immortal and spiritual and essential; the body, on the contrary, is not essential and it is more like a machine that operates according to its own physical laws than an organism with a “soul”. Today we have a philosophy of mind, but not a philosophy of soul: and this is perhaps the beginning of all difficulties in the understanding of the composition of the human being. Talk about the “soul” is rejected because it is felt that soul and religion are linked closely together, and no philosopher wishes to be seen dealing with semi-religious ideas. The word “mind” is more secular, but it indicates today all the features traditionally associated with the concept of soul.
The prevalent philosophical view of the soul/mind today is essentially materialist, and all efforts are directed at acquiring a deeper understanding of the workings of the brain. Few philosophers today doubt that the brain is the seat of all mental phenomena which will find a full explanation through science. The brain contains more than 100 billion nerve cells and each of these electrically-active units can be connected with up to 10,000 others – creating a structure of mind-boggling complexity. Scientists believe the human brain represents one of the last great mysteries of biology. If it can be understood – they claim – then we might finally know the true nature of consciousness, a concept that is at the heart of the philosophical debate over what it means to be human.
Here are some examples of scientific explanations of various mental phenomena:
Similar physical explanations have been given for smell, breathing, hearing, movement, touch and pain, taste, vision, coordination. It is easy to understand why the brain has become the focal point for the philosophy of mind, and why modern physicalist theories of the mind have banished as superstitious the idea of a mysterious spiritual soul.