The question of knowing if consciousness actually serves any function or if it is an epiphenomenon is important when appreciating individual responsibility. Indeed how a person can be convicted or hold as responsible if her/his actions are executed under the control of a consciousness which would be a by-product of neurons, e.g. of a genetic arrangement. If it is the case, individual would be no more than zombie that cannot be differentiated from a normal human except that it has no conscious experience; its brain would dictate its actions and it would have any responsibility as it would be the results of a given neuronal process. But what are the things that can be executed by a conscious creature but not by a non-conscious one? The answer to this question amounts to determine what the functions of the consciousness are and refers to the hard problem raised up by the consciousness (Chalmers, 1994), e.g. to its subjective dimension, the experience of the Self and the “qualia”.
But before entering into the debate it is important to define what consciousness is as the definition may encapsulate several meaning; the definition is not straightforward as consciousness is a private and subjective phenomenon, difficult to apprehend as impossible to measure or observed directly. Block (1995) distinguished four concepts: (i) the Access-consciousness (A- consciousness) which makes references to the consciousness immediately available as a premise to reasoning and which plays a role in the control of actions and language; it could be compared to the neuronal working space;(ii) the phenomenal consciousness (P- consciousness) which refers to the qualitative aspects of mental activity or qualia such as sensations or perceptions; (iii) the monitoring consciousness or awake state which refers to the different levels of vigilance and to our ability to inspect deliberately our thoughts and (iv) the self-consciousness as we are conscious of our self which provides an unity to our mental life. In this essay it will be referred essentially to the P- consciousness.
The term of phenomenal consciousness (Block, 1995) (as well as those of « what it is like » (Nagel, 1974) of « qualia » (Jackson, 1982) or « conscious experience ») designs the experiential and lived dimension of mental life. This « phenomenal consciousness » feeds for over thirty years many discussions in philosophy of mind, since it seems to pose a problem to scientist who are looking for observable and physical explanation, problem that Chalmers, (1995 ) named the « hard problem » of consciousness and that can be divided into two sub-questions (Chalmers, 1996): why and how a given set of brain processes is accompanied by a specific phenomenal experience and not another one – for example, a red experience rather than a green experience? (Problem of the phenomenal content). On the other hand, why and how a given set of brain processes is accompanied with a phenomenal experience whatsoever? (Problem of the de existence of phenomenality).
The underlying hypothesis under the hard problem” is that the brain which is observable is opposed to the mind which could be studied only from subjects’ subjective reports. As not directly observable, some researchers argued that it is an illusion, and that if a zombie can philosophically exists, then consciousness has no function; it is an epiphenomenon.
However if phenomenal consciousness exists it should serve some functions. What are they? One of the main functions that were attributed to consciousness was the control of the behaviour. However, the experiment made by Libet (1983) showed that the cerebral activation precedes conscious decision. This result was confirmed by iFRM observations which not only supported Libet’ s findings but also allowed to predict what will be the decision of the subject (Scoon et al., 2008; Fried et al., 2011).
Another function of consciousness could be helping us taking the right decisions but some researchers showed that “if simple choices produce better results after conscious thought, choices in complex matter should be left to unconscious thought (Dijksterhuis et al, 2006). This observation conducts psychologists such as Frith to say that consciousness allow us probably and essentially to explain and justify our decisions a posteriori (Frith, 2007, Dennett, 1991).
If consciousness does not help decision-making or controlling behaviour, experiments conducted by Murphy and Zajonc, 1993) showed that consciousness may allow participants to override affective responses to stimuli and help us making rational rather than emotional answers. Also, even if conscious processes require more cognitive resources that unconscious ones, Baddeley and Wilson (1994) suggested that the main function of explicit memory which is a correlate of consciousness is to help us learning from our mistakes. A function of consciousness would be then a better integration of what we learn and then an increased ability to apply our learning to novel situation. Experiences on altered states of conscience showed that consciousness operates with or on a selected part of multiple information that submerges us: “Consciousness also involves checking our mental states against incoming information from our environment and checking our behaviour against our intended goals” (Andrade, 2010). The processing of information involves working memory
Even if the functions of consciousness are not yet fully defined, it can be argued that if it appears during species’ evolution with the complexification of the nervous system, it is because it should bring an advantage (Darwin, 1859). For the evolutionists, consciousness is a response to social organization rather than to physical environment. For human or non-human which can learn, it is important to identify each individual and, therefore to become aware of his/her role for surviving. For the same reason, specialised neuronal systems such as face recognition developed and provided evolutionary advantages. Another competitive advantage is the capacity to predict the behaviour of other people or the capacity for building up a theory of mind. Piaget showed that during his development, a child understands gradually that other people have intentions and motivations different from himself through awareness of his self (Theory of mind, Paiget,2003).
The problem is that even if consciousness serves functions such as filtering information, controlling emotions or supporting social interactions, it is still difficult to define how the brain may produce consciousness and its correlates, the qualia? Dennett (1991) distinguished four properties to the qualia; (i) they are ineffable and cannot be communicated or apprehended only by direct experience; (ii) they are intrinsic or immediate i.e. without any relational properties; (iii) they are private: any interpersonal comparison is impossible; (iv) they are apprehended directly by consciousness, i.e. intuitively. According to its semantic composition, the word ‘consciousness’ comes from the Latin Consciencia, from Scrire- to know; qualia would then be the results of an intuitive knowledge.
So even if difficult to define, consciousness exists and has a functional role. In another hand, our brain is made up with neurons which interact according to the principle of causality and laws of physics. Then consciousness would not exist per se and would only be an epiphenomena or a consequence of the brain system. It is the position of the phenomenologists.
For Dennett as for phenomenologists, the qualia, e.g. properties of sensory experiences, do not exist and are illusions. Their approach for solving the hard problem of the consciousness were constructed on dualism and materialism: They opposed physical and subjective world and their view is explained by historical reason as behaviourist theories have been and still are influent in this domain of research. For behaviourists, “psychologists should concern themselves with objective data, publicly observable behaviour, rather than subjective introspections” (Andrade, 2010). The phenomenologists based their theory on dualism of properties according to which the matter is predominant and this matter may possess two types of properties: physical and mental, the latter being not reducible to the former. This claim is known as non-reductive physicalism and had produce theories such as the epiphenomenalism but also the emergentism (Mill, 1843).
For them mental processes would not have any causal influence on the physical world, e.g. the brain influences the consciousness but the not contrary. No mental states may influence the brain. The impression that our intentions, desires or feelings influence directly our behaviour would be only an illusion. We would be as a child with a plastic steering wheel in our hands near the father who is effectively driving the car. The child absorbed by his game comes to think that he is effectively driving as we think that our consciousness drives us.
However this theory does not explain differences in mental states within the same situation. No explanation is given on the fact that the same stimuli may activate the same process in the brain but mental states may be different from one individual to another. Mental states, as defined by reactions to a stimulus, are personal to each person and the epiphenomenalism does not explain why the same brain processes triggers different mental sates or perceptions.
Some theories such as functionalism based on materialism tried to answer to this problem by arguing that only the matter exists. The conscious states would not be different from physical sates as they are identical. They recognize the existence of conscious experiences but these experiences such as pain would be the consequence of neuronal activity. Thus the “hard” problem does not exist as the consciousness is associated to some structural properties of the brain. The analogy often used to describe their position is the comparison with the hardware and software of a computer. Conscious states are not just epiphenomena; they are direct causes of our behaviour. The brain is considered as hardware of a computer, receiving inputs and the mind is the software, processing information. This architecture may explain why different mental states are observed with the same stimuli as the “software” may be different from one person to another. However functionalism does not answer to criticisms based on the subjective aspects of mental states or the qualia. They are in the same position than the epiphenomenalism, e.g. they do not explain how mental states may influence the physical world as they deny this possibility.
The recent discoveries in neurosciences brought new approaches to consciousness and Dennett was one of the philosophers who tempted to integrate the data from neurosciences to the concept of consciousness. His theory aims to end up the Cartesian materialism and its dualism. He proposed two metaphors: multiple versions and virtual machine. According to the multiple versions, the consciousness is not an unitary but a distributed process. At any time several activated neurons compete with each other to get “fame in the brain”. The result of this competition is not an average of different versions but the most suitable to a given situation due to a selective process that Edelman called “a neural Darwinism”. The consciousness occurs from a quick succession of cerebral events which cannot be ordered sequentially. However Dennett considered qualia are residues that can be obtained once everything has been explained about, for example, perception.
The research on consciousness is one of the most dynamic areas. The cognitive neurosciences when trying to understand the mechanisms of consciousness according to a materialist or dualist vision are considered as reductionists and progress can only be made if the consciousness is considered as a variable and not if its existence is denied. The latter data in neurosciences showed that conscious intentions may play a causal role on its own within the deterministic chain of causes and effects, thereby enabling them to escape the simple epiphenomenon status: experiments on unconscious specialized circuits (Norman & Shallice, 1986), on visual perception, on neuronal workspace (Baar, 2002), somatic markers (Damasio) or on working memory (Dehaene & Naccache, 2001) contributes to our understanding of consciousness. All these theories challenge the classical theories on consciousness by assuming that consciousness is not an epiphenomenon and that it plays a functional role. In the current state of science, nobody has yet solved the mystery of consciousness.