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Theories of Consciousness - Historical & Contemporary

For millennia scientists and philosophers have contemplated the question: “what does it mean to be conscious?” In the 21st century, we are still far from an answer. We lack any hard evidence to support thousands of theories that have been developed over hundreds of years. Despite the difficulty, we have made slight progress in our scientific understanding of consciousness. We have a long way to go but we are all the wiser.

A Problem With Our Theories of Consciousness

One problem that is key in understanding theories of consciousness is that the term ‘conscious’ has varied in definition over time and even differs from person to person. For example, consciousness is easily linked to spirituality and religion as a way to measure a connection between the self and higher powers, such as God. Mystical psychiatrist Richard Maurice Bucke developed three stages of consciousness related to religion:

1. ‘Simple Consciousness’ – an awareness of the body, possessed by most animals.

2. ‘Self-Consciousness’ – an awareness of being able to be aware, possessed only by humans.

3. ‘Cosmic Consciousness’ – an awareness of life and order within the universe, possessed only by humans who are enlightened, e.g. religious or spiritual.

Aside from religious definitions of consciousness, definitions usually fall between a line of scientific psychology and a more theoretical philosophy. For example, the modern definition of ‘consciousness’ in the Routledge Encyclopaedia of Philosophy in 1998 contains four main topics:

1. Knowledge

2. Intentionality

3. Introspection

4. Phenomenal Experience

Ironically, each of these separate topics of ‘consciousness’ has its own definitions and again are all very likely to be further subjective and disputed. We can clearly see that the idea of consciousness is such a large concept that we struggle to narrowly define let alone find hard scientific evidence on the matter. However, one common link is awareness of the body and the mind in relation to the environment.

Epistemology (the study of knowledge) is a vast subject of such a small element of human consciousness. By analysing our thought processes, we can work our way down to the root of our cognitions in relation to our motivation, self-awareness and perception.

Cogito, ergo sum’ to ‘Introspection’.

The fundamental footnote on being was proposed by the famous phrase: "Cogito, ergo sum" (I think, therefore I am), coined by French philosopher René Descartes in the 17th century. This phrase has of course been up for much debate through the years with many different interpretations of the phrase but with the help of hundreds of years of historical retrospect, we are able to speculate what exactly Descartes’ phrase meant. Descartes later mentions his proposition in his Principles of Philosophy in which he explains “we cannot doubt our existence while we doubt”. This concept is known as ‘the cogito’ and has been aptly extended by Antoine Léonard Thomas as “I doubt, thus I think, therefore I am”. In terms of theoretical explanations of consciousness, this proposition speculates that as we are able to doubt and reflect on our own thoughts and existence, we can assure ourselves that we exist and are fully conscious. Thus, self-awareness is fundamental to existence and consciousness.

However, as Descartes predated modern science, this proposition is merely theoretical with no objective basis. Since this prospotion, inward thought has been analysed in many theories, some of which are increasingly objective as the scientific revolution took hold. Most famously, cogito - and more widely internal reflective thought - is the groundwork of the idea of ‘Introspection’. The father of psychology, Wilhelm Wundt, helped bring the theory into the realm of experimental science with more detailed definitions and in-depth studies. Although introspection is not strictly a study of consciousness, it does recognise the importance of cognition in relation to an individual’s view of self and the world. As such, the process of introspection is inwardly examining one’s mental state. Put simply, it means “thinking about an individual’s own thoughts”. This is the foundation of what we now call psychology and has led to over a century of the scientific study of the human mind.

Therefore, from early theoretical ideas of consciousness, we can strongly speculate that a common understanding of what it means ‘to be conscious’ is that we are able to self-reflect on ourselves and be self-aware of our own being and cognitions, which is, in fact, close to the universal definition that has been discussed previously.

‘Mind-body Problem’ and the ‘Hard Problem’

As is evident, a large factor of consciousness is being able to be self-aware of one's own mind. Thus, the other part of the equation is being able to connect cognition to a physical process involved with our environment such as our perception. Common-sense speculation would be that in order for an individual to become self-aware (conscious), they would require physical ques to achieve the mental processes which question what we see and develop this phenomenon. This would support the idea that ‘doubting’ our own thoughts and environment is what defines us as conscious. However, finding this connection between physical processes and inward mental process is what continues to confuse contempory scientists.

Cartesian Dualism

The first attempt to develop a theory between the link of physical processes and mental processes was once again the work of Descartes, which he named ‘Cartesian dualism’. In this, he proposes that consciousness is contained in an immate rial domain known as ‘res cogitans’ (the realm of thought) in contrast to the ‘res extensa’ (the realm of extension) which acts as a domain of material things. The link between these two domains is allegedly found in the brain in the pineal gland.

However, as we are now able to conduct advanced scans on human brains we have concluded that this theory is false. Despite this, we still do not have a valid theory to explain the link between a physical plane of the world and how it connects to our cognitions.

This problem of why and how these physical properties of our minds, bodies and the universe create phenomenal experiences is known as the ‘hard problem’. It has become recently known as the ‘mind-body problem’ by Australian philosopher David Chalmers. An example of this problem is understanding how different individuals see subjective experiences such as colours or the sounds of an ocean. As these theories have expanded in a more scientific era, neuroscientists and physicists have been attempting to further pick apart the idea through the use of experimental research which has now (for the first time) led to perhaps our first signs of progress towards a potential understanding of consciousness.

Integrated Information Theory

To counter this problem, Neuroscientist Giulio Tononi of the University of Wisconsin-Madison has created one of the highest potential theories of consciousness we have in our modern age referred to as ‘Integrated Information Theory’ (IIT). As most theories tend to try and understand the link between physical senses in relation to our cognitions and perception by starting from the mechanical and physical principles and working towards consciousness, IIT instead works backwards from consciousness by jumping from phenomenology (subjective experiences) to the mechanisms (physical principles, i.e. senses).

In order for this jump to occur, IIT assumes that if a conscious experience is perceived by physical senses then those physical senses must be constrained by the properties of the experience. IIT assumes that a conscious experience is constructed by the integration (or filtration) of a wider amount of information from the environment. This means that the experience is irreducible and purely a subjective experience and perception of objective physical properties. For example, we can safely presume that our vision is integrated from a wider range of information (the environment) which forms our conscious experiences as we are not able to control what we see or how we see it. This is how we cannot choose to see the world in black and white. Instead, we perceive the world through our senses as a predisposed set of information based on the properties and constraints of our senses, such as our perception of colours. This is why we cannot change what the colour red looks like to us.

This assumption explains the idea of subjective conscious experiences and the different levels of subjectivity in these experiences by relating it to the amount of complexity and levels of information integrated into our physical senses. Therefore, by using several studies in brain stimulation, we are able to measure the extent of complexity of integration in our brains with the numerical value ‘phi’ which in essence measures the level of consciousness in any form of matter.

Through a study of brain wave stimulation in both conscious and unconscious patients, we now understand that brain wave activity is more complex and has higher levels of phi in conscious patients, whereas activity in unconscious patients tends to be simpler with lower levels of phi. One can deduce that the higher the levels of phi that there are within the brain, the specimen will have a higher level of consciousness. Although cognitions are not analysed as Descartes once did, brain wave activity may relate to the extent of cognition active within the mind. This could conclude that phi – the level of integration in the specimen - is the cause of consciousness. This supports IIT’s explanation of how consciousness exists in varying degrees among humans and other animals and assumes that all organisms and objects are conscious up to an extent.

Problems of the Integrated Information Theory

One immediate problem of IIT is that it does answer the whole equation of explaining consciousness. For example, despite it giving a theoretical measurement and explanation of consciousness in terms of the amount of phi in a specimen, it does not mention why this supposedly may occur. Answering this why may perhaps be impossible within our time and the simple conclusion may be that IIT is completely wrong. Assuming that all things in the universe are conscious up to a point is a big assumption and is likely to be false.

Another problem is that IIT does not address subjective experience and cognition in as much detail as other theories. As science is based on a monist approach, many scientific theories are unable to disconnect the dualist difference between cognition and physical properties, further confusing the explanation of consciousness.


Despite having scientific theories such as IIT, we are still quite a distance away from developing a complete theory of consciousness. Perhaps it is not even possible to develop such a theory. Even if it was possible, many problems are still in our way – and even if we were to overcome these problems the massive question of free will could counter any complete theory. To conclude, the biggest problem that we face is simply proving the theories that we develop as collecting evidence on the cause of our own existence is incredibly complex especially when we consider that we exist within the very world that we are putting into question and so we naturally take a philosophical stance as opposed to a scientific one.

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