Consciousness is what makes ‘me’ unique from all the other living things in the world. It is the sum of everything I can remember and can call to mind, everything I am currently experiencing and thinking about, and all the things that make me feel what it feels like to be ‘me‘. (Definition of Consciousness by Richard Underwood)
Providing a definition of consciousness is difficult because there is nothing to see and little to examine. The only consciousness we can examine in real depth over a prolonged period of time is our own, and even our own consciousness is a mystery to us. Philosophers, neuroscientists, psychologists and others have all failed to agree on what consciousness is, or where it can be found, or even what it takes to be conscious, but that hasn’t prevented a plethora of theories. In early 2025 Google Scholar returned over 5.7 million results on a search for ‘consciousness’, and a search for ‘consciousness’ at the University of Manchester Library, where I conducted most of my research, listed over seventy-five thousand books or articles with the word ‘consciousness’ in the title.
That is not to say there are no experts on the subject of consciousness. There are many, each with their own unproven hypothesis. There is such a plethora of information about consciousness that I would not suggest trying to read all the books and research papers on all the different theories. It would be a never-ending process. That way, madness lies. I know! I’ve summarised almost all of the different theories of consciousness in my book ‘A Brief History of Consciousness‘.
In order to get to grips with providing a definition of consciousness, we first have to define the difference between sentience and consciousness. In the popular press, these terms are sometimes bandied about as though they are the same thing, but they are not. Sentience derives from the Latin word ‘sentire’, which means “to feel”, and we describe an organism as sentient if it is has sensory input enabling it to feel sensations and emotions, and to respond appropriately to good or bad experiences. All organisms, plants and animals, have some form of sensory input which enables them to differentiate between good and bad experiences, so at the most basic level they are all sentient. Even single-celled organisms have sensors which enable them to determine the difference between something that can be let through the cell membrane as food or kept out because it may be harmful. Sentience may be widespread, but it doesn’t necessarily follow that consciousness is widespread. Consciousness is more than sentience. It involves more than an awareness of sensory input. It involves self-awareness, the subjective awareness of your own thoughts and your own existence. Our perception of consciousness is personal; the personal internal reflections unique to each one of us.
Rays of light hit the lens in my eye, and an electrical impulse is sent to my brain which registers those impulses as an image. Sound waves hit my eardrum, and those vibrations are converted into an electrical impulse that is sent to my brain which registers those impulses as a sound. I touch something with my fingers, and the pressure is converted into an electrical impulse that is sent to my brain which registers those impulses as a feeling. I can think of music within my head, and those thought travel to my mouth and enable me to hum a tune or sing a song.
My laptop can do all those things too!
Rays of light hit the lens in my webcam, and an electrical impulse is sent to the processor of my computer which registers those impulses as an image on my monitor. Sound waves hit the microphone, and those vibrations are converted into an electrical impulse that is sent to a speaker and broadcast as sounds. I finger the touchpad, and the pressure is converted into an electrical impulse which is sent to the processor and registered as a touch.
Any definition of consciousness has to explain why I am conscious and my laptop is not.
The laptop takes light waves and converts them into pictures. I take light waves, convert them into pictures, and those images give me intense pleasure, intense pain, or every emotion in between depending upon my interpretation of what I have seen. Those images may even cause me to think about something different entirely, and I can simultaneously see one thing with my eyes whilst viewing another scene in my imagination with my mind’s eye.
The laptop takes sound waves and converts them into sounds. I take sound waves, convert them into sounds, and those sounds can make me happy or sad. Those sounds may even cause me to think about something entirely different, and I can simultaneously listen to music with my ears whilst being aware of the emotions the music engendered when and where I first heard it.
The computer takes the touch of my finger on a touch pad and converts that pressure into the movement of a cursor. I touch the same plastic touch pad, and as well as being aware of the moving cursor I am also simultaneously remembering the touch of a plastic toy I played with as a child, the pleasure that brought me, and the sense of loss that my mother who bought it for me is no longer living.
The computer and I have both processed our surroundings, but I am conscious of my surroundings and aware I have processed something, whereas the computer is unaware of its surroundings and unaware it has processed anything.
My consciousness is unique. Nobody has the consciousness I have, and the only person who knows what it feels like to be ‘me’ is ‘me’. Built up from everything I have seen, heard, tasted, touched and smelt, I am acutely aware of every thought, every emotion, every love, every loss, every fulfilment, and every disappointment. I can remember all those things, think about them, learn from them, and re-live them in my mind.
Consciousness is what makes ‘me’ unique from all the other living things in the world. It is the sum of everything I can remember and can call to mind, everything I am currently experiencing and thinking about, and all the things that make me feel what it feels like to be ‘me‘.
