Consciousness: What Do we Mean?

The term ‘consciousness’ is one of the most evoked concepts in the history of mankind. Today, it is consciousness, but centuries back it was either the soul, intuition, spirit, quintessence, essence, other man, alter ego, the immortal spark or simply the mind.
What does it mean to be conscious? What kind of things are conscious?
We turn to Philosophy to properly situate this argument, its terms and boundaries for a level playing ground. Why Philosophy? The answer is not because it has absolute responses but that it has a solid record of accomplishment of transforming questions into a structural and coherent form for dialogue among various fields of knowledge.
Let us begin from the most reliable evidence we have, ourselves. We can be completely certain that we exist because we are in fact, at this very moment contemplating our existence. This is the age-long assertion of Rene Descartes after his meditations called the cogito ergo sum- I think, therefore, I am. Based on the indubitable fact that I am, what is the nature of this 'I'? Descartes, a pioneering philosopher on this subject, after a series of careful meditations, concluded that the ‘I’ was an extended thing (a body) inhabited by an extensionless substance which is the soul. While the former is bound in space and time, subject to changes, the latter subsists long after death of the physical body.
Overtime, this duality of existence, because of the difficulty associated with understanding how two distinct substances with no common basis to interact are unified, most theorist have attempted to find alternative explanations. Today, the term consciousness emerged to describe the state of an organism as the self-awareness of the contents of its thoughts and interactions with his environment. It may appear quite simple yet there are several distinctions to be made. The organism referenced here is assumed to be in a wakeful or non-comatose state in order to be aware of his unique thoughts from a first-person perspective.
Using this definition, what kinds of organisms meet this criterion? What makes me conscious, yet my Alexa, non-conscious? In fact, I may have more responses from Alexa that I have ever had from my neighbor who barely says a word to me. Consciousness does not purely reside in verbal or non-verbal communication although it is enhanced by it. Patients who suffer from locked-in syndrome are believed to be conscious, yet are incapable of language communication.
This is where the philosophers become useful by attempting to provide a generic criterion for consciousness, one of which we have previously evoked, self-awareness. This quality is the knowledge of "what it feels like"(Nagel, 1974) to be that organism. This acquaintance is so subjective that it is extremely difficult to explain yet we all know it. [1]It is how I know that a zombie is unconscious even if it performs all the tasks that I perform, or that Sophia, the super intelligent AI, although can mimic emotions, does not know what it is like to actually have them. Sophia only acts in accordance with the programmed algorithms that her makers give her. When she says, “I have my own emotions too, roughly simulating human evolutionary psychology and various regions of the brain”[2] she has no true self-awareness of how it feels like to be a being with emotions just a functional bot.
The question then is how different are we? The answers to this are wide-ranging. Let us assess two main positions that cover the main responses in the field of philosophy, the reductive and the non-reductive physicalist.