If we are to explain consciousness in terms of some system or process (for the first steps towards such an explanation see here) what ate the essential properties of consciousness that our theory must account for? (And by account for I mean that they are not built into the explanation as fundamental constituents of consciousness, but instead arise as necessary properties of the systems that our theory picks out as conscious.) Ideally these essential properties are essential not only in the sense that all conscious systems must have them but also in the sense that by having these properties a system is by definition conscious (thus showing that our proposed theory really does capture consciousness). Without further ado then here is the short list:
First Person Perspective
The first person perspective can be defined as that which is responsible for a conscious being’s experiences (see next item) as being presented as belonging to them. Moreover, the first person perspective has a kind of temporal extension (or is at least felt to have a temporal extension), in the sense that the remembered experiences are remembered as being presented to this same first person perspective. Another way of putting this idea would be to say that the information that is part of the conscious system is structured in terms of how it relates to this perspective (which is itself constructed by the fact that conscious experiences and information are related to it). Of course my use of structured may itself seem a little vague. In some cases, such as a thinking about positions in space, this structure is simply the fact that they are presented in terms of the first person perspective (where things are in relation to me, or to where I place my mind’s eye when I think of them), and in other cases it may be as simple as knowing that they thought “2 + 2 = 4” is my thought, even though the mathematical fact itself isn’t dependant on my perspective in any way. I will omit arguments as to why the first person perspective is essential to consciousness, since it has long been held to be the defining feature of consciousness.
Another essential part of consciousness is experiences. Experiences, as I define them here, include not just sensory impressions, but mental activities that are consciously “experienced” as well, such as thinking, remembering, desiring, ect. The existence of a first person perspective and experiences are obviously very closely related, since in order to have a first person perspective there must by experiences that can be related to that perspective, and we might define some state as an experience only if there is a first person perspective it can be related to. However, I have separated them here, simply because an account of consciousness may give different accounts of them (for example: experiences may be generated by one process, the first person perspective by a second, and then a third may bind them together). Experiences, in theory, should also account for “qualia” (which is partly how experiences are presented) and the perceived unity of consciousness. Again, there is no real need to defend experience as necessary for consciousness, since without experiences there would be nothing to be conscious of.
Finally we come to self-consciousness. Sometimes self-consciousness is considered to be part of, or responsible for, the first person perspective (or vice versa). However I separate them, because I use self-consciousness to mean information about the system itself that becomes part of the experience. Obviously though this self-information works side-by-side with the properties of the experience that make it experienced from a first person perspective. Of components that I have pointed out as necessary for consciousness this self-information may seem the least important. For example, people with amnesia seem just as conscious as us, and clearly they have less of this self-information embedded into their experiences. However, this self-information can be seen as responsible for the existence of chains of thoughts (since each thought experience must contain some experiences about the previous thought experiences, information about the system, in order to build upon them in a rational manner). In addition this self-consciousness seems required to have a first person perspective with “temporal extension” since information about the usual form of the first person perspective, that it is like the current first person perspective, and that it as existed for some time would seem to make their way into experience via this self-information, and hence self-consciousness. However, the amount of self-consciousness required for a system to be conscious is probably minimal (much less than found in people), since we think that some animals may be conscious, and surely their powers of self-consciousness are less developed than ours.
Strictly speaking intentionality is not required for consciousness. We can conceive of conscious beings who have experiences that relate to nothing in the world (or who conceptualize those experiences in ways that don’t relate to the world). However, such conscious beings would not be recognizable as conscious to us; we wouldn’t know how to communicate with them or recognize them from their behavior or mental activity (since none of it would be world directed). Thus an explanation of intentionality should probably be part of our explanation of consciousness, or at least an easy addition to our theory of consciousness, given that the conscious beings we are theorizing about all possess some form of intentionality. Perhaps I am simply a little biased though, since the approach to consciousness that I am currently working with has the ability to provide a decent explanation of what makes a system intentional when turned to that problem.