When investigating anything it is extremely important to tie both the development of the theory itself and the content of the theory to experience. If we are investigating something then there is a distinction between our theories and the subject matter itself and so we need a way to evaluate our theories to see how well they conform to the subject matter. And the only way to do that is through experience of some kind, because as far as I can tell we lack any other way to get at things, except through our experiences. (This can be contrasted to a completely constructive enterprise, such as mathematics, where the standards are completely internal, meaning that the nature of the theory alone determines if it is good or bad.) Before turning to consciousness let us first look a little more closely at how we need to tie both the evaluative and constructive aspects of our theorizing to experience.
First let’s examine why we need to connect our theories in some way to experience in the context of evaluation, because it is easiest to see the need for such a connection in this context. In order to evaluate a theory I claim that each theoretical entity needs to be able to be experienced in some way. Now obviously many of the things we theorize about, such as atoms, are things we can’t directly look at. But that is not a problem, all our theory needs to do is to provide some indirect way to experience atoms (through their effects), which various instruments and experimental set-ups do in fact allow. With this connection we are then able to verify, at least in some cases, whether atoms are behaving as the theory claims they do, whether they are present or absent as claimed, whether they are moving quickly or slowly as claimed, and so on. To see why this connection is necessary simply consider a theory that lacks one, such as the hypothesis that all atoms are made of a mixture of substance X and substance Y in various proportions, and that the amount of X and Y present give each atom its properties. Unless X and Y are independently made to be specifically responsible for various properties we have no way to get at X and Y in any way, and thus the theory is essentially vacuous (it only seems to make assertions while it really asserts nothing).
There is also a need to associate our constructive theoretical activities with experience in some way (although a less rigorous one). Obviously when we begin an investigation we do so with some “theoretical” expectations. For example, we may be looking for a specific kind of thing, which means that we are looking for a class of things united by sharing certain features. But our starting point can’t be completely theoretical, we need something material to latch onto and to serve as our connection with experience for our initial hypothesizing. For example, we might be looking for a theory about the kind of things that appear a certain way or the kind of things that cause a certain event (causation being an additional “theoretical” expectation). Without any such connection the investigation can’t get started. Consider, for example, investigating some X, defined as the cause of Y and Z, Y and Z being the mirror images of each other. Obviously X, Y, and Z are all defined completely theoretically (without any reference to experience), which is why I am not naming them, to prevent accidentally associating them with experience in some way. There is simply no way to investigate this X, we can only elaborate on the theoretical commitments we began with, which obviously doesn’t add anything new to our understanding of X, nor does it bring us any closer to a theory that can be evaluated (as mentioned above).
With that in mind we are now ready to consider how we should investigate consciousness. I would argue that we should divide consciousness into two concepts, because the word is used in two distinct ways, with the hope of reuniting them later. Specifically I would separate “conscious” used as a description of other people from “our consciousness” used in an introspective sense to describe our own experience. The first sense of “conscious” is relatively easy to investigate, so long as we don’t trip ourselves up and cloud the issue with ideas stemming from “our consciousness”. “Conscious” is something that we ascribe to people primarily on the basis of their behavior, especially verbal behavior. Even more specifically we seem to call people conscious because they display introspective behavior, behavior that reflects on their own inner states, feelings, attitudes, goals, and so on. Obviously such behavior can be experienced, and so it can serve as a starting point for an investigation. We thus begin our investigation of consciousness, in the first sense, as that which is the cause of this behavior and which produces it as an accurate reflection of its operation (a theoretical requirement added because our expectation is that this behavior reflects what is really going on inside the person, and not an illusion, such as might be produced by a recording of such behavior). Such an investigation probably concludes with some kind of functional description of the kinds of systems that count as conscious.
Obviously investigating “our consciousness” starts in a quite different way. There are no specific experiences that are associated with “our consciousness”, rather every experience we have is part of it. Indeed even distinguishing our consciousness from the rest of the world requires a bit of theoretical sophistication, specifically accepting the hypothesis that there is an objective world out there and that we only experience some aspects of some parts of it (if someone was a solipsist and didn’t buy into this then “the world” and “consciousness” would designate the same thing, which would end the investigation rather early). What we are looking for then is something that unites or causes all of our experiences but is absent from everything that isn’t experienced. Obviously there are many directions to go at this point (because what this common feature is isn’t at all obvious), some worth considering, some absurd (absurd because they leave behind any hope of confirming the theory developed through experience). We might hypothesize at this point that we are one of the systems that is called conscious in the sense investigated above. If this is indeed that case then what unites all of our experiences would be the fact that they are all available to a certain kind of self-reflective activity (whatever exactly the theory developed by the previous investigation concludes). And that possibility can be confirmed (or disconfirmed) through experience by observing ourselves using our objective tools of inquiry and seeing whether we are such a system and whether our experiences coincide exactly with those that the theory predicts will be.