What are the data to be explained by a scientific theory of consciousness?
Human beings report internal, subjective experience, taking place in a private realm only they can access. At face value, this presents a hard problem: how does the raw matter of our brains come to have subjectivity? Consciousness seems inherently non-functional, and we can never know with certainty whether another creature is “really” conscious. But although intuitively compelling, the non-functional view is conspicuously silent on the question of how conscious experience manages to be a robust feature of our overt behaviour, in the sense of being much of the “subject matter” of what we say and do.
A more scientifically grounded starting point is take our tendency to intuit consciousness in this way as a key part of the data to be explained. Why do our brains represent our selves as disembodied agents, inhabiting a material body and observing the world through its senses? What does this self-model allow us to do that we wouldn't be able to do otherwise? One possibility is precisely that it allows us to reflect on, talk about, and act deliberatively with respect to how the world “seems” from our point of view. From this viewpoint, phenomenal experience does not arise as a mysterious correlate of certain kinds of information processing in the brain, but is instead part of the content of an egocentric world-model that underlies self-reports and other “me-oriented” behaviour.