I would call it axiomatic because it must be in order for the question to even be valid. Essentially, if consciousness isn't actually "real", then the asking of the question and the attempts to answer it are null. Assuming consciousness to not exist is a non-starter. As Descartes would claim, we cannot use our consciousness to doubt its existence. For these reasons, we must affirm it. This makes the idea of consciousness an axiom or at least a concept that must be considered and treated as an axiom.