On the model of Halliday's Systemic Functional Linguistic Theory, human (higher-order) consciousness is the symbolic processing made possible by language: mental and verbal, and the content of consciousness is the content plane of language: meaning (semantics) and wording (lexicogrammar).
The relation between consciousness and the content of consciousness is projection, which is the relation between different orders of experience. The content of consciousness is second-order experience with respect to the process of consciousness itself.
Each act of consciousness is an instance of symbolic processing, mental or verbal, and each projection is an instance of the content of consciousness, meaning or wording (spoken, signed or written text).
The content of consciousness is organised according to metafunction:
- content as the construal of experience (ideational),
- content as the enactment of social relations (interpersonal),
- content as coherent and relevant (textual).
Because every human language is a collective phenomenon that is individuated differently in each human, the content of consciousness is a collective phenomenon that is individuated differently in the ontogenesis of each human.
Edelman's Theory of Neuronal Group Selection provides an epistemologically-informed and scientifically-testable model of the material substrate that makes human consciousness possible.