Halliday & Matthiessen (1999: 609):
Edelman’s interpretation of higher–order consciousness … suggests that this form of consciousness (unlike primary consciousness) is constituted in language. Language is a socio–semiotic system, so it follows that higher–order consciousness is constituted socio–semiotically; and since socio–semiotic systems are collective, it follows that higher–order consciousness must also be collective. …
But it is the rôle of language in the construction of experience as meaning — as shared activity and collaboratively constructed resource — that gives substance to the concept of collective consciousness as an attribute of the human condition.
Cf Edelman (1992: 133):
higher–order consciousness adds socially constructed selfhood to this picture of biological individuality … but it is highly individual (indeed it is personal).
Cf Halliday & Matthiessen (1999: 193):
Human collectives: intermediate between conscious beings and institutions. These can function as Senser in sensing of all kinds … but they accept either singular or plural pronouns, and if singular pronominalise with it.
ie the grammar construes the consciousness of human collectives as impersonal.