Consciousness -- the mind, the sum, the individual awareness that lies at the core of every human being. No one can even define it, much less offer a naturalistic theory of its nature. Nowadays, many materialists simply dodge the question by denying that individual consciousness exists.
But, deep down inside, they all know it's there.
Consciousness is a mechanism? Really? Have you looked up the definition of mechanism lately? It is purely and simply a feature of the material world.
I agree that many scientists do dodge the question, but it is incorrect to say that nobody can define it, or offer a naturalistic theory of consciousness.
As evidenced by the fact that they know at all, and are self-aware.