Yes, but that just collapses into a solipsism, and would true of all possible definitions. At some point we must agree that there are conscious beings other than ourselves, which necessarily means that a definition such as I proposed is rational. The possibility of philosophical zombies does not imply that every observed entity is such. If we take it as an axiom that there are other conscious entities than ourselves, then one is still left with needing such a definition.

That's not what I said/meant though. I'm not disagreeing there are other conscious being other than ourselves. I'm just saying that it's very hard to craft a definition that is not circular or at least ambiguous enough for people to imagine the existence of non-conscious being that behave as if they were conscious (i.e. the P.zombies).

Quite contrary to solipsism, I'd posit that what matters is behaviour. If a cognitive process is able to communicate with us and convincingly recount its reflections about itself, for all intents and purposes that system is conscious. It doesn't matter if it differs from our consciousness in significant ways.

Let's consider a machine that is able to reflect on itself quote effectively but it's also to turn on and off that module "at will". This is quite different from our experience of consciousness, in that we're not able to turn off our own consciousness, to the extent that we believe we're "there" only while we're conscious of it, and thus we end up equating our existence with those surface experiences. But we're way more than that. Were made of a thousand brains and not all processing reaches what we call our consciousness.

A system that exhibits a different mixture of those mechanism shouldn't be ruled out as not meeting the arbitrarily anthropomorphic bar of consciousness.