I meant that perhaps consciousness cannot be consistently and meaningfully defined as a property of things, so as to enable us to say: a man is conscious, a rock is not.

What is consciousness, anyway? It comes to something when we need a whole book (Consciousness Explained) to tell us what a word means, instead of a simple definition. And even then we don't agree. I certainly sympathize with those who'd prefer to abolish the whole idea of consciousness, instead.