Full Idea
The possibility of zombies is founded on the idea that consciousness is related contingently to physical states and processes.
Clarification
'Contingent' means 'doesn't have to occur'
Gist of Idea
Zombies are based on the idea that consciousness relates contingently to the physical
Source
John Heil (From an Ontological Point of View [2003], 20.3)
Book Reference
Heil,John: 'From an Ontological Point of View' [OUP 2005], p.243
A Reaction
The question is, how do you decide whether the relationship is contingent or necessary? Hence the interest in whether conceivability entails possibility. Kripke attacks the idea of contingent identity, pointing towards necessity, and away from zombies.