 Conditional analysis. Another line of objection rests on conditional analyses of the concept of qualia. Roughly, the idea is that if there actually are certain nonphysical properties which fit our conception of qualia, then that is what qualia are, in which case zombies are conceivable; but if there are no such nonphysical properties, then qualia are whichever physical properties perform the appropriate functions, and zombies are not conceivable. It is argued that this approach enables physicalists to accept that the possibility of zombies is conceivable, while denying that zombies are conceivable (Hawthorne 2002a; Braddon-Mitchell 2003. See Stalnaker 2002 for a related point, and for criticism, Alter 2007; Chalmers 2010, pp. 159–59; Crane 2006).