 where a minimal physical duplicate is what results from duplicating all the physical facts and “stopping right there.” And David Chalmers says that physicalism is true in a world w just in case every positive fact that obtains in w also obtains in any world physically indiscernible from w (1996, 39–40). Each of these three definitions allows for a world in which the same physical facts obtain as obtain here in our world, but in which some extra non-physical facts obtain as well.