In addition to already discussed theories of dualism (particularly the Christian and Cartesian models) there are new theories in the defense of dualism. Naturalistic dualism comes from Australian philosopher, David Chalmers (born 1966) who argues there is an explanatory gap between objective and subjective experience that cannot be bridged by reductionism because consciousness is, at least, logically autonomous of the physical properties upon which it supervenes. According to Chalmers, a naturalistic account of property dualism requires a new fundamental category of properties described by new laws of supervenience; the challenge being analogous to that of understanding electricity based on the mechanistic and Newtonian models of materialism prior to Maxwell's equations.