Double-aspect theory

In the philosophy of mind, double-aspect theory is the view that the mental and the physical are two aspects of the same substance. The theory's relationship to neutral monism is ill-defined, but one proffered distinction says that whereas neutral monism allows the context of a given group of neutral elements to determine whether the group is mental, physical, both, or neither, double-aspect theory requires the mental and the physical to be inseparable and irreducible (though distinct). Notable double-aspect theorists include Baruch Spinoza, Gustav Fechner, Arthur Schopenhauer, George Henry Lewes, and Thomas Nagel. David Chalmers explores a double-aspect view of information.

The Scientist-theologian John Polkinghorne argues for "dual aspect monism" "there is only one stuff in the world (not two - the material and the mental) but it can occur in two contrasting states (material and mental phases, a physicist might say) which explain our perception of the difference between mind and matter"