Multisense Realism

The argument for my view is an inference from roughly four premises:

(1) Conscious experience exists.

(2) Conscious experience is not logically supervenient on the physical.

(3) If there are positive facts that are not logically supervenient on the physical facts, then physicalism is false.

(4) The physical domain is causally closed.

(1), (2), and (3) clearly imply the falsity of physicalism. This, taken in conjunction with

(4) and the plausible assumption that physically identical beings will have identical conscious experiences, implies the view that I have called natural supervenience: conscious experience arises from the physical according to some laws of nature, but is not itself physical.

The various alternative positions can be catalogued according to whether they deny (1), (2), (3), or (4). Of course some of these premises can be denied in more than one way.

Denying (1):

(i) Eliminativism. On this view, there are no facts about conscious experience. Nobody is conscious in the phenomenal sense.

Denying (2):

Premise (2) can be denied in various ways, depending on how the entailment in question proceeds—that is, depending on what sort of physical properties are centrally responsible for entailing consciousness. I call all of these views “reductive physicalist” views, because they suppose an analysis of the notion of consciousness that is compatible with reductive explanation.

(ii) Reductive functionalism. This view takes consciousness to be entailed by physical states in virtue of their functional properties, or their causal roles. On this view, what it means for a state to be conscious is for it to play a certain causal role. In a world physically identical to ours, all the relevant causal roles would be played, and therefore the conscious states would all be the same. The zombie world is therefore logically impossible.

(iii) Nonfunctionalist reductive physicalism. On this view, the facts about consciousness are entailed by some physical facts in virtue of their satisfaction of some nonfunctional property. Possible candidates might include biochemical and quantum properties, or properties yet to be determined.

(iv) Holding out for new physics. According to this view, we have no current idea of how physical facts could explain consciousness, but that is because our current conception of physical facts is too narrow. When one argues that a zombie world is logically possible, one is really arguing that all the fields and particles interacting in the space-time manifold, postulated by current physics, could exist in the absence of consciousness. But with a new physics, things might be different. The entities in a radically different theoretical framework might be sufficient to entail and explain consciousness.

Denying (3):

(v) Nonreductive physicalism. This is the view that although there may be no logical entailment from the physical facts to the facts about consciousness, and therefore no reductive explanation of consciousness, consciousness just is physical. The physical facts “metaphysically necessitate” the facts about consciousness. Even though the idea of a zombie world is quite coherent, such a world is metaphysically impossible.

Denying (4):

(vi) Interactionist dualism. This view accepts that consciousness is non-physical, but denies that the physical world is causally closed, so that consciousness can play an autonomous causal role.

Then there is my view, which accepts (1), (2), (3), and (4):

(vii) Property dualism. Consciousness supervenes naturally on the physical, without supervening logically or “metaphysically”.

There is also an eighth common view, which is generally underspecified:

(viii) Don’t-have-a-clue physicalism: “I don’t have a clue about consciousness. It seems utterly mysterious to me. But it must be physical, as physicalism must be true.” Such a view is held widely, but rarely in print (although see Fodor 1992).

To quickly summarize the situation as I see it: (i) seems to be manifestly false; (ii) and (iii) rely on false analyses of the notion of consciousness, and therefore change the subject; (iv) and (vi) place large and implausible bets on the way that physics will turn out, and also have fatal conceptual problems; and (vi) either makes an invalid appeal to Kripkean a posteriori necessity, or relies on a bizarre metaphysics. I have a certain amount of sympathy with (viii), but it presumably must eventually reduce to some more specific view, and none of these seem to work. This leaves (vii) as the only tenable option.

—David Chalmers, The Conscious Mind

My view would require an extra option in between vi and vii –

(vi.5) Oroborean monism. Physics supervenes reflexively on its own (proposed) capacities to experience. Interaction is not logical but self-evident, with multivalent causation to and from private intention and public extension as ordinary sensory-motor participation.