The difference between our views is that he thinks the reduction is logically necessary; that there is no sense to be made of the idea of a ‘zombie’ world physically identical to ours but lacking consciousness. I think that’s plainly false. There’s nothing incoherent about the idea of zombies. So the admitted link between the physical and phenomenal facts is merely contingent (taking the form of a natural law, rather than a reductive analysis).
“Plainly false?” You mean you can imagine a world identical to ours but lacking ‘consciousness’, therefore, it is logically possible? But logical possibility does not follow from conceptual possibility. You may simply have not yet proved the tautology
|- Inside(x, Hand) → Inside(x, Fingers)
which you would need to see that your conceptual imagining is logically impossible.
I don’t know whether 577 is prime, so it is conceptually possible to me that it is prime or composite, but only one of these two alternatives is logically possible. I can conceive that 577 is prime, or alternatively, that it is not prime, and yet 577+2 = 579 either way; but this does not imply that the primeness of 577 is a detachable property that floats around independently of its arithmetical behavior. It just means I don’t know.
This is the fundamental Mind Projection Fallacy I think you are committing in passing from “I can imagine zombies” to “Zombies are logically possible” to “The ‘bridging laws’ that imply consciousness are contingent physical facts rather than logical implications.”
Indeed, the whole notion of a “bridging law” consists of committing the Mind Projection Fallacy with respect to theorems like
|- Inside(x, Brain) → Inside(x, Mind)
and supposing that they describe physical causation, something that happens out there in the world, rather than knowledge deductions. The rule that states that a hand is present when fingers+palm+thumb are present, is not a physical cause, or a contingent bridging law, but a consequence of the definitions of the discovered referents of “hand” and “fingers+palm+thumb”. You don’t know the definition of the undiscovered referent of “consciousness” so you can’t see the logical identity, but it is there—this is what a reductionist believes.
Unknown, Dan has described very well the difference between “A bridging law did it!” and Conservation of Energy.
Sez Richard:
“Plainly false?” You mean you can imagine a world identical to ours but lacking ‘consciousness’, therefore, it is logically possible? But logical possibility does not follow from conceptual possibility. You may simply have not yet proved the tautology
|- Inside(x, Hand) → Inside(x, Fingers)
which you would need to see that your conceptual imagining is logically impossible.
I don’t know whether 577 is prime, so it is conceptually possible to me that it is prime or composite, but only one of these two alternatives is logically possible. I can conceive that 577 is prime, or alternatively, that it is not prime, and yet 577+2 = 579 either way; but this does not imply that the primeness of 577 is a detachable property that floats around independently of its arithmetical behavior. It just means I don’t know.
This is the fundamental Mind Projection Fallacy I think you are committing in passing from “I can imagine zombies” to “Zombies are logically possible” to “The ‘bridging laws’ that imply consciousness are contingent physical facts rather than logical implications.”
Indeed, the whole notion of a “bridging law” consists of committing the Mind Projection Fallacy with respect to theorems like
|- Inside(x, Brain) → Inside(x, Mind)
and supposing that they describe physical causation, something that happens out there in the world, rather than knowledge deductions. The rule that states that a hand is present when fingers+palm+thumb are present, is not a physical cause, or a contingent bridging law, but a consequence of the definitions of the discovered referents of “hand” and “fingers+palm+thumb”. You don’t know the definition of the undiscovered referent of “consciousness” so you can’t see the logical identity, but it is there—this is what a reductionist believes.
Unknown, Dan has described very well the difference between “A bridging law did it!” and Conservation of Energy.