VR: Because physically identical worlds can have different mental contents in them, and in a physical world identical to this one there are no one with any mental states at all. In that world, everyone is a zombie.
Zilch: Victor, do you have any evidence for this? Unless you can demonstrate that mental contents are not physical states, you are begging the question.
VR: Because, no amount of physical information can entail any definitive conclusion concerning mental content. This is the point of arch-naturalist W. V. Quine's argument for the indeterminacy of translation in Word and Object. Physical facts do not logically entail mental facts, just as physical facts do not logically entail moral facts. Getting an "about" from an "is" is just as impossible as getting an "ought" from an is, and for much the same reason. Even if mental states were token-identical to brain states, the brain facts do not and cannot entail the mental facts. So why do the mental facts exist?
Shygetz: Let's assume that a sense of purpose can possibly be couched in matter, and see if our observations are consistent with such an assumption. If such a sense could be arrived at by incremental change in a reproductive element, and if such a sense would increase reproductive success, then such a purpose would be arrived at through evolutionary processes. When we look at the evolutionary record, we see gradual increases in mental sophistication, which seem to correlate with increases in consciousness (e.g. the most mentally sophisticated non-human animals are also the ones with the most signs of consciousness). Were duality true, then there is no obvious reason for physical brain sophistication to correlate with cosciousness.
VR: Evolution can explain the development of mental states only if mental contents can play a causal role. If mental contents are epiphenomenal, then they are invisible to evolution. If the physical is causally closed, and physical states are insufficient to determine mental contents, that means that mental contents are epiphenomenal. It doesn't matter what they are or whether they exist or not. The physical will go its merry way regardless of them, and evolution, if it is purely physicalistic, will select for the physical substrate regardless of what the mental content is. Therefore the argument that reliable belief-forming mechanisms will be selected for by evolution goes by the boards.
Shygetz: Does consciousness increase fitness? Well, we are reproductively succeeding much more than our closest primate cousins that posess less consciousness, so I would say probably. So, it seems plausible that consciousness would evolve if it were couched in physical matter.
VR: This is considered to be a huge problem, however, which David Chalmers calls the Hard Problem of Consciousness. How can consciousness be physical. Plenty of people, like Chalmers, Colin McGinn, and even Jaegwon Kim, think that this is a complete mystery from the point of view of naturalism.
VR: You have not demonstrated that such a world is possible given the laws of the universe, and until you do you merely beg the question. The philosophical zombie is an impossibility if mental states are couched in physical states, and to simply argue that you can conceive otherwise is pointless. I can conceive of gravity being a repulsive force, but that doesn't demonstrate that gravity is not an attractive force.
VR: What do you mean by "couched in " physical states. Do you mean type-identical to physical states, or token-identical states, or supervenient upon physical states. I can conceive of a philosophical zombie without contradicting myself. If it isn't a self-contradictory idea, then it's logically possible, and we need to know why it is not the case.
Shygetz: If you are driven to postulate God, then you have just failed at science. God explains everything, and therefore nothing; it cannot be tested or disproven, and is worthless as an explanitory unit. God cannot be tested by science because it is not a coherent idea--it changes with the whim of the faithful to always remain a step away from the edges of science.
VR: One can conceive God in such a way that one can make testable theistic hypotheses. Lots of people say that theistic claims are untestable, but no one ever proves it. There are circumstances under which I would predict a miracle. And how about this "If God were to resurrect someone today, it would be more likely to be Mother Teresa than Adolf Hitler." That's a probabilistic expectation. If God resurrects Hitler, that disconfirms my theory.
Labels: The Argument from Reason