ctures and their movements. However, there is another sense of reduction which does not appeal to the notion of explanation, it appeals to how our world turns out. The possible materialist response to Chalmers' argument not only offers a viable alternative to property dualism, but also avoids the most counter-intuitive consequence of property dualism. This response involves acknowledging that zombies are logically possible and falling back on the claim that zombies are still metaphysically impossible. The article "On Leaving Out What It's Like" by Joseph Levine(3) illustrates why a materialist need not give up hope due to Chalmers' arguments. Levine contends that arguments based upon what is conceivable (e.g., the logical possibility of zombies) only establish epistemic conclusions rather than metaphysical conclusions. Merely being able to conceive of a zombie does not yet prove that a zombie could really exist, only that we can imagine that one could exist. Levine argues that an additional step is required to get from such an epistemic conclusion to the metaphysical conclusion which an anti-physicalist needs to refute materialism (i.e., the conclusion that a zombie could exist). Levine's objection to philosophers like Chalmers can be seen as the questions: Why should what is conceivable constrain how our universe really turns out? Just because we can conceive of a zombie, why should that limit how consciousness is instantiated? Or perhaps better: Just because we can't conceive of how consciousness could be a physical phenomenon, why should that mean that it can't be a physical phenomenon? Levine calls our current inability to reduce mental phenomena like consciousness to physical processes an explanatory gap, but he argues that the existence of an explanatory gap does not constrain how the metaphysics of our universe will turn out. The concept of metaphysical identity, when applied to consciousness, can be understood to show that consc...
