Let me try to explain those words, as they are very important for the zombie-argument to makes sense.
“Metaphysical” when talking about “metaphysical necessity” (or possibility), means that some claim is true, not because it happens to be a fact in this world, but that it is contradictory for it to be otherwise. An example would be e.g. that it is metaphysically necessary that if you have one and one more apple, you have two apples. So, when we talk about this kind of metaphysical necessities, we can have as examples truths from logic, mathematics, conceptual necessities (e.g. if we define bachelor as an unmarried male, it would be contradictory to claim that some bachelor is not male), etc… Because metaphysical truths are supposed to be true independent of the how the world happens to be, you don’t need to know any particular fact from the everyday experience in order to know them, so their knowledge is independent from knowledge gained from particular experience, and that is what that other term—A PRIORI means.
The physicalist claim is now, that the facts about there being consciousness and exactly what consciousness it is, are metaphysically necessary given the physical facts about the same system. So, basically one claims that facts about consciousness follow (as in logic/math etc..) from physical facts (a priori). So, for physicalism the truth about consciousness relation to physical IS of the same nature as the nature of math truths, i.e. independent of the way the world happens to be.
Sorry Dan,
Let me try to explain those words, as they are very important for the zombie-argument to makes sense.
“Metaphysical” when talking about “metaphysical necessity” (or possibility), means that some claim is true, not because it happens to be a fact in this world, but that it is contradictory for it to be otherwise. An example would be e.g. that it is metaphysically necessary that if you have one and one more apple, you have two apples. So, when we talk about this kind of metaphysical necessities, we can have as examples truths from logic, mathematics, conceptual necessities (e.g. if we define bachelor as an unmarried male, it would be contradictory to claim that some bachelor is not male), etc… Because metaphysical truths are supposed to be true independent of the how the world happens to be, you don’t need to know any particular fact from the everyday experience in order to know them, so their knowledge is independent from knowledge gained from particular experience, and that is what that other term—A PRIORI means.
The physicalist claim is now, that the facts about there being consciousness and exactly what consciousness it is, are metaphysically necessary given the physical facts about the same system. So, basically one claims that facts about consciousness follow (as in logic/math etc..) from physical facts (a priori). So, for physicalism the truth about consciousness relation to physical IS of the same nature as the nature of math truths, i.e. independent of the way the world happens to be.
Hope this helps.