fe could be explained by appeal to chemistry and minute particles rather than some miraculous vital spirits or other such substance. However, it appears likely that modern science will succeed in explaining life without appealing to any mysterious concepts such as souls or vital fluid, and we will be able to offer a reductive explanation of life in terms which do not make any reference to life. Materialists believe that someday we'll be able to do the same thing with consciousness, whereas Chalmers does not feel this will ever be possible. In Chapters 2 and 4, Chalmers explicitly argues against materialist responses of this sort. For this reason I view these sections as the most important sections of his book. Chalmers must rule out the above materialist response to the possibility of zombies if his theory is to be preferred. If he is successful in ruling out the metaphysical identity move, then I think many philosophers would agree that the dualistic theory he later develops follows from the available evidence. But Chalmers does not provide a convincing argument that the notion of metaphysical identity is unable to save materialism, and for this reason he fails to establish his own theory as a stronger alternative to materialism. In arguing against the materialist's metaphysical identity maneuver, Chalmers makes use of a distinction between primary and secondary intensions. An intension is something like the meaning or reference of a concept. The primary intension of a concept picks out whatever object or substance that concept refers to in the possible world that one is in. This idea is easier understood with an example such as water. The concept WATER refers to the clear, tasteless, drinkable liquid which is found in rivers, lakes, and oceans. This primary intension does not explain what the chemical composition of the stuff in the oceans happens to be. If it turned out that there was XYZ in the ocean, then the term 'water' would ref...
