David Chalmers provides an alternative to the more radical dualism of Descartes. He is known for the clear explication of the “hard problem” of consciousness, that being examining the question of why physical substrates [such as a brain] would give rise to subjective conscious experience [mind]. He suggests that the physical is necessary for conscious experience, but that the presence of consciousness is an emergent property that is of a higher level than the physical and, additionally, at least to some degree independent of it.
The famous thought experiment he devised to argue this perspective was that of a particular type of Zombie. These special Zombie creatures are exactly like you or I, and their behavior would be indistinguishable from ours. However, these Zombies lack one quality which we each possess: they lack all ability to actually experience anything, [which is termed qualia, the qualitative aspect of interacting with the world]. The Zombie acts just as a person would, but has no internal experience of pain, joy, love, beauty, or anything else.
Could such a Zombie exist, even in theory? Why or why not? If you think so, then you find some dualist perspectives persuasive. If not, you are clearly in the physicalist monist camp. If you’re in this latter category, then an additional question to ponder is: if a Zombie has no experience of qualia what leads it to act?
An interesting consequence of Chalmer’s theory is that any system which reaches adequate levels of complexity would cause an emergent quality of consciousness: including thermostats, computer programs, nations, etc. His theory is also consistent with a pan-psychic philosophy, although that is not the direction he argues to consider questions of consciousness. Pan-psychism will, interestingly, be quite compatible with several other theories to be discussed.