Over at the always thought-provoking Unequally Yoked, Leah recently wrote a series of posts on the mind-body problem and the unending argument between dualism and monism. This is a rich subject, philosophically and scientifically. Many philosophers, natural, analytic, or otherwise, have argued passionately that either substance dualism or monism is a bogus way of thinking about the world for thousands of years. Adding my voice to the chorus will do little shape the tide's direction, but like many of my predecessors, I'm fascinated by the arguments about the ultimate nature of reality posed by this line of metaphysics. Since most of my training on this subject comes from wikipedia, Philosophy Club meetings, and Douglas Hofstadter books, the usual bromide to take the following with a humble grain of salt is advised.
The argument for materialistic monism is so ubiquitous today I sometimes wonder if it's even possible to be taken seriously as a neuroscientist without renouncing the idea that mind, thought, sensation, or emotion exist in any manner separate from the physical brain states that correspond to these mental states. The idea that mind exists apart from a material universe, or that mental images and sequences are more fundamental to reality than matter is clearly down for the count in modern discourse on the mind-body problem. I don't want to dwell on the arguments for materialism too long, but my Cliff's Notes understanding of the philosophy goes something like this:
1) As scientific understanding of the brain advances, many mental states such as sensation and emotion seem to have strong correlations with quantifiable brain states.
2) It is reasonable to assume that as this scientific understanding advances, these correlations will be better understood and more complete.
3) If mental states can be fully explained through brain states, mental states are unnecessary to an understanding of mind.
4) Since mental states seem to have a one-to-one correspondence with brain states, ignoring the mental states completely is a better, more efficient, hypothesis in explaining mind/brain activity.
The road from part (4) to materialism and a rejection of consciousness as an illusion is straightforward enough. I've seen the case laid out plainly and passionately a number of times, and it's a tempting line of thought to follow. I'm pretty sure that it's wrong.
There's a fundamental mischaracterization that goes on here that's subtle but poisonous for the chain of thought. To put it briefly, the argument that since mental states correspond to physical states there is no explanatory power to mental states seems to me to be a non-sequitur. Typical arguments in favor of materialism glorify the property of emergence, that a collection of any entity can have radically different properties that don't exist for each individual entity. Fair enough. Individual water molecules don't have wetness, or pressure, or viscosity, although a trillion water molecules acting in concert certainly do. But the existence of a subjective experience of consciousness, of the bubbling flow of sensation and thought and the feelings of emotion, is such a fundamentally different thing from the aconscious interactions of matter that any theory that attempts to explain this sensation in terms of material interactions fails to grasp anything at all about what we're really interested in. I don't call that a good explanation.
Sometimes I wonder if I simply don't understand what the philosophers like Blackmore, Dennett, and Hofstadter really think, when the theories they posit seem so opposed to the reality I experience. I freely admit that consciousness could be, in some sense, a grand delusion, although I still have no idea what that would even entail. Last semester I discovered the writings of David Chalmers (video below), and I can't convey how relieved I was to see that there was someone in that great shouting chamber who seemed to be shouting at about the same pitch and timbre as me. Not feeling deluded is a wonderful feeling indeed.