“I think the existence of zombies would contradict certain laws of nature in our world. It seems to be a law of nature, in our world, that when you get a brain of a certain character you get consciousness going along with it.” –David Chalmers
I’m fascinated by the philosophy of mind. I find thinking about, and attempting to make sense of human consciousness, to be a lot of fun.
In the history of Western thought there are sort of three big theories regarding how the mind and body relate: dualism, materialism, and idealism. There are a plethora of permutations of each of these theories, and it would be a folly to claim that any of them are completely right or completely wrong since, at the end of the day, most folks would agree that consciousness is a big darn mystery. However, I personally would feel safe claiming that each of these big theories have fatal flaws which prevent me from holding too closely to any of them (I prefer a process-relational panexperientialism myself).
In the Western world, during the middle ages, dualism came online as the most prominent model or reality. This Cartesian vision of reality divided the world up into neat and tidy subjective and objective realities; the mind (or interior/subjective) was thought to be substantive, infinite, and eternal, while the body (or exterior/objective) was mechanical, finite, and temporary. This vision of reality lasted over two centuries and eventually gave way to the Modern era which brought with it the model that many still hold to today: materialism. This vision of reality prizes the objective and treats the mind (or subjective) as a secondary, illusory appearance that merely pops out of the objective at some point in time.
In the above quote, David Chalmers is describing his famous zombie problem which is meant to be a challenge to materialist notions of reality/consciousness. I happen to like it very much.
To set this thought experiment up, think of physicalism (which is a form of materialism). A physicalist would like to posit that all forms and aspects of human nature can be explained by physical means: specifically, all aspects of human nature and perception can be explained from a neurobiological standpoint. In other words, consciousness obviously has something to do with the brain, therefore, consciousness can be found by looking in the skull.
Now, think of a flower turning toward the sun. Someone like me would interpret this as the plant (or perhaps more accurately, all the organisms making up the plant) having the experience (not necessarily a unified one like those of humans) of feeling sunlight and purposefully turning toward it. A physicalist/materialist would balk at this notion and insist that the flower is merely responding to external stimuli and behaving in a purely mechanistic way. There is no intrinsic purpose to be had.
This is where Chalmers’ zombie problem could be applied.
We might ask, if plants don’t have sentience and are merely responding in a purely mechanical way to external stimulants, then why can’t humans be thought of in the same way? In other words, why do humans have awareness when the body could seemingly do everything necessary to survive unconsciously, like plants? From a purely hardcore materialist/physicalist perspective, there is no reason why humans should be self-aware. Humans should be zombies.