Courtesy of Steven Novella over at his very good blog:
As I have discussed many times before, the totality of neuroscientific evidence strongly supports the conclusion that consciousness is a phenomenon of brain function. Dualist philosophies, those that posit that consciousness is anything other than or in addition to brain function, are simply trumped by the scientific evidence.
He has discussed this many times before, and, just like the other times, he is mistaken (and, just like the other times, it’s impossible to create an account to comment on his blog aasdjkfa;dkjf). The problem of phenomenal consciousness is that our brain activity is accompanied by subjective experience – there is something it is like to be a human being. One answer is that there are two different substances at work, a mental substance and a material substance. This is dualism.
A dualist examines the phenomenon that we are trying to explain, subjective experience, and notes that consciousness has certain properties: intentionality (it is about something), private accesss, and a qualitative aspect to name a few. This seems hard to deny. When the dualist compares these properties to the sorts that are present among physical, mechanical things – of which the brain is one – she finds them to be radically different: physical things are publicly accessible, do not have any qualitative aspect, and are certainly not about anything (see my post on why ’emergence’ is not an answer for the materialist). She then concludes that two different sorts of properties means two different substances – if consciousness has properties that physical things do not then consciousness cannot be physical. Dualism has its problems, especially regarding mental causation, but that is beside the point here. The question to ask is which, if any, scientific advancement could refute the dualist?
Non-philosophers will point to the fact that taking drugs, damaging the brain, stimulating certain regions of the brain, etc will directly and predictably impact the conscious experience, and they will try to say that this makes dualism false. But this is just plain silly: the dualist happily accepts all of these phenomenon. To say that these shared scientific facts make materialism true and dualism false is just plain question begging. The argument against dualism has to involve something more (ie the problem of mental causation) and the materialist does in fact recognize this.
The assumption here is that because all of these physical changes so dramatically and consistently affect conscious experience that there is no reason to add a second substance to our ontology – it’s just plain excessive, does no work, or is just plain wishing for a soul. If the physical facts explain the entire phenomenon then it would be ridiculous to posit the existence of a second substance. If. There is as a matter of fact, however, good reason to doubt that materialism is sufficient to account for conscious experience, and materialist philosophers admit to this just as much as dualists/idealists/panpsychists/anomalous monists/etc; these arguments are a substantial obstacle that the materialist has to overcome – substantial enough that people like Dennett (disclaimer: post is under construction) are eliminativists about consciousness (they admit experiences and consciousness exist, but they use the terms in a completely different way; saying they deny consciousness is a fair statement).
Examples would be knowledge arguments, conceivability arguments, arguments from unity (consciousness is simple, matter is composite), and so on. Materialists require a metaphysically necessary connection between the physical facts and the phenomenal facts, and it is not clear how such a connection could exist. This is not to say materialism is wrong (I flop between that and panpsychism depending on my mood) but that showing we should accept the materialist position, and therefore reject dualism and friends, is not a scientific problem. The Hard Problem is about the limits of science in principle, not the limits of our current scientific knowledge.
Maybe I’ll figure out how to comment over at his highly recommended Neurologica Blog eventually.